docs: mark connection badge field-verified (2-machine call 2026-07-08)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: CI
+
+# Runs on the self-hosted host-mode runner on the desktop (label `arch`). The
+# gitbutter VPS only queues the job; all compile/test compute happens locally.
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  check:
+    runs-on: arch
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Toolchain versions
+        run: |
+          rustc --version
+          cargo --version
+          cargo clippy --version
+          cargo deny --version
+          cargo audit --version
+
+      - name: Format check
+        run: cargo fmt --all -- --check
+
+      - name: Clippy (all targets, warnings as errors)
+        run: cargo clippy --all-targets -- -D warnings
+
+      - name: Tests
+        run: cargo test --all-targets
+
+      - name: Doc tests
+        run: cargo test --doc
+
+      - name: cargo-deny (advisories, bans, licenses, sources)
+        run: cargo deny check
+
+      - name: cargo-audit
+        run: cargo audit

CHANGELOG.md

@@ -2,7 +2,19 @@
 
 All notable changes to PeerSpeak are documented here.
 
-## [Unreleased]
+## [0.6.3] — 2026-07-06
+
+### Added
+- **In-app screen-sharing controls.** A new **Screen sharing** section in Settings, plus a per-call **quality picker** on the Share control, put the whole share pipeline under your control without editing config files. Encode side: quality preset, bitrate, framerate, maximum resolution, maximum viewers, a force-software-encode switch, and an escape hatch for extra pixelpass arguments. Playback side: choose **mpv or VLC**, toggle **hardware decoding**, pick a buffering posture (low-latency vs. smooth), set the demuxer cache, and pass extra mpv arguments. Everything is stored locally in your config and defaults are unchanged, so existing setups keep working as-is.
+
+### Fixed
+- **Shared video no longer freezes on the first frame while audio keeps playing.** Hardware decoding now defaults **off**; forcing `--hwdec=auto` stalled some viewers' hardware decoder on frame 1. You can re-enable hardware decoding from the new Screen sharing settings if your machine handles it well.
+- **The per-call quality picker is now honored.** The inline quality dropdown next to the Share button was being reset to the saved default before a share started, so every share silently used the default quality regardless of what you picked.
+- **VLC now respects your playback settings.** VLC hardware-decodes by default, so a VLC viewer previously ignored the hardware-decode toggle (and could hit the same frame-1 freeze) and the buffering posture. VLC viewers now map both settings onto VLC's own options.
+
+[0.6.3]: https://gitbutter.xyz/mollusk/peerspeak/releases/tag/v0.6.3
+
+## [0.6.2] — 2026-07-03
 
 ### Fixed
 - **Friends list now reflects status changes without a restart.** A presence probe that fails now actively marks the friend **offline**, so a friend who goes offline, leaves a room, or turns invisible no longer lingers showing a stale "online" / "in a room" status until PeerSpeak is relaunched. Previously only successful probes updated the list, so it could ratchet a friend's status up but never down. The auto-refresh interval was also shortened from 60s to **15s** so the list tracks changes more closely.
@@ -13,6 +25,8 @@ All notable changes to PeerSpeak are documented here.
 ### Licensing
 - **PeerSpeak is now released under the MIT License** (previously an unlicensed private build). Added a `LICENSE` file and a `THIRD_PARTY_LICENSES` file enumerating the full dependency manifest plus the canonical text of every referenced license, with notices for the statically bundled Opus codec and the embedded fonts (Iced-Icons, Cantarell/OFL-1.1). Both files ship in the Arch and Debian packages.
 
+[0.6.2]: https://gitbutter.xyz/mollusk/peerspeak/releases/tag/v0.6.2
+
 ## [0.6.0] — 2026-06-28
 
 ### Added

Cargo.lock

@@ -200,9 +200,9 @@ checksum = "940b3a0ca603d1eade50a4846a2afffd5ef57a9feac2c0e2ec2e14f9ead76000"
 
 [[package]]
 name = "anyhow"
-version = "1.0.102"
+version = "1.0.103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
+checksum = "2a4385e2e34eb35d6b3efe798b9eb88096925d87726c0798709bf56d9ed84af3"
 
 [[package]]
 name = "arbitrary"
@@ -3682,9 +3682,9 @@ checksum = "6b947ae49db0d222b1dbc6b113ce7248a3fc3a6ca21b696717bfc000ba4484d8"
 
 [[package]]
 name = "memmap2"
-version = "0.9.10"
+version = "0.9.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "714098028fe011992e1c3962653c96b2d578c4b4bce9036e15ff220319b1e0e3"
+checksum = "d1219ed1b7f229ee7104d281dd01d6802fe28bb6e95d292942c4daacdeb798c0"
 dependencies = [
  "libc",
 ]
@@ -4871,7 +4871,7 @@ checksum = "35fb2e5f958ec131621fdd531e9fc186ed768cbe395337403ae56c17a74c68ec"
 
 [[package]]
 name = "peerspeak"
-version = "0.6.0"
+version = "0.6.3"
 dependencies = [
  "anyhow",
  "async-trait",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "peerspeak"
-version = "0.6.0"
+version = "0.6.3"
 edition = "2024"
 description = "Decentralized peer-to-peer voice chat (Rust/iroh/PipeWire/Opus/iced)"
 license = "MIT"

build.rs

@@ -0,0 +1,22 @@
+use std::process::Command;
+
+fn main() {
+    println!("cargo:rerun-if-changed=.git/HEAD");
+    if let Ok(head) = std::fs::read_to_string(".git/HEAD")
+        && let Some(reference) = head.strip_prefix("ref: ")
+    {
+        println!("cargo:rerun-if-changed=.git/{}", reference.trim());
+    }
+
+    let short = Command::new("git")
+        .args(["rev-parse", "--short=8", "HEAD"])
+        .output()
+        .ok()
+        .filter(|output| output.status.success())
+        .and_then(|output| String::from_utf8(output.stdout).ok())
+        .map(|value| value.trim().to_string())
+        .filter(|value| !value.is_empty())
+        .unwrap_or_else(|| "unknown".to_string());
+
+    println!("cargo:rustc-env=PEERSPEAK_GIT_SHORT={short}");
+}

docs/FEATURES.md

@@ -102,6 +102,7 @@ covers internals). When you ship a feature, add it here.
 | iroh QUIC transport | ✅ | |
 | Network mode picker | ✅ | `RelayNoDiscovery` (default), `N0Full`, `DirectOnly`. Takes effect next join. |
 | Retained-address reconnect | ✅ | Dials last-known full addr before falling back to bare id. |
+| Per-peer connection badge (direct/relay + RTT, hover for addr/loss/bitrate) | ✅ | Peer-card badge fed by a 1 Hz poll of the live audio link's selected QUIC path (`connection_stats` → `core::connstats::derive`). Field-verified on a real 2-machine call 2026-07-08. |
 | Reconnect + eviction model | ✅ | Incl. two-outage reconnect-eviction fix + regression test. |
 | Self-hosted relay | ❌ | Decided against — rely on n0 relays, `RelayNoDiscovery` default. |
 

docs/WINDOWS.md

@@ -1,19 +1,28 @@
 # PeerSpeak on Windows
 
-Current status: the Windows port cross-compiles to `x86_64-pc-windows-gnu` and the `.exe`
-launches under Wine. A real Windows/WASAPI host is still needed for the final audio-device
-checks listed below.
+Current status: PeerSpeak cross-compiles to `x86_64-pc-windows-gnu` from Linux and
+has passed an older native Windows 11 VM smoke test for launch, GUI render, call
+join, and audio flow. The build environment is **not** the Windows VM; current
+Windows binaries are built from Linux, normally inside the `peerspeak-win`
+distrobox or with the same GNU target environment.
+
+The Windows runtime still trails Linux in a few important areas. See the Claude
+handoff file `windows-parity-audit.md` for the full audit and task breakdown.
 
 ## What works today
 
 | Area | Status |
 |---|---|
-| GUI | Iced/wgpu builds and renders under Wine. |
-| Networking | Iroh QUIC transport and gossip compile on Windows. |
+| GUI | Iced/wgpu builds for Windows and rendered in the Windows 11 VM. |
+| Networking | Iroh QUIC transport and gossip compile on Windows; VM call reached two peers. |
 | Audio backend | `cpal` drives WASAPI capture/playback behind `AudioBackend`. |
+| Device selection | cpal enumerates input/output devices; see caveat below about stable IDs. |
+| Resampling/remap | WASAPI devices can run non-48 kHz formats; PeerSpeak converts at the backend boundary. |
 | Codec | Opus remains 48 kHz mono, 20 ms frames. |
-| Identity | `ring` identity generation/load is platform-neutral. |
+| Identity/config | Stored through `dirs` under the Windows profile. |
 | Chimes | Windows uses PowerShell `System.Media.SoundPlayer` for WAV playback. |
+| Game detection | Steam registry `RunningAppID` plus Toolhelp process-scan fallback compile on Windows. |
+| File dialogs | `rfd` uses the native Win32 dialog backend. |
 
 Windows paths are resolved through `dirs`:
 
@@ -23,55 +32,72 @@ Windows paths are resolved through `dirs`:
 
 ## Building
 
-### Native Windows
+### Cross-compile from Linux
 
-Install MSVC Build Tools and CMake, then build normally:
+Preferred local path:
 
-```powershell
-cargo build --release
+```sh
+distrobox enter peerspeak-win -- bash -lc '
+  cd ~/git/butter/peerspeak &&
+  RUSTC_BOOTSTRAP=1 ./win-cross-build.sh -Z build-std=std,panic_abort
+'
 ```
 
-If CMake is 4.x or newer, the vendored `opus`/`libopus` build may need:
+Equivalent direct command when the host has the GNU target, MinGW, `rust-src`, and
+CMake available:
+
+```sh
+CMAKE_POLICY_VERSION_MINIMUM=3.5 RUSTC_BOOTSTRAP=1 \
+  cargo build --release --target x86_64-pc-windows-gnu --bin peerspeak \
+  -Z build-std=std,panic_abort
+```
+
+`CMAKE_POLICY_VERSION_MINIMUM=3.5` is required with host CMake 4.x because the
+vendored Opus build used by `audiopus_sys` still declares an old minimum CMake
+version. Without that env var, the Windows build/check fails during Opus configure.
+
+### Native Windows
+
+A native MSVC build is not the active development path. If used, install MSVC Build
+Tools and CMake, then build normally:
 
 ```powershell
 $env:CMAKE_POLICY_VERSION_MINIMUM = "3.5"
 cargo build --release
 ```
 
-### Cross-compile from Linux
-
-The current dev path cross-compiles from an Arch environment to the GNU Windows target:
-
-```sh
-rustup target add x86_64-pc-windows-gnu
-sudo pacman -S mingw-w64-gcc cmake
-CMAKE_POLICY_VERSION_MINIMUM=3.5 cargo build --release --target x86_64-pc-windows-gnu --bin peerspeak
-```
-
-Wine is useful for launch/render smoke tests, but it is not a substitute for a real
-Windows audio-device pass. The deeper migration plan (phases, decisions, the opus build
-spike) lives in the maintainer's handoff docs, outside the repo.
-
 ## First run and networking
 
-Expect a Windows Firewall prompt the first time the app opens network sockets. Allow it:
-PeerSpeak uses UDP for QUIC, plus relay traffic when direct NAT traversal is not available.
+Expect a Windows Firewall prompt the first time the app opens network sockets, or
+use the Inno installer option that pre-adds a firewall allow rule. PeerSpeak uses
+UDP for QUIC plus relay traffic when direct NAT traversal is unavailable.
 
-The default network mode keeps the n0 relay available for NAT traversal without publishing
-presence to n0 DNS. Direct peer-to-peer paths may work when both networks allow them; relayed
-connections are expected and valid.
+The default network mode keeps the n0 relay available for NAT traversal without
+publishing presence to n0 DNS. Relayed connections are expected and valid.
 
 ## Known gaps
 
 | Item | Status |
 |---|---|
-| Echo cancellation | Linux-only PipeWire feature. The Windows UI shows it disabled as unavailable. |
-| Screen share | Requires a Windows `pixelpass.exe` on `PATH` or a configured override. |
-| Chimes | Now routed through Windows `SoundPlayer`; needs a real Windows host to audibly verify. |
-| Resampling/device format | Cross-compiled. cpal/WASAPI now chooses native 48 kHz when available and otherwise resamples/remaps at the device boundary; needs real Windows hardware audio verification. |
-| Device persistence | Open. WASAPI friendly names may duplicate or change across driver/profile changes. |
-| Playback pacing | Cross-compiled. The fixed playback target under WASAPI shared mode still needs real-hardware verification with `audio_probe`. |
+| Echo cancellation | Linux-only today. The Windows UI shows it disabled as unavailable. |
+| Screen share | Blocked by PixelPass, which is currently Linux-only in practice. PeerSpeak can spawn `pixelpass.exe`, but there is no Windows PixelPass host/viewer parity yet. |
+| Device persistence | Uses cpal friendly names as keys. These can duplicate or change across Windows driver/profile changes; stable WASAPI endpoint IDs are still needed. |
+| Release hygiene | Keep `.iss` and installer output in sync with `Cargo.toml`; rebuild Windows artifacts during each release. |
+| Runtime coverage | The Windows VM smoke test proved an older tester build. Current `main` needs a fresh VM smoke matrix before calling parity current. |
 
-Before calling Windows support done, verify a real Windows machine can create/join a room,
-capture mic audio, hear remote audio, select devices, restart with selections preserved, and
-play notification chimes.
+## Current smoke checklist
+
+Before calling a Windows build current, verify on the Windows VM or real Windows
+hardware:
+
+- Launch current `peerspeak.exe`; GUI renders and settings open.
+- Run `audio_probe.exe 440 30`; listen for glitches and inspect `playout-health`.
+- Create/join a Linux <-> Windows room; confirm mic and playback both directions.
+- Select input/output devices, restart, and confirm selections persist or fall back clearly.
+- Play chimes and custom chime paths.
+- Send chat, image/file attachments, and save an attachment through the native dialog.
+- Import/play/share/listen to music from Windows file paths.
+- Record mixed/stems/both and inspect the WAV output path.
+- Exercise friends/presence/recents and the clock-skew banner.
+- Test Steam and non-Steam game detection on a real Windows Steam install.
+- Install/upgrade/uninstall through the Inno installer, including firewall rule cleanup.

packaging/PKGBUILD

@@ -1,7 +1,7 @@
 # Maintainer: mollusk <jitty+lc1iz0dc@protonmail.com>
 pkgname=peerspeak-git
 _pkgname=peerspeak
-pkgver=0.5.0.r0.g0000000
+pkgver=0.6.2.r319.g8014edf
 pkgrel=1
 pkgdesc="Decentralized peer-to-peer voice chat (Rust/iroh/PipeWire/Opus/iced)"
 arch=('x86_64')

packaging/appimage/.gitignore

@@ -0,0 +1,4 @@
+.tools/
+AppDir/
+*.AppImage
+squashfs-root/

packaging/appimage/AppRun

@@ -0,0 +1,11 @@
+#!/bin/sh
+# AppRun for the PeerSpeak AppImage.
+#
+# PeerSpeak bundles the pixelpass screen-share helper in usr/bin. We prepend our
+# own usr/bin to PATH so peerspeak's $PATH lookup for `pixelpass` finds the
+# bundled copy, while the host's tools (gst-launch-1.0, pactl, mpv — which
+# pixelpass in turn shells out to) remain reachable via the appended host PATH.
+# That no-sandbox spawning is exactly why this app suits AppImage over Flatpak.
+HERE="$(dirname "$(readlink -f "$0")")"
+export PATH="$HERE/usr/bin:$PATH"
+exec "$HERE/usr/bin/peerspeak" "$@"

packaging/appimage/README.md

@@ -0,0 +1,76 @@
+# PeerSpeak AppImage
+
+A "thin" AppImage: the `peerspeak` binary, the bundled `pixelpass` screen-share
+helper, a launcher (`AppRun`), and the desktop entry + icon. Run
+`./build-appimage.sh` to produce `peerspeak-<version>-x86_64.AppImage`.
+
+## Why thin, and why pixelpass is bundled
+
+PeerSpeak owns voice; **pixelpass** owns pixels. They are never Cargo
+dependencies of each other — peerspeak shells out to the `pixelpass` binary over
+its CLI. The AppImage co-locates `pixelpass` in `usr/bin`, and `AppRun` prepends
+`usr/bin` to `PATH`, so peerspeak's normal `$PATH` lookup finds it with no code
+change. Joe gets one file, and screen-share works out of the box.
+
+Almost nothing is bundled: peerspeak's own assets (notification WAVs, avatar
+presets, window icon, fonts) are `include_bytes!`-embedded, and the graphics
+stack (`libGL`, `libvulkan`, `libwayland-*`, `libxkbcommon`, X11) is dlopen'd at
+runtime and on the AppImage excludelist because it must match the host driver.
+So the image carries just the two binaries plus a handful of small libs.
+
+## Host requirements
+
+The AppImage runs on any reasonably current glibc-based distro that has:
+
+- **A Vulkan-capable GPU + driver** (peerspeak's iced/wgpu renderer). Mesa/RADV
+  on AMD/Intel or the NVIDIA driver all work.
+- **PipeWire** (with the PulseAudio shim, for `pactl`).
+- For **screen-share only** — pixelpass shells out to these on the host `PATH`;
+  it prints the exact package names for your distro if any are missing:
+  - **GStreamer + plugins** (`gst-launch-1.0`/`gst-inspect-1.0`, base,
+    good/bad/ugly, libav, and the PipeWire plugin),
+  - **mpv** (or vlc) for the viewer side,
+  - on X11, `xwininfo` for single-window capture.
+
+On Arch/Artix that is one pacman line, e.g.:
+
+```sh
+sudo pacman -S gstreamer gst-plugins-base gst-plugins-good gst-plugins-bad \
+  gst-plugins-ugly gst-libav gst-plugin-pipewire mpv xorg-xwininfo libpulse
+```
+
+(Add `gstreamer-vaapi` for hardware H.264 encode on AMD/Intel; the software
+x264 path always works. On XLibre / X11 the capture path uses `ximagesrc` and
+needs no XDG portal — no systemd required.)
+
+## Building for broad compatibility (glibc baseline)
+
+An AppImage requires a host glibc **at least as new** as the build host's. Built
+on a rolling distro (glibc 2.43) it only runs on equally-new systems. Build
+inside **Ubuntu 24.04** (glibc 2.39, PipeWire 1.0.5) for wide reach — pixelpass's
+`pipewire` crate binds the system PipeWire headers and needs PipeWire >= 1.0, so
+the older Debian 12 `peerspeak-bookworm` box (PW 0.3.65) cannot build it. 2.39
+covers Debian 13+, Fedora 40+, and current rolling distros.
+
+```sh
+# One-time: an Ubuntu 24.04 distrobox that reuses the host rustup toolchain.
+distrobox create --yes --image ubuntu:24.04 --name peerspeak-appimage
+distrobox enter peerspeak-appimage -- sudo apt-get update
+distrobox enter peerspeak-appimage -- sudo apt-get install -y \
+  build-essential cmake clang libclang-dev pkg-config \
+  libpipewire-0.3-dev libspa-0.2-dev libasound2-dev libxcb1-dev \
+  curl ca-certificates file patchelf git
+
+# Build (the host's ~/.rustup toolchain is glibc-2.17-baseline, so it runs in the
+# box; isolated CARGO_TARGET_DIRs keep it off the host target/):
+distrobox enter peerspeak-appimage -- env \
+  PATH="$HOME/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin:$PATH" \
+  ./packaging/appimage/build-appimage.sh
+```
+
+## Caveats
+
+- **Hardware encode (VAAPI)** uses the host GPU driver and can't be bundled; the
+  software x264 path always works.
+- The bundled `pixelpass` is built headless (no `gui` feature) — it is only ever
+  driven by peerspeak, never launched standalone from this image.

packaging/appimage/build-appimage.sh

@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+# Build a "thin" PeerSpeak AppImage that also bundles the pixelpass screen-share
+# helper.
+#
+# PeerSpeak is an iced/wgpu GUI app; pixelpass is the separate screen-share
+# orchestrator peerspeak shells out to (never a Cargo dependency). Both link
+# almost nothing — the graphics stack (libGL, libvulkan, wayland, xkbcommon,
+# X11) is dlopen'd at runtime and is on the AppImage excludelist because it must
+# match the host driver, and pixelpass's capture/encode tools (gst-launch-1.0,
+# pactl, mpv) are expected on the host PATH. So the AppImage carries just the two
+# binaries plus their handful of non-excludelisted libs. The custom AppRun
+# prepends usr/bin to PATH so peerspeak's own $PATH lookup finds the bundled
+# pixelpass, while the host's tools stay reachable.
+#
+# All runtime assets (notification WAVs, avatar presets, window icon, fonts) are
+# include_bytes!-embedded in the peerspeak binary, so nothing else is bundled.
+#
+# Usage:   packaging/appimage/build-appimage.sh
+# Output:  packaging/appimage/peerspeak-<version>-x86_64.AppImage
+#
+# Build inside an Ubuntu 24.04 distrobox (glibc 2.39, PipeWire 1.0.5) for broad
+# reach — pixelpass's `pipewire` crate needs PipeWire >= 1.0 headers, so the
+# older peerspeak-bookworm box (PW 0.3.65) cannot build it. The 2.39 baseline
+# covers Debian 13+, Fedora 40+, and all current rolling distros. See README.md.
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+repo="$(cd "$here/../.." && pwd)"
+tools="$here/.tools"
+appdir="$here/AppDir"
+mkdir -p "$tools"
+
+# linuxdeploy is itself an AppImage; run it without FUSE so this works in a
+# container / on CI without libfuse2.
+export APPIMAGE_EXTRACT_AND_RUN=1
+VERSION="$(grep -m1 '^version' "$repo/Cargo.toml" | sed -E 's/.*"(.*)".*/\1/')"
+export VERSION
+
+# Isolated target dirs so an old-glibc box build never clobbers the host target/.
+cache="${PEERSPEAK_APPIMAGE_CACHE:-$HOME/.cache/peerspeak-appimage}"
+ps_target="$cache/peerspeak-target"
+pp_target="$cache/pixelpass-target"
+
+# The pixelpass screen-share helper we bundle. Sibling checkout by default.
+pixelpass_repo="${PIXELPASS_REPO:-$repo/../pixelpass}"
+if [ ! -d "$pixelpass_repo" ]; then
+  echo "!! pixelpass repo not found at $pixelpass_repo (set PIXELPASS_REPO)" >&2
+  exit 1
+fi
+
+echo ">> building peerspeak (release)"
+( cd "$repo" && CARGO_TARGET_DIR="$ps_target" cargo build --release )
+ps_bin="$ps_target/release/peerspeak"
+
+# Headless pixelpass: peerspeak drives it via `--host`/viewer + `--output json`,
+# never its GUI, so the default (no `gui` feature) keeps the GL toolkit out.
+echo ">> building pixelpass (release, headless) from $pixelpass_repo"
+( cd "$pixelpass_repo" && CARGO_TARGET_DIR="$pp_target" cargo build --release )
+pp_bin="$pp_target/release/pixelpass"
+
+echo ">> fetching linuxdeploy"
+ld="$tools/linuxdeploy-x86_64.AppImage"
+if [ ! -x "$ld" ]; then
+  curl -fL --retry 3 -o "$ld" \
+    "https://github.com/linuxdeploy/linuxdeploy/releases/download/continuous/linuxdeploy-x86_64.AppImage"
+  chmod +x "$ld"
+fi
+
+echo ">> assembling AppDir"
+rm -rf "$appdir"
+mkdir -p "$appdir/usr/bin"
+install -m755 "$ps_bin" "$appdir/usr/bin/peerspeak"
+install -m755 "$pp_bin" "$appdir/usr/bin/pixelpass"
+
+echo ">> running linuxdeploy (bundles libs, builds the AppImage)"
+# -e (repeated): analyse both binaries for libraries to bundle; excludelisted
+#   graphics/glibc libs are skipped. -d/-i: desktop entry + icon.
+# --custom-apprun: our launcher that puts the bundled pixelpass on PATH.
+( cd "$here" && OUTPUT="peerspeak-${VERSION}-x86_64.AppImage" "$ld" \
+    --appdir "$appdir" \
+    -e "$appdir/usr/bin/peerspeak" \
+    -e "$appdir/usr/bin/pixelpass" \
+    -d "$repo/packaging/peerspeak.desktop" \
+    -i "$repo/assets/icons/peerspeak-256.png" \
+    --icon-filename peerspeak \
+    --custom-apprun "$here/AppRun" \
+    --output appimage )
+
+echo ">> done: $here/peerspeak-${VERSION}-x86_64.AppImage"

packaging/debian/README.md

@@ -0,0 +1,87 @@
+# Debian / Ubuntu `.deb` build
+
+This documents how the `peerspeak_*.deb` is produced, so the deb path is as
+self-documenting as the Arch (`packaging/PKGBUILD`) and AppImage paths.
+
+The deb **recipe itself** lives in-repo as the `[package.metadata.deb]` block in
+the top-level `Cargo.toml` (cargo-deb's equivalent of a PKGBUILD). This file
+documents only the **build environment**, which is otherwise undiscoverable from
+a fresh clone.
+
+## TL;DR
+
+```sh
+# one-time: create + provision the build box (see "Build environment" below)
+distrobox enter peerspeak-bookworm -- bash -lc '
+  source ~/.cargo/env
+  cd ~/git/butter/peerspeak
+  export CARGO_TARGET_DIR=~/.cache/cargo-deb-targets/peerspeak   # MANDATORY, see below
+  cargo deb
+'
+# output: $CARGO_TARGET_DIR/debian/peerspeak_<version>-1_amd64.deb
+```
+
+## Build environment
+
+- **Base: a Debian 12 (bookworm) distrobox named `peerspeak-bookworm`.**
+  Created with `distrobox create --name peerspeak-bookworm --image debian:12`.
+  Bookworm ships **glibc 2.36**, which sets the widest practical compatibility
+  floor (see "glibc floor" below).
+- **NEVER build the `.deb` on the Arch host.** Two independent reasons:
+  1. The Arch host's glibc is far newer, so the resulting `.deb` would demand a
+     glibc no normal Debian/Ubuntu user has, and ships an empty `Depends`.
+  2. distrobox shares `$HOME` (and therefore the repo's `target/`) with the host,
+     so a host build links Arch-compiled C objects into the "Debian" binary.
+
+### One-time provisioning inside the box
+
+```sh
+distrobox enter peerspeak-bookworm
+sudo apt update
+sudo apt install -y build-essential pkg-config clang libclang-dev \
+    libpipewire-0.3-dev libopus-dev libasound2-dev libxcb1-dev
+# clang/libclang -> pipewire-sys bindgen ; libxcb1-dev -> link
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+source ~/.cargo/env
+cargo install cargo-deb
+```
+
+### The mandatory separate `CARGO_TARGET_DIR`
+
+Because distrobox shares `$HOME`, the repo's default `target/` is the **same
+directory** the Arch host builds into. If you run `cargo deb` without overriding
+the target dir, cargo will happily reuse Arch-built `.o`/rlib artifacts and link
+them into the Debian binary, producing a `.deb` that crashes or demands the
+host's glibc.
+
+Always point the build at a box-local cache:
+
+```sh
+export CARGO_TARGET_DIR=~/.cache/cargo-deb-targets/peerspeak
+```
+
+(Run `cargo clean` first if you ever suspect a polluted target dir.)
+
+## glibc floor
+
+The `.deb` is built against the build box's glibc, which becomes the install
+floor (`libc6 (>= 2.36)` lands in `Depends` via `$auto`):
+
+| Build box            | glibc | Runs on                              |
+|----------------------|-------|--------------------------------------|
+| `debian:12` (current)| 2.36  | Debian 12+, Ubuntu 24.04+ (glibc ≥ 2.36) |
+| `ubuntu:26.04` (old) | 2.43  | Ubuntu 26.04+ only — too narrow, abandoned |
+
+If a friend is on something even older than Debian 12, drop the floor further by
+recreating the box from an older base image and rebuilding.
+
+## Runtime `Depends` / `Recommends`
+
+- `Depends = "$auto"` — cargo-deb runs `dpkg-shlibdeps`, which discovers the
+  linked shared libraries (PipeWire, Opus, ALSA, xcb, glibc, …) automatically.
+- `Recommends = "pixelpass, mpv"` — `pixelpass` provides in-room screen sharing
+  and `mpv` is the screen-share viewer (these are companion programs invoked as
+  subprocesses, not linked libraries, so they are Recommends not Depends).
+
+See `pixelpass`'s own `packaging/debian/README.md` for why **its** `Depends`
+lists the whole GStreamer stack explicitly.

packaging/windows/INSTALL.md

@@ -8,7 +8,7 @@ it once, then you and I connect directly to each other.
 
 ## 1. Install it
 
-1. Double-click **`peerspeak-0.4.0-setup.exe`** (the file I sent you).
+1. Double-click **`peerspeak-<version>-setup.exe`** (the file I sent you).
 
 2. **Windows will probably show a blue "Windows protected your PC" warning.**
    This is normal — it shows up for any app that isn't from a big company with a

packaging/windows/README.md

@@ -11,8 +11,9 @@ runtime, so there are no extra DLLs to bundle. The installer payload is just the
 
 ## Version compatibility
 
-The installer version tracks the crate version in `Cargo.toml` (currently
-**0.4.0**) — keep `MyAppVersion` in `peerspeak.iss` in sync when it changes.
+The installer version tracks the release version in `Cargo.toml` — keep
+`MyAppVersion` in `peerspeak.iss` in sync when cutting a release. Do not reuse an
+old installer filename after a crate-version bump.
 
 Per `VERSIONING.md`, a **MINOR** bump in `0.x` is a **breaking wire change**:
 peers on different MINOR versions can't connect (they fail fast at the

packaging/windows/peerspeak.iss

@@ -12,7 +12,7 @@
 ; (x86_64-pc-windows-gnu, statically linked -- no extra DLLs needed).
 
 #define MyAppName "PeerSpeak"
-#define MyAppVersion "0.6.0"
+#define MyAppVersion "0.6.3"
 #define MyAppPublisher "mollusk"
 #define MyAppExeName "peerspeak.exe"
 

src/audio/cpal_impl.rs

@@ -578,7 +578,9 @@ fn choose_config(device: &Device, output: bool) -> Result<cpal::SupportedStreamC
     let pick = |channels: Option<u16>| {
         ranges
             .iter()
-            .find(|r| usable_range(r) && supports_48k(r) && channels.is_none_or(|c| r.channels() == c))
+            .find(|r| {
+                usable_range(r) && supports_48k(r) && channels.is_none_or(|c| r.channels() == c)
+            })
             .cloned()
     };
 
@@ -666,15 +668,30 @@ fn run_capture(
         let device_rate = config.sample_rate.0;
         let stream = match sample_format {
             SampleFormat::F32 => build_input::<f32, _>(
-                &device, &config, producer, channels, overrun.clone(), callbacks.clone(),
+                &device,
+                &config,
+                producer,
+                channels,
+                overrun.clone(),
+                callbacks.clone(),
                 err_code.clone(),
             ),
             SampleFormat::I16 => build_input::<i16, _>(
-                &device, &config, producer, channels, overrun.clone(), callbacks.clone(),
+                &device,
+                &config,
+                producer,
+                channels,
+                overrun.clone(),
+                callbacks.clone(),
                 err_code.clone(),
             ),
             SampleFormat::U16 => build_input::<u16, _>(
-                &device, &config, producer, channels, overrun.clone(), callbacks.clone(),
+                &device,
+                &config,
+                producer,
+                channels,
+                overrun.clone(),
+                callbacks.clone(),
                 err_code.clone(),
             ),
             other => Err(AudioError::Stream(format!(
@@ -764,7 +781,10 @@ fn run_capture(
         // Surface a stream error the RT callback flagged (it can't log itself).
         let ec = err_code.load(Ordering::Relaxed);
         if ec != STREAM_ERR_NONE && ec != last_err {
-            crate::log_msg(&format!("cpal capture stream error: {}", stream_err_text(ec)));
+            crate::log_msg(&format!(
+                "cpal capture stream error: {}",
+                stream_err_text(ec)
+            ));
             last_err = ec;
         }
         if !drained {
@@ -914,16 +934,34 @@ fn run_playback(
         let device_rate = config.sample_rate.0;
         let stream = match sample_format {
             SampleFormat::F32 => build_output::<f32, _>(
-                &device, &config, consumer, ring_fill.clone(), underrun.clone(),
-                max_cb.clone(), callbacks.clone(), err_code.clone(),
+                &device,
+                &config,
+                consumer,
+                ring_fill.clone(),
+                underrun.clone(),
+                max_cb.clone(),
+                callbacks.clone(),
+                err_code.clone(),
             ),
             SampleFormat::I16 => build_output::<i16, _>(
-                &device, &config, consumer, ring_fill.clone(), underrun.clone(),
-                max_cb.clone(), callbacks.clone(), err_code.clone(),
+                &device,
+                &config,
+                consumer,
+                ring_fill.clone(),
+                underrun.clone(),
+                max_cb.clone(),
+                callbacks.clone(),
+                err_code.clone(),
             ),
             SampleFormat::U16 => build_output::<u16, _>(
-                &device, &config, consumer, ring_fill.clone(), underrun.clone(),
-                max_cb.clone(), callbacks.clone(), err_code.clone(),
+                &device,
+                &config,
+                consumer,
+                ring_fill.clone(),
+                underrun.clone(),
+                max_cb.clone(),
+                callbacks.clone(),
+                err_code.clone(),
             ),
             other => Err(AudioError::Stream(format!(
                 "unsupported playback sample format: {other:?}"
@@ -1199,7 +1237,10 @@ fn spawn_health_logger(
             // Surface a stream error the RT callback flagged (it can't log itself).
             let ec = err_code.load(Ordering::Relaxed);
             if ec != STREAM_ERR_NONE && ec != last_err {
-                crate::log_msg(&format!("cpal playback stream error: {}", stream_err_text(ec)));
+                crate::log_msg(&format!(
+                    "cpal playback stream error: {}",
+                    stream_err_text(ec)
+                ));
                 last_err = ec;
             }
             // Report the device's per-cycle demand (in internal 48 kHz-stereo

src/audio/echo_cancel.rs

@@ -54,7 +54,10 @@ impl Drop for EchoCancelGuard {
             .arg("unload-module")
             .arg(&self.module_index)
             .output();
-        crate::log_msg(&format!("Echo cancel: unloaded module {}", self.module_index));
+        crate::log_msg(&format!(
+            "Echo cancel: unloaded module {}",
+            self.module_index
+        ));
     }
 }
 
@@ -65,7 +68,10 @@ impl Drop for EchoCancelGuard {
 /// `None` (or an empty string) to bind to the system defaults. Returns `Err` with
 /// a human-readable reason if `pactl` is missing, the load fails, or the nodes
 /// don't appear — the caller should fall back to the direct devices.
-pub fn enable(real_source: Option<&str>, real_sink: Option<&str>) -> Result<EchoCancelGuard, String> {
+pub fn enable(
+    real_source: Option<&str>,
+    real_sink: Option<&str>,
+) -> Result<EchoCancelGuard, String> {
     // Best-effort: clear any stale instance left by a crashed prior run so we
     // don't stack duplicate modules / fight over the virtual node names.
     unload_stale();
@@ -101,7 +107,11 @@ pub fn enable(real_source: Option<&str>, real_sink: Option<&str>) -> Result<Echo
     if module_index.parse::<u64>().is_err() {
         return Err(format!("unexpected pactl output: {module_index:?}"));
     }
-    let guard = EchoCancelGuard { module_index, source_name, sink_name };
+    let guard = EchoCancelGuard {
+        module_index,
+        source_name,
+        sink_name,
+    };
 
     // The virtual nodes appear shortly after the module loads; wait for both so
     // the subsequent capture/playback streams can actually target them. If they
@@ -134,7 +144,12 @@ fn wait_for_nodes(source_name: &str, sink_name: &str) -> bool {
 /// Whether `pactl list <kind> short` lists a node named `name`.
 /// `kind` is "sources" or "sinks".
 fn node_present(kind: &str, name: &str) -> bool {
-    let Ok(out) = Command::new("pactl").arg("list").arg(kind).arg("short").output() else {
+    let Ok(out) = Command::new("pactl")
+        .arg("list")
+        .arg(kind)
+        .arg("short")
+        .output()
+    else {
         return false;
     };
     String::from_utf8_lossy(&out.stdout)
@@ -167,7 +182,12 @@ fn process_is_alive(_pid: u32) -> bool {
 /// Unloads leftover PeerSpeak `module-echo-cancel` instances only when their
 /// owning process is gone. Best-effort and conservative on non-Linux platforms.
 fn unload_stale() {
-    let Ok(out) = Command::new("pactl").arg("list").arg("modules").arg("short").output() else {
+    let Ok(out) = Command::new("pactl")
+        .arg("list")
+        .arg("modules")
+        .arg("short")
+        .output()
+    else {
         return;
     };
     for line in String::from_utf8_lossy(&out.stdout).lines() {
@@ -179,7 +199,10 @@ fn unload_stale() {
             && ec_module_is_stale(args, process_is_alive)
             && index.parse::<u64>().is_ok()
         {
-            let _ = Command::new("pactl").arg("unload-module").arg(index).output();
+            let _ = Command::new("pactl")
+                .arg("unload-module")
+                .arg(index)
+                .output();
             crate::log_msg(&format!("Echo cancel: cleaned up stale module {index}"));
         }
     }
@@ -198,13 +221,25 @@ mod tests {
         let guard = enable(None, None).expect("module-echo-cancel should load");
         let source_name = guard.source_name().to_string();
         let sink_name = guard.sink_name().to_string();
-        assert!(node_present("sources", &source_name), "cleaned source must exist");
-        assert!(node_present("sinks", &sink_name), "reference sink must exist");
+        assert!(
+            node_present("sources", &source_name),
+            "cleaned source must exist"
+        );
+        assert!(
+            node_present("sinks", &sink_name),
+            "reference sink must exist"
+        );
         drop(guard);
         // Give pactl a moment to tear the nodes down.
         std::thread::sleep(Duration::from_millis(300));
-        assert!(!node_present("sources", &source_name), "source must be gone after unload");
-        assert!(!node_present("sinks", &sink_name), "sink must be gone after unload");
+        assert!(
+            !node_present("sources", &source_name),
+            "source must be gone after unload"
+        );
+        assert!(
+            !node_present("sinks", &sink_name),
+            "sink must be gone after unload"
+        );
     }
 
     #[test]
@@ -220,7 +255,10 @@ mod tests {
             pid_from_ec_args("source_name=peerspeak_echocancel_source.not-a-pid"),
             None
         );
-        assert_eq!(pid_from_ec_args("source_name=someone_elses_source.4242"), None);
+        assert_eq!(
+            pid_from_ec_args("source_name=someone_elses_source.4242"),
+            None
+        );
     }
 
     #[test]

src/audio/eq.rs

@@ -251,7 +251,10 @@ mod tests {
         let before = rms(&low);
         eq.process_frame(&mut low);
         let after = rms(&low);
-        assert!(after > before * 1.6, "low shelf should boost low RMS: {before} -> {after}");
+        assert!(
+            after > before * 1.6,
+            "low shelf should boost low RMS: {before} -> {after}"
+        );
     }
 
     #[test]
@@ -264,7 +267,10 @@ mod tests {
         let before = rms(&high);
         eq.process_frame(&mut high);
         let after = rms(&high);
-        assert!(after > before * 1.6, "high shelf should boost high RMS: {before} -> {after}");
+        assert!(
+            after > before * 1.6,
+            "high shelf should boost high RMS: {before} -> {after}"
+        );
     }
 
     #[test]
@@ -275,7 +281,10 @@ mod tests {
                 Biquad::peaking(DEFAULT_SAMPLE_RATE, MID_PEAK_HZ, gain, MID_Q),
                 Biquad::high_shelf(DEFAULT_SAMPLE_RATE, HIGH_SHELF_HZ, gain, SHELF_Q),
             ] {
-                assert!(b.coeffs.all_finite(), "coefficients must be finite at {gain} dB");
+                assert!(
+                    b.coeffs.all_finite(),
+                    "coefficients must be finite at {gain} dB"
+                );
             }
         }
     }
@@ -289,12 +298,11 @@ mod tests {
         });
         let mut frame = sine(1_000.0, 48_000, 30_000.0);
         eq.process_frame(&mut frame);
-        let peak = frame
-            .iter()
-            .map(|&s| i32::from(s).abs())
-            .max()
-            .unwrap_or(0);
-        assert!(peak > 1_000, "processed signal should retain audible energy");
+        let peak = frame.iter().map(|&s| i32::from(s).abs()).max().unwrap_or(0);
+        assert!(
+            peak > 1_000,
+            "processed signal should retain audible energy"
+        );
         assert!(
             frame.iter().any(|&s| s > 0) && frame.iter().any(|&s| s < 0),
             "a boosted sine should retain both polarities"

src/audio/gate.rs

@@ -169,7 +169,10 @@ mod tests {
             assert!(g.process(&mut f, 0.05), "loud frame must transmit");
             last = peak(&f);
         }
-        assert!(last >= 9900, "gain should reach ~1.0 on sustained loud input, got peak {last}");
+        assert!(
+            last >= 9900,
+            "gain should reach ~1.0 on sustained loud input, got peak {last}"
+        );
     }
 
     #[test]
@@ -179,8 +182,15 @@ mod tests {
         g.process(&mut f, 0.05);
         // 5ms attack @48k = 240 samples; across a 960-sample frame the gain ramps
         // 0->1, so the early samples are well below full scale (no instant click).
-        assert!(f[0].abs() < 5000, "attack should start near zero, got {}", f[0]);
-        assert!(f[FRAME - 1].abs() > 9000, "attack should complete within the frame");
+        assert!(
+            f[0].abs() < 5000,
+            "attack should start near zero, got {}",
+            f[0]
+        );
+        assert!(
+            f[FRAME - 1].abs() > 9000,
+            "attack should complete within the frame"
+        );
     }
 
     #[test]
@@ -193,8 +203,14 @@ mod tests {
         }
         // First quiet frame right after speech: hold keeps it open (not chopped).
         let mut q = frame(50); // rms ~0.0015, below close (0.03)
-        assert!(g.process(&mut q, 0.05), "first quiet frame must stay open (hangover)");
-        assert!(peak(&q) > 0, "held-open frame must not be silenced immediately");
+        assert!(
+            g.process(&mut q, 0.05),
+            "first quiet frame must stay open (hangover)"
+        );
+        assert!(
+            peak(&q) > 0,
+            "held-open frame must not be silenced immediately"
+        );
 
         // Hold is 200ms = 10 frames; keep feeding quiet until it fully closes.
         let mut closed = false;
@@ -205,7 +221,10 @@ mod tests {
                 break;
             }
         }
-        assert!(closed, "gate must eventually close and stop transmitting after sustained silence");
+        assert!(
+            closed,
+            "gate must eventually close and stop transmitting after sustained silence"
+        );
     }
 
     #[test]
@@ -216,8 +235,14 @@ mod tests {
         g.process(&mut f, 0.05); // open=0.05, close=0.03
         // A frame between close and open thresholds: rms ~0.04 (amp ~1310).
         let mut mid = frame(1310);
-        assert!(g.process(&mut mid, 0.05), "between-threshold frame must keep an open gate open");
-        assert!(g.open, "hysteresis: gate stays open above the close threshold");
+        assert!(
+            g.process(&mut mid, 0.05),
+            "between-threshold frame must keep an open gate open"
+        );
+        assert!(
+            g.open,
+            "hysteresis: gate stays open above the close threshold"
+        );
     }
 
     #[test]
@@ -225,7 +250,10 @@ mod tests {
         let mut g = NoiseGate::new(SR);
         // Never opened; feed silence — should report don't-transmit promptly.
         let mut f = frame(0);
-        assert!(!g.process(&mut f, 0.05), "an unopened gate on silence must not transmit");
+        assert!(
+            !g.process(&mut f, 0.05),
+            "an unopened gate on silence must not transmit"
+        );
     }
 
     #[test]
@@ -266,7 +294,11 @@ mod tests {
 
         let mut f2 = frame(10000);
         assert!(g.process(&mut f2, 0.05)); // enabled
-        assert!(f2[0].abs() > 9000, "expected first sample of enabled frame to have no fade-in, got {}", f2[0]);
+        assert!(
+            f2[0].abs() > 9000,
+            "expected first sample of enabled frame to have no fade-in, got {}",
+            f2[0]
+        );
     }
 
     #[test]
@@ -302,7 +334,10 @@ mod tests {
             let mut f = frame(1310);
             assert!(g.process(&mut f, 0.05));
         }
-        assert!(g.open, "gate must stay open (hold refreshed by mid-level input)");
+        assert!(
+            g.open,
+            "gate must stay open (hold refreshed by mid-level input)"
+        );
     }
 
     #[test]
@@ -333,6 +368,10 @@ mod tests {
             last_peak = peak(&f);
         }
         assert!(g.open);
-        assert!(last_peak >= 9900, "peak of the 3rd reopened frame must be >= 9900, got {}", last_peak);
+        assert!(
+            last_peak >= 9900,
+            "peak of the 3rd reopened frame must be >= 9900, got {}",
+            last_peak
+        );
     }
 }

src/audio/limiter.rs

@@ -123,7 +123,10 @@ mod tests {
         let out = lim.process(&loud, 1.0);
         let ceiling = lim.ceiling().ceil() as i16;
         for &s in &out {
-            assert!(s > 0, "positive loud input stays positive (no wrap), got {s}");
+            assert!(
+                s > 0,
+                "positive loud input stays positive (no wrap), got {s}"
+            );
             assert!(s <= ceiling, "sample {s} exceeded ceiling {ceiling}");
         }
     }
@@ -175,7 +178,10 @@ mod tests {
         let out_pos = lim.process(&pos_loud, 1.0);
         for &s in &out_pos {
             assert!(s > 0, "positive input stays positive, got {s}");
-            assert!(s <= ceiling_ceil, "positive sample {s} exceeded ceiling {ceiling_ceil}");
+            assert!(
+                s <= ceiling_ceil,
+                "positive sample {s} exceeded ceiling {ceiling_ceil}"
+            );
         }
 
         // Sustained negative loud sum
@@ -185,7 +191,10 @@ mod tests {
         let neg_ceiling = -ceiling_ceil;
         for &s in &out_neg {
             assert!(s < 0, "negative input stays negative, got {s}");
-            assert!(s >= neg_ceiling, "negative sample {s} exceeded negative ceiling {neg_ceiling}");
+            assert!(
+                s >= neg_ceiling,
+                "negative sample {s} exceeded negative ceiling {neg_ceiling}"
+            );
         }
     }
 
@@ -200,8 +209,14 @@ mod tests {
         let out = lim.process(&input, 8.0);
         for &s in &out {
             assert!(s > 0, "positive stays positive");
-            assert!(s <= ceiling_ceil, "sample {s} must be limited to ceiling {ceiling_ceil}");
-            assert!((s - ceiling_ceil).abs() <= 2, "sample {s} should ride the ceiling {ceiling_ceil}");
+            assert!(
+                s <= ceiling_ceil,
+                "sample {s} must be limited to ceiling {ceiling_ceil}"
+            );
+            assert!(
+                (s - ceiling_ceil).abs() <= 2,
+                "sample {s} should ride the ceiling {ceiling_ceil}"
+            );
         }
     }
 
@@ -213,7 +228,10 @@ mod tests {
         let out = lim.process(&input, 0.5);
         for (i, &s) in out.iter().enumerate() {
             let expected = (input[i] as f32 * 0.5).round() as i16;
-            assert!((s - expected).abs() <= 1, "sample {s} should be close to expected {expected}");
+            assert!(
+                (s - expected).abs() <= 1,
+                "sample {s} should be close to expected {expected}"
+            );
         }
 
         // Subsequently feed a new sample at unity gain. It must be transparent,
@@ -230,7 +248,12 @@ mod tests {
 
         let loud = vec![200_000i32; 10];
         let out = lim.process(&loud, 1.0);
-        assert!(out[0] <= ceiling_ceil, "first sample {} must not overshoot ceiling {}", out[0], ceiling_ceil);
+        assert!(
+            out[0] <= ceiling_ceil,
+            "first sample {} must not overshoot ceiling {}",
+            out[0],
+            ceiling_ceil
+        );
     }
 
     /// 5. Release direction & monotonicity.
@@ -247,13 +270,23 @@ mod tests {
 
         // Output should be monotonic (non-decreasing)
         for i in 1..out.len() {
-            assert!(out[i] >= out[i - 1], "output must be monotonic; index {} was {}, index {} was {}", i - 1, out[i - 1], i, out[i]);
+            assert!(
+                out[i] >= out[i - 1],
+                "output must be monotonic; index {} was {}, index {} was {}",
+                i - 1,
+                out[i - 1],
+                i,
+                out[i]
+            );
         }
 
         // The end sample should be closer to the original input than the start sample
         let start_diff = (mid_val as i16 - out[0]).abs();
         let end_diff = (mid_val as i16 - *out.last().unwrap()).abs();
-        assert!(end_diff < start_diff, "end diff {end_diff} should be smaller than start diff {start_diff}");
+        assert!(
+            end_diff < start_diff,
+            "end diff {end_diff} should be smaller than start diff {start_diff}"
+        );
     }
 
     /// 6. Release is gradual, not instantaneous.
@@ -265,7 +298,11 @@ mod tests {
 
         // Immediately follow with a sub-ceiling sample
         let out = lim.process(&[10_000i32], 1.0);
-        assert!(out[0] < 10_000, "first quiet sample should still be attenuated (got {})", out[0]);
+        assert!(
+            out[0] < 10_000,
+            "first quiet sample should still be attenuated (got {})",
+            out[0]
+        );
     }
 
     /// 7. State carries across process calls.
@@ -287,7 +324,10 @@ mod tests {
         let mut out_split = out_split1;
         out_split.extend(&out_split2);
 
-        assert_eq!(out_single, out_split, "splitting process calls must produce identical output to a single call");
+        assert_eq!(
+            out_single, out_split,
+            "splitting process calls must produce identical output to a single call"
+        );
 
         // Test 2: Pre-loaded limiter vs fresh limiter on the same input
         let mut lim_preloaded = SoftLimiter::new(SR);
@@ -299,8 +339,16 @@ mod tests {
         let out_preloaded = lim_preloaded.process(&test_input, 1.0);
         let out_fresh = lim_fresh.process(&test_input, 1.0);
 
-        assert_ne!(out_preloaded, out_fresh, "pre-loaded and fresh limiter outputs should differ");
-        assert!(out_preloaded[0] < out_fresh[0], "pre-loaded limiter first sample {} should be smaller than fresh limiter first sample {}", out_preloaded[0], out_fresh[0]);
+        assert_ne!(
+            out_preloaded, out_fresh,
+            "pre-loaded and fresh limiter outputs should differ"
+        );
+        assert!(
+            out_preloaded[0] < out_fresh[0],
+            "pre-loaded limiter first sample {} should be smaller than fresh limiter first sample {}",
+            out_preloaded[0],
+            out_fresh[0]
+        );
     }
 
     /// 8. Empty input.
@@ -320,7 +368,10 @@ mod tests {
         // Gain 0.0
         let out_zero = lim.process(&input, 0.0);
         assert_eq!(out_zero.len(), input.len());
-        assert!(out_zero.iter().all(|&s| s == 0), "0.0 gain should result in all zeros");
+        assert!(
+            out_zero.iter().all(|&s| s == 0),
+            "0.0 gain should result in all zeros"
+        );
 
         // Gain 1.0
         let out_unity = lim.process(&input, 1.0);
@@ -354,6 +405,9 @@ mod tests {
 
         let out = lim.process(&input, 1.0);
         let expected: Vec<i16> = input.iter().map(|&s| s as i16).collect();
-        assert_eq!(out, expected, "below ceiling input must be bit-exact at unity gain");
+        assert_eq!(
+            out, expected,
+            "below ceiling input must be bit-exact at unity gain"
+        );
     }
 }

src/audio/mod.rs

@@ -1,6 +1,6 @@
-use std::sync::mpsc::{Receiver, Sender};
 use std::sync::Arc;
 use std::sync::atomic::AtomicUsize;
+use std::sync::mpsc::{Receiver, Sender};
 use thiserror::Error;
 
 /// Playback output channel count. Capture/encode/network remain mono; only the
@@ -35,7 +35,11 @@ pub enum AudioError {
 pub trait AudioBackend: Send + Sync {
     /// Starts capturing raw PCM audio from the input device (microphone),
     /// sending chunks of samples (e.g. `Vec<i16>`) to the provided Sender.
-    fn start_capture(&self, tx: Sender<Vec<i16>>, target_node: Option<String>) -> Result<(), AudioError>;
+    fn start_capture(
+        &self,
+        tx: Sender<Vec<i16>>,
+        target_node: Option<String>,
+    ) -> Result<(), AudioError>;
 
     /// Starts playing back raw PCM audio to the output device (speaker),
     /// reading mixed/incoming chunks of samples from the provided Receiver.
@@ -65,16 +69,16 @@ pub mod pan;
 // Linear resamplers used by the Windows/cpal backend (W4). Platform-neutral and
 // pure, so it builds (and its tests run) everywhere even though only the cpal
 // backend wires it in.
-pub mod resample;
+#[cfg(windows)]
+pub mod cpal_impl;
 #[cfg(target_os = "linux")]
 pub mod echo_cancel;
 #[cfg(target_os = "linux")]
 pub mod pipewire_impl;
-#[cfg(windows)]
-pub mod cpal_impl;
 #[cfg(target_os = "linux")]
 pub mod pw_cli;
 pub mod recorder;
+pub mod resample;
 
 /// A selectable audio device for the input/output pickers. `name` is the stable
 /// identifier the backend uses to request the device (`target_node`);
@@ -96,10 +100,10 @@ impl std::fmt::Display for AudioDevice {
 // Enumerate audio input/output devices for the pickers (sorted by description),
 // returning the same `AudioDevice` shape regardless of platform: PipeWire
 // (`pw-cli`) on Linux, cpal/WASAPI on Windows.
-#[cfg(target_os = "linux")]
-pub use pw_cli::enumerate_audio_devices;
 #[cfg(windows)]
 pub use cpal_impl::enumerate_audio_devices;
+#[cfg(target_os = "linux")]
+pub use pw_cli::enumerate_audio_devices;
 
 /// The audio backend implementation for the current platform.
 ///

src/audio/multitrack.rs

@@ -12,9 +12,11 @@
 //! This module is pure plumbing over [`WavWriter`]: no audio decode, no
 //! networking, no realtime work. The mixer (a non-RT task) drives it.
 
-use std::collections::{HashMap, VecDeque};
+use std::collections::{HashMap, HashSet, VecDeque};
 use std::io;
 use std::path::{Path, PathBuf};
+use std::sync::mpsc::{self, SyncSender, TrySendError};
+use std::thread::{self, JoinHandle};
 
 use iroh::EndpointId;
 
@@ -24,6 +26,8 @@ use crate::core::jitter::FRAME_SAMPLES;
 /// Cap on the silence chunk written at once when pre-padding a late joiner, so a
 /// long-running call can't trigger a single multi-hundred-MB allocation.
 const SILENCE_CHUNK: usize = FRAME_SAMPLES * 256;
+const WRITER_QUEUE_CYCLES: usize = 256;
+const DROP_LOG_INTERVAL_CYCLES: u64 = 256;
 
 /// Cap on buffered mic samples (~200ms @ 48kHz). Bounds how far the mic track
 /// can drift if the capture clock runs ahead of the mixer cycle; past it the
@@ -56,41 +60,6 @@ pub fn create_session_dir(base: &Path, now_unix_secs: u64) -> io::Result<PathBuf
     ))
 }
 
-/// One output track: its WAV writer plus whether it has been written *this*
-/// cycle (so `end_cycle` knows which tracks to pad with silence).
-struct Track {
-    writer: WavWriter,
-    written_this_cycle: bool,
-}
-
-impl Track {
-    fn create(path: &Path) -> io::Result<Self> {
-        Ok(Self {
-            writer: WavWriter::new(path)?,
-            written_this_cycle: false,
-        })
-    }
-
-    /// Append `frame` fitted to exactly `frame_samples` (zero-padded if short),
-    /// and mark the track as written for this cycle.
-    fn write_frame(&mut self, frame: &[i16], frame_samples: usize) -> io::Result<()> {
-        self.writer.write_samples(&fit(frame, frame_samples))?;
-        self.written_this_cycle = true;
-        Ok(())
-    }
-
-    /// Append `samples` of silence (no cycle-marking — used for padding).
-    fn write_silence(&mut self, samples: usize) -> io::Result<()> {
-        let mut remaining = samples;
-        while remaining > 0 {
-            let n = remaining.min(SILENCE_CHUNK);
-            self.writer.write_samples(&vec![0i16; n])?;
-            remaining -= n;
-        }
-        Ok(())
-    }
-}
-
 /// Return `frame` resized to exactly `n` samples: truncated if longer (shouldn't
 /// happen — Opus frames are uniform), zero-padded if shorter.
 fn fit(frame: &[i16], n: usize) -> Vec<i16> {
@@ -108,7 +77,13 @@ pub fn track_filename(name: &str, id: &EndpointId) -> String {
     let clean = crate::sanitize::sanitize_name(name);
     let mut slug: String = clean
         .chars()
-        .map(|c| if c.is_ascii_alphanumeric() { c.to_ascii_lowercase() } else { '-' })
+        .map(|c| {
+            if c.is_ascii_alphanumeric() {
+                c.to_ascii_lowercase()
+            } else {
+                '-'
+            }
+        })
         .collect();
     // Collapse runs of '-' and trim them off the ends.
     while slug.contains("--") {
@@ -120,41 +95,210 @@ pub fn track_filename(name: &str, id: &EndpointId) -> String {
     format!("{slug}-{short}.wav")
 }
 
-/// A live multitrack recording: per-peer stems + your mic, plus an optional
-/// mixed track, all under one session directory and clocked together.
-pub struct MultitrackRecorder {
-    dir: PathBuf,
-    frame_samples: usize,
-    /// Cycles recorded so far = the shared length (in frames) of every track.
-    cycles: u64,
-    peers: HashMap<EndpointId, Track>,
-    /// Your mic track. Fed asynchronously from the capture thread via
-    /// [`push_mic`](MultitrackRecorder::push_mic) into `mic_fifo`, then drained
-    /// one frame per `end_cycle` so it aligns with the cycle clock.
-    mic: WavWriter,
-    mic_fifo: VecDeque<i16>,
-    /// Present in "Both" mode (stems + mixed), absent in "stems only".
-    mix: Option<Track>,
+#[derive(Default)]
+struct PendingCycle {
+    new_peers: Vec<NewPeer>,
+    peer_frames: HashMap<EndpointId, Vec<i16>>,
+    mix_frame: Option<Vec<i16>>,
 }
 
-impl MultitrackRecorder {
-    /// Create a recording in `dir` (which must already exist). `with_mix` adds
-    /// the convenience mixed track (`mix.wav`). Your mic is always `me.wav`.
-    pub fn create(dir: &Path, frame_samples: usize, with_mix: bool) -> io::Result<Self> {
+struct NewPeer {
+    id: EndpointId,
+    filename: String,
+}
+
+struct CycleBatch {
+    new_peers: Vec<NewPeer>,
+    mic_frame: Vec<i16>,
+    mix_frame: Option<Vec<i16>>,
+    peer_frames: HashMap<EndpointId, Vec<i16>>,
+}
+
+trait SampleWriter {
+    fn write_samples(&mut self, samples: &[i16]) -> io::Result<()>;
+    fn finalize(self) -> io::Result<()>;
+}
+
+impl SampleWriter for WavWriter {
+    fn write_samples(&mut self, samples: &[i16]) -> io::Result<()> {
+        WavWriter::write_samples(self, samples)
+    }
+
+    fn finalize(self) -> io::Result<()> {
+        WavWriter::finalize(self)
+    }
+}
+
+struct WriterState<W> {
+    dir: PathBuf,
+    frame_samples: usize,
+    peers: HashMap<EndpointId, W>,
+    mic: W,
+    mix: Option<W>,
+    cycles_written: u64,
+}
+
+impl WriterState<WavWriter> {
+    fn create(dir: &Path, frame_samples: usize, with_mix: bool) -> io::Result<Self> {
         let mic = WavWriter::new(&dir.join("me.wav"))?;
         let mix = if with_mix {
-            Some(Track::create(&dir.join("mix.wav"))?)
+            Some(WavWriter::new(&dir.join("mix.wav"))?)
         } else {
             None
         };
         Ok(Self {
             dir: dir.to_path_buf(),
             frame_samples,
-            cycles: 0,
             peers: HashMap::new(),
             mic,
-            mic_fifo: VecDeque::new(),
             mix,
+            cycles_written: 0,
+        })
+    }
+}
+
+impl<W: SampleWriter> WriterState<W> {
+    fn apply_batch<F>(&mut self, batch: &CycleBatch, mut create_peer: F) -> io::Result<()>
+    where
+        F: FnMut(&Path) -> io::Result<W>,
+    {
+        for peer in &batch.new_peers {
+            if !self.peers.contains_key(&peer.id) {
+                let writer = create_peer(&self.dir.join(&peer.filename))?;
+                self.peers.insert(peer.id, writer);
+                let pad = self.back_pad_samples()?;
+                let writer = self.peers.get_mut(&peer.id).unwrap();
+                Self::write_silence(writer, pad)?;
+            }
+        }
+
+        self.mic.write_samples(&batch.mic_frame)?;
+        if let Some(mix) = self.mix.as_mut() {
+            if let Some(frame) = batch.mix_frame.as_deref() {
+                mix.write_samples(frame)?;
+            } else {
+                Self::write_silence(mix, self.frame_samples)?;
+            }
+        }
+
+        let silence = vec![0i16; self.frame_samples];
+        for (id, writer) in &mut self.peers {
+            let frame = batch
+                .peer_frames
+                .get(id)
+                .map(Vec::as_slice)
+                .unwrap_or(&silence);
+            writer.write_samples(frame)?;
+        }
+        self.cycles_written += 1;
+        Ok(())
+    }
+
+    fn back_pad_samples(&self) -> io::Result<usize> {
+        let cycles = usize::try_from(self.cycles_written)
+            .map_err(|_| io::Error::other("multitrack recording too long"))?;
+        cycles
+            .checked_mul(self.frame_samples)
+            .ok_or_else(|| io::Error::other("multitrack recording too long"))
+    }
+
+    fn write_silence(writer: &mut W, samples: usize) -> io::Result<()> {
+        let mut remaining = samples;
+        let silence = vec![0i16; remaining.min(SILENCE_CHUNK)];
+        while remaining > 0 {
+            let n = remaining.min(silence.len());
+            writer.write_samples(&silence[..n])?;
+            remaining -= n;
+        }
+        Ok(())
+    }
+
+    fn finalize(self) -> io::Result<()> {
+        let mut first_finalize_error = None;
+        record_first_error(&mut first_finalize_error, self.mic.finalize());
+        if let Some(mix) = self.mix {
+            record_first_error(&mut first_finalize_error, mix.finalize());
+        }
+        for writer in self.peers.into_values() {
+            record_first_error(&mut first_finalize_error, writer.finalize());
+        }
+        if let Some(e) = first_finalize_error {
+            Err(e)
+        } else {
+            Ok(())
+        }
+    }
+}
+
+fn record_first_error(slot: &mut Option<io::Error>, result: io::Result<()>) {
+    if slot.is_none()
+        && let Err(e) = result
+    {
+        *slot = Some(e);
+    }
+}
+
+/// Applies whole-cycle batches on the writer thread. Each applied batch appends
+/// exactly `frame_samples` to every existing track, and a dropped batch never
+/// reaches this loop for any track, so stem lengths stay equal even when the
+/// bounded queue applies back-pressure.
+fn writer_thread_main(
+    mut state: WriterState<WavWriter>,
+    batch_rx: mpsc::Receiver<CycleBatch>,
+) -> io::Result<()> {
+    let mut first_write_error = None;
+
+    for batch in batch_rx {
+        if first_write_error.is_none()
+            && let Err(e) = state.apply_batch(&batch, WavWriter::new)
+        {
+            first_write_error = Some(e);
+        }
+    }
+
+    let finalize_result = state.finalize();
+    if let Some(e) = first_write_error {
+        Err(e)
+    } else {
+        finalize_result
+    }
+}
+
+/// A live multitrack recording: per-peer stems + your mic, plus an optional
+/// mixed track, all under one session directory and clocked together.
+pub struct MultitrackRecorder {
+    dir: PathBuf,
+    frame_samples: usize,
+    known_peers: HashSet<EndpointId>,
+    /// Your mic track. Fed asynchronously from the capture thread via
+    /// [`push_mic`](MultitrackRecorder::push_mic) into `mic_fifo`, then drained
+    /// one frame per `end_cycle` so it aligns with the cycle clock.
+    mic_fifo: VecDeque<i16>,
+    /// Present in "Both" mode (stems + mixed), absent in "stems only".
+    with_mix: bool,
+    batch_tx: SyncSender<CycleBatch>,
+    writer_thread: JoinHandle<io::Result<()>>,
+    dropped_cycles: u64,
+    pending: PendingCycle,
+}
+
+impl MultitrackRecorder {
+    /// Create a recording in `dir` (which must already exist). `with_mix` adds
+    /// the convenience mixed track (`mix.wav`). Your mic is always `me.wav`.
+    pub fn create(dir: &Path, frame_samples: usize, with_mix: bool) -> io::Result<Self> {
+        let writer_state = WriterState::create(dir, frame_samples, with_mix)?;
+        let (batch_tx, batch_rx) = mpsc::sync_channel(WRITER_QUEUE_CYCLES);
+        let writer_thread = thread::spawn(move || writer_thread_main(writer_state, batch_rx));
+        Ok(Self {
+            dir: dir.to_path_buf(),
+            frame_samples,
+            known_peers: HashSet::new(),
+            mic_fifo: VecDeque::new(),
+            with_mix,
+            batch_tx,
+            writer_thread,
+            dropped_cycles: 0,
+            pending: PendingCycle::default(),
         })
     }
 
@@ -167,12 +311,14 @@ impl MultitrackRecorder {
     /// so it aligns with the others. Idempotent: a peer already tracked is left
     /// as-is (re-announce / name change doesn't restart their file).
     pub fn add_peer(&mut self, id: EndpointId, name: &str) -> io::Result<()> {
-        if self.peers.contains_key(&id) {
+        if self.known_peers.contains(&id) {
             return Ok(());
         }
-        let mut track = Track::create(&self.dir.join(track_filename(name, &id)))?;
-        track.write_silence(self.cycles as usize * self.frame_samples)?;
-        self.peers.insert(id, track);
+        self.known_peers.insert(id);
+        self.pending.new_peers.push(NewPeer {
+            id,
+            filename: track_filename(name, &id),
+        });
         Ok(())
     }
 
@@ -180,11 +326,13 @@ impl MultitrackRecorder {
     /// registered yet (write raced ahead of the join event), auto-register it
     /// with an id-only name so no audio is dropped.
     pub fn write_peer(&mut self, id: EndpointId, frame: &[i16]) -> io::Result<()> {
-        if !self.peers.contains_key(&id) {
+        if !self.known_peers.contains(&id) {
             self.add_peer(id, "")?;
         }
-        let fs = self.frame_samples;
-        self.peers.get_mut(&id).unwrap().write_frame(frame, fs)
+        self.pending
+            .peer_frames
+            .insert(id, fit(frame, self.frame_samples));
+        Ok(())
     }
 
     /// Buffer a frame of your transmitted mic audio (called from the capture
@@ -209,9 +357,8 @@ impl MultitrackRecorder {
     /// Record the finished mixed-bus frame for the current cycle (no-op in
     /// stems-only mode).
     pub fn write_mix(&mut self, frame: &[i16]) -> io::Result<()> {
-        let fs = self.frame_samples;
-        if let Some(mix) = self.mix.as_mut() {
-            mix.write_frame(frame, fs)?;
+        if self.with_mix {
+            self.pending.mix_frame = Some(fit(frame, self.frame_samples));
         }
         Ok(())
     }
@@ -224,28 +371,63 @@ impl MultitrackRecorder {
         // Mic: always one frame per cycle, drained from the FIFO (silence on
         // underrun), so it tracks the cycle clock like the peer stems.
         let mic_frame = self.drain_mic(fs);
-        self.mic.write_samples(&mic_frame)?;
-        // Peers + the optional mix track: pad any not written this cycle.
-        for track in self.peers.values_mut().chain(self.mix.as_mut()) {
-            if !track.written_this_cycle {
-                track.write_silence(fs)?;
+        let mut pending = std::mem::take(&mut self.pending);
+        pending.new_peers.sort_by(|a, b| {
+            a.filename
+                .cmp(&b.filename)
+                .then_with(|| a.id.to_string().cmp(&b.id.to_string()))
+        });
+        let batch = CycleBatch {
+            new_peers: pending.new_peers,
+            mic_frame,
+            mix_frame: if self.with_mix {
+                pending.mix_frame
+            } else {
+                None
+            },
+            peer_frames: pending.peer_frames,
+        };
+        match self.batch_tx.try_send(batch) {
+            Ok(()) => Ok(()),
+            Err(TrySendError::Full(batch)) => {
+                for peer in &batch.new_peers {
+                    self.known_peers.remove(&peer.id);
+                }
+                self.dropped_cycles = self.dropped_cycles.saturating_add(1);
+                if self.dropped_cycles == 1
+                    || self.dropped_cycles.is_multiple_of(DROP_LOG_INTERVAL_CYCLES)
+                {
+                    crate::log_msg(&format!(
+                        "multitrack recording: writer queue full; dropped {} cycle(s)",
+                        self.dropped_cycles
+                    ));
+                }
+                Ok(())
             }
-            track.written_this_cycle = false;
+            Err(TrySendError::Disconnected(_)) => Err(io::Error::new(
+                io::ErrorKind::BrokenPipe,
+                "multitrack writer thread stopped",
+            )),
         }
-        self.cycles += 1;
-        Ok(())
     }
 
     /// Finalize every track's WAV header. Consumes the recorder.
     pub fn finalize(self) -> io::Result<()> {
-        self.mic.finalize()?;
-        if let Some(mix) = self.mix {
-            mix.writer.finalize()?;
-        }
-        for (_, track) in self.peers {
-            track.writer.finalize()?;
-        }
-        Ok(())
+        let Self {
+            dir: _,
+            frame_samples: _,
+            known_peers: _,
+            mic_fifo: _,
+            with_mix: _,
+            batch_tx,
+            writer_thread,
+            dropped_cycles: _,
+            pending: _,
+        } = self;
+        drop(batch_tx);
+        writer_thread
+            .join()
+            .unwrap_or_else(|_| Err(io::Error::other("multitrack writer thread panicked")))
     }
 }
 
@@ -271,6 +453,51 @@ mod tests {
         d
     }
 
+    #[derive(Default)]
+    struct TestWriter {
+        samples: Vec<i16>,
+    }
+
+    impl SampleWriter for TestWriter {
+        fn write_samples(&mut self, samples: &[i16]) -> io::Result<()> {
+            self.samples.extend_from_slice(samples);
+            Ok(())
+        }
+
+        fn finalize(self) -> io::Result<()> {
+            Ok(())
+        }
+    }
+
+    fn test_writer_state(frame_samples: usize, with_mix: bool) -> WriterState<TestWriter> {
+        WriterState {
+            dir: PathBuf::new(),
+            frame_samples,
+            peers: HashMap::new(),
+            mic: TestWriter::default(),
+            mix: if with_mix {
+                Some(TestWriter::default())
+            } else {
+                None
+            },
+            cycles_written: 0,
+        }
+    }
+
+    fn test_batch(
+        new_peers: Vec<NewPeer>,
+        mic_frame: Vec<i16>,
+        mix_frame: Option<Vec<i16>>,
+        peer_frames: Vec<(EndpointId, Vec<i16>)>,
+    ) -> CycleBatch {
+        CycleBatch {
+            new_peers,
+            mic_frame,
+            mix_frame,
+            peer_frames: peer_frames.into_iter().collect(),
+        }
+    }
+
     #[test]
     fn fit_pads_and_truncates() {
         assert_eq!(fit(&[1, 2], 4), vec![1, 2, 0, 0]);
@@ -284,7 +511,10 @@ mod tests {
         let short: String = id.to_string().chars().take(8).collect();
         assert_eq!(track_filename("Alice", &id), format!("alice-{short}.wav"));
         // Spaces / punctuation collapse to single dashes, trimmed.
-        assert_eq!(track_filename("  Bob the Builder! ", &id), format!("bob-the-builder-{short}.wav"));
+        assert_eq!(
+            track_filename("  Bob the Builder! ", &id),
+            format!("bob-the-builder-{short}.wav")
+        );
         // A name that sanitizes/slugs to nothing falls back to "peer".
         assert_eq!(track_filename("!!!", &id), format!("peer-{short}.wav"));
     }
@@ -302,6 +532,110 @@ mod tests {
         let _ = std::fs::remove_dir_all(&base);
     }
 
+    #[test]
+    fn apply_batch_advances_existing_tracks_and_back_pads_late_peer() {
+        let frame = 3;
+        let early = an_id();
+        let late = an_id();
+        let mut state = test_writer_state(frame, true);
+        state.cycles_written = 2;
+        state.mic.samples = vec![8; 2 * frame];
+        state.mix.as_mut().unwrap().samples = vec![6; 2 * frame];
+        state.peers.insert(
+            early,
+            TestWriter {
+                samples: vec![1; 2 * frame],
+            },
+        );
+
+        let batch = test_batch(
+            vec![NewPeer {
+                id: late,
+                filename: "late.wav".to_string(),
+            }],
+            vec![9; frame],
+            None,
+            vec![(early, vec![2; frame]), (late, vec![7; frame])],
+        );
+        state
+            .apply_batch(&batch, |_| Ok(TestWriter::default()))
+            .unwrap();
+
+        assert_eq!(state.cycles_written, 3);
+        assert_eq!(state.mic.samples.len(), 3 * frame);
+        assert_eq!(state.mix.as_ref().unwrap().samples.len(), 3 * frame);
+        assert_eq!(
+            &state.mix.as_ref().unwrap().samples[2 * frame..],
+            &[0, 0, 0]
+        );
+        assert_eq!(state.peers.get(&early).unwrap().samples.len(), 3 * frame);
+        assert_eq!(
+            &state.peers.get(&early).unwrap().samples[2 * frame..],
+            &[2, 2, 2]
+        );
+        assert_eq!(
+            state.peers.get(&late).unwrap().samples,
+            vec![0, 0, 0, 0, 0, 0, 7, 7, 7],
+            "late peer is back-padded by completed cycles before this batch"
+        );
+    }
+
+    #[test]
+    fn skipped_batches_keep_all_tracks_equal_length() {
+        let frame = 2;
+        let p1 = an_id();
+        let p2 = an_id();
+        let mut state = test_writer_state(frame, true);
+
+        let first = test_batch(
+            vec![
+                NewPeer {
+                    id: p1,
+                    filename: "p1.wav".to_string(),
+                },
+                NewPeer {
+                    id: p2,
+                    filename: "p2.wav".to_string(),
+                },
+            ],
+            vec![1; frame],
+            Some(vec![5; frame]),
+            vec![(p1, vec![10; frame]), (p2, vec![20; frame])],
+        );
+        state
+            .apply_batch(&first, |_| Ok(TestWriter::default()))
+            .unwrap();
+
+        let _dropped_cycle = test_batch(
+            Vec::new(),
+            vec![2; frame],
+            Some(vec![6; frame]),
+            vec![(p1, vec![11; frame])],
+        );
+
+        let after_drop = test_batch(
+            Vec::new(),
+            vec![3; frame],
+            None,
+            vec![(p1, vec![12; frame])],
+        );
+        state
+            .apply_batch(&after_drop, |_| Ok(TestWriter::default()))
+            .unwrap();
+
+        let expected = 2 * frame;
+        assert_eq!(state.cycles_written, 2);
+        assert_eq!(state.mic.samples.len(), expected);
+        assert_eq!(state.mix.as_ref().unwrap().samples.len(), expected);
+        assert_eq!(state.peers.get(&p1).unwrap().samples.len(), expected);
+        assert_eq!(state.peers.get(&p2).unwrap().samples.len(), expected);
+        assert_eq!(
+            &state.peers.get(&p2).unwrap().samples[frame..],
+            &[0, 0],
+            "peer absent from an applied batch gets silence for that cycle"
+        );
+    }
+
     #[test]
     fn all_tracks_equal_length_after_n_cycles() {
         let dir = tmpdir("equal");
@@ -327,10 +661,18 @@ mod tests {
         rec.finalize().unwrap();
 
         let expected = 3 * frame;
-        assert_eq!(wav_samples(&dir.join("me.wav")), expected, "mic padded to full length");
+        assert_eq!(
+            wav_samples(&dir.join("me.wav")),
+            expected,
+            "mic padded to full length"
+        );
         assert_eq!(wav_samples(&dir.join("mix.wav")), expected);
         assert_eq!(wav_samples(&dir.join(track_filename("p1", &p1))), expected);
-        assert_eq!(wav_samples(&dir.join(track_filename("p2", &p2))), expected, "silent peer still full length");
+        assert_eq!(
+            wav_samples(&dir.join(track_filename("p2", &p2))),
+            expected,
+            "silent peer still full length"
+        );
     }
 
     #[test]
@@ -357,8 +699,14 @@ mod tests {
         rec.finalize().unwrap();
 
         // Both tracks are the full 5 cycles long (late one was back-padded).
-        assert_eq!(wav_samples(&dir.join(track_filename("early", &early))), 5 * frame);
-        assert_eq!(wav_samples(&dir.join(track_filename("late", &late))), 5 * frame);
+        assert_eq!(
+            wav_samples(&dir.join(track_filename("early", &early))),
+            5 * frame
+        );
+        assert_eq!(
+            wav_samples(&dir.join(track_filename("late", &late))),
+            5 * frame
+        );
 
         // The late track's first 2 cycles are silence, then the real audio.
         let bytes = std::fs::read(dir.join(track_filename("late", &late))).unwrap();
@@ -378,6 +726,28 @@ mod tests {
         rec.end_cycle().unwrap();
         rec.finalize().unwrap();
         assert!(dir.join("me.wav").exists());
-        assert!(!dir.join("mix.wav").exists(), "no mix track in stems-only mode");
+        assert!(
+            !dir.join("mix.wav").exists(),
+            "no mix track in stems-only mode"
+        );
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn async_peer_create_error_surfaces_at_finalize() {
+        use std::os::unix::fs::PermissionsExt;
+
+        let dir = tmpdir("asyncerr");
+        let mut rec = MultitrackRecorder::create(&dir, 4, false).unwrap();
+        std::fs::set_permissions(&dir, std::fs::Permissions::from_mode(0o500)).unwrap();
+
+        rec.add_peer(an_id(), "blocked").unwrap();
+        rec.end_cycle().unwrap();
+        let result = rec.finalize();
+
+        std::fs::set_permissions(&dir, std::fs::Permissions::from_mode(0o700)).unwrap();
+        let err = result.unwrap_err();
+        assert_eq!(err.kind(), io::ErrorKind::PermissionDenied);
+        let _ = std::fs::remove_dir_all(&dir);
     }
 }

src/audio/pan.rs

@@ -23,7 +23,10 @@ pub fn pan_gains(pan: f32) -> (f32, f32) {
 /// still following the same equal-power curve as a peer is moved away from center.
 pub fn playback_pan_gains(pan: f32) -> (f32, f32) {
     let (left, right) = pan_gains(pan);
-    (left * std::f32::consts::SQRT_2, right * std::f32::consts::SQRT_2)
+    (
+        left * std::f32::consts::SQRT_2,
+        right * std::f32::consts::SQRT_2,
+    )
 }
 
 #[cfg(test)]
@@ -36,8 +39,14 @@ mod tests {
     fn hard_left_and_right_are_endpoints() {
         assert_eq!(pan_gains(-1.0), (1.0, 0.0));
         let (l, r) = pan_gains(1.0);
-        assert!(l.abs() < EPS, "left at hard-right should be zero-ish, got {l}");
-        assert!((r - 1.0).abs() < EPS, "right at hard-right should be one, got {r}");
+        assert!(
+            l.abs() < EPS,
+            "left at hard-right should be zero-ish, got {l}"
+        );
+        assert!(
+            (r - 1.0).abs() < EPS,
+            "right at hard-right should be one, got {r}"
+        );
     }
 
     #[test]
@@ -55,8 +64,14 @@ mod tests {
         let mut prev_r = f32::NEG_INFINITY;
         for pan in pans {
             let (l, r) = pan_gains(pan);
-            assert!(l <= prev_l + EPS, "left gain must not rise as pan moves right");
-            assert!(r >= prev_r - EPS, "right gain must not fall as pan moves right");
+            assert!(
+                l <= prev_l + EPS,
+                "left gain must not rise as pan moves right"
+            );
+            assert!(
+                r >= prev_r - EPS,
+                "right gain must not fall as pan moves right"
+            );
             prev_l = l;
             prev_r = r;
         }

src/audio/pipewire_impl.rs

@@ -1,13 +1,16 @@
 use crate::audio::{AudioBackend, AudioError};
-use std::sync::mpsc::{Sender, Receiver, RecvTimeoutError};
-use std::sync::{Arc, Mutex};
-use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
-use std::thread::{self, JoinHandle};
-use std::time::Duration;
 use pipewire as pw;
 use pw::{properties::properties, spa};
+use ringbuf::{
+    HeapRb,
+    traits::{Consumer, Producer, Split},
+};
 use spa::pod::Pod;
-use ringbuf::{HeapRb, traits::{Consumer, Producer, Split}};
+use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
+use std::sync::mpsc::{Receiver, RecvTimeoutError, Sender};
+use std::sync::{Arc, Mutex};
+use std::thread::{self, JoinHandle};
+use std::time::Duration;
 
 pub struct PipeWireBackend {
     capture_state: Mutex<Option<CaptureState>>,
@@ -41,7 +44,11 @@ impl PipeWireBackend {
 }
 
 impl AudioBackend for PipeWireBackend {
-    fn start_capture(&self, tx: Sender<Vec<i16>>, target_node: Option<String>) -> Result<(), AudioError> {
+    fn start_capture(
+        &self,
+        tx: Sender<Vec<i16>>,
+        target_node: Option<String>,
+    ) -> Result<(), AudioError> {
         let mut capture_guard = self.capture_state.lock().unwrap();
         if capture_guard.is_some() {
             return Err(AudioError::Stream("Capture already started".to_string()));
@@ -108,12 +115,17 @@ impl AudioBackend for PipeWireBackend {
     }
 }
 
-fn run_capture(cmd_rx: pw::channel::Receiver<()>, tx: Sender<Vec<i16>>, target_node: Option<String>) -> Result<(), AudioError> {
-    let mainloop = pw::main_loop::MainLoopRc::new(None)
-        .map_err(|e| AudioError::Init(e.to_string()))?;
+fn run_capture(
+    cmd_rx: pw::channel::Receiver<()>,
+    tx: Sender<Vec<i16>>,
+    target_node: Option<String>,
+) -> Result<(), AudioError> {
+    let mainloop =
+        pw::main_loop::MainLoopRc::new(None).map_err(|e| AudioError::Init(e.to_string()))?;
     let context = pw::context::ContextRc::new(&mainloop, None)
         .map_err(|e| AudioError::Init(e.to_string()))?;
-    let core = context.connect_rc(None)
+    let core = context
+        .connect_rc(None)
         .map_err(|e| AudioError::Init(e.to_string()))?;
 
     // Ring buffer setup: 9600 samples (200ms capacity for mono 48kHz)
@@ -181,15 +193,16 @@ fn run_capture(cmd_rx: pw::channel::Receiver<()>, tx: Sender<Vec<i16>>, target_n
 
     let mut params = [Pod::from_bytes(&values).unwrap()];
 
-    stream.connect(
-        spa::utils::Direction::Input,
-        None,
-        pw::stream::StreamFlags::AUTOCONNECT
-            | pw::stream::StreamFlags::MAP_BUFFERS
-            | pw::stream::StreamFlags::RT_PROCESS,
-        &mut params,
-    )
-    .map_err(|e| AudioError::Stream(e.to_string()))?;
+    stream
+        .connect(
+            spa::utils::Direction::Input,
+            None,
+            pw::stream::StreamFlags::AUTOCONNECT
+                | pw::stream::StreamFlags::MAP_BUFFERS
+                | pw::stream::StreamFlags::RT_PROCESS,
+            &mut params,
+        )
+        .map_err(|e| AudioError::Stream(e.to_string()))?;
 
     // Spawn the worker thread to pop from consumer and send Vec<i16> frames
     let running = Arc::new(AtomicBool::new(true));
@@ -257,11 +270,7 @@ const WORKER_POLL: Duration = Duration::from_millis(100);
 /// every `WORKER_POLL` even when no frames arrive — this is what lets `stop()`
 /// join the worker promptly instead of hanging on a parked blocking `recv()`
 /// (bug A7). Pure w.r.t. its inputs (no PipeWire), so it's unit-testable.
-fn drain_loop(
-    rx: &Receiver<Vec<i16>>,
-    running: &AtomicBool,
-    mut on_frame: impl FnMut(Vec<i16>),
-) {
+fn drain_loop(rx: &Receiver<Vec<i16>>, running: &AtomicBool, mut on_frame: impl FnMut(Vec<i16>)) {
     while running.load(Ordering::Relaxed) {
         match rx.recv_timeout(WORKER_POLL) {
             Ok(frame) => on_frame(frame),
@@ -293,7 +302,11 @@ fn publish_frame<P: Producer<Item = i16>>(
 fn frames_to_produce(requested: usize, mapped_frames: usize) -> usize {
     /// Safe per-cycle fallback when the graph doesn't report a quantum.
     const FALLBACK_FRAMES: usize = 1024;
-    let want = if requested > 0 { requested } else { FALLBACK_FRAMES };
+    let want = if requested > 0 {
+        requested
+    } else {
+        FALLBACK_FRAMES
+    };
     want.min(mapped_frames)
 }
 
@@ -303,11 +316,12 @@ fn run_playback(
     target_node: Option<String>,
     fill_gauge: Arc<AtomicUsize>,
 ) -> Result<(), AudioError> {
-    let mainloop = pw::main_loop::MainLoopRc::new(None)
-        .map_err(|e| AudioError::Init(e.to_string()))?;
+    let mainloop =
+        pw::main_loop::MainLoopRc::new(None).map_err(|e| AudioError::Init(e.to_string()))?;
     let context = pw::context::ContextRc::new(&mainloop, None)
         .map_err(|e| AudioError::Init(e.to_string()))?;
-    let core = context.connect_rc(None)
+    let core = context
+        .connect_rc(None)
         .map_err(|e| AudioError::Init(e.to_string()))?;
 
     // Ring buffer setup: 19200 interleaved samples (200ms capacity for stereo
@@ -428,7 +442,9 @@ fn run_playback(
                         }
                         if starved > 0 {
                             // One wait-free atomic add per quantum — RT-safe.
-                            user_data.underrun_samples.fetch_add(starved, Ordering::Relaxed);
+                            user_data
+                                .underrun_samples
+                                .fetch_add(starved, Ordering::Relaxed);
                         }
                         // Decrement the exact occupancy counter by the samples we
                         // actually pulled (excluding underruns, which removed
@@ -493,7 +509,11 @@ fn run_playback(
                 pw::spa::pod::Value::Choice(pw::spa::pod::ChoiceValue::Int(
                     pw::spa::utils::Choice(
                         pw::spa::utils::ChoiceFlags::empty(),
-                        pw::spa::utils::ChoiceEnum::Range { default: 8, min: 2, max: 64 },
+                        pw::spa::utils::ChoiceEnum::Range {
+                            default: 8,
+                            min: 2,
+                            max: 64,
+                        },
                     ),
                 )),
             ),
@@ -524,15 +544,16 @@ fn run_playback(
         Pod::from_bytes(&buffers_values).unwrap(),
     ];
 
-    stream.connect(
-        spa::utils::Direction::Output,
-        None,
-        pw::stream::StreamFlags::AUTOCONNECT
-            | pw::stream::StreamFlags::MAP_BUFFERS
-            | pw::stream::StreamFlags::RT_PROCESS,
-        &mut params,
-    )
-    .map_err(|e| AudioError::Stream(e.to_string()))?;
+    stream
+        .connect(
+            spa::utils::Direction::Output,
+            None,
+            pw::stream::StreamFlags::AUTOCONNECT
+                | pw::stream::StreamFlags::MAP_BUFFERS
+                | pw::stream::StreamFlags::RT_PROCESS,
+            &mut params,
+        )
+        .map_err(|e| AudioError::Stream(e.to_string()))?;
 
     // Spawn a worker thread to read from rx and push to producer
     let running = Arc::new(AtomicBool::new(true));
@@ -607,7 +628,10 @@ fn run_playback(
 #[cfg(test)]
 mod tests {
     use super::{drain_loop, for_each_capture_sample, frames_to_produce, publish_frame};
-    use ringbuf::{HeapRb, traits::{Consumer, Producer, Split}};
+    use ringbuf::{
+        HeapRb,
+        traits::{Consumer, Producer, Split},
+    };
     use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
     use std::sync::{Arc, Mutex};
     use std::time::Duration;
@@ -647,9 +671,7 @@ mod tests {
     #[test]
     fn capture_size_larger_than_mapping_is_clamped() {
         let mut samples = Vec::new();
-        for_each_capture_sample(&[1, 0, 2, 0, 3], usize::MAX, |sample| {
-            samples.push(sample)
-        });
+        for_each_capture_sample(&[1, 0, 2, 0, 3], usize::MAX, |sample| samples.push(sample));
         assert_eq!(samples, vec![1, 2]);
     }
 

src/audio/pw_cli.rs

@@ -16,11 +16,20 @@ pub fn enumerate_audio_devices() -> Vec<AudioDevice> {
 /// Emits the in-progress node as an `AudioDevice` if it's a complete Audio/*
 /// node, then resets the accumulators for the next block. Non-audio or
 /// incomplete blocks are dropped (but still reset).
-fn push_device(name: &mut String, desc: &mut String, class: &mut String, out: &mut Vec<AudioDevice>) {
+fn push_device(
+    name: &mut String,
+    desc: &mut String,
+    class: &mut String,
+    out: &mut Vec<AudioDevice>,
+) {
     if !name.is_empty() && class.starts_with("Audio/") {
         out.push(AudioDevice {
             name: name.clone(),
-            description: if desc.is_empty() { name.clone() } else { desc.clone() },
+            description: if desc.is_empty() {
+                name.clone()
+            } else {
+                desc.clone()
+            },
             is_input: class == "Audio/Source",
         });
     }
@@ -44,7 +53,12 @@ fn parse_pw_nodes(text: &str) -> Vec<AudioDevice> {
     for line in text.lines() {
         let line = line.trim();
         if line.starts_with("id ") {
-            push_device(&mut current_name, &mut current_desc, &mut current_class, &mut devices);
+            push_device(
+                &mut current_name,
+                &mut current_desc,
+                &mut current_class,
+                &mut devices,
+            );
         } else if let Some(val) = line.strip_prefix("node.name = \"") {
             current_name = val.trim_end_matches('"').to_string();
         } else if let Some(val) = line.strip_prefix("node.description = \"") {
@@ -53,7 +67,12 @@ fn parse_pw_nodes(text: &str) -> Vec<AudioDevice> {
             current_class = val.trim_end_matches('"').to_string();
         }
     }
-    push_device(&mut current_name, &mut current_desc, &mut current_class, &mut devices);
+    push_device(
+        &mut current_name,
+        &mut current_desc,
+        &mut current_class,
+        &mut devices,
+    );
 
     devices.sort_by(|a, b| a.description.cmp(&b.description));
     devices
@@ -108,8 +127,14 @@ mod tests {
     fn source_is_input_sink_is_output() {
         let devices = parse_pw_nodes(SAMPLE_NODES);
         // Find devices by name or description to verify is_input
-        let mic = devices.iter().find(|d| d.name == "alsa_input.builtin").unwrap();
-        let speakers = devices.iter().find(|d| d.name == "alsa_output.builtin").unwrap();
+        let mic = devices
+            .iter()
+            .find(|d| d.name == "alsa_input.builtin")
+            .unwrap();
+        let speakers = devices
+            .iter()
+            .find(|d| d.name == "alsa_output.builtin")
+            .unwrap();
         let bare = devices.iter().find(|d| d.name == "bare.sink").unwrap();
 
         assert!(mic.is_input);

src/audio/recorder.rs

@@ -2,21 +2,26 @@
 //!
 //! Records the **full call as you experienced it**: the mixed incoming audio
 //! (everyone you hear) summed with your own transmitted mic, into a single mono
-//! WAV. Writing is driven by the playout mixer (one [`Recorder::write_frame`]
-//! per produced 20ms frame, paced by the hardware clock); your mic arrives
-//! separately from the capture thread via [`Recorder::push_mic`] and is buffered
-//! in a small FIFO so the two independently-clocked streams stay roughly aligned.
+//! WAV. Mixing/enqueue is driven by the playout mixer (one
+//! [`Recorder::write_frame`] per produced 20ms frame, paced by the hardware
+//! clock), while disk writes happen on a dedicated writer thread; your mic
+//! arrives separately from the capture thread via [`Recorder::push_mic`] and is
+//! buffered in a small FIFO so the two independently-clocked streams stay
+//! roughly aligned.
 //! Minor clock drift just slowly grows/shrinks that FIFO (capped, so the lag
 //! between your voice and the recording is bounded) — harmless for a voice
 //! recording, no realtime crackle concern.
 //!
 //! No external crates: the WAV writer emits the 44-byte canonical header itself
-//! and patches the two size fields on [`Recorder::finalize`].
+//! and patches the two size fields on the writer thread during
+//! [`Recorder::finalize`].
 
 use std::collections::VecDeque;
 use std::fs::{File, OpenOptions};
 use std::io::{self, Seek, SeekFrom, Write};
 use std::path::{Path, PathBuf};
+use std::sync::mpsc::{self, SyncSender, TrySendError};
+use std::thread::{self, JoinHandle};
 
 /// Capture sample rate (mono, 48kHz, matching the rest of the audio path).
 const SAMPLE_RATE: u32 = 48_000;
@@ -25,6 +30,8 @@ const CHANNELS: u16 = 1;
 const RIFF_DATA_OVERHEAD: u64 = 36;
 const MAX_RIFF_DATA_BYTES: u64 = u32::MAX as u64 - RIFF_DATA_OVERHEAD;
 const MAX_NAME_ATTEMPTS: usize = 1_000;
+const WRITER_QUEUE_FRAMES: usize = 256;
+const DROP_LOG_INTERVAL_FRAMES: u64 = 256;
 
 /// Cap on buffered mic samples (~200ms). Bounds how far recording lag can drift
 /// if the capture clock runs persistently faster than playout — past this we drop
@@ -118,13 +125,15 @@ impl WavWriter {
     }
 }
 
-/// A live call recorder: a [`WavWriter`] plus a small mic FIFO that aligns your
-/// transmitted mic with the playout mixer's incoming-mix frames.
+/// A live call recorder: a writer-thread queue plus a small mic FIFO that aligns
+/// your transmitted mic with the playout mixer's incoming-mix frames.
 pub struct Recorder {
-    writer: WavWriter,
+    frame_tx: SyncSender<Vec<i16>>,
+    writer_thread: JoinHandle<io::Result<()>>,
     /// Your transmitted mic samples, awaiting alignment with the next mix frame.
     mic_fifo: VecDeque<i16>,
     path: PathBuf,
+    dropped_frames: u64,
 }
 
 impl Recorder {
@@ -142,10 +151,15 @@ impl Recorder {
             let path = dir.join(name);
             match OpenOptions::new().write(true).create_new(true).open(&path) {
                 Ok(file) => {
+                    let writer = WavWriter::from_file(file)?;
+                    let (frame_tx, frame_rx) = mpsc::sync_channel(WRITER_QUEUE_FRAMES);
+                    let writer_thread = thread::spawn(move || writer_thread_main(writer, frame_rx));
                     return Ok(Self {
-                        writer: WavWriter::from_file(file)?,
+                        frame_tx,
+                        writer_thread,
                         mic_fifo: VecDeque::new(),
                         path,
+                        dropped_frames: 0,
                     });
                 }
                 Err(e) if e.kind() == io::ErrorKind::AlreadyExists => continue,
@@ -179,21 +193,73 @@ impl Recorder {
     /// treated as silence (you weren't transmitting), so quiet stretches record
     /// the incoming mix alone.
     pub fn write_frame(&mut self, mixed: &[i16]) -> io::Result<()> {
-        let mut out = Vec::with_capacity(mixed.len());
-        for &m in mixed {
-            let mic = self.mic_fifo.pop_front().unwrap_or(0);
-            let sum = (m as i32 + mic as i32).clamp(i16::MIN as i32, i16::MAX as i32);
-            out.push(sum as i16);
+        let out = mix_with_mic(mixed, &mut self.mic_fifo);
+        match self.frame_tx.try_send(out) {
+            Ok(()) => Ok(()),
+            Err(TrySendError::Full(_)) => {
+                self.dropped_frames = self.dropped_frames.saturating_add(1);
+                if self.dropped_frames == 1
+                    || self.dropped_frames.is_multiple_of(DROP_LOG_INTERVAL_FRAMES)
+                {
+                    crate::log_msg(&format!(
+                        "recording: writer queue full; dropped {} frame(s)",
+                        self.dropped_frames
+                    ));
+                }
+                Ok(())
+            }
+            Err(TrySendError::Disconnected(_)) => Err(io::Error::new(
+                io::ErrorKind::BrokenPipe,
+                "recording writer thread stopped",
+            )),
         }
-        self.writer.write_samples(&out)
     }
 
     /// Finish the file, patching its size fields. Consumes the recorder.
     pub fn finalize(self) -> io::Result<()> {
-        self.writer.finalize()
+        let Self {
+            frame_tx,
+            writer_thread,
+            mic_fifo: _,
+            path: _,
+            dropped_frames: _,
+        } = self;
+        drop(frame_tx);
+        writer_thread
+            .join()
+            .unwrap_or_else(|_| Err(io::Error::other("recording writer thread panicked")))
     }
 }
 
+fn writer_thread_main(mut writer: WavWriter, frame_rx: mpsc::Receiver<Vec<i16>>) -> io::Result<()> {
+    let mut first_write_error = None;
+
+    for frame in frame_rx {
+        if first_write_error.is_none()
+            && let Err(e) = writer.write_samples(&frame)
+        {
+            first_write_error = Some(e);
+        }
+    }
+
+    let finalize_result = writer.finalize();
+    if let Some(e) = first_write_error {
+        Err(e)
+    } else {
+        finalize_result
+    }
+}
+
+fn mix_with_mic(mixed: &[i16], mic_fifo: &mut VecDeque<i16>) -> Vec<i16> {
+    let mut out = Vec::with_capacity(mixed.len());
+    for &m in mixed {
+        let mic = mic_fifo.pop_front().unwrap_or(0);
+        let sum = (m as i32 + mic as i32).clamp(i16::MIN as i32, i16::MAX as i32);
+        out.push(sum as i16);
+    }
+    out
+}
+
 /// Civil date (year, month, day) from a count of days since the Unix epoch.
 /// Howard Hinnant's `civil_from_days`; valid across the whole practical range.
 fn civil_from_days(z: i64) -> (i64, u32, u32) {
@@ -222,6 +288,23 @@ pub fn timestamp_filename(unix_secs: u64) -> String {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::sync::atomic::{AtomicU64, Ordering};
+
+    static NEXT_TEMP_ID: AtomicU64 = AtomicU64::new(0);
+
+    fn unique_temp_dir(prefix: &str) -> PathBuf {
+        let id = NEXT_TEMP_ID.fetch_add(1, Ordering::Relaxed);
+        std::env::temp_dir().join(format!("{prefix}-{}-{id}", std::process::id()))
+    }
+
+    fn read_wav_samples(path: &Path) -> (Vec<u8>, Vec<i16>) {
+        let bytes = std::fs::read(path).unwrap();
+        let samples = bytes[44..]
+            .chunks_exact(2)
+            .map(|sample| i16::from_le_bytes([sample[0], sample[1]]))
+            .collect();
+        (bytes, samples)
+    }
 
     #[test]
     fn timestamp_filename_is_utc_and_padded() {
@@ -236,10 +319,7 @@ mod tests {
 
     #[test]
     fn same_second_recordings_get_unique_files_without_truncation() {
-        let dir = std::env::temp_dir().join(format!(
-            "peerspeak-collision-{}",
-            std::process::id()
-        ));
+        let dir = unique_temp_dir("peerspeak-collision");
         let _ = std::fs::remove_dir_all(&dir);
         std::fs::create_dir_all(&dir).unwrap();
 
@@ -258,6 +338,40 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    #[test]
+    fn recorder_thread_writes_mixed_samples_and_header_on_finalize() {
+        let dir = unique_temp_dir("peerspeak-recorder-thread");
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+
+        let mut recorder = Recorder::create(&dir, 1_700_000_123).unwrap();
+        let path = recorder.path().to_path_buf();
+
+        recorder.push_mic(&[1000, i16::MAX, -1000, i16::MIN, 2222]);
+        recorder.write_frame(&[10, 20, -32700]).unwrap();
+        recorder.push_mic(&[300, -300]);
+        recorder
+            .write_frame(&[0, 1000, i16::MAX, i16::MIN])
+            .unwrap();
+        recorder.finalize().unwrap();
+
+        let expected = vec![1010, i16::MAX, i16::MIN, i16::MIN, 3222, i16::MAX, i16::MIN];
+        let expected_data_bytes = u32::try_from(expected.len() * 2).unwrap();
+        let (bytes, samples) = read_wav_samples(&path);
+
+        assert_eq!(&bytes[0..4], b"RIFF");
+        assert_eq!(&bytes[8..12], b"WAVE");
+        assert_eq!(&bytes[36..40], b"data");
+        let riff = u32::from_le_bytes([bytes[4], bytes[5], bytes[6], bytes[7]]);
+        let data = u32::from_le_bytes([bytes[40], bytes[41], bytes[42], bytes[43]]);
+        assert_eq!(data, expected_data_bytes);
+        assert_eq!(riff, RIFF_DATA_OVERHEAD as u32 + expected_data_bytes);
+        assert_eq!(bytes.len(), 44 + expected.len() * 2);
+        assert_eq!(samples, expected);
+
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     fn wav_header_round_trips_sizes() {
         let dir = std::env::temp_dir();
@@ -300,38 +414,32 @@ mod tests {
 
     #[test]
     fn mic_is_summed_with_mix_when_present() {
-        let dir = std::env::temp_dir();
-        let mut r = Recorder {
-            writer: WavWriter::new(&dir.join(format!("ps-sum-{}.wav", std::process::id())))
-                .unwrap(),
-            mic_fifo: VecDeque::new(),
-            path: PathBuf::new(),
-        };
-        r.push_mic(&[1000, 2000, 3000]);
-        // write_frame pops mic per-sample and sums; we can't read the file mid-stream,
-        // so assert the FIFO drains exactly by frame length.
-        r.write_frame(&[10, 20]).unwrap();
-        assert_eq!(r.mic_fifo.len(), 1, "two samples consumed, one mic left");
-        r.write_frame(&[0, 0]).unwrap();
+        let mut mic_fifo = VecDeque::from([1000, 2000, 3000]);
+
+        let first = mix_with_mic(&[10, 20], &mut mic_fifo);
+        assert_eq!(first, vec![1010, 2020]);
+        assert_eq!(mic_fifo.len(), 1, "two samples consumed, one mic left");
+
+        let second = mix_with_mic(&[0, 0], &mut mic_fifo);
+        assert_eq!(second, vec![3000, 0]);
         assert_eq!(
-            r.mic_fifo.len(),
+            mic_fifo.len(),
             0,
             "remaining mic sample consumed; rest is silence"
         );
-        let _ = r.finalize();
     }
 
     #[test]
     fn mic_fifo_is_capped() {
-        let dir = std::env::temp_dir();
-        let mut r = Recorder {
-            writer: WavWriter::new(&dir.join(format!("ps-cap-{}.wav", std::process::id())))
-                .unwrap(),
-            mic_fifo: VecDeque::new(),
-            path: PathBuf::new(),
-        };
+        let dir = unique_temp_dir("peerspeak-cap");
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+
+        let mut r = Recorder::create(&dir, 1_700_000_001).unwrap();
         r.push_mic(&vec![5i16; MAX_MIC_FIFO * 2]);
         assert_eq!(r.mic_fifo.len(), MAX_MIC_FIFO, "FIFO is bounded to the cap");
-        let _ = r.finalize();
+        r.finalize().unwrap();
+
+        let _ = std::fs::remove_dir_all(&dir);
     }
 }

src/audio/resample.rs

@@ -145,7 +145,10 @@ impl StereoPullResampler {
             self.frac -= 1.0;
         }
         let f = self.frac as f32;
-        let out = (lerp(self.prev.0, self.cur.0, f), lerp(self.prev.1, self.cur.1, f));
+        let out = (
+            lerp(self.prev.0, self.cur.0, f),
+            lerp(self.prev.1, self.cur.1, f),
+        );
         self.frac += self.step;
         Some(out)
     }
@@ -273,7 +276,10 @@ mod tests {
             }
         }
         // At step 2.0 we consume ~2 input frames per output frame.
-        assert!(idx > emitted, "consumed {idx} input, emitted {emitted} output");
+        assert!(
+            idx > emitted,
+            "consumed {idx} input, emitted {emitted} output"
+        );
     }
 
     /// A zero rate must not produce a zero `step` (which would spin `push`'s inner

src/avatar.rs

@@ -206,7 +206,10 @@ pub struct ByteLru<V> {
 impl<V: Clone> ByteLru<V> {
     /// Create an LRU holding at most `cap` entries (`cap` is clamped to >= 1).
     pub fn new(cap: usize) -> Self {
-        Self { cap: cap.max(1), entries: Vec::new() }
+        Self {
+            cap: cap.max(1),
+            entries: Vec::new(),
+        }
     }
 
     /// Return the cached value for these exact `bytes`, building and inserting it
@@ -349,7 +352,10 @@ mod tests {
     fn preset_png_in_range_and_out_of_range() {
         // Every declared preset index resolves to embedded bytes.
         for i in 0..PRESET_COUNT {
-            assert!(Avatar::Preset(i).preset_png().is_some(), "preset {i} missing");
+            assert!(
+                Avatar::Preset(i).preset_png().is_some(),
+                "preset {i} missing"
+            );
         }
         // Out-of-range index gracefully yields None (→ monogram fallback).
         assert!(Avatar::Preset(PRESET_COUNT).preset_png().is_none());
@@ -406,7 +412,10 @@ mod tests {
     #[test]
     fn sanitize_incoming_rejects_junk_and_oversize() {
         // Not valid base64 / not a PNG → downgraded to monogram.
-        assert_eq!(Avatar::Custom("not base64!!!".into()).sanitize_incoming(), Avatar::Monogram);
+        assert_eq!(
+            Avatar::Custom("not base64!!!".into()).sanitize_incoming(),
+            Avatar::Monogram
+        );
         // Over the byte cap → downgraded without even decoding.
         let huge = Avatar::Custom("A".repeat(CUSTOM_MAX_B64 + 1));
         assert_eq!(huge.sanitize_incoming(), Avatar::Monogram);

src/background.rs

@@ -66,7 +66,10 @@ pub fn game_background_filename(game_id: &str) -> String {
 /// recedes the image so body text and panel chrome stay readable, and it re-tints
 /// per theme since `base` comes from the active palette.
 pub fn scrim_color(base: Color, dim: f32) -> Color {
-    Color { a: dim.clamp(0.0, 1.0), ..base }
+    Color {
+        a: dim.clamp(0.0, 1.0),
+        ..base
+    }
 }
 
 #[cfg(test)]

src/bin/specview.rs

@@ -105,7 +105,11 @@ fn cmd_gen(args: &[String]) -> Result<(), String> {
         "pink" => generators::pink_noise(amp, len, seed),
         "impulse" => generators::impulse(amp, len),
         "silence" => generators::silence(len),
-        other => return Err(format!("unknown kind {other:?} (sine sweep white pink impulse silence)")),
+        other => {
+            return Err(format!(
+                "unknown kind {other:?} (sine sweep white pink impulse silence)"
+            ));
+        }
     };
 
     wav::write(Path::new(out), &samples, SAMPLE_RATE)?;
@@ -125,8 +129,12 @@ fn cmd_gen(args: &[String]) -> Result<(), String> {
 /// in which frequency range any residual lives.
 fn cmd_erle(args: &[String]) -> Result<(), String> {
     let (positional, flags) = parse_args(args);
-    let before = positional.first().ok_or("erle needs <before.wav> <after.wav>")?;
-    let after = positional.get(1).ok_or("erle needs <before.wav> <after.wav>")?;
+    let before = positional
+        .first()
+        .ok_or("erle needs <before.wav> <after.wav>")?;
+    let after = positional
+        .get(1)
+        .ok_or("erle needs <before.wav> <after.wav>")?;
 
     let b = wav::read(Path::new(before))?;
     let a = wav::read(Path::new(after))?;
@@ -239,17 +247,34 @@ fn cmd_aec(args: &[String]) -> Result<(), String> {
         1000.0 * tail as f32 / sr as f32,
         metrics::dbfs(atten),
     );
-    println!("  filter: {taps} taps, mu {mu}{}", if has_near { " (with near-end / double-talk)" } else { "" });
+    println!(
+        "  filter: {taps} taps, mu {mu}{}",
+        if has_near {
+            " (with near-end / double-talk)"
+        } else {
+            ""
+        }
+    );
     if has_near {
         let dtd = if flags.present("no-dtd") { "off" } else { "on" };
         println!(
             "  double-talk: detector {dtd}, threshold {dtd_threshold}, flagged {:.0}% of samples{}",
             100.0 * canceller.double_talk_rate(),
-            if onset > 0 { format!(", near-end onset {:.1}s", onset as f32 / sr as f32) } else { String::new() },
+            if onset > 0 {
+                format!(", near-end onset {:.1}s", onset as f32 / sr as f32)
+            } else {
+                String::new()
+            },
         );
     }
-    println!("  mic before: {:.1} dBFS rms", metrics::dbfs(metrics::rms(&mic)));
-    println!("  residual echo after: {:.1} dBFS rms", metrics::dbfs(metrics::rms(&residual)));
+    println!(
+        "  mic before: {:.1} dBFS rms",
+        metrics::dbfs(metrics::rms(&mic))
+    );
+    println!(
+        "  residual echo after: {:.1} dBFS rms",
+        metrics::dbfs(metrics::rms(&residual))
+    );
     println!("  ERLE broadband: {broadband:+.1} dB");
     println!("  ERLE early/late: {early:+.1} -> {late:+.1} dB  (rise = filter converging)");
 
@@ -278,9 +303,21 @@ fn cmd_aec(args: &[String]) -> Result<(), String> {
     }
     if flags.present("show") {
         println!("\n--- mic (echo present) ---");
-        print!("{}", render::render(&stft::analyze(&mic, sr, 2048, 512), &render::RenderOpts::default()));
+        print!(
+            "{}",
+            render::render(
+                &stft::analyze(&mic, sr, 2048, 512),
+                &render::RenderOpts::default()
+            )
+        );
         println!("\n--- cleaned (post-AEC) ---");
-        print!("{}", render::render(&stft::analyze(&cleaned, sr, 2048, 512), &render::RenderOpts::default()));
+        print!(
+            "{}",
+            render::render(
+                &stft::analyze(&cleaned, sr, 2048, 512),
+                &render::RenderOpts::default()
+            )
+        );
     }
     Ok(())
 }
@@ -339,13 +376,22 @@ impl Flags {
         self.bools.iter().any(|b| b == key) || self.map.contains_key(key)
     }
     fn f32_or(&self, key: &str, default: f32) -> f32 {
-        self.map.get(key).and_then(|v| v.parse().ok()).unwrap_or(default)
+        self.map
+            .get(key)
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(default)
     }
     fn usize_or(&self, key: &str, default: usize) -> usize {
-        self.map.get(key).and_then(|v| v.parse().ok()).unwrap_or(default)
+        self.map
+            .get(key)
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(default)
     }
     fn u64_or(&self, key: &str, default: u64) -> u64 {
-        self.map.get(key).and_then(|v| v.parse().ok()).unwrap_or(default)
+        self.map
+            .get(key)
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(default)
     }
 }
 

src/bin/test_net.rs

@@ -1,9 +1,6 @@
-use peerspeak::network::{
-    gossip::IrohGossipState,
-    RoomState, PeerState,
-};
 use iroh::{Endpoint, endpoint::presets};
 use iroh_gossip::net::Gossip;
+use peerspeak::network::{PeerState, RoomState, gossip::IrohGossipState};
 use tokio::time::{self, Duration};
 
 #[tokio::main]
@@ -18,7 +15,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         .address_lookup(lookup_a.clone())
         .bind()
         .await?;
-    
+
     endpoint_a.online().await;
     println!("Node A online. ID: {}", endpoint_a.id());
 
@@ -27,7 +24,12 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         .accept(iroh_gossip::net::GOSSIP_ALPN, gossip_a.clone())
         .spawn();
 
-    let room_a = IrohGossipState::new(endpoint_a.clone(), gossip_a.clone(), lookup_a.clone(), secret_a);
+    let room_a = IrohGossipState::new(
+        endpoint_a.clone(),
+        gossip_a.clone(),
+        lookup_a.clone(),
+        secret_a,
+    );
 
     // 2. Node B (Client) Setup
     let lookup_b = iroh::address_lookup::memory::MemoryLookup::new();
@@ -46,7 +48,12 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         .accept(iroh_gossip::net::GOSSIP_ALPN, gossip_b.clone())
         .spawn();
 
-    let room_b = IrohGossipState::new(endpoint_b.clone(), gossip_b.clone(), lookup_b.clone(), secret_b);
+    let room_b = IrohGossipState::new(
+        endpoint_b.clone(),
+        gossip_b.clone(),
+        lookup_b.clone(),
+        secret_b,
+    );
 
     // 3. Create room on Node A
     let topic_id = rand::random();

src/codec/mod.rs

@@ -20,6 +20,9 @@ pub trait AudioDecoder: Send {
     /// If `compressed` is `None` (or `Some(&[])`), it indicates packet loss,
     /// enabling the decoder to perform packet loss concealment (PLC).
     fn decode(&mut self, compressed: Option<&[u8]>) -> Result<Vec<i16>, CodecError>;
+
+    /// Reconstructs the previous lost frame from the next packet's in-band FEC.
+    fn decode_fec(&mut self, next_payload: &[u8]) -> Result<Vec<i16>, CodecError>;
 }
 
 pub mod opus_impl;

src/codec/opus_impl.rs

@@ -1,5 +1,49 @@
-use crate::codec::{AudioEncoder, AudioDecoder, CodecError};
-use opus::{Encoder, Decoder, Application, Channels};
+use crate::codec::{AudioDecoder, AudioEncoder, CodecError};
+use crate::config::AudioProfile;
+use opus::{Application, Bitrate, Channels, Decoder, Encoder};
+
+/// Concrete libopus encoder settings derived from an [`AudioProfile`]. Plain
+/// data, so the profile→params mapping ([`opus_params`]) stays a pure,
+/// unit-testable function (W12).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct OpusParams {
+    /// Target bitrate in bits/sec.
+    pub bitrate: i32,
+    /// Enable in-band forward error correction (loss redundancy in the bitstream).
+    pub inband_fec: bool,
+    /// Expected packet-loss percentage (0..=100); tunes how much FEC libopus adds.
+    pub packet_loss_perc: i32,
+    /// Discontinuous transmission: stop sending during silence to save bandwidth.
+    pub dtx: bool,
+}
+
+/// Map a named profile to concrete Opus parameters. Pure — the W12 testable seam.
+///
+/// `BadNetwork` deliberately runs a *lower* bitrate than `Balanced`: in-band FEC
+/// redundancy is carried inside the same bitstream, so trimming the base bitrate
+/// leaves headroom for the redundancy on a congested link.
+pub fn opus_params(profile: AudioProfile) -> OpusParams {
+    match profile {
+        AudioProfile::LowLatency => OpusParams {
+            bitrate: 24_000,
+            inband_fec: false,
+            packet_loss_perc: 0,
+            dtx: false,
+        },
+        AudioProfile::Balanced => OpusParams {
+            bitrate: 32_000,
+            inband_fec: true,
+            packet_loss_perc: 10,
+            dtx: false,
+        },
+        AudioProfile::BadNetwork => OpusParams {
+            bitrate: 20_000,
+            inband_fec: true,
+            packet_loss_perc: 25,
+            dtx: false,
+        },
+    }
+}
 
 pub struct OpusEncoder {
     encoder: Encoder,
@@ -8,11 +52,38 @@ pub struct OpusEncoder {
 impl OpusEncoder {
     /// Creates a new Opus encoder.
     /// Standard voice parameters: sample_rate = 48000, channels = Channels::Mono, application = Application::Voip
-    pub fn new(sample_rate: u32, channels: Channels, application: Application) -> Result<Self, CodecError> {
+    pub fn new(
+        sample_rate: u32,
+        channels: Channels,
+        application: Application,
+    ) -> Result<Self, CodecError> {
         let encoder = Encoder::new(sample_rate, channels, application)
             .map_err(|e| CodecError::Init(format!("Failed to create Opus encoder: {}", e)))?;
         Ok(Self { encoder })
     }
+
+    /// Apply concrete codec parameters to the live encoder. Safe to call between
+    /// frames, so the user can switch profile mid-call.
+    pub fn apply_params(&mut self, params: &OpusParams) -> Result<(), CodecError> {
+        self.encoder
+            .set_bitrate(Bitrate::Bits(params.bitrate))
+            .map_err(|e| CodecError::Init(format!("set_bitrate: {}", e)))?;
+        self.encoder
+            .set_inband_fec(params.inband_fec)
+            .map_err(|e| CodecError::Init(format!("set_inband_fec: {}", e)))?;
+        self.encoder
+            .set_packet_loss_perc(params.packet_loss_perc)
+            .map_err(|e| CodecError::Init(format!("set_packet_loss_perc: {}", e)))?;
+        self.encoder
+            .set_dtx(params.dtx)
+            .map_err(|e| CodecError::Init(format!("set_dtx: {}", e)))?;
+        Ok(())
+    }
+
+    /// Apply a named [`AudioProfile`] (shorthand for `apply_params(&opus_params(p))`).
+    pub fn apply_profile(&mut self, profile: AudioProfile) -> Result<(), CodecError> {
+        self.apply_params(&opus_params(profile))
+    }
 }
 
 impl AudioEncoder for OpusEncoder {
@@ -20,9 +91,11 @@ impl AudioEncoder for OpusEncoder {
         // We allocate a buffer for the compressed output.
         // A maximum packet size of 4000 bytes is more than enough for a single voice frame.
         let mut compressed = vec![0u8; 4000];
-        let len = self.encoder.encode(pcm, &mut compressed)
+        let len = self
+            .encoder
+            .encode(pcm, &mut compressed)
             .map_err(|e| CodecError::Encode(format!("Opus encoding failed: {}", e)))?;
-        
+
         compressed.truncate(len);
         Ok(compressed)
     }
@@ -42,10 +115,18 @@ impl OpusDecoder {
     /// Creates a new Opus decoder.
     /// Standard voice parameters: sample_rate = 48000, channels = Channels::Mono.
     /// `frame_samples` is the per-channel length of one transmitted frame (e.g. 960).
-    pub fn new(sample_rate: u32, channels: Channels, frame_samples: usize) -> Result<Self, CodecError> {
+    pub fn new(
+        sample_rate: u32,
+        channels: Channels,
+        frame_samples: usize,
+    ) -> Result<Self, CodecError> {
         let decoder = Decoder::new(sample_rate, channels)
             .map_err(|e| CodecError::Init(format!("Failed to create Opus decoder: {}", e)))?;
-        Ok(Self { decoder, channels, frame_samples })
+        Ok(Self {
+            decoder,
+            channels,
+            frame_samples,
+        })
     }
 
     fn channels_count(&self) -> usize {
@@ -73,18 +154,72 @@ impl AudioDecoder for OpusDecoder {
             }
         };
 
-        let decoded_per_channel = self.decoder.decode(input, &mut pcm, false)
+        let decoded_per_channel = self
+            .decoder
+            .decode(input, &mut pcm, false)
             .map_err(|e| CodecError::Decode(format!("Opus decoding failed: {}", e)))?;
 
         pcm.truncate(decoded_per_channel * channels_count);
         Ok(pcm)
     }
+
+    fn decode_fec(&mut self, next_payload: &[u8]) -> Result<Vec<i16>, CodecError> {
+        let channels_count = self.channels_count();
+        let mut pcm = vec![0i16; self.frame_samples * channels_count];
+
+        let decoded_per_channel = self
+            .decoder
+            .decode(next_payload, &mut pcm, true)
+            .map_err(|e| CodecError::Decode(format!("Opus FEC decoding failed: {}", e)))?;
+
+        pcm.truncate(decoded_per_channel * channels_count);
+        Ok(pcm)
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_opus_params_mapping() {
+        let low = opus_params(AudioProfile::LowLatency);
+        let bal = opus_params(AudioProfile::Balanced);
+        let bad = opus_params(AudioProfile::BadNetwork);
+
+        // LowLatency has no loss redundancy; the other two do.
+        assert!(!low.inband_fec);
+        assert_eq!(low.packet_loss_perc, 0);
+        assert!(bal.inband_fec);
+        assert!(bad.inband_fec);
+
+        // Capture-side gating suppresses silence; no profile adds Opus DTX.
+        assert!(!low.dtx && !bal.dtx && !bad.dtx);
+        assert!(bad.packet_loss_perc > bal.packet_loss_perc);
+
+        // BadNetwork trims base bitrate to make room for FEC redundancy.
+        assert!(bad.bitrate < bal.bitrate);
+
+        // All bitrates are sane positive voice rates.
+        for p in [low, bal, bad] {
+            assert!(p.bitrate > 0 && p.bitrate <= 64_000);
+            assert!((0..=100).contains(&p.packet_loss_perc));
+        }
+    }
+
+    #[test]
+    fn test_apply_profile_sets_bitrate() {
+        let mut encoder = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
+        // Every profile applies cleanly to a real encoder...
+        for profile in AudioProfile::ALL {
+            encoder.apply_profile(profile).unwrap();
+        }
+        // ...and the last-applied bitrate is reflected by the encoder.
+        encoder.apply_profile(AudioProfile::Balanced).unwrap();
+        let want = opus_params(AudioProfile::Balanced).bitrate;
+        assert_eq!(encoder.encoder.get_bitrate().unwrap(), Bitrate::Bits(want));
+    }
+
     #[test]
     fn test_round_trip() {
         let mut encoder = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
@@ -100,7 +235,10 @@ mod tests {
 
         // encode it
         let compressed = encoder.encode(&pcm).unwrap();
-        assert!(!compressed.is_empty(), "Compressed buffer should not be empty");
+        assert!(
+            !compressed.is_empty(),
+            "Compressed buffer should not be empty"
+        );
         assert!(
             compressed.len() < pcm.len() * std::mem::size_of::<i16>(),
             "Compressed size ({}) should be smaller than raw PCM size ({})",
@@ -110,13 +248,21 @@ mod tests {
 
         // decode it
         let decoded = decoder.decode(Some(&compressed)).unwrap();
-        assert_eq!(decoded.len(), 960, "Decoded sample count should be exactly 960");
+        assert_eq!(
+            decoded.len(),
+            960,
+            "Decoded sample count should be exactly 960"
+        );
 
         // 2. Round-trip carries signal energy (not silence)
         let sum_sq: f64 = decoded.iter().map(|&x| (x as f64).powi(2)).sum();
         let rms = (sum_sq / decoded.len() as f64).sqrt();
         // Since input had amplitude ~10000, let's verify RMS is significantly above 0 (e.g. > 100.0)
-        assert!(rms > 100.0, "Decoded signal should carry energy (RMS was {})", rms);
+        assert!(
+            rms > 100.0,
+            "Decoded signal should carry energy (RMS was {})",
+            rms
+        );
     }
 
     #[test]
@@ -125,11 +271,19 @@ mod tests {
 
         // decode(None) returns exactly frame_samples (960) samples
         let plc_none = decoder.decode(None).unwrap();
-        assert_eq!(plc_none.len(), 960, "decode(None) should yield exactly 960 samples");
+        assert_eq!(
+            plc_none.len(),
+            960,
+            "decode(None) should yield exactly 960 samples"
+        );
 
         // decode(Some(&[])) (empty slice) does the same
         let plc_empty = decoder.decode(Some(&[])).unwrap();
-        assert_eq!(plc_empty.len(), 960, "decode(Some(&[])) should yield exactly 960 samples");
+        assert_eq!(
+            plc_empty.len(),
+            960,
+            "decode(Some(&[])) should yield exactly 960 samples"
+        );
     }
 
     #[test]
@@ -140,7 +294,11 @@ mod tests {
         let pcm = vec![0i16; 960];
         let compressed = encoder.encode(&pcm).unwrap();
         let decoded = decoder.decode(Some(&compressed)).unwrap();
-        assert_eq!(decoded.len(), 960, "Decoded sample count should match packet duration");
+        assert_eq!(
+            decoded.len(),
+            960,
+            "Decoded sample count should match packet duration"
+        );
     }
 
     #[test]
@@ -149,11 +307,18 @@ mod tests {
 
         // decode(None) returns exactly frame_samples * 2 (1920) samples
         let plc_none = decoder.decode(None).unwrap();
-        assert_eq!(plc_none.len(), 960 * 2, "Stereo decode(None) should yield exactly 1920 samples");
+        assert_eq!(
+            plc_none.len(),
+            960 * 2,
+            "Stereo decode(None) should yield exactly 1920 samples"
+        );
 
         // decode(Some(&[])) (empty slice) does the same
         let plc_empty = decoder.decode(Some(&[])).unwrap();
-        assert_eq!(plc_empty.len(), 960 * 2, "Stereo decode(Some(&[])) should yield exactly 1920 samples");
+        assert_eq!(
+            plc_empty.len(),
+            960 * 2,
+            "Stereo decode(Some(&[])) should yield exactly 1920 samples"
+        );
     }
 }
-

src/config.rs

@@ -1,9 +1,12 @@
 use crate::notify::Sound;
 use crate::theme::AppTheme;
+use anyhow::Context;
 use serde::{Deserialize, Serialize};
 use std::collections::{BTreeMap, HashMap};
 use std::fs;
-use std::path::PathBuf;
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::time::{SystemTime, UNIX_EPOCH};
 
 /// Relay/discovery posture, trading connectivity against how much the n0
 /// infrastructure learns about you. See the network module for details.
@@ -24,8 +27,11 @@ pub enum NetworkMode {
 
 impl NetworkMode {
     /// All variants, for presentation in a picker.
-    pub const ALL: [NetworkMode; 3] =
-        [NetworkMode::RelayNoDiscovery, NetworkMode::N0Full, NetworkMode::DirectOnly];
+    pub const ALL: [NetworkMode; 3] = [
+        NetworkMode::RelayNoDiscovery,
+        NetworkMode::N0Full,
+        NetworkMode::DirectOnly,
+    ];
 }
 
 /// Arrangement of the in-call room screen, chosen via the layout picker.
@@ -42,8 +48,11 @@ pub enum RoomLayout {
 
 impl RoomLayout {
     /// All variants, in picker display order.
-    pub const ALL: [RoomLayout; 3] =
-        [RoomLayout::ThreeColumn, RoomLayout::BottomDock, RoomLayout::Drawer];
+    pub const ALL: [RoomLayout; 3] = [
+        RoomLayout::ThreeColumn,
+        RoomLayout::BottomDock,
+        RoomLayout::Drawer,
+    ];
 }
 
 /// What a call recording captures. `Mixed` is the original single-file behaviour;
@@ -62,8 +71,11 @@ pub enum RecordingMode {
 
 impl RecordingMode {
     /// All variants, in picker display order.
-    pub const ALL: [RecordingMode; 3] =
-        [RecordingMode::Mixed, RecordingMode::Multitrack, RecordingMode::Both];
+    pub const ALL: [RecordingMode; 3] = [
+        RecordingMode::Mixed,
+        RecordingMode::Multitrack,
+        RecordingMode::Both,
+    ];
 
     /// True when this mode writes per-peer stem tracks (Multitrack or Both).
     pub fn is_multitrack(self) -> bool {
@@ -81,6 +93,60 @@ impl std::fmt::Display for RecordingMode {
     }
 }
 
+/// Named Opus encoder / network-resilience policy (W12). The user picks a
+/// profile instead of raw codec knobs; the concrete libopus parameters live in
+/// `codec::opus_impl::opus_params`. Applies live to the running encoder.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub enum AudioProfile {
+    /// Lowest mouth-to-ear delay: modest bitrate, no FEC redundancy. Best on a
+    /// clean LAN / low-loss link where added latency matters more than loss.
+    LowLatency,
+    /// Sensible default: voice bitrate with in-band FEC for light packet loss.
+    #[default]
+    Balanced,
+    /// Maximum resilience on a lossy/congested link: in-band FEC tuned for heavy
+    /// loss, at a lower bitrate to leave headroom for the redundancy.
+    BadNetwork,
+}
+
+impl AudioProfile {
+    /// All variants, in picker display order.
+    pub const ALL: [AudioProfile; 3] = [
+        AudioProfile::LowLatency,
+        AudioProfile::Balanced,
+        AudioProfile::BadNetwork,
+    ];
+
+    /// Compact discriminant for handing the profile to the capture thread via an
+    /// atomic. Pairs with [`AudioProfile::from_u8`].
+    pub fn as_u8(self) -> u8 {
+        match self {
+            AudioProfile::LowLatency => 0,
+            AudioProfile::Balanced => 1,
+            AudioProfile::BadNetwork => 2,
+        }
+    }
+
+    /// Inverse of [`AudioProfile::as_u8`]; unknown values fall back to the default.
+    pub fn from_u8(v: u8) -> AudioProfile {
+        match v {
+            0 => AudioProfile::LowLatency,
+            2 => AudioProfile::BadNetwork,
+            _ => AudioProfile::Balanced,
+        }
+    }
+}
+
+impl std::fmt::Display for AudioProfile {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            AudioProfile::LowLatency => "Low latency",
+            AudioProfile::Balanced => "Balanced",
+            AudioProfile::BadNetwork => "Bad network",
+        })
+    }
+}
+
 impl std::fmt::Display for RoomLayout {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.write_str(match self {
@@ -102,6 +168,139 @@ impl std::fmt::Display for NetworkMode {
     }
 }
 
+/// Pixelpass host quality preset for screen shares. `Auto` leaves pixelpass free
+/// to choose from its bandwidth pre-flight; fixed presets are passed as CLI flags.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum ShareQuality {
+    #[default]
+    Auto,
+    Low,
+    Medium,
+    High,
+    Source,
+}
+
+impl ShareQuality {
+    pub const ALL: [ShareQuality; 5] = [
+        ShareQuality::Auto,
+        ShareQuality::Low,
+        ShareQuality::Medium,
+        ShareQuality::High,
+        ShareQuality::Source,
+    ];
+}
+
+impl std::fmt::Display for ShareQuality {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            ShareQuality::Auto => "Auto",
+            ShareQuality::Low => "Low",
+            ShareQuality::Medium => "Medium",
+            ShareQuality::High => "High",
+            ShareQuality::Source => "Source",
+        })
+    }
+}
+
+/// Preferred local player for watching a peer's screen share.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum SharePlayer {
+    #[default]
+    Mpv,
+    Vlc,
+}
+
+impl SharePlayer {
+    pub const ALL: [SharePlayer; 2] = [SharePlayer::Mpv, SharePlayer::Vlc];
+}
+
+impl std::fmt::Display for SharePlayer {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            SharePlayer::Mpv => "mpv",
+            SharePlayer::Vlc => "VLC",
+        })
+    }
+}
+
+/// Local player buffering posture for screen-share playback.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum ShareBuffering {
+    #[default]
+    LowLatency,
+    Smooth,
+}
+
+impl ShareBuffering {
+    pub const ALL: [ShareBuffering; 2] = [ShareBuffering::LowLatency, ShareBuffering::Smooth];
+}
+
+impl std::fmt::Display for ShareBuffering {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            ShareBuffering::LowLatency => "Low latency",
+            ShareBuffering::Smooth => "Smooth",
+        })
+    }
+}
+
+fn default_screen_share_cache_mb() -> u32 {
+    2
+}
+
+/// Local-only screen-share preferences. Host fields become pixelpass host CLI
+/// flags; viewer fields shape local mpv/VLC launch. None/empty/default values
+/// deliberately let pixelpass/player defaults stand.
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ScreenShareSettings {
+    #[serde(default)]
+    pub quality: ShareQuality,
+    #[serde(default)]
+    pub bitrate_mbps: Option<u32>,
+    #[serde(default)]
+    pub framerate: Option<u32>,
+    #[serde(default)]
+    pub max_height: Option<u32>,
+    #[serde(default)]
+    pub max_viewers: Option<u32>,
+    #[serde(default)]
+    pub force_software_encode: bool,
+    #[serde(default)]
+    pub extra_host_args: String,
+    #[serde(default)]
+    pub player: SharePlayer,
+    #[serde(default)]
+    pub hardware_decode: bool,
+    #[serde(default)]
+    pub buffering: ShareBuffering,
+    #[serde(default = "default_screen_share_cache_mb")]
+    pub cache_mb: u32,
+    #[serde(default)]
+    pub extra_mpv_args: String,
+}
+
+impl Default for ScreenShareSettings {
+    fn default() -> Self {
+        Self {
+            quality: ShareQuality::default(),
+            bitrate_mbps: None,
+            framerate: None,
+            max_height: None,
+            max_viewers: None,
+            force_software_encode: false,
+            extra_host_args: String::new(),
+            player: SharePlayer::default(),
+            hardware_decode: false,
+            buffering: ShareBuffering::default(),
+            cache_mb: default_screen_share_cache_mb(),
+            extra_mpv_args: String::new(),
+        }
+    }
+}
+
 fn default_true() -> bool {
     true
 }
@@ -187,6 +386,10 @@ pub struct AppConfig {
     pub clip_volume_universal: bool,
     #[serde(default)]
     pub network_mode: NetworkMode,
+    /// Opus encoder / network-resilience profile (W12). Applies live to the
+    /// running encoder; default `Balanced`.
+    #[serde(default)]
+    pub audio_profile: AudioProfile,
     /// Presence posture for the friends idle listener (W7): invisible / normal /
     /// discoverable. Default `Normal` = answer friends only, no DNS beacon.
     #[serde(default)]
@@ -299,6 +502,9 @@ pub struct AppConfig {
     /// Empty / unset = look it up on `$PATH`. Hand-editable; no Settings UI yet.
     #[serde(default)]
     pub pixelpass_path: Option<String>,
+    /// Local-only host/player controls for screen sharing.
+    #[serde(default)]
+    pub screen_share: ScreenShareSettings,
     /// Recently-joined rooms (W7), most-recent-first. Purely local UI state for a
     /// one-click rejoin; never sent over the wire. De-duped by room topic and
     /// capped (see `recents`). Defaulted empty so older configs upgrade cleanly.
@@ -345,6 +551,13 @@ pub struct AppConfig {
     pub window_y: Option<i32>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LoadOutcome {
+    Missing,
+    Loaded,
+    Recovered,
+}
+
 impl Default for AppConfig {
     fn default() -> Self {
         Self {
@@ -361,6 +574,7 @@ impl Default for AppConfig {
             show_player_bar: true,
             clip_volume_universal: true,
             network_mode: NetworkMode::default(),
+            audio_profile: AudioProfile::default(),
             presence_mode: crate::presence::PresenceMode::default(),
             echo_cancellation_enabled: false,
             notifications_enabled: true,
@@ -396,6 +610,7 @@ impl Default for AppConfig {
             sound_mic_toggle_enabled: true,
             sound_reconnect_failed_enabled: true,
             pixelpass_path: None,
+            screen_share: ScreenShareSettings::default(),
             recents: Vec::new(),
             peer_eq: HashMap::new(),
             peer_pan: HashMap::new(),
@@ -475,24 +690,115 @@ impl AppConfig {
     }
 
     pub fn load() -> Self {
-        if let Some(path) = Self::config_path()
-            && let Ok(contents) = fs::read_to_string(&path)
-                && let Ok(config) = serde_json::from_str(&contents) {
-                    return config;
-                }
-        Self::default()
+        let Some(path) = Self::config_path() else {
+            return Self::default();
+        };
+        let (config, _) = Self::load_from(&path);
+        config
     }
 
     pub fn save(&self) {
         if let Some(path) = Self::config_path() {
-            if let Some(dir) = path.parent() {
-                let _ = fs::create_dir_all(dir);
+            if let Err(e) = self.save_to(&path) {
+                crate::log_msg(&format!("config: save failed: {e:#}"));
             }
-            if let Ok(json) = serde_json::to_string_pretty(self) {
-                let _ = fs::write(path, json);
+        } else {
+            crate::log_msg("config: save failed: could not determine a config directory");
+        }
+    }
+
+    pub fn load_from(path: &Path) -> (Self, LoadOutcome) {
+        match fs::read_to_string(path) {
+            Ok(contents) => match serde_json::from_str(&contents) {
+                Ok(config) => (config, LoadOutcome::Loaded),
+                Err(e) => {
+                    let backup = recover_corrupt_config(path, &format!("failed to parse: {e}"));
+                    (Self::default(), backup)
+                }
+            },
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
+                (Self::default(), LoadOutcome::Missing)
+            }
+            Err(e) => {
+                let backup = recover_corrupt_config(path, &format!("failed to read: {e}"));
+                (Self::default(), backup)
             }
         }
     }
+
+    pub fn save_to(&self, path: &Path) -> anyhow::Result<()> {
+        let parent = path
+            .parent()
+            .context("config path has no parent directory")?;
+        fs::create_dir_all(parent)
+            .with_context(|| format!("failed to create {}", parent.display()))?;
+
+        let json = serde_json::to_string_pretty(self).context("failed to encode config")?;
+        let tmp = config_tmp_path(path)?;
+        let result = (|| -> anyhow::Result<()> {
+            {
+                let mut f = fs::File::create(&tmp)
+                    .with_context(|| format!("failed to create {}", tmp.display()))?;
+                f.write_all(json.as_bytes())
+                    .with_context(|| format!("failed to write {}", tmp.display()))?;
+                f.sync_all().ok();
+            }
+            fs::rename(&tmp, path).with_context(|| {
+                format!("failed to rename {} -> {}", tmp.display(), path.display())
+            })?;
+            Ok(())
+        })();
+
+        if result.is_err() {
+            let _ = fs::remove_file(&tmp);
+        }
+        result
+    }
+}
+
+fn config_tmp_path(path: &Path) -> anyhow::Result<PathBuf> {
+    let parent = path
+        .parent()
+        .context("config path has no parent directory")?;
+    let mut name = path
+        .file_name()
+        .context("config path has no file name")?
+        .to_os_string();
+    name.push(format!(".tmp.{}", std::process::id()));
+    Ok(parent.join(name))
+}
+
+fn corrupt_backup_path(path: &Path) -> PathBuf {
+    let secs = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|d| d.as_secs())
+        .unwrap_or(0);
+    let parent = path.parent().unwrap_or_else(|| Path::new("."));
+    let mut name = path
+        .file_name()
+        .map(|n| n.to_os_string())
+        .unwrap_or_else(|| "config.json".into());
+    name.push(format!(".corrupt.{secs}"));
+    parent.join(name)
+}
+
+fn recover_corrupt_config(path: &Path, reason: &str) -> LoadOutcome {
+    let backup = corrupt_backup_path(path);
+    match fs::rename(path, &backup) {
+        Ok(()) => {
+            crate::log_msg(&format!(
+                "config: {reason}; moved damaged config to {}",
+                backup.display()
+            ));
+        }
+        Err(e) => {
+            crate::log_msg(&format!(
+                "config: {reason}; failed to move damaged config to {}: {e}",
+                backup.display()
+            ));
+        }
+    }
+    LoadOutcome::Recovered
 }
 
 #[cfg(test)]
@@ -507,14 +813,109 @@ mod tests {
         assert_eq!(original, deserialized);
     }
 
+    fn temp_config_path(tag: &str) -> PathBuf {
+        let mut p = std::env::temp_dir();
+        p.push(format!(
+            "peerspeak-configtest-{}-{}",
+            std::process::id(),
+            tag
+        ));
+        p.push("config.json");
+        p
+    }
+
+    #[test]
+    fn save_to_then_load_from_round_trips() {
+        let path = temp_config_path("roundtrip");
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+        let cfg = AppConfig {
+            username: "Ada".into(),
+            input_device: "mic".into(),
+            output_device: "speaker".into(),
+            noise_gate_threshold: 0.42,
+            ..AppConfig::default()
+        };
+
+        cfg.save_to(&path).unwrap();
+        let (loaded, outcome) = AppConfig::load_from(&path);
+
+        assert_eq!(outcome, LoadOutcome::Loaded);
+        assert_eq!(loaded, cfg);
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+    }
+
+    #[test]
+    fn load_from_missing_returns_default_without_corrupt_backup() {
+        let path = temp_config_path("missing");
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+
+        let (loaded, outcome) = AppConfig::load_from(&path);
+
+        assert_eq!(outcome, LoadOutcome::Missing);
+        assert_eq!(loaded, AppConfig::default());
+        assert!(!path.parent().unwrap().exists());
+    }
+
+    #[test]
+    fn load_from_corrupt_file_preserves_original_bytes() {
+        let path = temp_config_path("corrupt");
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+        fs::create_dir_all(path.parent().unwrap()).unwrap();
+        let corrupt = b"{ this is not json";
+        fs::write(&path, corrupt).unwrap();
+
+        let (loaded, outcome) = AppConfig::load_from(&path);
+
+        assert_eq!(outcome, LoadOutcome::Recovered);
+        assert_eq!(loaded, AppConfig::default());
+        assert_ne!(fs::read(&path).ok().as_deref(), Some(corrupt.as_slice()));
+        let backups: Vec<_> = fs::read_dir(path.parent().unwrap())
+            .unwrap()
+            .map(|entry| entry.unwrap().path())
+            .filter(|entry| {
+                entry
+                    .file_name()
+                    .and_then(|name| name.to_str())
+                    .is_some_and(|name| name.starts_with("config.json.corrupt."))
+            })
+            .collect();
+        assert_eq!(backups.len(), 1, "expected one corrupt backup");
+        assert_eq!(fs::read(&backups[0]).unwrap(), corrupt);
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+    }
+
+    #[test]
+    fn save_to_leaves_no_tmp_file_after_success() {
+        let path = temp_config_path("atomic");
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+
+        AppConfig::default().save_to(&path).unwrap();
+
+        let tmp_files: Vec<_> = fs::read_dir(path.parent().unwrap())
+            .unwrap()
+            .map(|entry| entry.unwrap().path())
+            .filter(|entry| {
+                entry
+                    .file_name()
+                    .and_then(|name| name.to_str())
+                    .is_some_and(|name| name.contains(".tmp."))
+            })
+            .collect();
+        assert!(tmp_files.is_empty(), "leftover temp files: {tmp_files:?}");
+        let _ = fs::remove_dir_all(path.parent().unwrap());
+    }
+
     #[test]
     fn test_backward_compat_default_fill() {
         let minimal_json = r#"{"input_device":"","output_device":"","noise_gate_threshold":0.01}"#;
         let deserialized: AppConfig = serde_json::from_str(minimal_json).unwrap();
-        
+
         assert_eq!(deserialized.network_mode, NetworkMode::RelayNoDiscovery);
         // Configs predating the presence posture load as friends-only (no beacon).
-        assert_eq!(deserialized.presence_mode, crate::presence::PresenceMode::Normal);
+        assert_eq!(
+            deserialized.presence_mode,
+            crate::presence::PresenceMode::Normal
+        );
         assert!(!deserialized.echo_cancellation_enabled);
         assert!(deserialized.notifications_enabled);
         // Configs predating the volume sliders must load at unity gain.
@@ -539,10 +940,21 @@ mod tests {
         assert!(deserialized.custom_sound_self_leave.is_none());
         assert!(deserialized.custom_sound_mic_toggle.is_none());
         assert!(deserialized.custom_sound_reconnect_failed.is_none());
+        assert_eq!(deserialized.screen_share, ScreenShareSettings::default());
+        assert_eq!(deserialized.screen_share.quality, ShareQuality::Auto);
+        assert_eq!(deserialized.screen_share.player, SharePlayer::Mpv);
+        assert_eq!(
+            deserialized.screen_share.buffering,
+            ShareBuffering::LowLatency
+        );
+        assert_eq!(deserialized.screen_share.cache_mb, 2);
         // Configs predating the per-sound flags (W6) enable every chime, so an
         // upgrade is silent-change-free.
         for sound in Sound::ALL {
-            assert!(deserialized.sound_enabled(sound), "{sound:?} should default on");
+            assert!(
+                deserialized.sound_enabled(sound),
+                "{sound:?} should default on"
+            );
         }
         // The accessor and mutator agree round-trip.
         let mut cfg = AppConfig::default();
@@ -589,7 +1001,10 @@ mod tests {
         }"#;
         let cfg: AppConfig = serde_json::from_str(legacy_json).unwrap();
         // The pre-existing single background survives untouched (still Option<String>).
-        assert_eq!(cfg.background.as_deref(), Some("/home/eric/.config/peerspeak/background.png"));
+        assert_eq!(
+            cfg.background.as_deref(),
+            Some("/home/eric/.config/peerspeak/background.png")
+        );
         assert!((cfg.background_dim - 0.4).abs() < f32::EPSILON);
         // The new game-detection fields default to off/empty → silent, opt-in upgrade.
         assert!(!cfg.game_presence_enabled);
@@ -601,9 +1016,12 @@ mod tests {
     fn test_game_maps_serialize_deterministically() {
         // BTreeMap ordering makes the serialized config stable across runs.
         let mut cfg = AppConfig::default();
-        cfg.game_backgrounds.insert("steam:730".into(), "/a.png".into());
-        cfg.game_backgrounds.insert("exe:hl2_linux".into(), "/b.png".into());
-        cfg.game_process_map.insert("hl2_linux".into(), "Half-Life 2".into());
+        cfg.game_backgrounds
+            .insert("steam:730".into(), "/a.png".into());
+        cfg.game_backgrounds
+            .insert("exe:hl2_linux".into(), "/b.png".into());
+        cfg.game_process_map
+            .insert("hl2_linux".into(), "Half-Life 2".into());
         let json = serde_json::to_string(&cfg).unwrap();
         // Keys appear in sorted order (exe: before steam:).
         let bg = json.find("game_backgrounds").unwrap();
@@ -661,8 +1079,7 @@ mod tests {
             recording_mode: RecordingMode::Both,
             ..AppConfig::default()
         };
-        let back: AppConfig =
-            serde_json::from_str(&serde_json::to_string(&cfg).unwrap()).unwrap();
+        let back: AppConfig = serde_json::from_str(&serde_json::to_string(&cfg).unwrap()).unwrap();
         assert_eq!(back.recording_mode, RecordingMode::Both);
         // is_multitrack() classifies correctly.
         assert!(!RecordingMode::Mixed.is_multitrack());
@@ -748,7 +1165,10 @@ mod tests {
         assert_eq!(round_tripped.input_volume, 1.5);
         assert_eq!(round_tripped.output_volume, 0.25);
         assert_eq!(round_tripped.clip_volume, 0.7);
-        assert_eq!(round_tripped.music_playlist, vec!["/tmp/song.ogg".to_string()]);
+        assert_eq!(
+            round_tripped.music_playlist,
+            vec!["/tmp/song.ogg".to_string()]
+        );
         assert_eq!(round_tripped.music_volume, 0.6);
         assert!(round_tripped.music_broadcast);
         assert!(!round_tripped.show_player_bar);
@@ -757,7 +1177,8 @@ mod tests {
 
     #[test]
     fn test_notifications_enabled_specifically() {
-        let missing_notifications = r#"{"input_device":"","output_device":"","noise_gate_threshold":0.01}"#;
+        let missing_notifications =
+            r#"{"input_device":"","output_device":"","noise_gate_threshold":0.01}"#;
         let config_missing: AppConfig = serde_json::from_str(missing_notifications).unwrap();
         assert!(config_missing.notifications_enabled);
 
@@ -802,6 +1223,38 @@ mod tests {
         assert_ne!(display_0, display_2);
     }
 
+    #[test]
+    fn test_audio_profile() {
+        // Default is Balanced.
+        assert_eq!(AudioProfile::default(), AudioProfile::Balanced);
+
+        // ALL holds the three variants.
+        assert_eq!(AudioProfile::ALL.len(), 3);
+        assert!(AudioProfile::ALL.contains(&AudioProfile::LowLatency));
+        assert!(AudioProfile::ALL.contains(&AudioProfile::Balanced));
+        assert!(AudioProfile::ALL.contains(&AudioProfile::BadNetwork));
+
+        // as_u8 / from_u8 round-trip every variant, and unknown bytes fall back
+        // to the default rather than panicking.
+        for p in AudioProfile::ALL {
+            assert_eq!(AudioProfile::from_u8(p.as_u8()), p);
+        }
+        assert_eq!(AudioProfile::from_u8(99), AudioProfile::Balanced);
+
+        // serde round-trips, and Display strings are non-empty + distinct.
+        let mut labels = Vec::new();
+        for p in AudioProfile::ALL {
+            let s = serde_json::to_string(&p).unwrap();
+            assert_eq!(serde_json::from_str::<AudioProfile>(&s).unwrap(), p);
+            let label = p.to_string();
+            assert!(!label.is_empty());
+            labels.push(label);
+        }
+        labels.sort();
+        labels.dedup();
+        assert_eq!(labels.len(), 3);
+    }
+
     #[test]
     fn test_unknown_field_tolerance() {
         // Unknown/extra field tolerance: a config JSON containing an extra unrecognized key should still deserialize.
@@ -813,11 +1266,14 @@ mod tests {
             "unrecognized_field_xyz_123": "some_value"
         }"#;
         let deserialized_res: Result<AppConfig, _> = serde_json::from_str(json_with_extra);
-        
+
         // Assert that deserialization succeeds even with unrecognized/unknown fields.
         // This confirms that serde does not reject unknown fields (i.e. default behavior).
-        assert!(deserialized_res.is_ok(), "Config deserialization failed when an unknown field was present");
-        
+        assert!(
+            deserialized_res.is_ok(),
+            "Config deserialization failed when an unknown field was present"
+        );
+
         let config = deserialized_res.unwrap();
         assert_eq!(config.input_device, "");
         assert_eq!(config.output_device, "");

src/core/connstats.rs

@@ -0,0 +1,187 @@
+//! Per-peer connection-transparency derivation.
+//!
+//! The transport hands us cumulative counters for each peer's selected QUIC
+//! path ([`PathSnapshot`]); this module turns two consecutive snapshots into
+//! the human-facing [`PeerConnInfo`] the UI renders (badge + tooltip): path
+//! type, RTT, and loss/bitrate over the poll window. Pure functions only —
+//! the polling task in `core::mod` owns the clock and the previous-snapshot
+//! map.
+
+use crate::network::PathSnapshot;
+use std::time::Duration;
+
+/// How often the core polls the transport for path snapshots.
+pub const POLL_INTERVAL: Duration = Duration::from_secs(1);
+
+/// Derived, display-ready connection info for one peer, sent to the UI via
+/// `UiEvent::ConnectionStats`. Window-relative fields are `None` when they
+/// can't be derived yet (first poll, path switch, or an idle window).
+#[derive(Debug, Clone, PartialEq)]
+pub struct PeerConnInfo {
+    /// True = relayed path, false = direct IP path.
+    pub relay: bool,
+    /// `ip:port` for a direct path, the relay URL for a relayed one.
+    pub remote_addr: String,
+    /// Path round-trip time, rounded to whole milliseconds.
+    pub rtt_ms: u32,
+    /// Percentage of packets sent in the window that were detected lost.
+    pub loss_pct: Option<f32>,
+    /// Outbound bitrate over the window, kilobits per second.
+    pub up_kbps: Option<f32>,
+    /// Inbound bitrate over the window, kilobits per second.
+    pub down_kbps: Option<f32>,
+}
+
+/// Derive display info from the current snapshot and (when comparable) the
+/// previous one. `prev` is comparable only if it's the same path — a relay→
+/// direct migration or a reconnect resets the counters, so those windows
+/// yield `None` rates rather than garbage (negative deltas show up as
+/// `cur < prev` and are treated the same way).
+pub fn derive(prev: Option<&PathSnapshot>, cur: &PathSnapshot, elapsed: Duration) -> PeerConnInfo {
+    let rates = prev
+        .filter(|p| comparable(p, cur))
+        .and_then(|p| window_rates(p, cur, elapsed));
+    PeerConnInfo {
+        relay: cur.is_relay,
+        remote_addr: cur.remote_addr.clone(),
+        rtt_ms: cur.rtt.as_millis().min(u128::from(u32::MAX)) as u32,
+        loss_pct: rates.and_then(|r| r.loss_pct),
+        up_kbps: rates.map(|r| r.up_kbps),
+        down_kbps: rates.map(|r| r.down_kbps),
+    }
+}
+
+/// True when `cur`'s counters continue `prev`'s: same path (address) and
+/// monotonically non-decreasing counters (a reconnect on the same address
+/// restarts them from zero).
+fn comparable(prev: &PathSnapshot, cur: &PathSnapshot) -> bool {
+    prev.remote_addr == cur.remote_addr
+        && cur.tx_bytes >= prev.tx_bytes
+        && cur.rx_bytes >= prev.rx_bytes
+        && cur.tx_datagrams >= prev.tx_datagrams
+        && cur.lost_packets >= prev.lost_packets
+}
+
+#[derive(Debug, Clone, Copy)]
+struct WindowRates {
+    loss_pct: Option<f32>,
+    up_kbps: f32,
+    down_kbps: f32,
+}
+
+fn window_rates(prev: &PathSnapshot, cur: &PathSnapshot, elapsed: Duration) -> Option<WindowRates> {
+    let secs = elapsed.as_secs_f64();
+    if secs <= 0.0 {
+        return None;
+    }
+    let sent = cur.tx_datagrams - prev.tx_datagrams;
+    let lost = cur.lost_packets - prev.lost_packets;
+    // Loss detection lags sending (it needs ACK timeouts), so a window can see
+    // more losses than sends; clamp to 100% rather than exceeding it. An idle
+    // window (nothing sent or lost) has no loss story to tell.
+    let loss_pct = if sent == 0 && lost == 0 {
+        None
+    } else {
+        Some(((lost as f64 / (sent.max(lost)) as f64) * 100.0) as f32)
+    };
+    let kbps = |bytes: u64| ((bytes as f64 * 8.0 / 1000.0) / secs) as f32;
+    Some(WindowRates {
+        loss_pct,
+        up_kbps: kbps(cur.tx_bytes - prev.tx_bytes),
+        down_kbps: kbps(cur.rx_bytes - prev.rx_bytes),
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn snap(addr: &str, tx_b: u64, rx_b: u64, tx_d: u64, lost: u64) -> PathSnapshot {
+        PathSnapshot {
+            is_relay: false,
+            remote_addr: addr.to_string(),
+            rtt: Duration::from_millis(12),
+            tx_bytes: tx_b,
+            rx_bytes: rx_b,
+            tx_datagrams: tx_d,
+            lost_packets: lost,
+        }
+    }
+
+    #[test]
+    fn first_poll_has_type_and_rtt_but_no_rates() {
+        let cur = snap("1.2.3.4:5", 1000, 2000, 50, 0);
+        let info = derive(None, &cur, POLL_INTERVAL);
+        assert_eq!(info.rtt_ms, 12);
+        assert!(!info.relay);
+        assert_eq!(info.remote_addr, "1.2.3.4:5");
+        assert_eq!(info.loss_pct, None);
+        assert_eq!(info.up_kbps, None);
+        assert_eq!(info.down_kbps, None);
+    }
+
+    #[test]
+    fn steady_window_yields_rates_and_loss() {
+        let prev = snap("1.2.3.4:5", 0, 0, 0, 0);
+        // 1s window: 4000 bytes up (32 kbps), 2000 down (16 kbps), 2 of 100 lost.
+        let cur = snap("1.2.3.4:5", 4000, 2000, 100, 2);
+        let info = derive(Some(&prev), &cur, Duration::from_secs(1));
+        assert_eq!(info.up_kbps, Some(32.0));
+        assert_eq!(info.down_kbps, Some(16.0));
+        assert_eq!(info.loss_pct, Some(2.0));
+    }
+
+    #[test]
+    fn idle_window_has_no_loss_story() {
+        let prev = snap("1.2.3.4:5", 4000, 2000, 100, 2);
+        let cur = prev.clone();
+        let info = derive(Some(&prev), &cur, Duration::from_secs(1));
+        assert_eq!(info.loss_pct, None);
+        assert_eq!(info.up_kbps, Some(0.0));
+    }
+
+    #[test]
+    fn loss_detected_in_an_idle_window_clamps_to_full() {
+        // Losses can be *detected* after sending stops (ACK timeouts fire late).
+        let prev = snap("1.2.3.4:5", 4000, 2000, 100, 0);
+        let cur = snap("1.2.3.4:5", 4000, 2000, 100, 3);
+        let info = derive(Some(&prev), &cur, Duration::from_secs(1));
+        assert_eq!(info.loss_pct, Some(100.0));
+    }
+
+    #[test]
+    fn path_switch_resets_the_window() {
+        let prev = snap("relay.example:443", 9000, 9000, 900, 5);
+        let cur = snap("1.2.3.4:5", 100, 100, 10, 0);
+        let info = derive(Some(&prev), &cur, Duration::from_secs(1));
+        assert_eq!(info.up_kbps, None);
+        assert_eq!(info.loss_pct, None);
+    }
+
+    #[test]
+    fn counter_reset_on_same_address_resets_the_window() {
+        // Same address but the connection was rebuilt → counters restarted.
+        let prev = snap("1.2.3.4:5", 9000, 9000, 900, 5);
+        let cur = snap("1.2.3.4:5", 100, 100, 10, 0);
+        let info = derive(Some(&prev), &cur, Duration::from_secs(1));
+        assert_eq!(info.up_kbps, None);
+        assert_eq!(info.loss_pct, None);
+    }
+
+    #[test]
+    fn zero_elapsed_yields_no_rates() {
+        let prev = snap("1.2.3.4:5", 0, 0, 0, 0);
+        let cur = snap("1.2.3.4:5", 4000, 2000, 100, 2);
+        let info = derive(Some(&prev), &cur, Duration::ZERO);
+        assert_eq!(info.up_kbps, None);
+        assert_eq!(info.loss_pct, None);
+    }
+
+    #[test]
+    fn oversized_rtt_saturates_instead_of_wrapping() {
+        let mut cur = snap("1.2.3.4:5", 0, 0, 0, 0);
+        cur.rtt = Duration::from_secs(u64::MAX);
+        let info = derive(None, &cur, POLL_INTERVAL);
+        assert_eq!(info.rtt_ms, u32::MAX);
+    }
+}

src/core/jitter.rs

@@ -202,11 +202,15 @@ impl JitterBuffer {
                     None
                 } else {
                     // Gap with later packets already buffered: a packet was lost
-                    // or reordered out of window. Conceal this frame via Opus PLC
-                    // and grow the cushion — the jitter beat our current delay.
+                    // or reordered out of window. First try Opus in-band FEC from
+                    // the next packet; if unavailable, fall back to plain PLC.
                     self.next_seq = Some(next.wrapping_add(1));
                     self.note_disruption();
-                    self.decoder.decode(None).ok()
+                    let next_payload = self.packets.values().next().expect("non-empty");
+                    self.decoder
+                        .decode_fec(next_payload)
+                        .or_else(|_| self.decoder.decode(None))
+                        .ok()
                 }
             }
         }
@@ -221,8 +225,8 @@ impl JitterBuffer {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::codec::AudioEncoder;
-    use crate::codec::opus_impl::OpusEncoder;
+    use crate::codec::opus_impl::{OpusDecoder, OpusEncoder, OpusParams};
+    use crate::codec::{AudioDecoder, AudioEncoder};
     use opus::{Application, Channels};
 
     /// A real, decodable Opus packet for one 20ms mono frame at amplitude `amp`.
@@ -233,6 +237,32 @@ mod tests {
         enc.encode(&pcm).unwrap()
     }
 
+    fn tone_frame(enc: &mut OpusEncoder, amp: i16, frame_index: usize) -> Vec<u8> {
+        let pcm: Vec<i16> = (0..FRAME_SAMPLES)
+            .map(|i| {
+                let sample_index = frame_index * FRAME_SAMPLES + i;
+                let t = sample_index as f32 / 48_000.0;
+                let fundamental = (t * 220.0 * 2.0 * std::f32::consts::PI).sin();
+                let harmonic = (t * 440.0 * 2.0 * std::f32::consts::PI).sin();
+                ((fundamental * 0.7 + harmonic * 0.3) * amp as f32) as i16
+            })
+            .collect();
+        enc.encode(&pcm).unwrap()
+    }
+
+    fn rms_error(a: &[i16], b: &[i16]) -> f64 {
+        assert_eq!(a.len(), b.len());
+        let sum_sq: f64 = a
+            .iter()
+            .zip(b)
+            .map(|(&left, &right)| {
+                let diff = left as f64 - right as f64;
+                diff * diff
+            })
+            .sum();
+        (sum_sq / a.len() as f64).sqrt()
+    }
+
     #[test]
     fn buffers_then_plays_in_order() {
         let mut enc = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
@@ -289,6 +319,66 @@ mod tests {
         assert!(jb.pop_frame().is_none());
     }
 
+    #[test]
+    fn uses_in_band_fec_from_next_packet_for_gap() {
+        let mut enc = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
+        enc.apply_params(&OpusParams {
+            bitrate: 20_000,
+            inband_fec: true,
+            packet_loss_perc: 60,
+            dtx: false,
+        })
+        .unwrap();
+
+        let dropped_seq = 5usize;
+        let amps = [1800, 1800, 1800, 1800, 1800, 12_000, 12_000, 12_000];
+        let packets: Vec<Vec<u8>> = amps
+            .into_iter()
+            .enumerate()
+            .map(|(seq, amp)| tone_frame(&mut enc, amp, seq))
+            .collect();
+
+        let mut expected_decoder = OpusDecoder::new(48000, Channels::Mono, FRAME_SAMPLES).unwrap();
+        for packet in packets.iter().take(dropped_seq) {
+            expected_decoder.decode(Some(packet)).unwrap();
+        }
+        let expected_lost = expected_decoder
+            .decode(Some(&packets[dropped_seq]))
+            .unwrap();
+
+        let mut plc_decoder = OpusDecoder::new(48000, Channels::Mono, FRAME_SAMPLES).unwrap();
+        for packet in packets.iter().take(dropped_seq) {
+            plc_decoder.decode(Some(packet)).unwrap();
+        }
+        let pure_plc = plc_decoder.decode(None).unwrap();
+
+        let mut jb = JitterBuffer::new().unwrap();
+        for (seq, packet) in packets.iter().enumerate() {
+            if seq != dropped_seq {
+                jb.insert(seq as u32, packet.clone());
+            }
+        }
+
+        for _ in 0..dropped_seq {
+            assert_eq!(jb.pop_frame().map(|frame| frame.len()), Some(FRAME_SAMPLES));
+        }
+
+        let recovered = jb.pop_frame().expect("gap should be reconstructed");
+        assert_eq!(recovered.len(), FRAME_SAMPLES);
+        assert!(
+            jb.packets.contains_key(&(dropped_seq as u32 + 1)),
+            "FEC source packet must remain buffered for normal decode"
+        );
+        assert_eq!(jb.pop_frame().map(|frame| frame.len()), Some(FRAME_SAMPLES));
+
+        let fec_error = rms_error(&recovered, &expected_lost);
+        let plc_error = rms_error(&pure_plc, &expected_lost);
+        assert!(
+            fec_error < plc_error * 0.75,
+            "FEC reconstruction should be materially closer than PLC (fec_error={fec_error}, plc_error={plc_error})"
+        );
+    }
+
     #[test]
     fn drops_packets_already_played() {
         let mut enc = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();

src/core/messages.rs

@@ -1,4 +1,4 @@
-use crate::config::{NetworkMode, RecordingMode};
+use crate::config::{AudioProfile, NetworkMode, RecordingMode, ScreenShareSettings, ShareQuality};
 use crate::friends::Friend;
 use crate::network::PeerState;
 use crate::presence::{FriendPresence, PresenceMode};
@@ -9,7 +9,15 @@ pub enum CoreCommand {
     /// Join a room. `ticket` is "create" (or empty) to mint a fresh room, else a
     /// share ticket to join. `room_name` is the creator's chosen cosmetic label
     /// for a NEW room; it's ignored when joining (the label rides in the ticket).
-    Join { name: String, ticket: String, room_name: String, input_device: Option<String>, output_device: Option<String>, echo_cancellation: bool, avatar: crate::avatar::Avatar },
+    Join {
+        name: String,
+        ticket: String,
+        room_name: String,
+        input_device: Option<String>,
+        output_device: Option<String>,
+        echo_cancellation: bool,
+        avatar: crate::avatar::Avatar,
+    },
     Leave,
     /// Orderly app shutdown: finalize recordings, leave any active room, stop local
     /// audio/screen-share work, close the persistent network stack, then ack with
@@ -41,10 +49,17 @@ pub enum CoreCommand {
     /// Start/stop a standalone capture-only stream that reports the raw mic
     /// level via [`UiEvent::MicLevel`], for gate calibration outside a call.
     /// Ignored while a room session is active (the in-call meter covers that).
-    SetMicMonitor { enabled: bool, input_device: Option<String> },
+    SetMicMonitor {
+        enabled: bool,
+        input_device: Option<String>,
+    },
     /// Set the relay/discovery posture. Takes effect on the next room join,
     /// since the endpoint is (re)built then.
     SetNetworkMode(NetworkMode),
+    /// Set the Opus encoder / network-resilience profile (W12). Applies live to
+    /// the running capture encoder, and to the next call's encoder. Sent at
+    /// startup from config and whenever the user changes it.
+    SetAudioProfile(AudioProfile),
     /// Start/stop recording the call to a local WAV (your mic + the incoming
     /// mix). No-op start if already recording / not in a call.
     SetRecording(bool),
@@ -56,22 +71,40 @@ pub enum CoreCommand {
     /// Send a chat message carrying a file attachment. The app has already read +
     /// capped the file and built the descriptor; core makes the bytes available
     /// on the file plane and broadcasts the descriptor.
-    SendChatFile { text: String, attachment: crate::files::ChatAttachment, data: Vec<u8> },
+    SendChatFile {
+        text: String,
+        attachment: crate::files::ChatAttachment,
+        data: Vec<u8>,
+    },
     /// Fetch a received attachment's bytes from its sender over the file plane
     /// (used for on-demand file/chip downloads; images are auto-fetched on
     /// receipt). Replies with `AttachmentReady`/`AttachmentFailed`.
-    FetchAttachment { from: EndpointId, attachment: crate::files::ChatAttachment },
+    FetchAttachment {
+        from: EndpointId,
+        attachment: crate::files::ChatAttachment,
+    },
     /// Register `data` as fetchable under `id` for room members (the current
     /// broadcast track). Called once per track when broadcasting.
-    ServeMusicTrack { id: crate::files::AttachmentId, data: std::sync::Arc<Vec<u8>> },
+    ServeMusicTrack {
+        id: crate::files::AttachmentId,
+        data: std::sync::Arc<Vec<u8>>,
+    },
     /// Drop a music blob that is no longer current-or-next.
     ForgetMusicTrack(crate::files::AttachmentId),
     /// Set (or clear) our broadcast music timeline and re-announce presence.
     SetMusicPresence(Option<crate::network::MusicPresence>),
     /// Fetch a source peer's current track bytes after tuning into them.
-    FetchMusic { from: EndpointId, id: crate::files::AttachmentId, size: u64 },
+    FetchMusic {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        size: u64,
+    },
     /// Fetch a source peer's advertised next track bytes before it becomes current.
-    PrefetchMusic { from: EndpointId, id: crate::files::AttachmentId, size: u64 },
+    PrefetchMusic {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        size: u64,
+    },
     /// Set the pixelpass binary location (config override, empty = use `$PATH`).
     /// Sent at startup so screen-share can resolve the binary.
     SetPixelpassPath(Option<String>),
@@ -84,13 +117,20 @@ pub enum CoreCommand {
     /// `audio_app` selects which app's audio to capture: `Some(name)` captures
     /// only that app (avoiding the call-loopback echo, A23); `None` shares the
     /// whole desktop audio (the legacy behavior).
-    StartScreenShare { audio_app: Option<String> },
+    StartScreenShare {
+        audio_app: Option<String>,
+        settings: ScreenShareSettings,
+        quality: ShareQuality,
+    },
     /// Stop sharing our screen: kill the pixelpass host and clear the presence
     /// ticket. No-op when not sharing.
     StopScreenShare,
     /// Watch a peer's screen share: spawn a pixelpass viewer for `ticket` and
     /// open it in a local player.
-    ViewShare(String),
+    ViewShare {
+        ticket: String,
+        settings: ScreenShareSettings,
+    },
     /// Mint a fresh persistent identity (W7), discarding the old one. Takes effect
     /// on the next room join (the endpoint is rebuilt then). The core replies with
     /// an updated [`UiEvent::IdentityStatus`].
@@ -98,7 +138,11 @@ pub enum CoreCommand {
     /// Add a friend (W7). Core owns the friends store: it mutates + persists it and
     /// replies with [`UiEvent::FriendsUpdated`]. `addr` seeds `last_addr` if known
     /// (e.g. added from a room). Idempotent — re-adding an existing id is a no-op.
-    AddFriend { id: EndpointId, name: String, addr: Option<EndpointAddr> },
+    AddFriend {
+        id: EndpointId,
+        name: String,
+        addr: Option<EndpointAddr>,
+    },
     /// Remove a friend by id (W7).
     RemoveFriend(EndpointId),
     /// Locally rename a friend (W7).
@@ -130,6 +174,17 @@ pub enum DeliveryClass {
     BestEffort,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum CoalesceKey {
+    InputVolume,
+    OutputVolume,
+    NoiseGate,
+    PeerVolume(EndpointId),
+    PeerPan(EndpointId),
+    PeerGate(EndpointId),
+    PeerEq(EndpointId),
+}
+
 /// Route a command by how bad it is to drop it. Discrete, human-paced user
 /// actions are Reliable (must land). The only high-frequency commands are the
 /// continuous audio sliders, where dropping intermediate values is harmless;
@@ -166,6 +221,7 @@ pub fn delivery_class(cmd: &CoreCommand) -> DeliveryClass {
             input_device: _,
         }
         | CoreCommand::SetNetworkMode(_)
+        | CoreCommand::SetAudioProfile(_)
         | CoreCommand::SetRecording(_)
         | CoreCommand::SetRecordingMode(_)
         | CoreCommand::SendChat(_)
@@ -178,10 +234,7 @@ pub fn delivery_class(cmd: &CoreCommand) -> DeliveryClass {
             from: _,
             attachment: _,
         }
-        | CoreCommand::ServeMusicTrack {
-            id: _,
-            data: _,
-        }
+        | CoreCommand::ServeMusicTrack { id: _, data: _ }
         | CoreCommand::ForgetMusicTrack(_)
         | CoreCommand::SetMusicPresence(_)
         | CoreCommand::FetchMusic {
@@ -196,9 +249,16 @@ pub fn delivery_class(cmd: &CoreCommand) -> DeliveryClass {
         }
         | CoreCommand::SetPixelpassPath(_)
         | CoreCommand::ListAudioApps
-        | CoreCommand::StartScreenShare { audio_app: _ }
+        | CoreCommand::StartScreenShare {
+            audio_app: _,
+            settings: _,
+            quality: _,
+        }
         | CoreCommand::StopScreenShare
-        | CoreCommand::ViewShare(_)
+        | CoreCommand::ViewShare {
+            ticket: _,
+            settings: _,
+        }
         | CoreCommand::RegenerateIdentity
         | CoreCommand::AddFriend {
             id: _,
@@ -215,57 +275,201 @@ pub fn delivery_class(cmd: &CoreCommand) -> DeliveryClass {
     }
 }
 
+/// Coalescing bucket for high-frequency continuous controls. A key exists
+/// exactly for [`DeliveryClass::BestEffort`] commands.
+pub fn coalesce_key(cmd: &CoreCommand) -> Option<CoalesceKey> {
+    match cmd {
+        CoreCommand::SetPeerVolume(peer_id, _) => Some(CoalesceKey::PeerVolume(*peer_id)),
+        CoreCommand::SetPeerPan(peer_id, _) => Some(CoalesceKey::PeerPan(*peer_id)),
+        CoreCommand::SetPeerGate(peer_id, _) => Some(CoalesceKey::PeerGate(*peer_id)),
+        CoreCommand::SetPeerEq(peer_id, _) => Some(CoalesceKey::PeerEq(*peer_id)),
+        CoreCommand::SetInputVolume(_) => Some(CoalesceKey::InputVolume),
+        CoreCommand::SetOutputVolume(_) => Some(CoalesceKey::OutputVolume),
+        CoreCommand::SetNoiseGateThreshold(_) => Some(CoalesceKey::NoiseGate),
+
+        CoreCommand::Join {
+            name: _,
+            ticket: _,
+            room_name: _,
+            input_device: _,
+            output_device: _,
+            echo_cancellation: _,
+            avatar: _,
+        }
+        | CoreCommand::Leave
+        | CoreCommand::Shutdown
+        | CoreCommand::ToggleMute
+        | CoreCommand::SetAvatar(_)
+        | CoreCommand::ToggleDeafen
+        | CoreCommand::SetPttMode(_)
+        | CoreCommand::SetPttActive(_)
+        | CoreCommand::SetPeerMuted(_, _)
+        | CoreCommand::SetMicMonitor {
+            enabled: _,
+            input_device: _,
+        }
+        | CoreCommand::SetNetworkMode(_)
+        | CoreCommand::SetAudioProfile(_)
+        | CoreCommand::SetRecording(_)
+        | CoreCommand::SetRecordingMode(_)
+        | CoreCommand::SendChat(_)
+        | CoreCommand::SendChatFile {
+            text: _,
+            attachment: _,
+            data: _,
+        }
+        | CoreCommand::FetchAttachment {
+            from: _,
+            attachment: _,
+        }
+        | CoreCommand::ServeMusicTrack { id: _, data: _ }
+        | CoreCommand::ForgetMusicTrack(_)
+        | CoreCommand::SetMusicPresence(_)
+        | CoreCommand::FetchMusic {
+            from: _,
+            id: _,
+            size: _,
+        }
+        | CoreCommand::PrefetchMusic {
+            from: _,
+            id: _,
+            size: _,
+        }
+        | CoreCommand::SetPixelpassPath(_)
+        | CoreCommand::ListAudioApps
+        | CoreCommand::StartScreenShare {
+            audio_app: _,
+            settings: _,
+            quality: _,
+        }
+        | CoreCommand::StopScreenShare
+        | CoreCommand::ViewShare {
+            ticket: _,
+            settings: _,
+        }
+        | CoreCommand::RegenerateIdentity
+        | CoreCommand::AddFriend {
+            id: _,
+            name: _,
+            addr: _,
+        }
+        | CoreCommand::RemoveFriend(_)
+        | CoreCommand::RenameFriend(_, _)
+        | CoreCommand::RefreshFriends
+        | CoreCommand::SetPresenceMode(_)
+        | CoreCommand::SetGamePresenceEnabled(_)
+        | CoreCommand::SetGameOverride(_)
+        | CoreCommand::SetGameProcessMap(_) => None,
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum UiEvent {
-    RoomJoined { ticket: String, self_id: String },
+    RoomJoined {
+        ticket: String,
+        self_id: String,
+    },
     RoomLeft,
     /// Clear room-scoped UI state after a failed in-call room switch, without a
     /// leave chime. The persistent identity remains unchanged.
     RoomReset,
-    PeerJoined { id: EndpointId, state: PeerState },
-    PeerLeft { id: EndpointId },
+    PeerJoined {
+        id: EndpointId,
+        state: PeerState,
+    },
+    PeerLeft {
+        id: EndpointId,
+    },
     /// The fixed reconnect grace expired and bounded background gossip recovery
     /// has started. This is non-terminal and must not play the failure chime.
-    PeerRecoveryStarted { id: EndpointId },
-    PeerConnectionFailed { id: EndpointId },
-    PeerUpdated { id: EndpointId, state: PeerState },
+    PeerRecoveryStarted {
+        id: EndpointId,
+    },
+    PeerConnectionFailed {
+        id: EndpointId,
+    },
+    PeerUpdated {
+        id: EndpointId,
+        state: PeerState,
+    },
     /// Audio link to a peer is being (re)established — show a connecting state.
-    PeerConnecting { id: EndpointId },
+    PeerConnecting {
+        id: EndpointId,
+    },
     /// Audio link to a peer is up and carrying audio.
-    PeerConnected { id: EndpointId },
+    PeerConnected {
+        id: EndpointId,
+    },
     AudioLevels(Vec<(EndpointId, f32)>),
+    /// Periodic per-peer connection transparency snapshot (~1/sec): path type
+    /// (direct/relay), RTT, and window loss/bitrate for every peer with a live
+    /// audio link. A FULL replacement each time — a peer absent from the list
+    /// has no live link right now, so its badge should disappear.
+    ConnectionStats(Vec<(EndpointId, crate::core::connstats::PeerConnInfo)>),
     /// Raw (pre-gate, pre-mute) normalized RMS of the local mic, `0.0..=1.0`,
     /// for the settings level meter. Throttled to ~10/sec.
     MicLevel(f32),
     /// Call recording started; carries the absolute WAV path being written.
-    RecordingStarted { path: String },
+    RecordingStarted {
+        path: String,
+    },
     /// Call recording stopped; carries the finished WAV path.
-    RecordingStopped { path: String },
+    RecordingStopped {
+        path: String,
+    },
     /// A room text-chat message arrived from a peer (never our own — local
     /// messages are echoed by the UI on send). `from` is the sender's node id
     /// string, used to key their avatar (W4).
-    ChatMessage { from: String, name: String, text: String, attachment: Option<crate::files::ChatAttachment> },
+    ChatMessage {
+        from: String,
+        name: String,
+        text: String,
+        attachment: Option<crate::files::ChatAttachment>,
+    },
     /// An attachment's bytes are now available (auto-fetched for images, or
     /// fetched on demand for files). Keyed by `(from, id)`: the id is
     /// attacker-chosen, so a malicious peer can reuse a victim's id — the author
     /// disambiguates whose bytes these are and stops content aliasing (Tier C
     /// F-12).
-    AttachmentReady { from: EndpointId, id: crate::files::AttachmentId, data: Vec<u8> },
+    AttachmentReady {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        data: Vec<u8>,
+    },
     /// An attachment fetch failed (sender gone, too large, decode error, etc.).
-    AttachmentFailed { from: EndpointId, id: crate::files::AttachmentId, error: String },
+    AttachmentFailed {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        error: String,
+    },
     /// A tuned-in source's track bytes arrived; play them in the music sink.
-    MusicReady { from: EndpointId, id: crate::files::AttachmentId, data: Vec<u8> },
+    MusicReady {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        data: Vec<u8>,
+    },
     /// A tuned-in source's next-track bytes arrived; cache them for a gapless swap.
-    MusicPrefetched { from: EndpointId, id: crate::files::AttachmentId, data: Vec<u8> },
+    MusicPrefetched {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        data: Vec<u8>,
+    },
     /// A music-track fetch failed (source gone, too large, etc.).
-    MusicFetchFailed { from: EndpointId, id: crate::files::AttachmentId, error: String },
+    MusicFetchFailed {
+        from: EndpointId,
+        id: crate::files::AttachmentId,
+        error: String,
+    },
     /// The apps currently producing audio, for the screen-share audio picker
     /// (A23). Sorted, deduplicated `application.name`s; empty when nothing is
     /// playing or enumeration isn't available. `app_audio_supported` reports
     /// whether the resolved pixelpass understands `--strict-audio`: when `false`
     /// (an older pixelpass) the picker must offer whole-desktop audio only, since
     /// a per-app share would pass a flag that older binary rejects (audit P2).
-    AudioAppsListed { apps: Vec<String>, app_audio_supported: bool },
+    AudioAppsListed {
+        apps: Vec<String>,
+        app_audio_supported: bool,
+    },
     /// Our own screen share started; the UI flips the Share button to "Stop".
     ScreenShareStarted,
     /// Our own screen share stopped (or failed to start).
@@ -278,24 +482,37 @@ pub enum UiEvent {
     /// A validly signed peer cannot be admitted because its gossip timestamp is
     /// outside the replay freshness window. `peer_ahead` describes the peer's
     /// sender-stamped timestamp relative to this machine's clock.
-    ClockSkewWarning { skew_secs: u64, peer_ahead: bool },
+    ClockSkewWarning {
+        skew_secs: u64,
+        peer_ahead: bool,
+    },
     /// Our node identity (W7): the current node id string, and whether it is
     /// PERSISTED to disk. Sent once at startup and again after a regenerate.
     /// `persisted = false` means the key file couldn't be read/written and we're
     /// running on an ephemeral fallback — a degraded state the UI must surface,
     /// since the id (and thus friend recognition) won't survive the next launch.
     /// `error` carries the reason when degraded, for the UI explainer.
-    IdentityStatus { node_id: String, persisted: bool, error: Option<String> },
+    IdentityStatus {
+        node_id: String,
+        persisted: bool,
+        error: Option<String>,
+    },
     /// The friends list (W7), now owned by core. Sent at startup (after load) and
     /// after every add/remove/rename so the GUI renders from this snapshot instead
     /// of owning the store. `read_only` is true when `friends.json` failed to load
     /// (malformed) — the GUI shows a degraded warning and disables edits so we never
     /// overwrite the damaged file (backlog A16).
-    FriendsUpdated { friends: Vec<Friend>, read_only: bool },
+    FriendsUpdated {
+        friends: Vec<Friend>,
+        read_only: bool,
+    },
     /// A friend's live presence from a successful ping reply (W7): online, or in a
     /// joinable gathering (with a one-click ticket). Emitted by the outbound ping
     /// scheduler; absence of a recent event = treat as offline.
-    FriendPresence { id: EndpointId, presence: FriendPresence },
+    FriendPresence {
+        id: EndpointId,
+        presence: FriendPresence,
+    },
     /// A manual "Rescan" pass finished (every friend has been probed and its
     /// per-friend `FriendPresence` already emitted). Lets the GUI clear the
     /// transient "Rescanning…" status. Sent only for the on-demand button, not the
@@ -305,7 +522,9 @@ pub enum UiEvent {
     /// time-box elapsed and the core auto-reverted to `Normal`; on discovery apply
     /// failure, this carries the previous truthful mode. The GUI must mirror +
     /// persist this so its presence picker matches the endpoint's discovery state.
-    PresenceModeReverted { mode: PresenceMode },
+    PresenceModeReverted {
+        mode: PresenceMode,
+    },
     /// The locally-detected running game changed (game detection). Carries the
     /// debounced `DetectedGame` (id + display name + source) or `None` when nothing
     /// is detected. The GUI uses the stable `id` to switch the per-game background
@@ -319,7 +538,7 @@ pub enum UiEvent {
 
 #[cfg(test)]
 mod tests {
-    use super::{delivery_class, CoreCommand, DeliveryClass};
+    use super::{CoalesceKey, CoreCommand, DeliveryClass, coalesce_key, delivery_class};
     use crate::audio::eq::EqSettings;
     use crate::presence::PresenceMode;
     use iroh::{EndpointId, SecretKey};
@@ -332,17 +551,37 @@ mod tests {
     fn continuous_audio_controls_are_best_effort() {
         let peer = endpoint_id();
         let commands = [
-            CoreCommand::SetPeerVolume(peer, 0.7),
-            CoreCommand::SetPeerPan(peer, -0.2),
-            CoreCommand::SetPeerGate(peer, 0.1),
-            CoreCommand::SetPeerEq(peer, EqSettings::default()),
-            CoreCommand::SetInputVolume(0.8),
-            CoreCommand::SetOutputVolume(0.9),
-            CoreCommand::SetNoiseGateThreshold(0.02),
+            (
+                CoreCommand::SetPeerVolume(peer, 0.7),
+                CoalesceKey::PeerVolume(peer),
+            ),
+            (
+                CoreCommand::SetPeerPan(peer, -0.2),
+                CoalesceKey::PeerPan(peer),
+            ),
+            (
+                CoreCommand::SetPeerGate(peer, 0.1),
+                CoalesceKey::PeerGate(peer),
+            ),
+            (
+                CoreCommand::SetPeerEq(peer, EqSettings::default()),
+                CoalesceKey::PeerEq(peer),
+            ),
+            (CoreCommand::SetInputVolume(0.8), CoalesceKey::InputVolume),
+            (CoreCommand::SetOutputVolume(0.9), CoalesceKey::OutputVolume),
+            (
+                CoreCommand::SetNoiseGateThreshold(0.02),
+                CoalesceKey::NoiseGate,
+            ),
         ];
 
-        for cmd in commands {
+        for (cmd, key) in commands {
             assert_eq!(delivery_class(&cmd), DeliveryClass::BestEffort);
+            assert_eq!(coalesce_key(&cmd), Some(key));
+            assert_eq!(
+                coalesce_key(&cmd).is_some(),
+                delivery_class(&cmd) == DeliveryClass::BestEffort
+            );
         }
     }
 
@@ -365,11 +604,17 @@ mod tests {
             },
             CoreCommand::SetPeerMuted(peer, true),
             CoreCommand::SetPresenceMode(PresenceMode::Normal),
+            CoreCommand::SetAudioProfile(crate::config::AudioProfile::BadNetwork),
             CoreCommand::SendChat("hello".to_string()),
         ];
 
         for cmd in commands {
             assert_eq!(delivery_class(&cmd), DeliveryClass::Reliable);
+            assert_eq!(coalesce_key(&cmd), None);
+            assert_eq!(
+                coalesce_key(&cmd).is_some(),
+                delivery_class(&cmd) == DeliveryClass::BestEffort
+            );
         }
     }
 }

src/dsp/aec.rs

@@ -283,8 +283,14 @@ mod tests {
         let q = echo.len() / 4;
         let early = erle(&echo[..q], &cleaned[..q]);
         let late = erle(&echo[3 * q..], &cleaned[3 * q..]);
-        assert!(late > early + 10.0, "should improve markedly: early {early:.1} late {late:.1}");
-        assert!(late > 20.0, "converged ERLE should exceed 20 dB, got {late:.1}");
+        assert!(
+            late > early + 10.0,
+            "should improve markedly: early {early:.1} late {late:.1}"
+        );
+        assert!(
+            late > 20.0,
+            "converged ERLE should exceed 20 dB, got {late:.1}"
+        );
     }
 
     #[test]
@@ -307,7 +313,10 @@ mod tests {
         let mut aec = Nlms::new(128, 0.5, 1e-6);
         let out = aec.process(&silent_ref, &near);
         for (a, b) in near.iter().zip(&out) {
-            assert!((a - b).abs() < 1e-6, "near-end should pass through: {a} vs {b}");
+            assert!(
+                (a - b).abs() < 1e-6,
+                "near-end should pass through: {a} vs {b}"
+            );
         }
     }
 
@@ -341,14 +350,24 @@ mod tests {
         let mut late_hits = 0;
         for i in 0..far.len() {
             if dtd.update(far[i], mic[i]) {
-                if i < onset { early_hits += 1 } else { late_hits += 1 }
+                if i < onset {
+                    early_hits += 1
+                } else {
+                    late_hits += 1
+                }
             }
         }
         // Echo-only stretch should rarely trip; near-end stretch should trip a lot.
         let early_rate = early_hits as f32 / onset as f32;
         let late_rate = late_hits as f32 / (far.len() - onset) as f32;
-        assert!(early_rate < 0.10, "false-positive rate {early_rate:.2} too high");
-        assert!(late_rate > 0.50, "missed double-talk, rate only {late_rate:.2}");
+        assert!(
+            early_rate < 0.10,
+            "false-positive rate {early_rate:.2} too high"
+        );
+        assert!(
+            late_rate > 0.50,
+            "missed double-talk, rate only {late_rate:.2}"
+        );
     }
 
     #[test]
@@ -380,6 +399,9 @@ mod tests {
             erle_dtd > erle_no + 15.0,
             "DTD should hold the echo path: with {erle_dtd:.1} dB vs without {erle_no:.1} dB"
         );
-        assert!(erle_dtd > 15.0, "held filter should still cancel echo: {erle_dtd:.1} dB");
+        assert!(
+            erle_dtd > 15.0,
+            "held filter should still cancel echo: {erle_dtd:.1} dB"
+        );
     }
 }

src/dsp/echo_path.rs

@@ -115,7 +115,10 @@ mod tests {
         let path = EchoPath::synthetic(480, 480, 0.5, 99);
         let echo = path.apply(&far);
         let ratio = rms(&echo) / rms(&far);
-        assert!((0.3..0.7).contains(&ratio), "echo/far rms ratio {ratio} off target");
+        assert!(
+            (0.3..0.7).contains(&ratio),
+            "echo/far rms ratio {ratio} off target"
+        );
     }
 
     #[test]

src/dsp/fft.rs

@@ -141,7 +141,10 @@ mod tests {
         buf[0] = Complex::new(1.0, 0.0);
         fft(&mut buf);
         for c in &buf {
-            assert!(approx(c.magnitude(), 1.0, 1e-9), "expected flat 1.0, got {c:?}");
+            assert!(
+                approx(c.magnitude(), 1.0, 1e-9),
+                "expected flat 1.0, got {c:?}"
+            );
         }
     }
 

src/dsp/metrics.rs

@@ -62,11 +62,31 @@ pub struct Band {
 
 /// Voice-relevant bands for spotting *where* residual echo or noise lives.
 pub const VOICE_BANDS: &[Band] = &[
-    Band { label: "low (80-300)", low_hz: 80.0, high_hz: 300.0 },
-    Band { label: "low-mid (300-1k)", low_hz: 300.0, high_hz: 1000.0 },
-    Band { label: "mid (1k-3k)", low_hz: 1000.0, high_hz: 3000.0 },
-    Band { label: "high-mid (3k-6k)", low_hz: 3000.0, high_hz: 6000.0 },
-    Band { label: "high (6k-12k)", low_hz: 6000.0, high_hz: 12000.0 },
+    Band {
+        label: "low (80-300)",
+        low_hz: 80.0,
+        high_hz: 300.0,
+    },
+    Band {
+        label: "low-mid (300-1k)",
+        low_hz: 300.0,
+        high_hz: 1000.0,
+    },
+    Band {
+        label: "mid (1k-3k)",
+        low_hz: 1000.0,
+        high_hz: 3000.0,
+    },
+    Band {
+        label: "high-mid (3k-6k)",
+        low_hz: 3000.0,
+        high_hz: 6000.0,
+    },
+    Band {
+        label: "high (6k-12k)",
+        low_hz: 6000.0,
+        high_hz: 12000.0,
+    },
 ];
 
 /// Sums the linear magnitude energy within `[low_hz, high_hz)` across a single

src/dsp/render.rs

@@ -202,7 +202,8 @@ fn legend(opts: &RenderOpts) -> String {
     if opts.ascii {
         for i in 0..steps {
             let v = i as f32 / (steps - 1) as f32;
-            let idx = ((v * (ASCII_RAMP.len() - 1) as f32).round() as usize).min(ASCII_RAMP.len() - 1);
+            let idx =
+                ((v * (ASCII_RAMP.len() - 1) as f32).round() as usize).min(ASCII_RAMP.len() - 1);
             s.push(ASCII_RAMP[idx] as char);
         }
     } else {
@@ -243,7 +244,11 @@ mod tests {
     fn render_produces_grid_of_expected_height() {
         let sig = generators::sine(2000.0, 0.8, 48_000, 48_000);
         let spec = stft::analyze(&sig, 48_000, 1024, 512);
-        let opts = RenderOpts { width: 40, height: 10, ..Default::default() };
+        let opts = RenderOpts {
+            width: 40,
+            height: 10,
+            ..Default::default()
+        };
         let out = render(&spec, &opts);
         // Header + 10 body rows + time axis (2) + legend = non-trivial.
         let lines = out.lines().count();

src/dsp/stft.rs

@@ -94,7 +94,10 @@ mod tests {
             .unwrap()
             .0;
         let peak_hz = s.bin_hz(peak_bin);
-        assert!((peak_hz - freq as f32).abs() < 100.0, "peak at {peak_hz} Hz, want {freq}");
+        assert!(
+            (peak_hz - freq as f32).abs() < 100.0,
+            "peak at {peak_hz} Hz, want {freq}"
+        );
     }
 
     #[test]

src/dsp/wav.rs

@@ -34,7 +34,12 @@ pub fn read(path: &Path) -> Result<WavData, String> {
     let mut pos = 12usize;
     while pos + 8 <= bytes.len() {
         let id = &bytes[pos..pos + 4];
-        let size = u32::from_le_bytes([bytes[pos + 4], bytes[pos + 5], bytes[pos + 6], bytes[pos + 7]]) as usize;
+        let size = u32::from_le_bytes([
+            bytes[pos + 4],
+            bytes[pos + 5],
+            bytes[pos + 6],
+            bytes[pos + 7],
+        ]) as usize;
         let body_start = pos + 8;
         let body_end = (body_start + size).min(bytes.len());
         match id {
@@ -45,7 +50,9 @@ pub fn read(path: &Path) -> Result<WavData, String> {
                 sample_rate = u32::from_le_bytes([fmt[4], fmt[5], fmt[6], fmt[7]]);
                 bits = u16::from_le_bytes([fmt[14], fmt[15]]);
                 if audio_format != 1 {
-                    return Err(format!("unsupported WAV format tag {audio_format} (need PCM=1)"));
+                    return Err(format!(
+                        "unsupported WAV format tag {audio_format} (need PCM=1)"
+                    ));
                 }
             }
             b"data" => {
@@ -75,7 +82,10 @@ pub fn read(path: &Path) -> Result<WavData, String> {
         samples.push(avg / 32768.0);
     }
 
-    Ok(WavData { samples, sample_rate })
+    Ok(WavData {
+        samples,
+        sample_rate,
+    })
 }
 
 /// Writes mono `f32` samples (clamped to `[-1, 1]`) as a 16-bit PCM WAV. Used by

src/files.rs

@@ -76,10 +76,7 @@ pub fn sanitize_filename(raw: &str) -> String {
         .trim();
 
     // Drop control chars; turn other whitespace into single spaces later.
-    let cleaned: String = base
-        .chars()
-        .filter(|c| !c.is_control())
-        .collect();
+    let cleaned: String = base.chars().filter(|c| !c.is_control()).collect();
     let collapsed = cleaned.split_whitespace().collect::<Vec<_>>().join(" ");
     let collapsed = collapsed.trim_matches('.').trim();
 
@@ -145,7 +142,10 @@ pub fn looks_like_audio_name(name: &str) -> bool {
     let Some((_, extension)) = name.rsplit_once('.') else {
         return false;
     };
-    matches!(extension.to_ascii_lowercase().as_str(), "wav" | "mp3" | "ogg" | "oga" | "flac")
+    matches!(
+        extension.to_ascii_lowercase().as_str(),
+        "wav" | "mp3" | "ogg" | "oga" | "flac"
+    )
 }
 
 /// The attachment kind for some file bytes: [`AttachmentKind::Image`] if it
@@ -240,7 +240,11 @@ mod tests {
         let long_stem = "x".repeat(200);
         let name = format!("{long_stem}.png");
         let out = sanitize_filename(&name);
-        assert!(out.chars().count() <= MAX_FILENAME_LEN, "len was {}", out.chars().count());
+        assert!(
+            out.chars().count() <= MAX_FILENAME_LEN,
+            "len was {}",
+            out.chars().count()
+        );
         assert!(out.ends_with(".png"), "extension preserved: {out}");
     }
 
@@ -254,7 +258,9 @@ mod tests {
 
     #[test]
     fn image_sniffing_recognizes_containers() {
-        assert!(is_probably_image(&[0x89, b'P', b'N', b'G', 0x0D, 0x0A, 0x1A, 0x0A, 0, 0]));
+        assert!(is_probably_image(&[
+            0x89, b'P', b'N', b'G', 0x0D, 0x0A, 0x1A, 0x0A, 0, 0
+        ]));
         assert!(is_probably_image(&[0xFF, 0xD8, 0xFF, 0xE0]));
         assert!(is_probably_image(b"GIF89a...."));
         let mut webp = b"RIFF".to_vec();

src/friends.rs

@@ -66,7 +66,11 @@ impl FriendStore {
         if self.contains(&id) {
             return false;
         }
-        self.friends.push(Friend { id, name, last_addr: addr });
+        self.friends.push(Friend {
+            id,
+            name,
+            last_addr: addr,
+        });
         true
     }
 
@@ -118,21 +122,24 @@ pub fn friends_path() -> Option<PathBuf> {
 /// *parse* error bubbles up so a hand-edit being debugged isn't silently
 /// overwritten with an empty list.
 pub fn load() -> Result<FriendStore> {
-    let path = friends_path().context("could not determine a config directory for the friends list")?;
+    let path =
+        friends_path().context("could not determine a config directory for the friends list")?;
     load_at(&path)
 }
 
 /// Save the store. Atomic via tempfile-in-same-dir + rename.
 pub fn save(store: &FriendStore) -> Result<()> {
-    let path = friends_path().context("could not determine a config directory for the friends list")?;
+    let path =
+        friends_path().context("could not determine a config directory for the friends list")?;
     save_at(&path, store)
 }
 
 /// Path-injectable core of [`load`], so the round-trip is testable in a temp dir.
 fn load_at(path: &Path) -> Result<FriendStore> {
     match fs::read_to_string(path) {
-        Ok(s) => serde_json::from_str(&s)
-            .with_context(|| format!("failed to parse {}", path.display())),
+        Ok(s) => {
+            serde_json::from_str(&s).with_context(|| format!("failed to parse {}", path.display()))
+        }
         Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(FriendStore::default()),
         Err(e) => Err(e).with_context(|| format!("failed to read {}", path.display())),
     }
@@ -141,11 +148,14 @@ fn load_at(path: &Path) -> Result<FriendStore> {
 /// Path-injectable core of [`save`]. Atomic write: tempfile-in-same-dir, then
 /// rename, so a crash mid-write can't leave a truncated list.
 fn save_at(path: &Path, store: &FriendStore) -> Result<()> {
-    let parent = path.parent().context("friends path has no parent directory")?;
+    let parent = path
+        .parent()
+        .context("friends path has no parent directory")?;
     fs::create_dir_all(parent).with_context(|| format!("failed to create {}", parent.display()))?;
     let json = serde_json::to_string_pretty(store).context("failed to encode the friends list")?;
     let tmp = parent.join(format!(".friends.json.tmp.{}", std::process::id()));
-    fs::write(&tmp, json.as_bytes()).with_context(|| format!("failed to write {}", tmp.display()))?;
+    fs::write(&tmp, json.as_bytes())
+        .with_context(|| format!("failed to write {}", tmp.display()))?;
     fs::rename(&tmp, path)
         .with_context(|| format!("failed to rename {} -> {}", tmp.display(), path.display()))?;
     Ok(())
@@ -219,7 +229,11 @@ mod tests {
     /// A unique temp path; `save_at` creates the nested dir (exercises create_dir_all).
     fn temp_path(tag: &str) -> PathBuf {
         let mut p = std::env::temp_dir();
-        p.push(format!("peerspeak-friendstest-{}-{}", std::process::id(), tag));
+        p.push(format!(
+            "peerspeak-friendstest-{}-{}",
+            std::process::id(),
+            tag
+        ));
         p.push("friends.json");
         p
     }

src/game/detector.rs

@@ -9,11 +9,9 @@
 //! is factored into the pure [`poll_once`] so the wiring of resolve + match +
 //! debounce is unit-tested without any I/O.
 
-use super::{
-    builtin_denylist, match_processes, resolve, Debouncer, DetectedGame, ManualOverride,
-};
 use super::scan;
 use super::steam::SteamProbe;
+use super::{Debouncer, DetectedGame, ManualOverride, builtin_denylist, match_processes, resolve};
 use std::collections::BTreeMap;
 use std::io;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -145,9 +143,14 @@ fn worker_loop(
         let steam_game = steam.detect();
         let processes = scan::running_executables();
 
-        if let Some(new_current) =
-            poll_once(&mut debouncer, &override_, steam_game, &processes, &process_map, &denylist)
-        {
+        if let Some(new_current) = poll_once(
+            &mut debouncer,
+            &override_,
+            steam_game,
+            &processes,
+            &process_map,
+            &denylist,
+        ) {
             // A closed receiver means core shut down; stop quietly.
             if tx.send(new_current).is_err() {
                 return;
@@ -169,11 +172,18 @@ mod tests {
     use super::*;
 
     fn game(id: &str, name: &str, source: GameSource) -> DetectedGame {
-        DetectedGame { id: id.into(), name: Some(name.into()), source }
+        DetectedGame {
+            id: id.into(),
+            name: Some(name.into()),
+            source,
+        }
     }
 
     fn map(pairs: &[(&str, &str)]) -> BTreeMap<String, String> {
-        pairs.iter().map(|(k, v)| (k.to_string(), v.to_string())).collect()
+        pairs
+            .iter()
+            .map(|(k, v)| (k.to_string(), v.to_string()))
+            .collect()
     }
 
     #[test]
@@ -185,17 +195,38 @@ mod tests {
 
         // First poll: detected but not yet published (needs two hits).
         assert_eq!(
-            poll_once(&mut d, &ManualOverride::Auto, Some(steam.clone()), &[], &empty, &deny),
+            poll_once(
+                &mut d,
+                &ManualOverride::Auto,
+                Some(steam.clone()),
+                &[],
+                &empty,
+                &deny
+            ),
             None
         );
         // Second poll: published.
         assert_eq!(
-            poll_once(&mut d, &ManualOverride::Auto, Some(steam.clone()), &[], &empty, &deny),
+            poll_once(
+                &mut d,
+                &ManualOverride::Auto,
+                Some(steam.clone()),
+                &[],
+                &empty,
+                &deny
+            ),
             Some(Some(steam))
         );
         // Third identical poll: no change event.
         assert_eq!(
-            poll_once(&mut d, &ManualOverride::Auto, Some(game("steam:730", "CS2", GameSource::Steam)), &[], &empty, &deny),
+            poll_once(
+                &mut d,
+                &ManualOverride::Auto,
+                Some(game("steam:730", "CS2", GameSource::Steam)),
+                &[],
+                &empty,
+                &deny
+            ),
             None
         );
     }
@@ -209,7 +240,9 @@ mod tests {
 
         poll_once(&mut d, &ManualOverride::Auto, None, &procs, &user, &deny);
         let change = poll_once(&mut d, &ManualOverride::Auto, None, &procs, &user, &deny);
-        let published = change.expect("should publish on second hit").expect("a game");
+        let published = change
+            .expect("should publish on second hit")
+            .expect("a game");
         assert_eq!(published.id, "exe:hl2_linux");
         assert_eq!(published.name.as_deref(), Some("Half-Life 2"));
     }

src/game/mod.rs

@@ -92,11 +92,20 @@ pub fn resolve(
     processes: &[DetectedGame],
 ) -> Resolution {
     match override_ {
-        ManualOverride::ForceNone => Resolution { game: None, immediate: true },
-        ManualOverride::Force(g) => Resolution { game: Some(g.clone()), immediate: true },
+        ManualOverride::ForceNone => Resolution {
+            game: None,
+            immediate: true,
+        },
+        ManualOverride::Force(g) => Resolution {
+            game: Some(g.clone()),
+            immediate: true,
+        },
         ManualOverride::Auto => {
             let game = steam.or_else(|| processes.first().cloned());
-            Resolution { game, immediate: false }
+            Resolution {
+                game,
+                immediate: false,
+            }
         }
     }
 }
@@ -192,7 +201,11 @@ impl Debouncer {
 /// lowercase it. Keeps any extension (`minecraft.exe` stays distinct from a
 /// hypothetical `minecraft`), trims surrounding whitespace.
 pub fn normalize_exe(raw: &str) -> String {
-    raw.rsplit(['/', '\\']).next().unwrap_or(raw).trim().to_lowercase()
+    raw.rsplit(['/', '\\'])
+        .next()
+        .unwrap_or(raw)
+        .trim()
+        .to_lowercase()
 }
 
 /// Launcher/helper executables that must NEVER be reported as a game even if a
@@ -245,8 +258,10 @@ pub fn match_processes(
     denylist: &BTreeSet<&str>,
 ) -> Vec<DetectedGame> {
     // Normalize the user map once so lookups are basename/case-insensitive.
-    let normalized_map: BTreeMap<String, &String> =
-        user_map.iter().map(|(k, v)| (normalize_exe(k), v)).collect();
+    let normalized_map: BTreeMap<String, &String> = user_map
+        .iter()
+        .map(|(k, v)| (normalize_exe(k), v))
+        .collect();
 
     let mut seen: BTreeSet<String> = BTreeSet::new();
     let mut out: Vec<DetectedGame> = Vec::new();
@@ -288,8 +303,14 @@ mod tests {
     #[test]
     fn stable_ids_are_namespaced() {
         assert_eq!(DetectedGame::steam_id(730), "steam:730");
-        assert_eq!(DetectedGame::exe_id("/usr/games/hl2_linux"), "exe:hl2_linux");
-        assert_eq!(DetectedGame::exe_id("C:\\Games\\Minecraft.exe"), "exe:minecraft.exe");
+        assert_eq!(
+            DetectedGame::exe_id("/usr/games/hl2_linux"),
+            "exe:hl2_linux"
+        );
+        assert_eq!(
+            DetectedGame::exe_id("C:\\Games\\Minecraft.exe"),
+            "exe:minecraft.exe"
+        );
     }
 
     #[test]
@@ -318,8 +339,16 @@ mod tests {
     #[test]
     fn resolve_falls_back_to_first_process_then_none() {
         let procs = vec![
-            DetectedGame { id: "exe:a".into(), name: Some("A".into()), source: GameSource::Process },
-            DetectedGame { id: "exe:b".into(), name: Some("B".into()), source: GameSource::Process },
+            DetectedGame {
+                id: "exe:a".into(),
+                name: Some("A".into()),
+                source: GameSource::Process,
+            },
+            DetectedGame {
+                id: "exe:b".into(),
+                name: Some("B".into()),
+                source: GameSource::Process,
+            },
         ];
         let r = resolve(&ManualOverride::Auto, None, &procs);
         assert_eq!(r.game.as_ref().unwrap().id, "exe:a");
@@ -426,7 +455,10 @@ mod tests {
     // --- process matching --------------------------------------------------
 
     fn map(pairs: &[(&str, &str)]) -> BTreeMap<String, String> {
-        pairs.iter().map(|(k, v)| (k.to_string(), v.to_string())).collect()
+        pairs
+            .iter()
+            .map(|(k, v)| (k.to_string(), v.to_string()))
+            .collect()
     }
 
     #[test]
@@ -461,14 +493,13 @@ mod tests {
         let user = map(&[("zed", "Zed"), ("alpha", "Alpha")]);
         let deny = builtin_denylist();
         // Same game twice (two processes) + reverse discovery order.
-        let running = vec![
-            "/b/zed".into(),
-            "/a/alpha".into(),
-            "/c/alpha".into(),
-        ];
+        let running = vec!["/b/zed".into(), "/a/alpha".into(), "/c/alpha".into()];
         let got = match_processes(&running, &user, &deny);
         // Deduped to two, sorted by id (alpha before zed) regardless of scan order.
-        assert_eq!(got.iter().map(|g| g.id.as_str()).collect::<Vec<_>>(), vec!["exe:alpha", "exe:zed"]);
+        assert_eq!(
+            got.iter().map(|g| g.id.as_str()).collect::<Vec<_>>(),
+            vec!["exe:alpha", "exe:zed"]
+        );
     }
 
     #[test]

src/game/scan.rs

@@ -62,7 +62,7 @@ fn linux_proc_executables() -> Vec<String> {
 fn windows_toolhelp_executables() -> Vec<String> {
     use windows_sys::Win32::Foundation::{CloseHandle, INVALID_HANDLE_VALUE};
     use windows_sys::Win32::System::Diagnostics::ToolHelp::{
-        CreateToolhelp32Snapshot, Process32FirstW, Process32NextW, PROCESSENTRY32W,
+        CreateToolhelp32Snapshot, PROCESSENTRY32W, Process32FirstW, Process32NextW,
         TH32CS_SNAPPROCESS,
     };
 
@@ -78,7 +78,11 @@ fn windows_toolhelp_executables() -> Vec<String> {
     let mut ok = unsafe { Process32FirstW(snapshot, &mut entry) };
     while ok != 0 {
         // szExeFile is a NUL-terminated UTF-16 array (the basename, e.g. game.exe).
-        let end = entry.szExeFile.iter().position(|&c| c == 0).unwrap_or(entry.szExeFile.len());
+        let end = entry
+            .szExeFile
+            .iter()
+            .position(|&c| c == 0)
+            .unwrap_or(entry.szExeFile.len());
         let name = String::from_utf16_lossy(&entry.szExeFile[..end]);
         if !name.is_empty() {
             out.push(name);
@@ -93,15 +97,16 @@ fn windows_toolhelp_executables() -> Vec<String> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-
     #[cfg(target_os = "linux")]
     #[test]
     fn enumerates_at_least_this_process() {
         // The test runner itself is a process, so /proc enumeration must be
         // non-empty and include something that normalizes to our own exe basename.
-        let exes = running_executables();
-        assert!(!exes.is_empty(), "expected to see running processes via /proc");
+        let exes = super::running_executables();
+        assert!(
+            !exes.is_empty(),
+            "expected to see running processes via /proc"
+        );
         // Our own /proc/self/exe basename should appear among them.
         let me = std::fs::read_link("/proc/self/exe")
             .ok()
@@ -109,7 +114,8 @@ mod tests {
         if let Some(me) = me {
             let me_norm = super::super::normalize_exe(&me);
             assert!(
-                exes.iter().any(|e| super::super::normalize_exe(e) == me_norm),
+                exes.iter()
+                    .any(|e| super::super::normalize_exe(e) == me_norm),
                 "running list should include our own executable {me_norm:?}"
             );
         }

src/game/steam.rs

@@ -25,8 +25,7 @@ const MAX_STEAM_PATH_BYTES: u32 = 4 * 1024;
 
 #[cfg(any(windows, test))]
 fn validate_reg_len(len: u32) -> Option<usize> {
-    (len != 0 && len.is_multiple_of(2) && len <= MAX_STEAM_PATH_BYTES)
-        .then_some(len as usize / 2)
+    (len != 0 && len.is_multiple_of(2) && len <= MAX_STEAM_PATH_BYTES).then_some(len as usize / 2)
 }
 
 #[cfg(any(windows, test))]
@@ -48,7 +47,14 @@ fn decode_reg_sz(mut buf: Vec<u16>, returned_bytes: u32) -> Option<String> {
 pub fn parse_running_app_id(registry_vdf: &str) -> Option<u32> {
     let root = vdf::parse(registry_vdf).ok()?;
     let raw = root
-        .get_path(&["Registry", "HKCU", "Software", "Valve", "Steam", "RunningAppID"])
+        .get_path(&[
+            "Registry",
+            "HKCU",
+            "Software",
+            "Valve",
+            "Steam",
+            "RunningAppID",
+        ])
         .and_then(Value::as_str)?;
     let id: u32 = raw.trim().parse().ok()?;
     (id != 0).then_some(id)
@@ -196,7 +202,13 @@ impl SteamProbe {
             return cached.name.clone();
         }
         let name = read_capped(&manifest).and_then(|c| parse_app_name(&c));
-        self.manifests.insert(app_id, CachedManifest { mtime, name: name.clone() });
+        self.manifests.insert(
+            app_id,
+            CachedManifest {
+                mtime,
+                name: name.clone(),
+            },
+        );
         name
     }
 
@@ -240,7 +252,11 @@ impl SteamProbe {
                 paths.push(root.clone());
             }
         }
-        self.libraries = CachedLibraries { source, mtime, paths: paths.clone() };
+        self.libraries = CachedLibraries {
+            source,
+            mtime,
+            paths: paths.clone(),
+        };
         paths
     }
 }
@@ -360,8 +376,8 @@ mod win {
     use std::path::PathBuf;
     use windows_sys::Win32::Foundation::ERROR_SUCCESS;
     use windows_sys::Win32::System::Registry::{
-        RegCloseKey, RegOpenKeyExW, RegQueryValueExW, HKEY, HKEY_CURRENT_USER, KEY_READ,
-        REG_DWORD, REG_SZ,
+        HKEY, HKEY_CURRENT_USER, KEY_READ, REG_DWORD, REG_SZ, RegCloseKey, RegOpenKeyExW,
+        RegQueryValueExW,
     };
 
     /// UTF-16, NUL-terminated, for a Win32 wide-string argument.
@@ -374,9 +390,8 @@ mod win {
         let subkey = wide("Software\\Valve\\Steam");
         let mut hkey: HKEY = std::ptr::null_mut();
         // SAFETY: valid HKEY constant, NUL-terminated subkey, out-param for the handle.
-        let rc = unsafe {
-            RegOpenKeyExW(HKEY_CURRENT_USER, subkey.as_ptr(), 0, KEY_READ, &mut hkey)
-        };
+        let rc =
+            unsafe { RegOpenKeyExW(HKEY_CURRENT_USER, subkey.as_ptr(), 0, KEY_READ, &mut hkey) };
         (rc == ERROR_SUCCESS).then_some(hkey)
     }
 
@@ -463,13 +478,20 @@ mod tests {
 
     #[test]
     fn registry_string_lengths_are_bounded_and_trimmed() {
-        assert_eq!(validate_reg_len(5), None, "odd byte lengths are invalid UTF-16");
+        assert_eq!(
+            validate_reg_len(5),
+            None,
+            "odd byte lengths are invalid UTF-16"
+        );
         assert_eq!(validate_reg_len(MAX_STEAM_PATH_BYTES + 2), None);
         assert_eq!(validate_reg_len(8), Some(4));
 
         let raw = "C:\\Steam\0ignored".encode_utf16().collect::<Vec<_>>();
         let returned_bytes = ("C:\\Steam\0".encode_utf16().count() * 2) as u32;
-        assert_eq!(decode_reg_sz(raw, returned_bytes).as_deref(), Some("C:\\Steam"));
+        assert_eq!(
+            decode_reg_sz(raw, returned_bytes).as_deref(),
+            Some("C:\\Steam")
+        );
     }
 
     #[test]
@@ -495,10 +517,13 @@ mod tests {
             "contentstatsid" "12345"
         }"#;
         let got = parse_library_paths(current);
-        assert_eq!(got, vec![
-            PathBuf::from("/home/eric/.local/share/Steam"),
-            PathBuf::from("/mnt/games/SteamLibrary"),
-        ]);
+        assert_eq!(
+            got,
+            vec![
+                PathBuf::from("/home/eric/.local/share/Steam"),
+                PathBuf::from("/mnt/games/SteamLibrary"),
+            ]
+        );
 
         // Legacy shape: numeric keys map straight to path strings.
         let legacy = r#""LibraryFolders" {
@@ -522,13 +547,25 @@ mod tests {
         let environ = b"PATH=/usr/bin\0SteamAppId=440\0HOME=/home/x\0SteamGameId=440\0";
         assert_eq!(parse_steam_app_id_from_environ(environ), Some(440));
         // Nonzero requirement: SteamAppId=0 (the launcher itself) is ignored.
-        assert_eq!(parse_steam_app_id_from_environ(b"SteamAppId=0\0FOO=bar\0"), None);
+        assert_eq!(
+            parse_steam_app_id_from_environ(b"SteamAppId=0\0FOO=bar\0"),
+            None
+        );
         // Absent → None (a non-Steam process).
-        assert_eq!(parse_steam_app_id_from_environ(b"PATH=/usr/bin\0HOME=/home/x\0"), None);
+        assert_eq!(
+            parse_steam_app_id_from_environ(b"PATH=/usr/bin\0HOME=/home/x\0"),
+            None
+        );
         // Not fooled by a different var that merely contains the substring.
-        assert_eq!(parse_steam_app_id_from_environ(b"MY_SteamAppId=999\0"), None);
+        assert_eq!(
+            parse_steam_app_id_from_environ(b"MY_SteamAppId=999\0"),
+            None
+        );
         // Garbage value → None, no panic.
-        assert_eq!(parse_steam_app_id_from_environ(b"SteamAppId=notanumber\0"), None);
+        assert_eq!(
+            parse_steam_app_id_from_environ(b"SteamAppId=notanumber\0"),
+            None
+        );
     }
 
     #[test]

src/game/vdf.rs

@@ -234,10 +234,20 @@ mod tests {
 }
 "#;
         let root = parse(acf).unwrap();
-        assert_eq!(root.get_path(&["AppState", "name"]).and_then(Value::as_str), Some("Counter-Strike 2"));
-        assert_eq!(root.get_path(&["AppState", "appid"]).and_then(Value::as_str), Some("730"));
+        assert_eq!(
+            root.get_path(&["AppState", "name"]).and_then(Value::as_str),
+            Some("Counter-Strike 2")
+        );
+        assert_eq!(
+            root.get_path(&["AppState", "appid"])
+                .and_then(Value::as_str),
+            Some("730")
+        );
         // Case-insensitive key lookup.
-        assert_eq!(root.get_path(&["appstate", "NAME"]).and_then(Value::as_str), Some("Counter-Strike 2"));
+        assert_eq!(
+            root.get_path(&["appstate", "NAME"]).and_then(Value::as_str),
+            Some("Counter-Strike 2")
+        );
     }
 
     #[test]
@@ -262,8 +272,14 @@ mod tests {
 "#;
         let root = parse(vdf).unwrap();
         let lf = root.get("libraryfolders").unwrap();
-        assert_eq!(lf.get_path(&["0", "path"]).and_then(Value::as_str), Some(r"C:\Program Files (x86)\Steam"));
-        assert_eq!(lf.get_path(&["1", "path"]).and_then(Value::as_str), Some("/home/eric/.local/share/Steam"));
+        assert_eq!(
+            lf.get_path(&["0", "path"]).and_then(Value::as_str),
+            Some(r"C:\Program Files (x86)\Steam")
+        );
+        assert_eq!(
+            lf.get_path(&["1", "path"]).and_then(Value::as_str),
+            Some("/home/eric/.local/share/Steam")
+        );
         // The library folder ids are iterable for discovery.
         let ids: Vec<&str> = lf.entries().iter().map(|(k, _)| k.as_str()).collect();
         assert_eq!(ids, vec!["0", "1"]);
@@ -292,7 +308,14 @@ mod tests {
 "#;
         let root = parse(reg).unwrap();
         let appid = root
-            .get_path(&["Registry", "HKCU", "Software", "Valve", "Steam", "RunningAppID"])
+            .get_path(&[
+                "Registry",
+                "HKCU",
+                "Software",
+                "Valve",
+                "Steam",
+                "RunningAppID",
+            ])
             .and_then(Value::as_str);
         assert_eq!(appid, Some("570"));
     }
@@ -301,7 +324,10 @@ mod tests {
     fn handles_comments_and_barewords() {
         let vdf = "// a comment\n\"root\"\n{\n\tbarekey barevalue // trailing\n}\n";
         let root = parse(vdf).unwrap();
-        assert_eq!(root.get_path(&["root", "barekey"]).and_then(Value::as_str), Some("barevalue"));
+        assert_eq!(
+            root.get_path(&["root", "barekey"]).and_then(Value::as_str),
+            Some("barevalue")
+        );
     }
 
     #[test]

src/hotkeys.rs

@@ -89,9 +89,9 @@ impl HotkeyAction {
 
     pub fn tier(self) -> HotkeyTier {
         match self {
-            HotkeyAction::ToggleMute
-            | HotkeyAction::ToggleDeafen
-            | HotkeyAction::OpenSettings => HotkeyTier::AppWide,
+            HotkeyAction::ToggleMute | HotkeyAction::ToggleDeafen | HotkeyAction::OpenSettings => {
+                HotkeyTier::AppWide
+            }
             HotkeyAction::PushToTalk | HotkeyAction::LeaveRoom => HotkeyTier::RoomOnly,
         }
     }
@@ -278,7 +278,10 @@ mod tests {
 
     #[test]
     fn parse_single_character_case_folds() {
-        assert_eq!(parse_binding("M"), Some(KeyBinding::Character("m".to_string())));
+        assert_eq!(
+            parse_binding("M"),
+            Some(KeyBinding::Character("m".to_string()))
+        );
         assert_eq!(format_binding(parse_binding("m").as_ref()), "M");
     }
 }

src/identity.rs

@@ -41,7 +41,8 @@ pub fn identity_path() -> Option<PathBuf> {
 /// A *missing* file (first ever run, or right after a reset) is the normal
 /// create path.
 pub fn load_or_create() -> Result<SecretKey> {
-    let path = identity_path().context("could not determine a config directory for the identity key")?;
+    let path =
+        identity_path().context("could not determine a config directory for the identity key")?;
     load_or_create_at(&path)
 }
 
@@ -49,7 +50,8 @@ pub fn load_or_create() -> Result<SecretKey> {
 /// deliberate "Regenerate identity" / unlink action — the old id is discarded and
 /// unrecoverable, so callers should confirm with the user first.
 pub fn regenerate() -> Result<SecretKey> {
-    let path = identity_path().context("could not determine a config directory for the identity key")?;
+    let path =
+        identity_path().context("could not determine a config directory for the identity key")?;
     let key = SecretKey::generate();
     save_at(&path, &key)?;
     Ok(key)
@@ -57,7 +59,8 @@ pub fn regenerate() -> Result<SecretKey> {
 
 /// Atomic, `0600` write at the default identity path. See [`save_at`].
 pub fn save(key: &SecretKey) -> Result<()> {
-    let path = identity_path().context("could not determine a config directory for the identity key")?;
+    let path =
+        identity_path().context("could not determine a config directory for the identity key")?;
     save_at(&path, key)
 }
 
@@ -80,13 +83,15 @@ fn load_or_create_at(path: &std::path::Path) -> Result<SecretKey> {
 /// perms are applied before the rename so the secret is never briefly
 /// world-readable.
 fn save_at(path: &std::path::Path, key: &SecretKey) -> Result<()> {
-    let parent = path.parent().context("identity path has no parent directory")?;
+    let parent = path
+        .parent()
+        .context("identity path has no parent directory")?;
     fs::create_dir_all(parent).with_context(|| format!("failed to create {}", parent.display()))?;
 
     let tmp = parent.join(format!(".identity.key.tmp.{}", std::process::id()));
     {
-        let mut f =
-            fs::File::create(&tmp).with_context(|| format!("failed to create {}", tmp.display()))?;
+        let mut f = fs::File::create(&tmp)
+            .with_context(|| format!("failed to create {}", tmp.display()))?;
         #[cfg(unix)]
         {
             use std::os::unix::fs::PermissionsExt;

src/lib.rs

@@ -1,27 +1,27 @@
-pub mod audio;
-pub mod codec;
-pub mod dsp;
-pub mod network;
-pub mod protocol;
-pub mod core;
 pub mod app;
-pub mod config;
-pub mod identity;
-pub mod friends;
-pub mod presence;
-pub mod presence_net;
-pub mod theme;
-pub mod notify;
-pub mod screenshare;
-pub mod sanitize;
+pub mod audio;
 pub mod avatar;
 pub mod background;
-pub mod recents;
+pub mod codec;
+pub mod config;
+pub mod core;
 pub mod discovery;
-pub mod hotkeys;
+pub mod dsp;
 pub mod files;
-pub mod playlist;
+pub mod friends;
 pub mod game;
+pub mod hotkeys;
+pub mod identity;
+pub mod network;
+pub mod notify;
+pub mod playlist;
+pub mod presence;
+pub mod presence_net;
+pub mod protocol;
+pub mod recents;
+pub mod sanitize;
+pub mod screenshare;
+pub mod theme;
 pub mod widget;
 
 use std::fs::File;
@@ -75,7 +75,8 @@ pub fn redact_for_log(value: &str) -> String {
 }
 
 pub fn short_bytes_hex(bytes: &[u8]) -> String {
-    bytes.iter()
+    bytes
+        .iter()
         .take(6)
         .map(|b| format!("{b:02x}"))
         .collect::<Vec<_>>()
@@ -83,7 +84,10 @@ pub fn short_bytes_hex(bytes: &[u8]) -> String {
 }
 
 fn rotated_log_path(path: &Path) -> PathBuf {
-    let file_name = path.file_name().and_then(|n| n.to_str()).unwrap_or("peerspeak.log");
+    let file_name = path
+        .file_name()
+        .and_then(|n| n.to_str())
+        .unwrap_or("peerspeak.log");
     path.with_file_name(format!("{file_name}.1"))
 }
 
@@ -100,7 +104,10 @@ fn prepare_log_file_with_limit(path: &Path, max_bytes: u64) -> std::io::Result<F
         let rotated = rotated_log_path(path);
         let _ = std::fs::remove_file(&rotated);
         if std::fs::rename(path, &rotated).is_err() {
-            let _ = std::fs::OpenOptions::new().write(true).truncate(true).open(path);
+            let _ = std::fs::OpenOptions::new()
+                .write(true)
+                .truncate(true)
+                .open(path);
         }
     }
 

src/network/gossip.rs

@@ -1,14 +1,14 @@
-use crate::network::{RoomState, NetError, PeerState, RoomEvent, PeerSpeakTicket};
+use crate::network::{NetError, PeerSpeakTicket, PeerState, RoomEvent, RoomState};
+use async_trait::async_trait;
 use iroh::{Endpoint, EndpointAddr, EndpointId, SecretKey, Signature, TransportAddr};
 use iroh_gossip::net::Gossip;
 use iroh_gossip::proto::TopicId;
+use serde::{Deserialize, Serialize};
+use std::collections::{BTreeSet, HashMap, HashSet};
+use std::sync::{Arc, Mutex};
 use tokio::sync::mpsc;
 use tokio::sync::mpsc::Receiver;
-use std::sync::{Arc, Mutex};
-use std::collections::{BTreeSet, HashMap, HashSet};
-use async_trait::async_trait;
 use tokio_stream::StreamExt;
-use serde::{Serialize, Deserialize};
 
 /// Domain-separation tag mixed into every signed gossip payload so a signature
 /// can never be lifted out of this protocol/version into another context.
@@ -78,7 +78,12 @@ fn signable_bytes(topic: &[u8; 32], author: &EndpointId, ts: u64, msg: &GossipMe
 fn sign_gossip(secret: &SecretKey, topic: &[u8; 32], ts: u64, msg: GossipMessage) -> GossipPayload {
     let author = secret.public();
     let sig = secret.sign(&signable_bytes(topic, &author, ts, &msg));
-    GossipPayload { author, ts, msg, sig }
+    GossipPayload {
+        author,
+        ts,
+        msg,
+        sig,
+    }
 }
 
 /// Why a received gossip payload was rejected (logging + tests).
@@ -233,7 +238,10 @@ impl ClockSkewMonitor {
     }
 
     fn drop_oldest_authors(&mut self) {
-        let remove_count = self.authors.len().saturating_sub(CLOCK_SKEW_AUTHORS_SOFT_CAP);
+        let remove_count = self
+            .authors
+            .len()
+            .saturating_sub(CLOCK_SKEW_AUTHORS_SOFT_CAP);
         let mut by_age: Vec<_> = self
             .authors
             .iter()
@@ -339,7 +347,8 @@ fn verify_gossip(
         return Err(GossipReject::OutOfWindow);
     }
     if let GossipMessage::Announce(state) = &payload.msg
-        && state.addr.id != payload.author {
+        && state.addr.id != payload.author
+    {
         return Err(GossipReject::AnnounceAddressMismatch);
     }
     Ok(())
@@ -466,7 +475,8 @@ impl RoomState for IrohGossipState {
         // Make every dial target resolvable: the ticket host plus any retained
         // peers handed in (their addresses may have aged out of a fresh endpoint's
         // book even though the persistent lookup usually still holds them).
-        self.address_lookup.add_endpoint_info(ticket.host_addr.clone());
+        self.address_lookup
+            .add_endpoint_info(ticket.host_addr.clone());
         for addr in &extra_bootstrap {
             self.address_lookup.add_endpoint_info(addr.clone());
         }
@@ -478,7 +488,10 @@ impl RoomState for IrohGossipState {
             compute_bootstrap(self_state.addr.id, ticket.host_addr.id, &extra_bootstrap);
         crate::log_msg(&format!("Bootstrap peers for join: {:?}", bootstrap_peers));
 
-        let gossip_topic = self.gossip.subscribe(topic_id, bootstrap_peers).await
+        let gossip_topic = self
+            .gossip
+            .subscribe(topic_id, bootstrap_peers)
+            .await
             .map_err(|e| {
                 let err = format!("Failed to join gossip topic: {}", e);
                 crate::log_msg(&err);
@@ -505,32 +518,44 @@ impl RoomState for IrohGossipState {
         let topic_bytes = ticket.topic_id;
 
         let handle = tokio::spawn(async move {
-            crate::log_msg(&format!("Spawned gossip topic loop for self_id={:?}", self_id));
+            crate::log_msg(&format!(
+                "Spawned gossip topic loop for self_id={:?}",
+                self_id
+            ));
             let mut state_mutations_seen = HashMap::new();
             let mut clock_skew_monitor = ClockSkewMonitor::default();
 
             // Broadcast initial state
             let initial_payload = {
                 let guard = self_state_clone.lock().unwrap();
-                guard.as_ref().map(|s| sign_gossip(
-                    &secret_key,
-                    &topic_bytes,
-                    now_millis(),
-                    GossipMessage::Announce(s.clone()),
-                ))
+                guard.as_ref().map(|s| {
+                    sign_gossip(
+                        &secret_key,
+                        &topic_bytes,
+                        now_millis(),
+                        GossipMessage::Announce(s.clone()),
+                    )
+                })
             };
 
             if let Some(payload) = initial_payload
-                && let Ok(bytes) = serde_json::to_vec(&payload) {
-                    crate::log_msg(&format!("Broadcasting initial state from self_id={:?}", self_id));
-                    let _ = gossip_sender_clone.broadcast(bytes.into()).await;
-                }
+                && let Ok(bytes) = serde_json::to_vec(&payload)
+            {
+                crate::log_msg(&format!(
+                    "Broadcasting initial state from self_id={:?}",
+                    self_id
+                ));
+                let _ = gossip_sender_clone.broadcast(bytes.into()).await;
+            }
 
             // Stream topic messages
             while let Some(res) = gossip_receiver.next().await {
                 match res {
                     Ok(iroh_gossip::api::Event::Received(msg)) => {
-                        crate::log_msg(&format!("Gossip received Event::Received from delivery={:?}", msg.delivered_from));
+                        crate::log_msg(&format!(
+                            "Gossip received Event::Received from delivery={:?}",
+                            msg.delivered_from
+                        ));
                         // Reject oversized frames BEFORE deserializing: parsing
                         // allocates, so a size check has to precede `from_slice` to
                         // bound the memory a hostile peer can make us hold.
@@ -577,13 +602,13 @@ impl RoomState for IrohGossipState {
                                     continue;
                                 }
                                 let our_id = {
-                                    self_state_clone.lock().unwrap()
-                                        .as_ref()
-                                        .map(|s| s.addr.id)
+                                    self_state_clone.lock().unwrap().as_ref().map(|s| s.addr.id)
                                 };
-                                
+
                                 if Some(payload.author) == our_id {
-                                    crate::log_msg("Gossip Event::Received from ourselves; ignoring");
+                                    crate::log_msg(
+                                        "Gossip Event::Received from ourselves; ignoring",
+                                    );
                                     continue;
                                 }
 
@@ -635,7 +660,9 @@ impl RoomState for IrohGossipState {
                                         // Screen-share tickets are capabilities and
                                         // peer-supplied: cap/validate once at ingest
                                         // so invalid offers never render a Watch button.
-                                        state.sharing = state.sharing.and_then(crate::screenshare::sanitize_ticket);
+                                        state.sharing = state
+                                            .sharing
+                                            .and_then(crate::screenshare::sanitize_ticket);
                                         // The game-presence label is untrusted
                                         // peer text like the name: sanitize +
                                         // length-cap at ingest (strip bidi/control,
@@ -651,8 +678,11 @@ impl RoomState for IrohGossipState {
                                         // bounds a future fetch (reject anything
                                         // outside the attachment cap).
                                         state.music = state.music.and_then(|mut m| {
-                                            let name = crate::sanitize::sanitize_game_label(&m.name);
-                                            if name.is_empty() || !crate::files::size_within_cap(m.size) {
+                                            let name =
+                                                crate::sanitize::sanitize_game_label(&m.name);
+                                            if name.is_empty()
+                                                || !crate::files::size_within_cap(m.size)
+                                            {
                                                 return None;
                                             }
                                             m.name = name;
@@ -679,8 +709,10 @@ impl RoomState for IrohGossipState {
                                         // cleared ONLY once re-admitted — clearing it before
                                         // a possible reject would orphan its recovery state
                                         // (Tier C F-01 audit).
-                                        let is_reconnecting =
-                                            disconnected_peers.lock().unwrap().contains(&payload.author);
+                                        let is_reconnecting = disconnected_peers
+                                            .lock()
+                                            .unwrap()
+                                            .contains(&payload.author);
                                         let admitted = {
                                             let mut peer_map = peers.lock().unwrap();
                                             let is_new = !peer_map.contains_key(&payload.author);
@@ -689,11 +721,17 @@ impl RoomState for IrohGossipState {
                                             // memory/tasks/dials without bound (Tier C
                                             // F-01). Existing-peer updates and reconnects
                                             // are exempt; only brand-new authors are gated.
-                                            let subject_to_cap = announce_subject_to_cap(is_new, is_reconnecting);
-                                            if !admit_into_roster(peer_map.len(), subject_to_cap, MAX_ACTIVE_PEERS) {
+                                            let subject_to_cap =
+                                                announce_subject_to_cap(is_new, is_reconnecting);
+                                            if !admit_into_roster(
+                                                peer_map.len(),
+                                                subject_to_cap,
+                                                MAX_ACTIVE_PEERS,
+                                            ) {
                                                 None
                                             } else {
-                                                let state_changed = peer_map.get(&payload.author) != Some(&state);
+                                                let state_changed =
+                                                    peer_map.get(&payload.author) != Some(&state);
                                                 if is_new || state_changed {
                                                     peer_map.insert(payload.author, state.clone());
                                                 }
@@ -723,35 +761,54 @@ impl RoomState for IrohGossipState {
                                             // address set, so leave/re-announce cycles
                                             // can't accumulate attacker-supplied history
                                             // (Tier C F-01).
-                                            let _ = address_lookup.set_endpoint_info(state.addr.clone());
-                                            let _ = event_tx.send(RoomEvent::PeerJoined(payload.author, state)).await;
+                                            let _ = address_lookup
+                                                .set_endpoint_info(state.addr.clone());
+                                            let _ = event_tx
+                                                .send(RoomEvent::PeerJoined(payload.author, state))
+                                                .await;
                                         } else if state_changed {
                                             crate::log_msg(&format!(
                                                 "Gossip peer state updated: {}, state: {}",
                                                 crate::short_id(&payload.author.to_string()),
                                                 peer_state_for_log(&state)
                                             ));
-                                            let _ = event_tx.send(RoomEvent::PeerUpdated(payload.author, state)).await;
+                                            let _ = event_tx
+                                                .send(RoomEvent::PeerUpdated(payload.author, state))
+                                                .await;
                                         }
                                     }
                                     GossipMessage::Leave => {
-                                        crate::log_msg(&format!("Gossip peer leave request from author={:?}", payload.author));
+                                        crate::log_msg(&format!(
+                                            "Gossip peer leave request from author={:?}",
+                                            payload.author
+                                        ));
                                         // Drop this id's address-lookup entry so cycling
                                         // distinct identities through Announce→Leave can't
                                         // grow the lookup for the room's lifetime (Tier C
                                         // F-01 audit). Re-announce re-populates it.
                                         let _ = address_lookup.remove_endpoint_info(payload.author);
-                                        let removed = peers.lock().unwrap().remove(&payload.author).is_some();
+                                        let removed =
+                                            peers.lock().unwrap().remove(&payload.author).is_some();
                                         let was_disconnected = disconnected_peers
                                             .lock()
                                             .unwrap()
                                             .remove(&payload.author);
                                         if removed || was_disconnected {
-                                            let _ = event_tx.send(RoomEvent::PeerLeft(payload.author)).await;
+                                            let _ = event_tx
+                                                .send(RoomEvent::PeerLeft(payload.author))
+                                                .await;
                                         }
                                     }
-                                    GossipMessage::Chat { name, text, ts, attachment } => {
-                                        crate::log_msg(&format!("Gossip chat from author={:?}", payload.author));
+                                    GossipMessage::Chat {
+                                        name,
+                                        text,
+                                        ts,
+                                        attachment,
+                                    } => {
+                                        crate::log_msg(&format!(
+                                            "Gossip chat from author={:?}",
+                                            payload.author
+                                        ));
                                         // Defensively normalize an untrusted attachment
                                         // descriptor: sanitize the filename and drop it
                                         // entirely if it declares an out-of-cap size.
@@ -762,18 +819,23 @@ impl RoomState for IrohGossipState {
                                             a.name = crate::files::sanitize_filename(&a.name);
                                             Some(a)
                                         });
-                                        let _ = event_tx.send(RoomEvent::ChatMessage {
-                                            from: payload.author,
-                                            name,
-                                            text,
-                                            ts,
-                                            attachment,
-                                        }).await;
+                                        let _ = event_tx
+                                            .send(RoomEvent::ChatMessage {
+                                                from: payload.author,
+                                                name,
+                                                text,
+                                                ts,
+                                                attachment,
+                                            })
+                                            .await;
                                     }
                                 }
                             }
                             Err(e) => {
-                                crate::log_msg(&format!("Gossip failed to deserialize payload: {:?}", e));
+                                crate::log_msg(&format!(
+                                    "Gossip failed to deserialize payload: {:?}",
+                                    e
+                                ));
                             }
                         }
                     }
@@ -782,18 +844,24 @@ impl RoomState for IrohGossipState {
                         // Resend state on new neighbor connection to guarantee synchronization
                         let payload_opt = {
                             let guard = self_state_clone.lock().unwrap();
-                            guard.as_ref().map(|state| sign_gossip(
-                                &secret_key,
-                                &topic_bytes,
-                                now_millis(),
-                                GossipMessage::Announce(state.clone()),
-                            ))
+                            guard.as_ref().map(|state| {
+                                sign_gossip(
+                                    &secret_key,
+                                    &topic_bytes,
+                                    now_millis(),
+                                    GossipMessage::Announce(state.clone()),
+                                )
+                            })
                         };
                         if let Some(payload) = payload_opt
-                            && let Ok(bytes) = serde_json::to_vec(&payload) {
-                                crate::log_msg(&format!("Broadcasting state to new neighbor={:?}", peer_id));
-                                let _ = gossip_sender_clone.broadcast(bytes.into()).await;
-                            }
+                            && let Ok(bytes) = serde_json::to_vec(&payload)
+                        {
+                            crate::log_msg(&format!(
+                                "Broadcasting state to new neighbor={:?}",
+                                peer_id
+                            ));
+                            let _ = gossip_sender_clone.broadcast(bytes.into()).await;
+                        }
                     }
                     Ok(iroh_gossip::api::Event::NeighborDown(peer_id)) => {
                         crate::log_msg(&format!("Gossip event: NeighborDown={:?}", peer_id));
@@ -807,7 +875,10 @@ impl RoomState for IrohGossipState {
                         let removed = peers.lock().unwrap().remove(&peer_id).is_some();
                         if removed {
                             disconnected_peers.lock().unwrap().insert(peer_id);
-                            crate::log_msg(&format!("Peer connection lost (NeighborDown): {:?}", peer_id));
+                            crate::log_msg(&format!(
+                                "Peer connection lost (NeighborDown): {:?}",
+                                peer_id
+                            ));
                             let _ = event_tx.send(RoomEvent::PeerConnectionLost(peer_id)).await;
                         }
                     }
@@ -844,7 +915,9 @@ impl RoomState for IrohGossipState {
             );
             if let Ok(bytes) = serde_json::to_vec(&payload) {
                 crate::log_msg("Broadcasting updated self state to gossip");
-                sender.broadcast(bytes.into()).await
+                sender
+                    .broadcast(bytes.into())
+                    .await
                     .map_err(|e| NetError::Gossip(e.to_string()))?;
             }
         }
@@ -909,10 +982,17 @@ impl RoomState for IrohGossipState {
                 &self.secret_key,
                 &topic,
                 ts,
-                GossipMessage::Chat { name, text, ts, attachment },
+                GossipMessage::Chat {
+                    name,
+                    text,
+                    ts,
+                    attachment,
+                },
             );
             if let Ok(bytes) = serde_json::to_vec(&payload) {
-                sender.broadcast(bytes.into()).await
+                sender
+                    .broadcast(bytes.into())
+                    .await
                     .map_err(|e| NetError::Gossip(e.to_string()))?;
             }
         }
@@ -934,12 +1014,7 @@ impl RoomState for IrohGossipState {
 
         let sender_opt = self.active_sender.lock().unwrap().take();
         if let (Some(sender), Some(topic)) = (sender_opt, topic_opt) {
-            let payload = sign_gossip(
-                &self.secret_key,
-                &topic,
-                now_millis(),
-                GossipMessage::Leave,
-            );
+            let payload = sign_gossip(&self.secret_key, &topic, now_millis(), GossipMessage::Leave);
             if let Ok(bytes) = serde_json::to_vec(&payload) {
                 crate::log_msg("Broadcasting Leave message to gossip");
                 let _ = sender.broadcast(bytes.into()).await;
@@ -1060,7 +1135,9 @@ mod tests {
     #[test]
     fn reconnecting_and_existing_peers_are_exempt_from_the_cap() {
         // A brand-new author counts against the cap...
-        assert!(announce_subject_to_cap(/* is_new */ true, /* is_reconnecting */ false));
+        assert!(announce_subject_to_cap(
+            /* is_new */ true, /* is_reconnecting */ false
+        ));
         // ...but an ordinary update from an in-roster peer does not...
         assert!(!announce_subject_to_cap(false, false));
         // ...and neither does a re-announce from a peer mid-reconnect, even
@@ -1070,7 +1147,11 @@ mod tests {
         // Combined with admit_into_roster: a reconnecting author passes at a full
         // roster, a brand-new one does not.
         assert!(admit_into_roster(3, announce_subject_to_cap(true, true), 3));
-        assert!(!admit_into_roster(3, announce_subject_to_cap(true, false), 3));
+        assert!(!admit_into_roster(
+            3,
+            announce_subject_to_cap(true, false),
+            3
+        ));
     }
 
     #[test]
@@ -1105,7 +1186,10 @@ mod tests {
         assert_eq!(monitor.observe(author, -122_000, 40_000), None);
         assert_eq!(
             monitor.observe(author, -123_000, 69_999),
-            Some(ClockSkewWarning { author, skew_ms: -123_000 })
+            Some(ClockSkewWarning {
+                author,
+                skew_ms: -123_000
+            })
         );
         assert_eq!(monitor.observe(author, -124_000, 70_000), None);
     }
@@ -1125,7 +1209,10 @@ mod tests {
         assert_eq!(monitor.observe(author, 127_000, 319_999), None);
         assert_eq!(
             monitor.observe(author, 128_000, 320_000),
-            Some(ClockSkewWarning { author, skew_ms: 128_000 })
+            Some(ClockSkewWarning {
+                author,
+                skew_ms: 128_000
+            })
         );
     }
 
@@ -1141,11 +1228,17 @@ mod tests {
         assert_eq!(monitor.observe(b, 121_000, 1_000), None);
         assert_eq!(
             monitor.observe(b, 121_000, 2_000),
-            Some(ClockSkewWarning { author: b, skew_ms: 121_000 })
+            Some(ClockSkewWarning {
+                author: b,
+                skew_ms: 121_000
+            })
         );
         assert_eq!(
             monitor.observe(a, -121_000, 2_000),
-            Some(ClockSkewWarning { author: a, skew_ms: -121_000 })
+            Some(ClockSkewWarning {
+                author: a,
+                skew_ms: -121_000
+            })
         );
     }
 
@@ -1202,7 +1295,10 @@ mod tests {
         assert!(long.as_str().len() > MAX_RELAY_URL_LEN);
         let addr = EndpointAddr::from_parts(
             id,
-            [TransportAddr::Relay(short.clone()), TransportAddr::Relay(long)],
+            [
+                TransportAddr::Relay(short.clone()),
+                TransportAddr::Relay(long),
+            ],
         );
         let out = sanitize_endpoint_addr(&addr);
         let relays: Vec<_> = out.relay_urls().cloned().collect();
@@ -1222,7 +1318,12 @@ mod tests {
         let secret = SecretKey::generate();
         let topic = [9u8; 32];
         let peer_state = sample_peer_state_for(secret.public());
-        let payload = sign_gossip(&secret, &topic, 1000, GossipMessage::Announce(peer_state.clone()));
+        let payload = sign_gossip(
+            &secret,
+            &topic,
+            1000,
+            GossipMessage::Announce(peer_state.clone()),
+        );
 
         let serialized = serde_json::to_string(&payload).unwrap();
         let deserialized: GossipPayload = serde_json::from_str(&serialized).unwrap();
@@ -1252,7 +1353,13 @@ mod tests {
         };
         let serialized = serde_json::to_string(&original).unwrap();
         let deserialized: GossipMessage = serde_json::from_str(&serialized).unwrap();
-        if let GossipMessage::Chat { name, text, ts, attachment } = deserialized {
+        if let GossipMessage::Chat {
+            name,
+            text,
+            ts,
+            attachment,
+        } = deserialized
+        {
             assert_eq!(name, "Alice");
             assert_eq!(text, "Hello");
             assert_eq!(ts, 123456789);
@@ -1305,7 +1412,10 @@ mod tests {
         // defaulting the attachment to None (serde(default)).
         let legacy = r#"{"Chat":{"name":"Old","text":"hi","ts":7}}"#;
         let parsed: GossipMessage = serde_json::from_str(legacy).unwrap();
-        if let GossipMessage::Chat { name, attachment, .. } = parsed {
+        if let GossipMessage::Chat {
+            name, attachment, ..
+        } = parsed
+        {
             assert_eq!(name, "Old");
             assert_eq!(attachment, None);
         } else {
@@ -1368,7 +1478,10 @@ mod tests {
         let secret = SecretKey::generate();
         let topic = [1u8; 32];
         let p = sign_gossip(&secret, &topic, 5_000, GossipMessage::Leave);
-        assert_eq!(verify_gossip(&p, &topic, 5_000, GOSSIP_FRESHNESS_MS), Ok(()));
+        assert_eq!(
+            verify_gossip(&p, &topic, 5_000, GOSSIP_FRESHNESS_MS),
+            Ok(())
+        );
     }
 
     #[test]
@@ -1392,7 +1505,12 @@ mod tests {
         let secret = SecretKey::generate();
         let topic = [4u8; 32];
         let mut p = sign_gossip(&secret, &topic, 5_000, GossipMessage::Leave);
-        p.msg = GossipMessage::Chat { name: "x".into(), text: "y".into(), ts: 5_000, attachment: None };
+        p.msg = GossipMessage::Chat {
+            name: "x".into(),
+            text: "y".into(),
+            ts: 5_000,
+            attachment: None,
+        };
         assert_eq!(
             verify_gossip(&p, &topic, 5_000, GOSSIP_FRESHNESS_MS),
             Err(GossipReject::BadSignature)
@@ -1418,16 +1536,34 @@ mod tests {
         let p = sign_gossip(&secret, &topic, 1_000_000, GossipMessage::Leave);
         // Far in the past relative to "now" → stale (replay).
         assert_eq!(
-            verify_gossip(&p, &topic, 1_000_000 + GOSSIP_FRESHNESS_MS + 1, GOSSIP_FRESHNESS_MS),
+            verify_gossip(
+                &p,
+                &topic,
+                1_000_000 + GOSSIP_FRESHNESS_MS + 1,
+                GOSSIP_FRESHNESS_MS
+            ),
             Err(GossipReject::OutOfWindow)
         );
         // Implausibly future.
         assert_eq!(
-            verify_gossip(&p, &topic, 1_000_000 - GOSSIP_FRESHNESS_MS - 1, GOSSIP_FRESHNESS_MS),
+            verify_gossip(
+                &p,
+                &topic,
+                1_000_000 - GOSSIP_FRESHNESS_MS - 1,
+                GOSSIP_FRESHNESS_MS
+            ),
             Err(GossipReject::OutOfWindow)
         );
         // Within the window (clock skew tolerance) → accepted.
-        assert!(verify_gossip(&p, &topic, 1_000_000 + GOSSIP_FRESHNESS_MS - 1, GOSSIP_FRESHNESS_MS).is_ok());
+        assert!(
+            verify_gossip(
+                &p,
+                &topic,
+                1_000_000 + GOSSIP_FRESHNESS_MS - 1,
+                GOSSIP_FRESHNESS_MS
+            )
+            .is_ok()
+        );
     }
 
     #[test]
@@ -1449,10 +1585,30 @@ mod tests {
         let author = fresh_id();
         let mut seen = HashMap::new();
 
-        assert!(admit_state_mutation(&mut seen, author, &GossipMessage::Leave, 10));
-        assert!(!admit_state_mutation(&mut seen, author, &GossipMessage::Leave, 10));
-        assert!(!admit_state_mutation(&mut seen, author, &GossipMessage::Leave, 9));
-        assert!(admit_state_mutation(&mut seen, author, &GossipMessage::Leave, 11));
+        assert!(admit_state_mutation(
+            &mut seen,
+            author,
+            &GossipMessage::Leave,
+            10
+        ));
+        assert!(!admit_state_mutation(
+            &mut seen,
+            author,
+            &GossipMessage::Leave,
+            10
+        ));
+        assert!(!admit_state_mutation(
+            &mut seen,
+            author,
+            &GossipMessage::Leave,
+            9
+        ));
+        assert!(admit_state_mutation(
+            &mut seen,
+            author,
+            &GossipMessage::Leave,
+            11
+        ));
 
         let announce = GossipMessage::Announce(sample_peer_state_for(author));
         assert!(admit_state_mutation(&mut seen, author, &announce, 10));
@@ -1465,13 +1621,26 @@ mod tests {
     fn state_mutation_replay_gate_leaves_chat_ordering_untouched() {
         let author = fresh_id();
         let mut seen = HashMap::new();
-        let later_chat = GossipMessage::Chat { name: "A".into(), text: "later".into(), ts: 200, attachment: None };
-        let earlier_chat = GossipMessage::Chat { name: "A".into(), text: "earlier".into(), ts: 100, attachment: None };
+        let later_chat = GossipMessage::Chat {
+            name: "A".into(),
+            text: "later".into(),
+            ts: 200,
+            attachment: None,
+        };
+        let earlier_chat = GossipMessage::Chat {
+            name: "A".into(),
+            text: "earlier".into(),
+            ts: 100,
+            attachment: None,
+        };
 
         assert!(admit_state_mutation(&mut seen, author, &later_chat, 200));
         assert!(admit_state_mutation(&mut seen, author, &earlier_chat, 100));
         assert!(admit_state_mutation(&mut seen, author, &later_chat, 200));
-        assert!(seen.is_empty(), "chat must not populate the state-mutation replay map");
+        assert!(
+            seen.is_empty(),
+            "chat must not populate the state-mutation replay map"
+        );
     }
 
     #[test]
@@ -1481,8 +1650,18 @@ mod tests {
         let mut seen = HashMap::new();
         let announce = GossipMessage::Announce(sample_peer_state_for(author));
 
-        assert!(admit_state_mutation(&mut seen, author, &GossipMessage::Leave, 5));
+        assert!(admit_state_mutation(
+            &mut seen,
+            author,
+            &GossipMessage::Leave,
+            5
+        ));
         assert!(admit_state_mutation(&mut seen, author, &announce, 5));
-        assert!(admit_state_mutation(&mut seen, other, &GossipMessage::Leave, 5));
+        assert!(admit_state_mutation(
+            &mut seen,
+            other,
+            &GossipMessage::Leave,
+            5
+        ));
     }
 }

src/network/iroh_impl.rs

@@ -1,16 +1,16 @@
-use crate::network::{NetworkTransport, NetError, ConnEvent};
-use iroh::{Endpoint, EndpointId};
-use iroh::endpoint::{Connection, ConnectionError, VarInt};
+use crate::network::{ConnEvent, NetError, NetworkTransport};
+use async_trait::async_trait;
 use bytes::Bytes;
+use iroh::endpoint::{Connection, ConnectionError, VarInt};
+use iroh::{Endpoint, EndpointId};
+use std::collections::{HashMap, HashSet};
+use std::sync::{Arc, Mutex as StdMutex};
+use std::time::Duration;
 use tokio::sync::mpsc;
 use tokio::sync::mpsc::Receiver;
-use std::sync::{Arc, Mutex as StdMutex};
-use std::collections::{HashMap, HashSet};
-use std::time::Duration;
-use async_trait::async_trait;
 
-use crate::protocol::{AUDIO_ALPN, FILES_ALPN};
 use crate::files::{AttachmentId, ChatAttachment};
+use crate::protocol::{AUDIO_ALPN, FILES_ALPN};
 
 /// Per-peer datagram send queue depth. Audio is real-time, so a backlog is
 /// useless latency — keep it shallow and drop the oldest frame when full.
@@ -111,7 +111,13 @@ impl Shared {
         let shared = self.clone();
         let supervisor = tokio::spawn(supervise(shared, peer_id, inbound_rx));
         let inbound_tx_ret = inbound_tx.clone();
-        peers.insert(peer_id, PeerHandle { supervisor, inbound_tx });
+        peers.insert(
+            peer_id,
+            PeerHandle {
+                supervisor,
+                inbound_tx,
+            },
+        );
         crate::log_msg(&format!("Transport: supervising peer {:?}", peer_id));
         inbound_tx_ret
     }
@@ -123,7 +129,10 @@ impl Shared {
         self.addrs.lock().unwrap().remove(&peer_id);
         if let Some(handle) = self.peers.lock().await.remove(&peer_id) {
             handle.supervisor.abort();
-            crate::log_msg(&format!("Transport: stopped supervising peer {:?}", peer_id));
+            crate::log_msg(&format!(
+                "Transport: stopped supervising peer {:?}",
+                peer_id
+            ));
         }
     }
 
@@ -208,12 +217,15 @@ async fn supervise(
     let mut backoff = INITIAL_BACKOFF;
 
     // Show "connecting" until the first link is actually up.
-    let _ = shared.conn_events_tx.try_send(ConnEvent::Connecting(peer_id));
+    let _ = shared
+        .conn_events_tx
+        .try_send(ConnEvent::Connecting(peer_id));
 
-    let mut conn = match obtain_conn(&shared, peer_id, is_dialer, &mut inbound_rx, &mut backoff).await {
-        Some(conn) => conn,
-        None => return, // retired before we ever connected
-    };
+    let mut conn =
+        match obtain_conn(&shared, peer_id, is_dialer, &mut inbound_rx, &mut backoff).await {
+            Some(conn) => conn,
+            None => return, // retired before we ever connected
+        };
 
     loop {
         // A healthy link resets the dialer's backoff for the next outage.
@@ -223,8 +235,14 @@ async fn supervise(
         shared.senders.lock().unwrap().insert(peer_id, send_tx);
         // Publish the live connection so an intentional leave can close it with
         // the goodbye code.
-        shared.live_conns.lock().unwrap().insert(peer_id, conn.clone());
-        let _ = shared.conn_events_tx.try_send(ConnEvent::Connected(peer_id));
+        shared
+            .live_conns
+            .lock()
+            .unwrap()
+            .insert(peer_id, conn.clone());
+        let _ = shared
+            .conn_events_tx
+            .try_send(ConnEvent::Connected(peer_id));
         crate::log_msg(&format!("Transport: peer {:?} link up", peer_id));
 
         // Run until the link dies, a replacement arrives, or we're retired. The
@@ -272,21 +290,36 @@ async fn supervise(
         match wake {
             Wake::Shutdown => return,
             Wake::Replacement(new_conn) => {
-                crate::log_msg(&format!("Transport: peer {:?} replaced with new inbound link", peer_id));
-                let _ = shared.conn_events_tx.try_send(ConnEvent::Connecting(peer_id));
+                crate::log_msg(&format!(
+                    "Transport: peer {:?} replaced with new inbound link",
+                    peer_id
+                ));
+                let _ = shared
+                    .conn_events_tx
+                    .try_send(ConnEvent::Connecting(peer_id));
                 conn = new_conn;
             }
             Wake::Closed(reason) => {
                 // A graceful application close means the peer left on purpose —
                 // don't reconnect; tell the core to evict it now.
                 if is_graceful_leave(&reason) {
-                    crate::log_msg(&format!("Transport: peer {:?} left gracefully ({:?})", peer_id, reason));
+                    crate::log_msg(&format!(
+                        "Transport: peer {:?} left gracefully ({:?})",
+                        peer_id, reason
+                    ));
                     let _ = shared.conn_events_tx.try_send(ConnEvent::Left(peer_id));
                     return;
                 }
-                crate::log_msg(&format!("Transport: peer {:?} link dropped; reconnecting", peer_id));
-                let _ = shared.conn_events_tx.try_send(ConnEvent::Connecting(peer_id));
-                conn = match obtain_conn(&shared, peer_id, is_dialer, &mut inbound_rx, &mut backoff).await {
+                crate::log_msg(&format!(
+                    "Transport: peer {:?} link dropped; reconnecting",
+                    peer_id
+                ));
+                let _ = shared
+                    .conn_events_tx
+                    .try_send(ConnEvent::Connecting(peer_id));
+                conn = match obtain_conn(&shared, peer_id, is_dialer, &mut inbound_rx, &mut backoff)
+                    .await
+                {
                     Some(conn) => conn,
                     None => return, // retired while reconnecting
                 };
@@ -405,7 +438,10 @@ impl iroh::protocol::ProtocolHandler for AudioRouter {
             // only happens if links are churning, and the supervisor gets the next one.
             let inbound_tx = shared.ensure_supervisor(peer_id).await;
             if inbound_tx.try_send(connection).is_err() {
-                crate::log_msg(&format!("Transport: dropped inbound link from {:?} (queue full)", peer_id));
+                crate::log_msg(&format!(
+                    "Transport: dropped inbound link from {:?} (queue full)",
+                    peer_id
+                ));
             }
             Ok(())
         }
@@ -545,7 +581,14 @@ impl IrohTransport {
     /// all supervisors so none linger redialing the about-to-close endpoint.
     /// Call this before shutting the router down.
     pub async fn leave(&self) {
-        let conns: Vec<Connection> = self.shared.live_conns.lock().unwrap().drain().map(|(_, c)| c).collect();
+        let conns: Vec<Connection> = self
+            .shared
+            .live_conns
+            .lock()
+            .unwrap()
+            .drain()
+            .map(|(_, c)| c)
+            .collect();
         for conn in &conns {
             conn.close(VarInt::from_u32(GOODBYE_CODE), b"leave");
         }
@@ -639,11 +682,64 @@ impl IrohTransport {
             .map_err(|_| NetError::Other("file fetch: read timed out".to_string()))?
             .map_err(|e| NetError::Other(format!("file fetch: read failed: {e}")))?;
         if bytes.is_empty() {
-            return Err(NetError::Other("file fetch: sender no longer has the file".to_string()));
+            return Err(NetError::Other(
+                "file fetch: sender no longer has the file".to_string(),
+            ));
         }
         Ok(bytes)
     }
 
+    /// Snapshot the selected QUIC path of every live audio connection, for the
+    /// UI's per-peer connection badge (direct/relay, RTT, loss, bitrate).
+    /// Cheap and lock-light: the `live_conns` guard is released before touching
+    /// any connection, and `Connection::paths()` reads shared state without I/O.
+    pub fn connection_stats(&self) -> Vec<(EndpointId, crate::network::PathSnapshot)> {
+        // Clone the connections out so the map lock isn't held while we inspect
+        // paths (a supervisor inserts/removes entries as links come and go).
+        let conns: Vec<(EndpointId, Connection)> = self
+            .shared
+            .live_conns
+            .lock()
+            .unwrap()
+            .iter()
+            .map(|(id, conn)| (*id, conn.clone()))
+            .collect();
+        conns
+            .into_iter()
+            .filter_map(|(id, conn)| {
+                let paths = conn.paths();
+                // The selected path is the one carrying application data. In the
+                // brief window where none is flagged (e.g. mid-migration), fall
+                // back to the first open path rather than dropping the badge.
+                let path = paths
+                    .iter()
+                    .find(|p| p.is_selected())
+                    .or_else(|| paths.iter().next())?;
+                let stats = path.stats();
+                // Per-variant display: `TransportAddr`'s own `Display` prefixes
+                // a scheme ("ip:1.2.3.4:5") that's noise next to the badge's
+                // Direct/Relay label.
+                let remote_addr = match path.remote_addr() {
+                    iroh::TransportAddr::Ip(sock) => sock.to_string(),
+                    iroh::TransportAddr::Relay(url) => url.to_string(),
+                    other => other.to_string(),
+                };
+                Some((
+                    id,
+                    crate::network::PathSnapshot {
+                        is_relay: path.remote_addr().is_relay(),
+                        remote_addr,
+                        rtt: stats.rtt,
+                        tx_bytes: stats.udp_tx.bytes,
+                        rx_bytes: stats.udp_rx.bytes,
+                        tx_datagrams: stats.udp_tx.datagrams,
+                        lost_packets: stats.lost_packets,
+                    },
+                ))
+            })
+            .collect()
+    }
+
     /// Fetch a chat attachment's bytes from its sender over the file plane.
     pub async fn fetch_attachment(
         &self,

src/network/mod.rs

@@ -1,10 +1,10 @@
-use iroh::{EndpointId, EndpointAddr};
+use async_trait::async_trait;
 use bytes::Bytes;
+use iroh::{EndpointAddr, EndpointId};
+use serde::{Deserialize, Serialize};
+use std::str::FromStr;
 use thiserror::Error;
 use tokio::sync::mpsc::Receiver;
-use async_trait::async_trait;
-use serde::{Serialize, Deserialize};
-use std::str::FromStr;
 
 #[derive(Error, Debug)]
 pub enum NetError {
@@ -148,7 +148,10 @@ pub enum RoomEvent {
     /// A validly signed gossip payload was rejected only because its timestamp is
     /// outside the replay-protection window. The peer is not in the roster yet,
     /// so this surfaces as a room-level warning instead of a peer-card state.
-    ClockSkewSuspected { author: EndpointId, skew_ms: i64 },
+    ClockSkewSuspected {
+        author: EndpointId,
+        skew_ms: i64,
+    },
     /// A peer sent a room text-chat message. Carries the sender's id, their
     /// display name (embedded so it shows even without a presence entry), the
     /// text, and a sender-stamped millisecond timestamp.
@@ -181,6 +184,32 @@ pub enum ConnEvent {
     Left(EndpointId),
 }
 
+/// Owned snapshot of a peer's *selected* QUIC path (the one currently carrying
+/// application data), taken from the live audio connection for the UI's
+/// connection-transparency badge. Counters are cumulative for the path's
+/// lifetime; rate/loss derivation over a poll window happens in
+/// `core::connstats` (which also detects path switches via `remote_addr`).
+#[derive(Debug, Clone, PartialEq)]
+pub struct PathSnapshot {
+    /// True when the path runs through a relay server, false for a direct
+    /// (holepunched or local) IP path.
+    pub is_relay: bool,
+    /// The path's remote transport address: `ip:port` for a direct path, the
+    /// relay URL for a relayed one.
+    pub remote_addr: String,
+    /// Current QUIC round-trip-time estimate for the path.
+    pub rtt: std::time::Duration,
+    /// Cumulative bytes sent in UDP datagrams on the path.
+    pub tx_bytes: u64,
+    /// Cumulative bytes received in UDP datagrams on the path.
+    pub rx_bytes: u64,
+    /// Cumulative UDP datagrams sent on the path (the loss denominator: for our
+    /// small voice frames these map ~1:1 to QUIC packets).
+    pub tx_datagrams: u64,
+    /// Cumulative packets detected lost on the path.
+    pub lost_packets: u64,
+}
+
 #[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct PeerSpeakTicket {
     pub host_addr: iroh::EndpointAddr,
@@ -203,10 +232,12 @@ impl PeerSpeakTicket {
     /// is idempotent.
     pub fn restamp(ticket_str: &str, my_addr: iroh::EndpointAddr) -> String {
         match ticket_str.parse::<PeerSpeakTicket>() {
-            Ok(t) => {
-                PeerSpeakTicket { host_addr: my_addr, topic_id: t.topic_id, name: t.name }
-                    .to_string()
+            Ok(t) => PeerSpeakTicket {
+                host_addr: my_addr,
+                topic_id: t.topic_id,
+                name: t.name,
             }
+            .to_string(),
             Err(_) => ticket_str.to_string(),
         }
     }
@@ -215,7 +246,10 @@ impl PeerSpeakTicket {
     /// can't be parsed or carries no label. Pure; used to label the gathering both
     /// in the room UI and in the presence we report to friends.
     pub fn label_of(ticket_str: &str) -> String {
-        ticket_str.parse::<PeerSpeakTicket>().map(|t| t.name).unwrap_or_default()
+        ticket_str
+            .parse::<PeerSpeakTicket>()
+            .map(|t| t.name)
+            .unwrap_or_default()
     }
 
     /// The room's `topic_id` embedded in a ticket string, or `None` if the ticket
@@ -223,7 +257,10 @@ impl PeerSpeakTicket {
     /// the recents list (the host address and label change between members/sessions,
     /// but the topic uniquely identifies the gathering).
     pub fn topic_of(ticket_str: &str) -> Option<[u8; 32]> {
-        ticket_str.parse::<PeerSpeakTicket>().ok().map(|t| t.topic_id)
+        ticket_str
+            .parse::<PeerSpeakTicket>()
+            .ok()
+            .map(|t| t.topic_id)
     }
 }
 
@@ -246,8 +283,8 @@ impl FromStr for PeerSpeakTicket {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let decoded = base64::Engine::decode(&base64::engine::general_purpose::URL_SAFE_NO_PAD, s)
             .map_err(|e| NetError::InvalidTicket(e.to_string()))?;
-        let ticket: PeerSpeakTicket = serde_json::from_slice(&decoded)
-            .map_err(|e| NetError::InvalidTicket(e.to_string()))?;
+        let ticket: PeerSpeakTicket =
+            serde_json::from_slice(&decoded).map_err(|e| NetError::InvalidTicket(e.to_string()))?;
         Ok(ticket)
     }
 }
@@ -327,13 +364,13 @@ pub trait RoomState: Send + Sync {
     async fn subscribe_events(&self) -> Result<Receiver<RoomEvent>, NetError>;
 }
 
-pub mod iroh_impl;
 pub mod gossip;
+pub mod iroh_impl;
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use iroh::{SecretKey, EndpointAddr};
+    use iroh::{EndpointAddr, SecretKey};
 
     fn sample_peer_state() -> PeerState {
         let secret = SecretKey::generate();
@@ -371,9 +408,12 @@ mod tests {
         let host = SecretKey::generate().public();
         let topic_id = [3u8; 32];
         // A labelled ticket: restamp keeps the label, label_of reads it.
-        let labelled =
-            PeerSpeakTicket { host_addr: EndpointAddr::from(host), topic_id, name: "HangOut".into() }
-                .to_string();
+        let labelled = PeerSpeakTicket {
+            host_addr: EndpointAddr::from(host),
+            topic_id,
+            name: "HangOut".into(),
+        }
+        .to_string();
         assert_eq!(PeerSpeakTicket::label_of(&labelled), "HangOut");
         let member = SecretKey::generate().public();
         let restamped = PeerSpeakTicket::restamp(&labelled, EndpointAddr::from(member));
@@ -410,10 +450,8 @@ mod tests {
 
         // valid URL-safe-base64 that decodes to non-JSON bytes
         let bad_json = b"hello world";
-        let encoded = base64::Engine::encode(
-            &base64::engine::general_purpose::URL_SAFE_NO_PAD,
-            bad_json,
-        );
+        let encoded =
+            base64::Engine::encode(&base64::engine::general_purpose::URL_SAFE_NO_PAD, bad_json);
         let res3 = encoded.parse::<PeerSpeakTicket>();
         assert!(matches!(res3, Err(NetError::InvalidTicket(_))));
     }
@@ -424,9 +462,12 @@ mod tests {
         let host = SecretKey::generate().public();
         let member = SecretKey::generate().public();
         let topic_id = [42u8; 32];
-        let original =
-            PeerSpeakTicket { host_addr: EndpointAddr::from(host), topic_id, name: "HangOut".into() }
-                .to_string();
+        let original = PeerSpeakTicket {
+            host_addr: EndpointAddr::from(host),
+            topic_id,
+            name: "HangOut".into(),
+        }
+        .to_string();
 
         let restamped_str = PeerSpeakTicket::restamp(&original, EndpointAddr::from(member));
         let restamped = restamped_str.parse::<PeerSpeakTicket>().unwrap();
@@ -441,18 +482,27 @@ mod tests {
     fn test_restamp_is_idempotent_for_same_addr() {
         let me = SecretKey::generate().public();
         let topic_id = [7u8; 32];
-        let mine =
-            PeerSpeakTicket { host_addr: EndpointAddr::from(me), topic_id, name: String::new() }
-                .to_string();
+        let mine = PeerSpeakTicket {
+            host_addr: EndpointAddr::from(me),
+            topic_id,
+            name: String::new(),
+        }
+        .to_string();
         // Re-stamping my own ticket with my own addr changes nothing.
-        assert_eq!(PeerSpeakTicket::restamp(&mine, EndpointAddr::from(me)), mine);
+        assert_eq!(
+            PeerSpeakTicket::restamp(&mine, EndpointAddr::from(me)),
+            mine
+        );
     }
 
     #[test]
     fn test_restamp_passes_through_unparseable() {
         let me = SecretKey::generate().public();
         // A malformed ticket is returned unchanged (the join will fail anyway).
-        assert_eq!(PeerSpeakTicket::restamp("not-a-ticket", EndpointAddr::from(me)), "not-a-ticket");
+        assert_eq!(
+            PeerSpeakTicket::restamp("not-a-ticket", EndpointAddr::from(me)),
+            "not-a-ticket"
+        );
     }
 
     #[test]

src/notify.rs

@@ -11,12 +11,16 @@
 //! missing chime should never disrupt a call.
 
 use std::collections::HashMap;
+use std::fs::OpenOptions;
+use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
 use std::sync::{Mutex, OnceLock};
+use std::time::{SystemTime, UNIX_EPOCH};
 
 static ENABLED: AtomicBool = AtomicBool::new(true);
+static TEMP_WAV_COUNTER: AtomicU64 = AtomicU64::new(0);
 
 /// Per-sound enable flags (W6), indexed by `Sound::index`. The master `ENABLED`
 /// toggle gates everything; these silence individual events while the master
@@ -57,7 +61,6 @@ pub fn should_play(master_enabled: bool, sound_enabled: bool) -> bool {
     master_enabled && sound_enabled
 }
 
-
 /// A notification event with a distinct chime.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum Sound {
@@ -195,14 +198,38 @@ fn cached_path(sound: Sound) -> Option<PathBuf> {
     if let Some(path) = guard.get(sound.name()) {
         return Some(path.clone());
     }
-    let path = std::env::temp_dir().join(format!("peerspeak-{}.wav", sound.name()));
-    if std::fs::write(&path, sound.bytes()).is_err() {
-        return None;
-    }
+    let path = match write_private_wav(&std::env::temp_dir(), sound.name(), sound.bytes()) {
+        Ok(path) => path,
+        Err(_) => return None,
+    };
     guard.insert(sound.name(), path.clone());
     Some(path)
 }
 
+fn write_private_wav(dir: &Path, stem: &str, bytes: &[u8]) -> std::io::Result<PathBuf> {
+    let counter = TEMP_WAV_COUNTER.fetch_add(1, Ordering::Relaxed);
+    let nanos = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_nanos();
+    let path = dir.join(format!(
+        "peerspeak-{stem}-{}-{counter}-{nanos}.wav",
+        std::process::id()
+    ));
+
+    let mut options = OpenOptions::new();
+    options.write(true).create_new(true);
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::OpenOptionsExt;
+        options.mode(0o600);
+    }
+
+    let mut file = options.open(&path)?;
+    file.write_all(bytes)?;
+    Ok(path)
+}
+
 #[cfg(any(windows, test))]
 fn escape_powershell_single_quoted(s: &str) -> String {
     s.replace('\'', "''")
@@ -249,6 +276,19 @@ fn spawn_player(path: &Path) {
 mod tests {
     use super::*;
 
+    static TEST_TEMP_COUNTER: AtomicU64 = AtomicU64::new(0);
+
+    fn temp_wav_dir(tag: &str) -> PathBuf {
+        let counter = TEST_TEMP_COUNTER.fetch_add(1, Ordering::Relaxed);
+        let dir = std::env::temp_dir().join(format!(
+            "peerspeak-notifytest-{}-{tag}-{counter}",
+            std::process::id()
+        ));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+
     #[test]
     fn test_should_play_truth_table() {
         // Plays only when BOTH the master and the per-sound flag are on.
@@ -264,10 +304,7 @@ mod tests {
             escape_powershell_single_quoted(r"C:\Users\O'Brien\chime.wav"),
             r"C:\Users\O''Brien\chime.wav"
         );
-        assert_eq!(
-            escape_powershell_single_quoted("a'b'c"),
-            "a''b''c"
-        );
+        assert_eq!(escape_powershell_single_quoted("a'b'c"), "a''b''c");
     }
 
     #[test]
@@ -297,7 +334,10 @@ mod tests {
             // bare `~` -> home dir
             assert_eq!(expand_tilde("~"), home);
             // `~/sub/dir/file.wav` -> home joined with `sub/dir/file.wav`
-            assert_eq!(expand_tilde("~/sub/dir/file.wav"), home.join("sub/dir/file.wav"));
+            assert_eq!(
+                expand_tilde("~/sub/dir/file.wav"),
+                home.join("sub/dir/file.wav")
+            );
         }
         // absolute path (`/etc/foo.wav`) -> unchanged
         assert_eq!(expand_tilde("/etc/foo.wav"), PathBuf::from("/etc/foo.wav"));
@@ -310,10 +350,19 @@ mod tests {
         // leading/trailing whitespace is trimmed
         if let Some(home) = dirs::home_dir() {
             assert_eq!(expand_tilde("  ~  "), home);
-            assert_eq!(expand_tilde("  ~/sub/dir/file.wav  "), home.join("sub/dir/file.wav"));
+            assert_eq!(
+                expand_tilde("  ~/sub/dir/file.wav  "),
+                home.join("sub/dir/file.wav")
+            );
         }
-        assert_eq!(expand_tilde("  /etc/foo.wav  "), PathBuf::from("/etc/foo.wav"));
-        assert_eq!(expand_tilde("  foo/bar.wav  "), PathBuf::from("foo/bar.wav"));
+        assert_eq!(
+            expand_tilde("  /etc/foo.wav  "),
+            PathBuf::from("/etc/foo.wav")
+        );
+        assert_eq!(
+            expand_tilde("  foo/bar.wav  "),
+            PathBuf::from("foo/bar.wav")
+        );
     }
 
     #[test]
@@ -332,4 +381,61 @@ mod tests {
         // a `~`-prefixed path that resolves to a non-existent file -> Some(false)
         assert_eq!(validate_custom_path("~/non/existent/file.wav"), Some(false));
     }
+
+    #[test]
+    fn write_private_wav_writes_exact_bytes() {
+        let dir = temp_wav_dir("writes");
+        let bytes = b"RIFFpeerspeak-test";
+
+        let path = write_private_wav(&dir, "unit", bytes).unwrap();
+
+        assert!(path.exists());
+        assert_eq!(std::fs::read(&path).unwrap(), bytes);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn write_private_wav_creates_0600_file() {
+        use std::os::unix::fs::PermissionsExt;
+
+        let dir = temp_wav_dir("mode");
+        let path = write_private_wav(&dir, "unit", b"mode").unwrap();
+
+        let mode = std::fs::metadata(&path).unwrap().permissions().mode() & 0o777;
+        assert_eq!(mode, 0o600);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn write_private_wav_uses_unique_paths() {
+        let dir = temp_wav_dir("unique");
+
+        let first = write_private_wav(&dir, "same-stem", b"first").unwrap();
+        let second = write_private_wav(&dir, "same-stem", b"second").unwrap();
+
+        assert_ne!(first, second);
+        assert!(first.exists());
+        assert!(second.exists());
+        assert_eq!(std::fs::read(&first).unwrap(), b"first");
+        assert_eq!(std::fs::read(&second).unwrap(), b"second");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn create_new_refuses_existing_path() {
+        let dir = temp_wav_dir("create-new");
+        let path = dir.join("preexisting.wav");
+        std::fs::write(&path, b"original").unwrap();
+
+        let err = std::fs::OpenOptions::new()
+            .write(true)
+            .create_new(true)
+            .open(&path)
+            .unwrap_err();
+
+        assert_eq!(err.kind(), std::io::ErrorKind::AlreadyExists);
+        assert_eq!(std::fs::read(&path).unwrap(), b"original");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
 }

src/playlist.rs

@@ -49,9 +49,7 @@ pub fn parse_playlist(contents: &str, base_dir: &Path, kind: PlaylistKind) -> Ve
 
 fn playlist_entry_path(entry: &str, base_dir: &Path) -> Option<PathBuf> {
     let lower = entry.to_ascii_lowercase();
-    if lower.starts_with("http://")
-        || lower.starts_with("https://")
-        || lower.starts_with("ftp://")
+    if lower.starts_with("http://") || lower.starts_with("https://") || lower.starts_with("ftp://")
     {
         return None;
     }
@@ -107,7 +105,10 @@ File3=/var/audio/two.MP3
     #[test]
     fn playlist_kind_is_case_insensitive() {
         assert_eq!(playlist_kind(Path::new("mix.M3U")), Some(PlaylistKind::M3u));
-        assert_eq!(playlist_kind(Path::new("mix.m3u8")), Some(PlaylistKind::M3u));
+        assert_eq!(
+            playlist_kind(Path::new("mix.m3u8")),
+            Some(PlaylistKind::M3u)
+        );
         assert_eq!(playlist_kind(Path::new("mix.PLS")), Some(PlaylistKind::Pls));
         assert_eq!(playlist_kind(Path::new("mix.txt")), None);
     }

src/presence.rs

@@ -36,8 +36,11 @@ pub enum PresenceMode {
 
 impl PresenceMode {
     /// All postures, default first — the option list for the Settings/home picker.
-    pub const ALL: [PresenceMode; 3] =
-        [PresenceMode::Normal, PresenceMode::Invisible, PresenceMode::Discoverable];
+    pub const ALL: [PresenceMode; 3] = [
+        PresenceMode::Normal,
+        PresenceMode::Invisible,
+        PresenceMode::Discoverable,
+    ];
 
     /// Whether this posture publishes to discovery (the only mode that does).
     pub fn publishes_to_discovery(self) -> bool {
@@ -193,7 +196,11 @@ mod tests {
         assert!(!should_answer(&friend, &friends, PresenceMode::Invisible));
         // Stranger is NEVER answered, in any mode.
         assert!(!should_answer(&stranger, &friends, PresenceMode::Normal));
-        assert!(!should_answer(&stranger, &friends, PresenceMode::Discoverable));
+        assert!(!should_answer(
+            &stranger,
+            &friends,
+            PresenceMode::Discoverable
+        ));
         assert!(!should_answer(&stranger, &friends, PresenceMode::Invisible));
     }
 
@@ -214,7 +221,10 @@ mod tests {
             ControlMsg::Ping,
             ControlMsg::Pong { room: None },
             ControlMsg::Pong {
-                room: Some(RoomPresence { name: "HangOut".into(), ticket: "abc".into() }),
+                room: Some(RoomPresence {
+                    name: "HangOut".into(),
+                    ticket: "abc".into(),
+                }),
             },
         ];
         for msg in cases {
@@ -245,19 +255,37 @@ mod tests {
         );
         // Valid ticket -> InRoom with a sanitized name.
         let t = valid_ticket(friend);
-        let got = interpret_pong(&ControlMsg::Pong {
-            room: Some(RoomPresence { name: "HangOut".into(), ticket: t.clone() }),
-        }, friend);
-        assert_eq!(got, Some(FriendPresence::InRoom { name: "HangOut".into(), ticket: t }));
+        let got = interpret_pong(
+            &ControlMsg::Pong {
+                room: Some(RoomPresence {
+                    name: "HangOut".into(),
+                    ticket: t.clone(),
+                }),
+            },
+            friend,
+        );
+        assert_eq!(
+            got,
+            Some(FriendPresence::InRoom {
+                name: "HangOut".into(),
+                ticket: t
+            })
+        );
     }
 
     #[test]
     fn interpret_pong_downgrades_a_garbage_ticket_to_online() {
         // A friend reporting a room with an unparseable ticket is treated as just
         // Online — no dead/hostile Join button is surfaced.
-        let got = interpret_pong(&ControlMsg::Pong {
-            room: Some(RoomPresence { name: "Trap".into(), ticket: "not-a-ticket".into() }),
-        }, id());
+        let got = interpret_pong(
+            &ControlMsg::Pong {
+                room: Some(RoomPresence {
+                    name: "Trap".into(),
+                    ticket: "not-a-ticket".into(),
+                }),
+            },
+            id(),
+        );
         assert_eq!(got, Some(FriendPresence::Online));
     }
 
@@ -266,9 +294,15 @@ mod tests {
         let friend = id();
         let attacker = id();
         let t = valid_ticket(attacker);
-        let got = interpret_pong(&ControlMsg::Pong {
-            room: Some(RoomPresence { name: "Redirect".into(), ticket: t }),
-        }, friend);
+        let got = interpret_pong(
+            &ControlMsg::Pong {
+                room: Some(RoomPresence {
+                    name: "Redirect".into(),
+                    ticket: t,
+                }),
+            },
+            friend,
+        );
         assert_eq!(got, Some(FriendPresence::Online));
     }
 
@@ -287,10 +321,18 @@ mod tests {
         let t = valid_ticket(friend);
         assert_eq!(
             presence_from_probe(Some((
-                &ControlMsg::Pong { room: Some(RoomPresence { name: "Den".into(), ticket: t.clone() }) },
+                &ControlMsg::Pong {
+                    room: Some(RoomPresence {
+                        name: "Den".into(),
+                        ticket: t.clone()
+                    })
+                },
                 friend,
             ))),
-            FriendPresence::InRoom { name: "Den".into(), ticket: t }
+            FriendPresence::InRoom {
+                name: "Den".into(),
+                ticket: t
+            }
         );
         // A non-reply (a stray Ping) is not a presence -> Offline, never a false Online.
         assert_eq!(
@@ -304,9 +346,15 @@ mod tests {
         // Control/bidi characters in a peer-supplied name are stripped.
         let friend = id();
         let t = valid_ticket(friend);
-        let got = interpret_pong(&ControlMsg::Pong {
-            room: Some(RoomPresence { name: "Hang\u{202e}Out\u{0007}".into(), ticket: t.clone() }),
-        }, friend);
+        let got = interpret_pong(
+            &ControlMsg::Pong {
+                room: Some(RoomPresence {
+                    name: "Hang\u{202e}Out\u{0007}".into(),
+                    ticket: t.clone(),
+                }),
+            },
+            friend,
+        );
         match got {
             Some(FriendPresence::InRoom { name, .. }) => {
                 assert!(!name.contains('\u{202e}'), "bidi override must be stripped");

src/presence_net.rs

@@ -54,7 +54,10 @@ fn decode(bytes: &[u8]) -> Result<ControlMsg> {
 /// malformed) — the caller treats that as "appears offline". `peer` is usually a
 /// bare [`EndpointId`] (friends store the stable id); a full [`EndpointAddr`] is
 /// also accepted (and used by hermetic tests).
-pub async fn probe(endpoint: &Endpoint, peer: impl Into<EndpointAddr>) -> Result<(EndpointId, ControlMsg)> {
+pub async fn probe(
+    endpoint: &Endpoint,
+    peer: impl Into<EndpointAddr>,
+) -> Result<(EndpointId, ControlMsg)> {
     let conn = tokio::time::timeout(IO_TIMEOUT, endpoint.connect(peer, FRIENDS_ALPN))
         .await
         .context("timed out connecting to peer")?
@@ -62,7 +65,10 @@ pub async fn probe(endpoint: &Endpoint, peer: impl Into<EndpointAddr>) -> Result
     let from = conn.remote_id();
 
     let io = async {
-        let (mut send, mut recv) = conn.open_bi().await.context("failed to open control stream")?;
+        let (mut send, mut recv) = conn
+            .open_bi()
+            .await
+            .context("failed to open control stream")?;
         send.write_all(&encode(&ControlMsg::Ping)?)
             .await
             .context("failed to write ping")?;
@@ -118,7 +124,10 @@ async fn exchange(conn: &iroh::endpoint::Connection, handler: &Handler) -> Resul
 
     let io = async {
         let (mut send, mut recv) = conn.accept_bi().await.context("failed to accept stream")?;
-        let bytes = recv.read_to_end(MAX_MSG).await.context("failed to read ping")?;
+        let bytes = recv
+            .read_to_end(MAX_MSG)
+            .await
+            .context("failed to read ping")?;
         match decode(&bytes)? {
             ControlMsg::Ping => {}
             other => bail!("expected a ping, got {other:?}"),
@@ -211,7 +220,10 @@ mod tests {
         let handler: Handler = Arc::new(move |from| {
             if from == allowed {
                 Some(ControlMsg::Pong {
-                    room: Some(RoomPresence { name: "HangOut".into(), ticket: "t".into() }),
+                    room: Some(RoomPresence {
+                        name: "HangOut".into(),
+                        ticket: "t".into(),
+                    }),
                 })
             } else {
                 None // stranger -> no reply
@@ -221,10 +233,11 @@ mod tests {
         let serve_task = tokio::spawn(async move { serve(server_ep, handler).await });
 
         // The allowed prober gets a Pong with the room.
-        let (from, pong) = tokio::time::timeout(Duration::from_secs(15), probe(&prober, server_addr.clone()))
-            .await
-            .expect("probe timed out")
-            .expect("probe failed");
+        let (from, pong) =
+            tokio::time::timeout(Duration::from_secs(15), probe(&prober, server_addr.clone()))
+                .await
+                .expect("probe timed out")
+                .expect("probe failed");
         assert_eq!(from, server_addr.id);
         match pong {
             ControlMsg::Pong { room: Some(r) } => assert_eq!(r.name, "HangOut"),

src/protocol.rs

@@ -33,12 +33,16 @@ pub const FRIENDS_PROTO: u32 = 1;
 /// change is isolated into its own topic + signature domain so v2 and v3 peers
 /// never share a swarm. Resync everyone, exactly like the W4 avatar bump.
 ///
-/// v4 (0.6.0): `PeerState` gained an optional `music` presence field carrying a
-/// current shared-listening track descriptor and playback timeline. Bytes still
-/// ride the files plane by id; gossip carries only the descriptor/timeline.
-///
-/// v5 (0.7.0): `MusicPresence` gained optional prefetch hints for the next
-/// track so tuned-in listeners can fetch it before the DJ advances.
+/// v4–v5 (0.6.0): the W22 shared-listening / music presence work. `PeerState`
+/// gained an optional `music` presence field (a current shared-listening track
+/// descriptor + playback timeline; the audio bytes still ride the files plane by
+/// id, gossip carries only the descriptor/timeline), and `MusicPresence` then
+/// gained optional prefetch hints for the next track so tuned-in listeners can
+/// fetch it before the DJ advances. Both shipped together in the **0.6.0** release
+/// (commit `bca2ccd`), where the const advanced straight `3 → 5`: there was never
+/// a `GOSSIP_PROTO == 4` build — 4 is a skipped step. (Per `VERSIONING.md` this
+/// breaking gossip change rode the `0.5.1 → 0.6.0` MINOR bump, so the discipline
+/// was honoured; 0.6.1 is a wire-compatible PATCH on top, still proto 5.)
 pub const GOSSIP_PROTO: u32 = 5;
 /// File-transfer plane version (chat attachment request/stream shape). Bump on
 /// any change. Mirrored in [`FILES_ALPN`].
@@ -83,10 +87,22 @@ mod tests {
     /// so a version bump can't silently forget to update the wire string.
     #[test]
     fn alpns_match_their_proto_versions() {
-        assert_eq!(AUDIO_ALPN, format!("peerspeak/audio/{AUDIO_PROTO}").as_bytes());
-        assert_eq!(FRIENDS_ALPN, format!("peerspeak/friends/{FRIENDS_PROTO}").as_bytes());
-        assert_eq!(FILES_ALPN, format!("peerspeak/files/{FILES_PROTO}").as_bytes());
-        assert_eq!(GOSSIP_SIG_DOMAIN, format!("peerspeak-gossip-v{GOSSIP_PROTO}"));
+        assert_eq!(
+            AUDIO_ALPN,
+            format!("peerspeak/audio/{AUDIO_PROTO}").as_bytes()
+        );
+        assert_eq!(
+            FRIENDS_ALPN,
+            format!("peerspeak/friends/{FRIENDS_PROTO}").as_bytes()
+        );
+        assert_eq!(
+            FILES_ALPN,
+            format!("peerspeak/files/{FILES_PROTO}").as_bytes()
+        );
+        assert_eq!(
+            GOSSIP_SIG_DOMAIN,
+            format!("peerspeak-gossip-v{GOSSIP_PROTO}")
+        );
     }
 
     #[test]
@@ -95,7 +111,11 @@ mod tests {
         let mut b = a;
         b[5] = 10;
         assert_eq!(versioned_topic(a), versioned_topic(a), "deterministic");
-        assert_ne!(versioned_topic(a), versioned_topic(b), "distinct rooms stay distinct");
+        assert_ne!(
+            versioned_topic(a),
+            versioned_topic(b),
+            "distinct rooms stay distinct"
+        );
     }
 
     #[test]

src/recents.rs

@@ -51,7 +51,14 @@ fn same_room(a: &str, b: &str) -> bool {
 /// supplies `now` (unix seconds) and persists the list afterwards.
 pub fn push_recent(list: &mut Vec<Recent>, name: String, ticket: String, now: u64) {
     list.retain(|r| !same_room(&r.ticket, &ticket));
-    list.insert(0, Recent { name, ticket, joined_at: now });
+    list.insert(
+        0,
+        Recent {
+            name,
+            ticket,
+            joined_at: now,
+        },
+    );
     list.truncate(RECENTS_MAX);
 }
 
@@ -86,8 +93,12 @@ mod tests {
     /// Build a real, parseable ticket for a fresh room with the given label.
     fn ticket(name: &str, topic: [u8; 32]) -> String {
         let host = SecretKey::generate().public();
-        PeerSpeakTicket { host_addr: EndpointAddr::from(host), topic_id: topic, name: name.into() }
-            .to_string()
+        PeerSpeakTicket {
+            host_addr: EndpointAddr::from(host),
+            topic_id: topic,
+            name: name.into(),
+        }
+        .to_string()
     }
 
     #[test]

src/sanitize.rs

@@ -85,7 +85,10 @@ pub enum Segment {
 /// Trailing characters commonly adjacent to a URL in prose that should NOT be
 /// part of the link (so "see http://x.com." or "(http://x.com)" linkify cleanly).
 fn is_url_trailing_punct(c: char) -> bool {
-    matches!(c, '.' | ',' | '!' | '?' | ';' | ':' | ')' | ']' | '}' | '>' | '"' | '\'')
+    matches!(
+        c,
+        '.' | ',' | '!' | '?' | ';' | ':' | ')' | ']' | '}' | '>' | '"' | '\''
+    )
 }
 
 /// Find the byte index of the earliest `http://` or `https://` scheme in `s`,
@@ -144,7 +147,10 @@ mod tests {
     fn strips_control_chars_and_collapses_whitespace() {
         // NUL, CR/LF, TAB, and ANSI ESC are control chars → become spaces, then
         // collapse; ends trim.
-        assert_eq!(sanitize_name("  a\u{0}b\r\nc\td\u{1b}[31m  "), "a b c d [31m");
+        assert_eq!(
+            sanitize_name("  a\u{0}b\r\nc\td\u{1b}[31m  "),
+            "a b c d [31m"
+        );
         // A name that is only control/whitespace cleans to empty.
         assert_eq!(sanitize_name("\u{0}\r\n\t   "), "");
     }
@@ -183,7 +189,10 @@ mod tests {
         let mid = "g".repeat(56);
         assert_eq!(sanitize_game_label(&mid).chars().count(), 56);
         let long = "g".repeat(GAME_LABEL_MAX_CHARS + 100);
-        assert_eq!(sanitize_game_label(&long).chars().count(), GAME_LABEL_MAX_CHARS);
+        assert_eq!(
+            sanitize_game_label(&long).chars().count(),
+            GAME_LABEL_MAX_CHARS
+        );
     }
 
     #[test]
@@ -220,7 +229,10 @@ mod tests {
     #[test]
     fn linkify_plain_text_has_no_links() {
         let segs = linkify("just a normal message, nothing here");
-        assert_eq!(segs, vec![Segment::Text("just a normal message, nothing here".into())]);
+        assert_eq!(
+            segs,
+            vec![Segment::Text("just a normal message, nothing here".into())]
+        );
     }
 
     #[test]
@@ -280,7 +292,12 @@ mod tests {
     fn linkify_only_matches_http_schemes() {
         // Non-web schemes and bare domains are NOT linkified (conservative).
         let segs = linkify("email me@x.com or ftp://x.com or visit x.com");
-        assert_eq!(segs, vec![Segment::Text("email me@x.com or ftp://x.com or visit x.com".into())]);
+        assert_eq!(
+            segs,
+            vec![Segment::Text(
+                "email me@x.com or ftp://x.com or visit x.com".into()
+            )]
+        );
     }
 
     #[test]
@@ -293,7 +310,11 @@ mod tests {
             "weird))) http://c.com]]] tail",
             "unicode 世界 http://d.com/路径 more 世界",
         ] {
-            assert_eq!(reassemble(&linkify(msg)), msg, "roundtrip failed for {msg:?}");
+            assert_eq!(
+                reassemble(&linkify(msg)),
+                msg,
+                "roundtrip failed for {msg:?}"
+            );
         }
     }
 }

src/screenshare/mod.rs

@@ -21,6 +21,8 @@ use std::time::Duration;
 use tokio::io::{AsyncBufReadExt, BufReader};
 use tokio::process::{Child, Command};
 
+use crate::config::{ScreenShareSettings, ShareBuffering, SharePlayer, ShareQuality};
+
 /// The binary we shell out to. Looked up on `$PATH` unless a config override
 /// points elsewhere.
 const PIXELPASS_BIN: &str = "pixelpass";
@@ -139,7 +141,11 @@ fn json_u32(v: &serde_json::Value, key: &str) -> u32 {
 /// otherwise rejects hyphen-leading option values). The name is locally chosen
 /// (our own enumeration / the user's pick), not peer-supplied, but is still
 /// sanitized via [`sanitize_app_name`] before reaching here. Pure: no I/O.
-pub fn host_args(audio_app: Option<&str>) -> Vec<String> {
+pub fn host_args(
+    audio_app: Option<&str>,
+    settings: &ScreenShareSettings,
+    quality: ShareQuality,
+) -> Vec<String> {
     let mut args = vec![
         "--host".to_string(),
         "--output".to_string(),
@@ -149,18 +155,52 @@ pub fn host_args(audio_app: Option<&str>) -> Vec<String> {
         args.push(format!("--app={name}"));
         args.push("--strict-audio".to_string());
     }
+    if quality != ShareQuality::Auto {
+        args.push(format!("--quality={}", pixelpass_quality(quality)));
+    }
+    if let Some(height) = settings.max_height {
+        args.push(format!("--max-height={height}"));
+    }
+    if let Some(mbps) = settings.bitrate_mbps {
+        args.push(format!("--bitrate={}", mbps.saturating_mul(1000)));
+    }
+    if let Some(fps) = settings.framerate {
+        args.push(format!("--framerate={fps}"));
+    }
+    if settings.force_software_encode {
+        args.push("--no-hwencode".to_string());
+    }
+    if let Some(max) = settings.max_viewers {
+        args.push(format!("--max-viewers={max}"));
+    }
+    args.extend(split_extra_args(&settings.extra_host_args));
     args
 }
 
+fn pixelpass_quality(quality: ShareQuality) -> &'static str {
+    match quality {
+        ShareQuality::Auto => "auto",
+        ShareQuality::Low => "low",
+        ShareQuality::Medium => "medium",
+        ShareQuality::High => "high",
+        ShareQuality::Source => "source",
+    }
+}
+
+/// Split user-supplied advanced argv text into separate tokens. Peerspeak does
+/// not depend on a shell lexer, so quoted values are not interpreted here.
+fn split_extra_args(raw: &str) -> impl Iterator<Item = String> + '_ {
+    raw.split_whitespace().map(str::to_string)
+}
+
 /// Validate a locally-chosen audio app name before it becomes a `--app` value:
 /// trim, reject empty / overlong, and reject names carrying control characters
 /// (newlines etc.) that have no place in a real `application.name`. `None` means
 /// "no valid app selected" — the caller then shares the whole desktop audio.
 pub fn sanitize_app_name(name: &str) -> Option<String> {
     let name = name.trim();
-    let ok = !name.is_empty()
-        && name.len() <= MAX_APP_NAME_LEN
-        && !name.chars().any(|c| c.is_control());
+    let ok =
+        !name.is_empty() && name.len() <= MAX_APP_NAME_LEN && !name.chars().any(|c| c.is_control());
     ok.then(|| name.to_string())
 }
 
@@ -321,15 +361,22 @@ pub fn is_available(config_override: Option<&str>) -> bool {
 /// whole desktop sink, which avoids the call-loopback echo (A23). The child keeps
 /// running (streaming to viewers) until killed or dropped; remaining stdout is
 /// drained in a background task so a full pipe can't stall the host. We do
-/// **not** pass `--max-viewers`: pixelpass bandwidth-measures its own safe cap,
-/// protecting the sharer's uplink, and refuses extras with `viewer_refused`.
+/// not pass encode/viewer overrides unless the local settings explicitly ask for
+/// them, so pixelpass keeps its own defaults in the common case.
 pub async fn spawn_host(
     bin: &Path,
     audio_app: Option<&str>,
+    settings: &ScreenShareSettings,
+    quality: ShareQuality,
     notices: Option<tokio::sync::mpsc::UnboundedSender<PixelpassEvent>>,
 ) -> std::io::Result<(Child, String)> {
+    let args = host_args(audio_app, settings, quality);
+    // Log the exact argv we hand pixelpass so a field log can confirm which
+    // encode/quality flags (e.g. --bitrate) actually reached the host — these
+    // are local flags with no ticket/secret, so logging them verbatim is safe.
+    crate::log_msg(&format!("pixelpass host spawn: {} {}", bin.display(), args.join(" ")));
     let mut child = Command::new(bin)
-        .args(host_args(audio_app))
+        .args(&args)
         .stdin(Stdio::null())
         .stdout(Stdio::piped())
         // Capture stderr (not null): pixelpass prints its startup precondition
@@ -429,10 +476,14 @@ pub fn pixelpass_failure_detail(stderr: &str) -> String {
 }
 
 /// Spawn a pixelpass viewer for `ticket`, wait for it to connect, and open the
-/// stream in a local player (mpv, falling back to vlc). Returns the live viewer
-/// child so the caller can kill it on room-leave; it also self-exits when the
-/// player window closes (its tunnel ends).
-pub async fn spawn_viewer(bin: &Path, ticket: &str) -> std::io::Result<Child> {
+/// stream in a local player (mpv/VLC in the configured order, then fallback).
+/// Returns the live viewer child so the caller can kill it on room-leave; it also
+/// self-exits when the player window closes (its tunnel ends).
+pub async fn spawn_viewer(
+    bin: &Path,
+    ticket: &str,
+    settings: &ScreenShareSettings,
+) -> std::io::Result<Child> {
     let mut child = Command::new(bin)
         .args(viewer_args(ticket))
         .stdin(Stdio::null())
@@ -466,7 +517,7 @@ pub async fn spawn_viewer(bin: &Path, ticket: &str) -> std::io::Result<Child> {
         }
     };
 
-    if let Err(e) = launch_player(&url) {
+    if let Err(e) = launch_player(&url, settings) {
         let _ = child.kill().await;
         return Err(e);
     }
@@ -548,23 +599,33 @@ fn event_for_log(ev: &PixelpassEvent) -> String {
     }
 }
 
-/// Open the viewer stream URL in a media player. Mirrors pixelpass's own
-/// low-latency mpv invocation; falls back to vlc. The player is reaped in a
-/// background task so it doesn't linger as a zombie when its window closes.
-fn launch_player(url: &str) -> std::io::Result<()> {
-    const MPV_ARGS: &[&str] = &[
-        "--profile=low-latency",
-        "--untimed",
-        "--hwdec=auto",
-        "--audio-buffer=0.2",
-        "--demuxer-max-bytes=2M",
-        "--demuxer-readahead-secs=0.5",
-    ];
-    const VLC_ARGS: &[&str] = &["--network-caching=200", "--live-caching=200"];
+/// Open the viewer stream URL in a media player, then fall back to vlc. The
+/// player is reaped in a background task so it doesn't linger as a zombie when
+/// its window closes.
+///
+/// The flags keep latency low while preserving A/V sync. We deliberately do
+/// NOT pass mpv's `--untimed`: that displays each video frame the instant it
+/// decodes, ignoring audio timestamps, which makes a shared *video* drift
+/// progressively out of sync with its audio. Pacing to the audio clock costs a
+/// little latency (negligible for pointing at a desktop) and keeps a shared
+/// video in sync. We also leave hwdec at the `low-latency` default (software
+/// decode): forcing `--hwdec=auto` froze some viewers on frame 1 while audio
+/// kept playing.
+fn launch_player(url: &str, settings: &ScreenShareSettings) -> std::io::Result<()> {
+    let mpv_args = mpv_args(settings);
+    let vlc_args = vlc_args(settings);
+    let first = match settings.player {
+        SharePlayer::Mpv => ("mpv", &mpv_args),
+        SharePlayer::Vlc => ("vlc", &vlc_args),
+    };
+    let second = match settings.player {
+        SharePlayer::Mpv => ("vlc", &vlc_args),
+        SharePlayer::Vlc => ("mpv", &mpv_args),
+    };
 
-    let child = match spawn_player("mpv", MPV_ARGS, url) {
+    let child = match spawn_player(first.0, first.1, url) {
         Ok(c) => c,
-        Err(_) => spawn_player("vlc", VLC_ARGS, url).map_err(|_| {
+        Err(_) => spawn_player(second.0, second.1, url).map_err(|_| {
             std::io::Error::new(
                 std::io::ErrorKind::NotFound,
                 "no media player found — install mpv or vlc to watch screen shares",
@@ -578,7 +639,64 @@ fn launch_player(url: &str) -> std::io::Result<()> {
     Ok(())
 }
 
-fn spawn_player(bin: &str, args: &[&str], url: &str) -> std::io::Result<Child> {
+pub fn mpv_args(settings: &ScreenShareSettings) -> Vec<String> {
+    let mut args = Vec::new();
+    match settings.buffering {
+        ShareBuffering::LowLatency => {
+            args.push("--profile=low-latency".to_string());
+            args.push("--audio-buffer=0.2".to_string());
+            args.push("--demuxer-readahead-secs=0.5".to_string());
+        }
+        ShareBuffering::Smooth => {
+            args.push("--cache=yes".to_string());
+            args.push("--demuxer-readahead-secs=2".to_string());
+        }
+    }
+    args.push(format!("--demuxer-max-bytes={}M", settings.cache_mb));
+    if settings.hardware_decode {
+        args.push("--hwdec=auto".to_string());
+    }
+    args.extend(split_extra_args(&settings.extra_mpv_args));
+    args
+}
+
+/// Build the argv for a VLC viewer. VLC honors the subset of viewer settings
+/// that map cleanly onto its option set: the buffering posture (network/live
+/// caching, in ms) and hardware decoding. The rest of the viewer knobs are
+/// mpv-specific — `cache_mb` is an mpv demuxer *byte* cache (VLC's caching is
+/// time-based, already covered by `buffering`) and `extra_mpv_args` is literally
+/// mpv flags — so they are deliberately not mapped here; the Settings UI labels
+/// them as mpv-only. Pure: no I/O.
+///
+/// The hardware-decode mapping is the load-bearing one: VLC hardware-decodes by
+/// default, so without an explicit `--avcodec-hw=none` a VLC viewer would ignore
+/// the (default-off) hardware-decode toggle and could hit the frame-1 freeze
+/// that default exists to avoid — the same A-bug that made us drop mpv's forced
+/// `--hwdec=auto`.
+fn vlc_args(settings: &ScreenShareSettings) -> Vec<String> {
+    let caching_ms = match settings.buffering {
+        ShareBuffering::LowLatency => 200,
+        ShareBuffering::Smooth => 1500,
+    };
+    let hw = if settings.hardware_decode {
+        "--avcodec-hw=any"
+    } else {
+        "--avcodec-hw=none"
+    };
+    vec![
+        format!("--network-caching={caching_ms}"),
+        format!("--live-caching={caching_ms}"),
+        hw.to_string(),
+    ]
+}
+
+fn spawn_player(bin: &str, args: &[String], url: &str) -> std::io::Result<Child> {
+    // Log the player + its flags (mpv/vlc, incl. hardware-decode: --hwdec /
+    // --avcodec-hw) so a field log can confirm the viewer settings reached the
+    // player. The `url` is omitted deliberately — it is the local stream address
+    // and is not needed to verify the flags. Logged on each attempt, so a
+    // fallback from the preferred player to the other one is visible too.
+    crate::log_msg(&format!("player spawn: {bin} {}", args.join(" ")));
     Command::new(bin)
         .args(args)
         .arg(url)
@@ -599,7 +717,10 @@ mod tests {
         // i.e. after the `--` end-of-options guard, never parsed as a flag.
         let args = viewer_args("--malicious-flag");
         assert_eq!(args.last().unwrap(), "--malicious-flag", "ticket is last");
-        let guard = args.iter().position(|a| a == "--").expect("`--` guard present");
+        let guard = args
+            .iter()
+            .position(|a| a == "--")
+            .expect("`--` guard present");
         let ticket = args.len() - 1;
         assert!(guard < ticket, "ticket must follow the `--` guard");
         // The real flags are parsed before the guard.
@@ -619,7 +740,11 @@ mod tests {
     fn host_args_without_app_shares_whole_desktop() {
         // No app selected → no --app flag → pixelpass keeps its default
         // (whole-desktop) audio capture.
-        assert_eq!(host_args(None), vec!["--host", "--output", "json"]);
+        let settings = ScreenShareSettings::default();
+        assert_eq!(
+            host_args(None, &settings, ShareQuality::Auto),
+            vec!["--host", "--output", "json"]
+        );
     }
 
     #[test]
@@ -627,13 +752,20 @@ mod tests {
         // The chosen app rides in the `--app=<name>` single-token form so a
         // name beginning with `-` can never be reparsed as a flag (A23), plus
         // `--strict-audio` so pixelpass never falls back to whole-desktop audio.
+        let settings = ScreenShareSettings::default();
         assert_eq!(
-            host_args(Some("Firefox")),
-            vec!["--host", "--output", "json", "--app=Firefox", "--strict-audio"]
+            host_args(Some("Firefox"), &settings, ShareQuality::Auto),
+            vec![
+                "--host",
+                "--output",
+                "json",
+                "--app=Firefox",
+                "--strict-audio"
+            ]
         );
         // The hyphen-leading name is still bound to --app as a single token;
         // --strict-audio is the trailing flag.
-        let args = host_args(Some("-rm -rf"));
+        let args = host_args(Some("-rm -rf"), &settings, ShareQuality::Auto);
         assert_eq!(args[3], "--app=-rm -rf");
         assert_eq!(args[4], "--strict-audio");
     }
@@ -642,13 +774,130 @@ mod tests {
     fn host_args_blank_or_control_app_is_dropped() {
         // An empty / whitespace / control-laden selection is sanitized away,
         // falling back to whole-desktop capture rather than a broken flag.
-        assert_eq!(host_args(Some("   ")), vec!["--host", "--output", "json"]);
-        assert_eq!(host_args(Some("bad\nname")), vec!["--host", "--output", "json"]);
+        let settings = ScreenShareSettings::default();
+        assert_eq!(
+            host_args(Some("   "), &settings, ShareQuality::Auto),
+            vec!["--host", "--output", "json"]
+        );
+        assert_eq!(
+            host_args(Some("bad\nname"), &settings, ShareQuality::Auto),
+            vec!["--host", "--output", "json"]
+        );
+    }
+
+    #[test]
+    fn host_args_apply_screen_share_settings_and_extra_args_last() {
+        let settings = ScreenShareSettings {
+            bitrate_mbps: Some(5),
+            framerate: Some(60),
+            max_height: Some(1080),
+            max_viewers: Some(4),
+            force_software_encode: true,
+            extra_host_args: "--relay https://relay.example --verbose".to_string(),
+            ..ScreenShareSettings::default()
+        };
+
+        assert_eq!(
+            host_args(Some("Firefox"), &settings, ShareQuality::High),
+            vec![
+                "--host",
+                "--output",
+                "json",
+                "--app=Firefox",
+                "--strict-audio",
+                "--quality=high",
+                "--max-height=1080",
+                "--bitrate=5000",
+                "--framerate=60",
+                "--no-hwencode",
+                "--max-viewers=4",
+                "--relay",
+                "https://relay.example",
+                "--verbose",
+            ]
+        );
+    }
+
+    #[test]
+    fn mpv_args_default_matches_low_latency_software_decode() {
+        assert_eq!(
+            mpv_args(&ScreenShareSettings::default()),
+            vec![
+                "--profile=low-latency",
+                "--audio-buffer=0.2",
+                "--demuxer-readahead-secs=0.5",
+                "--demuxer-max-bytes=2M",
+            ]
+        );
+    }
+
+    #[test]
+    fn mpv_args_smooth_hwdecode_and_extra_args_last() {
+        let settings = ScreenShareSettings {
+            hardware_decode: true,
+            buffering: ShareBuffering::Smooth,
+            cache_mb: 16,
+            extra_mpv_args: "--no-osc --vd-lavc-threads=2".to_string(),
+            ..ScreenShareSettings::default()
+        };
+
+        assert_eq!(
+            mpv_args(&settings),
+            vec![
+                "--cache=yes",
+                "--demuxer-readahead-secs=2",
+                "--demuxer-max-bytes=16M",
+                "--hwdec=auto",
+                "--no-osc",
+                "--vd-lavc-threads=2",
+            ]
+        );
+    }
+
+    #[test]
+    fn vlc_args_default_disables_hardware_decode() {
+        // The A-bug fix default (hardware_decode = false) must reach VLC too:
+        // VLC hardware-decodes by default, so without an explicit
+        // `--avcodec-hw=none` a VLC viewer would ignore the toggle and could hit
+        // the frame-1 freeze. Low-latency buffering keeps the 200 ms caches.
+        assert_eq!(
+            vlc_args(&ScreenShareSettings::default()),
+            vec![
+                "--network-caching=200",
+                "--live-caching=200",
+                "--avcodec-hw=none",
+            ]
+        );
+    }
+
+    #[test]
+    fn vlc_args_smooth_buffering_and_hwdecode() {
+        // Enabling hardware decode flips VLC to `--avcodec-hw=any`; Smooth
+        // buffering raises the network/live caches. cache_mb / extra_mpv_args are
+        // mpv-only and must NOT leak into the VLC argv.
+        let settings = ScreenShareSettings {
+            hardware_decode: true,
+            buffering: ShareBuffering::Smooth,
+            cache_mb: 16,
+            extra_mpv_args: "--no-osc".to_string(),
+            ..ScreenShareSettings::default()
+        };
+        assert_eq!(
+            vlc_args(&settings),
+            vec![
+                "--network-caching=1500",
+                "--live-caching=1500",
+                "--avcodec-hw=any",
+            ]
+        );
     }
 
     #[test]
     fn sanitize_app_name_trims_and_rejects_garbage() {
-        assert_eq!(sanitize_app_name("  Firefox \n"), Some("Firefox".to_string()));
+        assert_eq!(
+            sanitize_app_name("  Firefox \n"),
+            Some("Firefox".to_string())
+        );
         assert_eq!(sanitize_app_name(""), None);
         assert_eq!(sanitize_app_name("   "), None);
         assert_eq!(sanitize_app_name("a\tb"), None);
@@ -667,7 +916,11 @@ mod tests {
         ]"#;
         assert_eq!(
             parse_audio_apps(stdout),
-            vec!["Firefox".to_string(), "Spotify".to_string(), "mpv".to_string()]
+            vec![
+                "Firefox".to_string(),
+                "Spotify".to_string(),
+                "mpv".to_string()
+            ]
         );
     }
 
@@ -754,13 +1007,19 @@ Install hint: sudo apt install gstreamer1.0-plugins-bad
     #[test]
     fn sanitize_ticket_accepts_pixelpass_endpoint_ticket_shape() {
         let ticket = "endpointaabwxjexzensznfvuudiapn5tyzws3angd2merarm";
-        assert_eq!(sanitize_ticket(format!("  {ticket}\n")), Some(ticket.to_string()));
+        assert_eq!(
+            sanitize_ticket(format!("  {ticket}\n")),
+            Some(ticket.to_string())
+        );
     }
 
     #[test]
     fn sanitize_ticket_rejects_oversized_or_garbage_ticket() {
         assert_eq!(sanitize_ticket("not-a-ticket".into()), None);
-        assert_eq!(sanitize_ticket(format!("endpoint{}", "a".repeat(MAX_TICKET_LEN))), None);
+        assert_eq!(
+            sanitize_ticket(format!("endpoint{}", "a".repeat(MAX_TICKET_LEN))),
+            None
+        );
         assert_eq!(sanitize_ticket("endpointabc-def".into()), None);
     }
 
@@ -784,7 +1043,9 @@ Install hint: sudo apt install gstreamer1.0-plugins-bad
     fn parses_connected_url() {
         assert_eq!(
             parse_pixelpass_event(r#"{"event":"connected","url":"http://127.0.0.1:5500"}"#),
-            Some(PixelpassEvent::Connected("http://127.0.0.1:5500".to_string()))
+            Some(PixelpassEvent::Connected(
+                "http://127.0.0.1:5500".to_string()
+            ))
         );
     }
 
@@ -919,7 +1180,10 @@ Install hint: sudo apt install gstreamer1.0-plugins-bad
         let dir = Path::new("bin");
         let candidates: Vec<PathBuf> = pixelpass_path_candidates(dir).into_iter().collect();
         #[cfg(windows)]
-        assert_eq!(candidates, vec![dir.join("pixelpass"), dir.join("pixelpass.exe")]);
+        assert_eq!(
+            candidates,
+            vec![dir.join("pixelpass"), dir.join("pixelpass.exe")]
+        );
         #[cfg(not(windows))]
         assert_eq!(candidates, vec![dir.join("pixelpass")]);
     }

src/theme.rs

@@ -211,7 +211,7 @@ impl AppTheme {
                 overlay: hex(0x6272a4),
                 text: hex(0xf8f8f2),
                 subtext: hex(0xbdc0d4),
-                blue: hex(0xbd93f9),  // Dracula's signature purple as the primary accent
+                blue: hex(0xbd93f9), // Dracula's signature purple as the primary accent
                 lavender: hex(0x8be9fd), // cyan
                 red: hex(0xff5555),
                 maroon: hex(0xff79c6), // pink
@@ -400,7 +400,11 @@ mod tests {
         for theme in AppTheme::ALL {
             let p = theme.palette();
             let sub = contrast_ratio(p.subtext, p.base);
-            assert!(sub >= 3.0, "{}: subtext contrast {sub:.2} < 3.0", theme.label());
+            assert!(
+                sub >= 3.0,
+                "{}: subtext contrast {sub:.2} < 3.0",
+                theme.label()
+            );
             let accent = contrast_ratio(p.blue, p.base);
             assert!(
                 accent >= 3.0,

src/widget/context_input.rs

@@ -9,8 +9,8 @@ use iced::advanced::widget::{self, Widget};
 use iced::advanced::{Layout, Shell};
 use iced::widget::text_input;
 use iced::{
-    alignment, Background, Border, Color, Element, Event, Length, Padding,
-    Pixels, Point, Rectangle, Shadow, Size, Vector,
+    Background, Border, Color, Element, Event, Length, Padding, Pixels, Point, Rectangle, Shadow,
+    Size, Vector, alignment,
 };
 use std::rc::Rc;
 
@@ -27,11 +27,7 @@ pub fn copy_selection(value: &str, start: usize, end: usize) -> Option<String> {
     (start != end).then(|| value.select(start, end).to_string())
 }
 
-pub fn cut_selection(
-    value: &str,
-    start: usize,
-    end: usize,
-) -> (Edit, Option<String>) {
+pub fn cut_selection(value: &str, start: usize, end: usize) -> (Edit, Option<String>) {
     let mut value = text_input::Value::new(value);
     let (start, end) = normalized_range(&value, start, end);
 
@@ -74,24 +70,26 @@ pub fn paste(value: &str, start: usize, end: usize, clip: &str) -> Edit {
     }
 }
 
+/// Strip control characters (e.g. a trailing newline on an X11 PRIMARY
+/// selection) from clipboard text before it is pasted. Shared by the
+/// right-click menu Paste and the middle-click PRIMARY paste.
+pub fn sanitize_clip(raw: &str) -> String {
+    raw.chars().filter(|c| !c.is_control()).collect()
+}
+
 pub fn select_all_range(value: &str) -> (usize, usize) {
     let value = text_input::Value::new(value);
 
     (0, value.len())
 }
 
-fn normalized_range(
-    value: &text_input::Value,
-    start: usize,
-    end: usize,
-) -> (usize, usize) {
+fn normalized_range(value: &text_input::Value, start: usize, end: usize) -> (usize, usize) {
     let len = value.len();
 
     (start.min(end).min(len), start.max(end).min(len))
 }
 
-type InputStyleFn<'a, Theme> =
-    Rc<dyn Fn(&Theme, text_input::Status) -> text_input::Style + 'a>;
+type InputStyleFn<'a, Theme> = Rc<dyn Fn(&Theme, text_input::Status) -> text_input::Style + 'a>;
 
 pub fn context_input<'a, Message, Theme, Renderer>(
     placeholder: &str,
@@ -119,12 +117,8 @@ where
         .locked(true)
 }
 
-pub struct ContextInput<
-    'a,
-    Message,
-    Theme = iced::Theme,
-    Renderer = iced::Renderer,
-> where
+pub struct ContextInput<'a, Message, Theme = iced::Theme, Renderer = iced::Renderer>
+where
     Theme: text_input::Catalog,
     Renderer: text::Renderer,
 {
@@ -137,8 +131,7 @@ pub struct ContextInput<
     style: Option<InputStyleFn<'a, Theme>>,
 }
 
-impl<'a, Message, Theme, Renderer>
-    ContextInput<'a, Message, Theme, Renderer>
+impl<'a, Message, Theme, Renderer> ContextInput<'a, Message, Theme, Renderer>
 where
     Message: Clone + 'a,
     Theme: text_input::Catalog + 'a,
@@ -172,16 +165,13 @@ where
         self
     }
 
-    pub fn on_input(
-        mut self,
-        on_input: impl Fn(String) -> Message + 'a,
-    ) -> Self {
-        let on_input: Rc<dyn Fn(String) -> Message + 'a> =
-            Rc::new(on_input);
+    pub fn on_input(mut self, on_input: impl Fn(String) -> Message + 'a) -> Self {
+        let on_input: Rc<dyn Fn(String) -> Message + 'a> = Rc::new(on_input);
         let input_callback = Rc::clone(&on_input);
 
-        self.input =
-            self.input.on_input(move |value| input_callback.as_ref()(value));
+        self.input = self
+            .input
+            .on_input(move |value| input_callback.as_ref()(value));
         self.on_input = Some(on_input);
         self
     }
@@ -196,16 +186,13 @@ where
         self
     }
 
-    pub fn on_paste(
-        mut self,
-        on_paste: impl Fn(String) -> Message + 'a,
-    ) -> Self {
-        let on_paste: Rc<dyn Fn(String) -> Message + 'a> =
-            Rc::new(on_paste);
+    pub fn on_paste(mut self, on_paste: impl Fn(String) -> Message + 'a) -> Self {
+        let on_paste: Rc<dyn Fn(String) -> Message + 'a> = Rc::new(on_paste);
         let paste_callback = Rc::clone(&on_paste);
 
-        self.input =
-            self.input.on_paste(move |value| paste_callback.as_ref()(value));
+        self.input = self
+            .input
+            .on_paste(move |value| paste_callback.as_ref()(value));
         self.on_paste = Some(on_paste);
         self
     }
@@ -235,18 +222,12 @@ where
         self
     }
 
-    pub fn line_height(
-        mut self,
-        line_height: impl Into<text::LineHeight>,
-    ) -> Self {
+    pub fn line_height(mut self, line_height: impl Into<text::LineHeight>) -> Self {
         self.input = self.input.line_height(line_height);
         self
     }
 
-    pub fn align_x(
-        mut self,
-        alignment: impl Into<alignment::Horizontal>,
-    ) -> Self {
+    pub fn align_x(mut self, alignment: impl Into<alignment::Horizontal>) -> Self {
         self.input = self.input.align_x(alignment);
         self
     }
@@ -379,11 +360,51 @@ where
                 }
             };
 
-            tree.state.downcast_mut::<ContextInputState>().menu =
-                cursor.position().map(|anchor| MenuState {
-                    anchor,
-                    selection,
-                });
+            tree.state.downcast_mut::<ContextInputState>().menu = cursor
+                .position()
+                .map(|anchor| MenuState { anchor, selection });
+
+            shell.capture_event();
+            shell.request_redraw();
+            return;
+        }
+
+        // Middle-click pastes the X11 PRIMARY selection at the cursor. iced's
+        // base text_input only wires Ctrl+V to the Standard (CLIPBOARD)
+        // selection, so without this the common "select text, middle-click to
+        // paste" workflow does nothing on X11.
+        let middle_click_on_input = matches!(
+            event,
+            Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle))
+        ) && cursor.is_over(layout.bounds());
+
+        if middle_click_on_input && !self.locked {
+            let clip = sanitize_clip(&clipboard.read(clipboard::Kind::Primary).unwrap_or_default());
+
+            if !clip.is_empty() {
+                let value = text_input::Value::new(&self.value);
+                let input_state = tree.children[0]
+                    .state
+                    .downcast_mut::<text_input::State<Renderer::Paragraph>>();
+                let (start, end) = match input_state.cursor().state(&value) {
+                    text_input::cursor::State::Index(index) => {
+                        let index = index.min(value.len());
+                        (index, index)
+                    }
+                    text_input::cursor::State::Selection { start, end } => {
+                        normalized_range(&value, start, end)
+                    }
+                };
+
+                let edit = paste(&self.value, start, end, &clip);
+                input_state.move_cursor_to(edit.cursor);
+
+                if let Some(on_paste) = &self.on_paste {
+                    shell.publish(on_paste.as_ref()(edit.value));
+                } else if let Some(on_input) = &self.on_input {
+                    shell.publish(on_input.as_ref()(edit.value));
+                }
+            }
 
             shell.capture_event();
             shell.request_redraw();
@@ -477,8 +498,7 @@ where
     }
 }
 
-impl<'a, Message, Theme, Renderer>
-    From<ContextInput<'a, Message, Theme, Renderer>>
+impl<'a, Message, Theme, Renderer> From<ContextInput<'a, Message, Theme, Renderer>>
     for Element<'a, Message, Theme, Renderer>
 where
     Message: Clone + 'a,
@@ -516,12 +536,7 @@ enum MenuAction {
 }
 
 impl MenuAction {
-    const ALL: [Self; 4] = [
-        Self::Cut,
-        Self::Copy,
-        Self::Paste,
-        Self::SelectAll,
-    ];
+    const ALL: [Self; 4] = [Self::Cut, Self::Copy, Self::Paste, Self::SelectAll];
 
     fn label(self) -> &'static str {
         match self {
@@ -564,8 +579,7 @@ where
         cursor: mouse::Cursor,
     ) {
         let active_style = input_style(theme, self.style.as_ref(), text_input::Status::Active);
-        let hovered_style =
-            input_style(theme, self.style.as_ref(), text_input::Status::Hovered);
+        let hovered_style = input_style(theme, self.style.as_ref(), text_input::Status::Hovered);
         let bounds = layout.bounds();
         let viewport = Rectangle::INFINITE;
 
@@ -640,9 +654,7 @@ where
     ) {
         match event {
             Event::Keyboard(iced::keyboard::Event::KeyPressed {
-                key: iced::keyboard::Key::Named(
-                    iced::keyboard::key::Named::Escape,
-                ),
+                key: iced::keyboard::Key::Named(iced::keyboard::key::Named::Escape),
                 ..
             }) => {
                 self.close(shell);
@@ -718,11 +730,7 @@ where
         )
     }
 
-    fn hit_action(
-        &self,
-        bounds: Rectangle,
-        position: Point,
-    ) -> Option<MenuAction> {
+    fn hit_action(&self, bounds: Rectangle, position: Point) -> Option<MenuAction> {
         if !bounds.contains(position) {
             return None;
         }
@@ -758,12 +766,7 @@ where
                 }
             }
             MenuAction::Paste => {
-                let clip = clipboard
-                    .read(clipboard::Kind::Standard)
-                    .unwrap_or_default()
-                    .chars()
-                    .filter(|c| !c.is_control())
-                    .collect::<String>();
+                let clip = sanitize_clip(&clipboard.read(clipboard::Kind::Standard).unwrap_or_default());
                 let edit = paste(self.value, start, end, &clip);
 
                 self.publish_paste(edit, shell);
@@ -883,6 +886,16 @@ mod tests {
         assert_eq!(clip, None);
     }
 
+    #[test]
+    fn sanitize_clip_strips_control_chars_keeps_text() {
+        // An X11 PRIMARY selection commonly carries a trailing newline.
+        assert_eq!(sanitize_clip("pixelpassF1:abc\n"), "pixelpassF1:abc");
+        assert_eq!(sanitize_clip("a\tb\r\nc"), "abc");
+        // Non-control unicode is preserved.
+        assert_eq!(sanitize_clip("héllo🦀"), "héllo🦀");
+        assert_eq!(sanitize_clip(""), "");
+    }
+
     #[test]
     fn paste_replaces_selection_or_inserts_at_cursor() {
         assert_eq!(
@@ -932,12 +945,48 @@ mod tests {
 
     #[test]
     fn locked_menu_allows_copy_and_select_all_only() {
-        assert!(!menu_action_enabled(MenuAction::Cut, true, true, false, true));
-        assert!(menu_action_enabled(MenuAction::Copy, true, true, false, true));
-        assert!(!menu_action_enabled(MenuAction::Paste, true, true, false, true));
-        assert!(menu_action_enabled(MenuAction::SelectAll, true, true, false, true));
+        assert!(!menu_action_enabled(
+            MenuAction::Cut,
+            true,
+            true,
+            false,
+            true
+        ));
+        assert!(menu_action_enabled(
+            MenuAction::Copy,
+            true,
+            true,
+            false,
+            true
+        ));
+        assert!(!menu_action_enabled(
+            MenuAction::Paste,
+            true,
+            true,
+            false,
+            true
+        ));
+        assert!(menu_action_enabled(
+            MenuAction::SelectAll,
+            true,
+            true,
+            false,
+            true
+        ));
 
-        assert!(!menu_action_enabled(MenuAction::Copy, false, true, false, true));
-        assert!(!menu_action_enabled(MenuAction::SelectAll, false, false, false, true));
+        assert!(!menu_action_enabled(
+            MenuAction::Copy,
+            false,
+            true,
+            false,
+            true
+        ));
+        assert!(!menu_action_enabled(
+            MenuAction::SelectAll,
+            false,
+            false,
+            false,
+            true
+        ));
     }
 }

src/widget/selectable_text.rs

@@ -3,16 +3,15 @@ use iced::advanced::layout;
 use iced::advanced::mouse;
 use iced::advanced::renderer;
 use iced::advanced::text::{self as advanced_text, Paragraph, Span};
-use iced::advanced::widget::tree::{self, Tree};
 use iced::advanced::widget::Widget;
+use iced::advanced::widget::tree::{self, Tree};
 use iced::advanced::{Layout, Shell};
 use iced::widget::text::{
-    self as widget_text, Alignment, Catalog, LineHeight, Shaping, Style, StyleFn,
-    Wrapping,
+    self as widget_text, Alignment, Catalog, LineHeight, Shaping, Style, StyleFn, Wrapping,
 };
 use iced::{
-    alignment, Background, Border, Color, Element, Event, Length, Pixels, Point,
-    Rectangle, Size, Vector, keyboard,
+    Background, Border, Color, Element, Event, Length, Pixels, Point, Rectangle, Size, Vector,
+    alignment, keyboard,
 };
 
 const DRAG_THRESHOLD: f32 = 3.0;
@@ -28,11 +27,7 @@ const HIT_SEARCH_STEPS: usize = 24;
 // widget's per-line offsets would stop being global and selection/copy across
 // lines would break — revisit then.
 
-pub fn selected_substring(
-    text: &str,
-    anchor: usize,
-    cursor: usize,
-) -> Option<String> {
+pub fn selected_substring(text: &str, anchor: usize, cursor: usize) -> Option<String> {
     let (start, end) = normalized_byte_range(text, anchor, cursor);
 
     (start != end).then(|| text[start..end].to_owned())
@@ -42,11 +37,7 @@ pub fn select_all(text: &str) -> (usize, usize) {
     (0, text.len())
 }
 
-fn normalized_byte_range(
-    text: &str,
-    anchor: usize,
-    cursor: usize,
-) -> (usize, usize) {
+fn normalized_byte_range(text: &str, anchor: usize, cursor: usize) -> (usize, usize) {
     let start = clamp_to_char_boundary(text, anchor.min(cursor));
     let end = clamp_to_char_boundary(text, anchor.max(cursor));
 
@@ -75,13 +66,8 @@ where
     SelectableRichText::with_spans(spans)
 }
 
-pub struct SelectableRichText<
-    'a,
-    Link,
-    Message,
-    Theme = iced::Theme,
-    Renderer = iced::Renderer,
-> where
+pub struct SelectableRichText<'a, Link, Message, Theme = iced::Theme, Renderer = iced::Renderer>
+where
     Link: Clone + 'static,
     Theme: Catalog,
     Renderer: advanced_text::Renderer,
@@ -101,8 +87,7 @@ pub struct SelectableRichText<
     selection_color: Color,
 }
 
-impl<'a, Link, Message, Theme, Renderer>
-    SelectableRichText<'a, Link, Message, Theme, Renderer>
+impl<'a, Link, Message, Theme, Renderer> SelectableRichText<'a, Link, Message, Theme, Renderer>
 where
     Link: Clone + 'static,
     Theme: Catalog,
@@ -127,9 +112,7 @@ where
         }
     }
 
-    pub fn with_spans(
-        spans: impl AsRef<[Span<'a, Link, Renderer::Font>]> + 'a,
-    ) -> Self {
+    pub fn with_spans(spans: impl AsRef<[Span<'a, Link, Renderer::Font>]> + 'a) -> Self {
         Self {
             spans: Box::new(spans),
             ..Self::new()
@@ -166,10 +149,7 @@ where
         self
     }
 
-    pub fn align_y(
-        mut self,
-        alignment: impl Into<alignment::Vertical>,
-    ) -> Self {
+    pub fn align_y(mut self, alignment: impl Into<alignment::Vertical>) -> Self {
         self.align_y = alignment.into();
         self
     }
@@ -179,10 +159,7 @@ where
         self
     }
 
-    pub fn on_link_click(
-        mut self,
-        on_link_click: impl Fn(Link) -> Message + 'a,
-    ) -> Self {
+    pub fn on_link_click(mut self, on_link_click: impl Fn(Link) -> Message + 'a) -> Self {
         self.on_link_click = Some(Box::new(on_link_click));
         self
     }
@@ -356,26 +333,16 @@ where
         }
 
         for (index, span) in spans.iter().enumerate() {
-            let is_hovered_link = self.on_link_click.is_some()
-                && Some(index) == self.hovered_link;
+            let is_hovered_link = self.on_link_click.is_some() && Some(index) == self.hovered_link;
 
-            if span.highlight.is_some()
-                || span.underline
-                || span.strikethrough
-                || is_hovered_link
-            {
+            if span.highlight.is_some() || span.underline || span.strikethrough || is_hovered_link {
                 let regions = state.paragraph.span_bounds(index);
 
                 if let Some(highlight) = span.highlight {
                     for bounds in &regions {
                         let bounds = Rectangle::new(
-                            bounds.position()
-                                - Vector::new(
-                                    span.padding.left,
-                                    span.padding.top,
-                                ),
-                            bounds.size()
-                                + Size::new(span.padding.x(), span.padding.y()),
+                            bounds.position() - Vector::new(span.padding.left, span.padding.top),
+                            bounds.size() + Size::new(span.padding.x(), span.padding.y()),
                         );
 
                         renderer.fill_quad(
@@ -390,26 +357,17 @@ where
                 }
 
                 if span.underline || span.strikethrough || is_hovered_link {
-                    let size = span
-                        .size
-                        .or(self.size)
-                        .unwrap_or(renderer.default_size());
+                    let size = span.size.or(self.size).unwrap_or(renderer.default_size());
 
                     let line_height = span
                         .line_height
                         .unwrap_or(self.line_height)
                         .to_absolute(size);
 
-                    let color = span
-                        .color
-                        .or(style.color)
-                        .unwrap_or(defaults.text_color);
+                    let color = span.color.or(style.color).unwrap_or(defaults.text_color);
 
-                    let baseline = translation
-                        + Vector::new(
-                            0.0,
-                            size.0 + (line_height.0 - size.0) / 2.0,
-                        );
+                    let baseline =
+                        translation + Vector::new(0.0, size.0 + (line_height.0 - size.0) / 2.0);
 
                     if span.underline || is_hovered_link {
                         for bounds in &regions {
@@ -497,13 +455,10 @@ where
                     state.dragging = true;
                     state.press_position = Some(position);
                     state.span_pressed = self.hovered_link;
-                    state.selection = state
-                        .paragraph
-                        .hit_test(position)
-                        .map(|hit| {
-                            let offset = hit.cursor().min(flat_text.len());
-                            (offset, offset)
-                        });
+                    state.selection = state.paragraph.hit_test(position).map(|hit| {
+                        let offset = hit.cursor().min(flat_text.len());
+                        (offset, offset)
+                    });
                     shell.capture_event();
                     shell.request_redraw();
                 } else if state.active || state.selection.is_some() {
@@ -521,8 +476,7 @@ where
                     && let Some(hit) = state.paragraph.hit_test(position)
                     && let Some((anchor, _)) = state.selection
                 {
-                    state.selection =
-                        Some((anchor, hit.cursor().min(flat_text.len())));
+                    state.selection = Some((anchor, hit.cursor().min(flat_text.len())));
                     shell.request_redraw();
                 }
             }
@@ -540,16 +494,14 @@ where
                         && let Some(hit) = state.paragraph.hit_test(position)
                         && let Some((anchor, _)) = state.selection
                     {
-                        state.selection =
-                            Some((anchor, hit.cursor().min(flat_text.len())));
+                        state.selection = Some((anchor, hit.cursor().min(flat_text.len())));
                     }
 
                     if !dragged {
                         if let (Some(on_link_clicked), Some(span)) =
                             (&self.on_link_click, state.span_pressed)
                             && Some(span) == self.hovered_link
-                            && let Some(link) =
-                                spans.get(span).and_then(|span| span.link.clone())
+                            && let Some(link) = spans.get(span).and_then(|span| span.link.clone())
                         {
                             shell.publish(on_link_clicked(link));
                         }
@@ -570,25 +522,22 @@ where
                 physical_key,
                 modifiers,
                 ..
-            }) if state.active && modifiers.command() => {
-                match key.to_latin(*physical_key) {
-                    Some('c') | Some('C') => {
-                        if let Some((anchor, cursor)) = state.selection
-                            && let Some(selected) =
-                                selected_substring(&flat_text, anchor, cursor)
-                        {
-                            clipboard.write(clipboard::Kind::Standard, selected);
-                            shell.capture_event();
-                        }
-                    }
-                    Some('a') | Some('A') => {
-                        state.selection = Some(select_all(&flat_text));
+            }) if state.active && modifiers.command() => match key.to_latin(*physical_key) {
+                Some('c') | Some('C') => {
+                    if let Some((anchor, cursor)) = state.selection
+                        && let Some(selected) = selected_substring(&flat_text, anchor, cursor)
+                    {
+                        clipboard.write(clipboard::Kind::Standard, selected);
                         shell.capture_event();
-                        shell.request_redraw();
                     }
-                    _ => {}
                 }
-            }
+                Some('a') | Some('A') => {
+                    state.selection = Some(select_all(&flat_text));
+                    shell.capture_event();
+                    shell.request_redraw();
+                }
+                _ => {}
+            },
             _ => {}
         }
     }
@@ -657,14 +606,8 @@ where
         };
 
         if state.spans != config.spans {
-            state.paragraph =
-                Renderer::Paragraph::with_spans(text_with_spans());
-            state.spans = config
-                .spans
-                .iter()
-                .cloned()
-                .map(Span::to_static)
-                .collect();
+            state.paragraph = Renderer::Paragraph::with_spans(text_with_spans());
+            state.spans = config.spans.iter().cloned().map(Span::to_static).collect();
         } else {
             match state.paragraph.compare(advanced_text::Text {
                 content: (),
@@ -682,8 +625,7 @@ where
                     state.paragraph.resize(bounds);
                 }
                 advanced_text::Difference::Shape => {
-                    state.paragraph =
-                        Renderer::Paragraph::with_spans(text_with_spans());
+                    state.paragraph = Renderer::Paragraph::with_spans(text_with_spans());
                 }
             }
         }
@@ -761,13 +703,7 @@ fn selection_rect_for_line<P: Paragraph>(
     })
 }
 
-fn x_for_offset<P: Paragraph>(
-    paragraph: &P,
-    y: f32,
-    offset: usize,
-    left: f32,
-    right: f32,
-) -> f32 {
+fn x_for_offset<P: Paragraph>(paragraph: &P, y: f32, offset: usize, left: f32, right: f32) -> f32 {
     let mut low = left;
     let mut high = right.max(left);
 
@@ -787,10 +723,7 @@ fn x_for_offset<P: Paragraph>(
     high
 }
 
-fn visual_lines<P: Paragraph>(
-    paragraph: &P,
-    span_count: usize,
-) -> Vec<Rectangle> {
+fn visual_lines<P: Paragraph>(paragraph: &P, span_count: usize) -> Vec<Rectangle> {
     let mut lines: Vec<Rectangle> = Vec::new();
 
     for span in 0..span_count {
@@ -820,10 +753,7 @@ fn union(a: Rectangle, b: Rectangle) -> Rectangle {
     let right = (a.x + a.width).max(b.x + b.width);
     let bottom = (a.y + a.height).max(b.y + b.height);
 
-    Rectangle::new(
-        Point::new(left, top),
-        Size::new(right - left, bottom - top),
-    )
+    Rectangle::new(Point::new(left, top), Size::new(right - left, bottom - top))
 }
 
 fn clamped_position(cursor: mouse::Cursor, bounds: Rectangle) -> Option<Point> {

tests/file_transfer_loopback.rs

@@ -21,7 +21,7 @@ use iroh::endpoint::presets;
 use iroh::protocol::Router;
 use iroh::{Endpoint, RelayMode};
 
-use peerspeak::files::{ChatAttachment, AttachmentKind};
+use peerspeak::files::{AttachmentKind, ChatAttachment};
 use peerspeak::network::NetworkTransport;
 use peerspeak::network::iroh_impl::{FileRouter, IrohTransport};
 use peerspeak::protocol::FILES_ALPN;
@@ -52,7 +52,12 @@ async fn spawn_node() -> Node {
         .accept(FILES_ALPN, file_router)
         .spawn();
 
-    Node { endpoint, transport, _router: router, lookup }
+    Node {
+        endpoint,
+        transport,
+        _router: router,
+        lookup,
+    }
 }
 
 /// A pseudo-random-ish multi-megabyte payload spanning many QUIC packets, so a
@@ -86,7 +91,9 @@ async fn loopback_attachment_round_trips_intact() {
 
     let blob = big_blob();
     let id = [42u8; 32];
-    server.transport.serve_attachment(id, Arc::new(blob.clone()));
+    server
+        .transport
+        .serve_attachment(id, Arc::new(blob.clone()));
 
     let att = ChatAttachment {
         name: "exterior-landscape.jpg".to_string(),

tests/reconnect_eviction.rs

@@ -62,7 +62,7 @@ async fn evicted_within(
             Ok(Some(UiEvent::PeerConnectionFailed { id })) if id == peer => return true,
             Ok(Some(_)) => continue, // ignore PeerConnecting / PeerConnected / PeerLeft
             Ok(None) => return false, // channel closed
-            Err(_) => return false,   // timed out — no eviction
+            Err(_) => return false,  // timed out — no eviction
         }
     }
 }
@@ -80,7 +80,7 @@ async fn left_within(
             Ok(Some(UiEvent::PeerLeft { id })) if id == peer => return true,
             Ok(Some(_)) => continue, // ignore PeerConnecting / PeerConnected
             Ok(None) => return false, // channel closed
-            Err(_) => return false,   // timed out — no leave
+            Err(_) => return false,  // timed out — no leave
         }
     }
 }

tests/transport_loopback.rs

@@ -23,8 +23,8 @@ use iroh::protocol::{AcceptError, ProtocolHandler};
 use peerspeak::codec::AudioEncoder;
 use peerspeak::codec::opus_impl::OpusEncoder;
 use peerspeak::core::jitter::{FRAME_SAMPLES, JitterBuffer};
-use peerspeak::network::{ConnEvent, NetworkTransport};
 use peerspeak::network::iroh_impl::{AudioRouter, IrohTransport};
+use peerspeak::network::{ConnEvent, NetworkTransport};
 use peerspeak::protocol::AUDIO_ALPN;
 
 struct Node {
@@ -91,7 +91,12 @@ async fn spawn_capture_peer(secret: iroh::SecretKey) -> CapturePeer {
         .accept(AUDIO_ALPN, CaptureProtocol { conns_tx })
         .spawn();
 
-    CapturePeer { endpoint, _router: router, lookup, conns_rx }
+    CapturePeer {
+        endpoint,
+        _router: router,
+        lookup,
+        conns_rx,
+    }
 }
 
 /// Spawn a node with a specific secret key. Reusing a key gives the respawned
@@ -208,7 +213,11 @@ async fn loopback_sequenced_audio_reaches_peer_and_decodes() {
         received += 1;
 
         if let Some(frame) = jitter.pop_frame() {
-            assert_eq!(frame.len(), FRAME_SAMPLES, "decoded frame is one 20ms frame");
+            assert_eq!(
+                frame.len(),
+                FRAME_SAMPLES,
+                "decoded frame is one 20ms frame"
+            );
             decoded_frames += 1;
         }
         if received >= N {
@@ -235,6 +244,71 @@ async fn loopback_sequenced_audio_reaches_peer_and_decodes() {
     );
 }
 
+/// Connection transparency: over a real loopback link, `connection_stats()`
+/// must report the peer's selected path as direct (relay disabled here), with
+/// an IP remote address and counters that advance while audio flows — and the
+/// `connstats::derive` seam must turn two such snapshots into badge info with
+/// live rates.
+#[tokio::test]
+async fn connection_stats_report_a_direct_path_with_live_counters() {
+    let a = spawn_node().await;
+    let b = spawn_node().await;
+
+    a.lookup.add_endpoint_info(b.endpoint.addr());
+    b.lookup.add_endpoint_info(a.endpoint.addr());
+
+    let a_id = a.endpoint.id();
+    let b_id = b.endpoint.id();
+    a.transport.admit_audio_sender(b_id);
+    b.transport.admit_audio_sender(a_id);
+
+    // Keep B's receive path subscribed like production (drained implicitly).
+    let _b_rx = b.transport.receive_datagrams().await.expect("subscribe B");
+
+    a.transport.connect_peer(b.endpoint.addr()).await;
+    b.transport.connect_peer(a.endpoint.addr()).await;
+    tokio::time::sleep(Duration::from_millis(500)).await;
+
+    let snap = |stats: Vec<(iroh::EndpointId, peerspeak::network::PathSnapshot)>| {
+        stats
+            .into_iter()
+            .find(|(id, _)| *id == b_id)
+            .map(|(_, s)| s)
+            .expect("peer B should appear in A's connection stats")
+    };
+    let s1 = snap(a.transport.connection_stats());
+    assert!(!s1.is_relay, "loopback with relay disabled must be direct");
+    assert!(
+        s1.remote_addr.parse::<std::net::SocketAddr>().is_ok(),
+        "direct path address should be ip:port, got {}",
+        s1.remote_addr
+    );
+
+    // Stream real audio so the path counters move.
+    let mut enc = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
+    for seq in 0..25u32 {
+        a.transport.broadcast(packet(&mut enc, seq));
+        tokio::time::sleep(Duration::from_millis(5)).await;
+    }
+
+    let s2 = snap(a.transport.connection_stats());
+    assert!(s2.tx_bytes > s1.tx_bytes, "sent bytes should advance");
+    assert!(
+        s2.tx_datagrams > s1.tx_datagrams,
+        "sent datagrams should advance"
+    );
+
+    // The derivation seam turns the two snapshots into live badge info.
+    let info = peerspeak::core::connstats::derive(Some(&s1), &s2, Duration::from_millis(200));
+    assert!(!info.relay);
+    assert_eq!(info.remote_addr, s2.remote_addr);
+    assert!(info.rtt_ms < 1000, "localhost RTT should be sane");
+    assert!(
+        info.up_kbps.expect("same path + positive window has a rate") > 0.0,
+        "audio was flowing, so the upstream rate must be non-zero"
+    );
+}
+
 /// Read datagrams off a raw connection until `target` arrive or the deadline
 /// passes, asserting each carries the 4-byte sequence header.
 async fn count_audio(conn: &Connection, target: u32, deadline: tokio::time::Instant) -> u32 {
@@ -290,7 +364,11 @@ async fn dialer_reconnects_after_link_drops() {
         .expect("timed out awaiting initial connection")
         .expect("connection channel closed");
     assert!(
-        await_reconnect(&mut conn_events, tokio::time::Instant::now() + Duration::from_secs(10)).await,
+        await_reconnect(
+            &mut conn_events,
+            tokio::time::Instant::now() + Duration::from_secs(10)
+        )
+        .await,
         "initial link should report Connecting then Connected"
     );
 
@@ -306,7 +384,11 @@ async fn dialer_reconnects_after_link_drops() {
         .expect("timed out awaiting reconnect")
         .expect("connection channel closed");
     assert!(
-        await_reconnect(&mut conn_events, tokio::time::Instant::now() + Duration::from_secs(15)).await,
+        await_reconnect(
+            &mut conn_events,
+            tokio::time::Instant::now() + Duration::from_secs(15)
+        )
+        .await,
         "dropped link should report Connecting (down) then Connected (recovered)"
     );
 
@@ -319,7 +401,12 @@ async fn dialer_reconnects_after_link_drops() {
         tokio::time::sleep(Duration::from_millis(5)).await;
     }
 
-    let received = count_audio(&conn2, 25, tokio::time::Instant::now() + Duration::from_secs(3)).await;
+    let received = count_audio(
+        &conn2,
+        25,
+        tokio::time::Instant::now() + Duration::from_secs(3),
+    )
+    .await;
     assert!(
         received >= 20,
         "audio should resume after reconnect; got {received} frames"
@@ -359,7 +446,11 @@ async fn dialer_reports_left_on_graceful_close() {
         .expect("timed out awaiting initial connection")
         .expect("connection channel closed");
     assert!(
-        await_reconnect(&mut conn_events, tokio::time::Instant::now() + Duration::from_secs(10)).await,
+        await_reconnect(
+            &mut conn_events,
+            tokio::time::Instant::now() + Duration::from_secs(10)
+        )
+        .await,
         "initial link should report Connecting then Connected"
     );
 
@@ -384,7 +475,10 @@ async fn dialer_reports_left_on_graceful_close() {
 
     // And no re-dial reaches the peer within a short window.
     let redial = tokio::time::timeout(Duration::from_secs(2), peer.conns_rx.recv()).await;
-    assert!(redial.is_err(), "supervisor must not re-dial after a graceful leave");
+    assert!(
+        redial.is_err(),
+        "supervisor must not re-dial after a graceful leave"
+    );
 }
 
 #[tokio::test]
@@ -429,7 +523,11 @@ async fn dialer_connects_and_reconnects_without_an_address_lookup() {
         .expect("timed out awaiting initial connection (retained address path)")
         .expect("connection channel closed");
     assert!(
-        await_reconnect(&mut conn_events, tokio::time::Instant::now() + Duration::from_secs(10)).await,
+        await_reconnect(
+            &mut conn_events,
+            tokio::time::Instant::now() + Duration::from_secs(10)
+        )
+        .await,
         "initial link should report Connecting then Connected"
     );
 
@@ -443,7 +541,11 @@ async fn dialer_connects_and_reconnects_without_an_address_lookup() {
         .expect("timed out awaiting reconnect (retained address path)")
         .expect("connection channel closed");
     assert!(
-        await_reconnect(&mut conn_events, tokio::time::Instant::now() + Duration::from_secs(15)).await,
+        await_reconnect(
+            &mut conn_events,
+            tokio::time::Instant::now() + Duration::from_secs(15)
+        )
+        .await,
         "reconnect should report Connecting then Connected with no lookup at all"
     );
 
@@ -455,7 +557,12 @@ async fn dialer_connects_and_reconnects_without_an_address_lookup() {
         tokio::time::sleep(Duration::from_millis(5)).await;
     }
 
-    let received = count_audio(&conn2, 25, tokio::time::Instant::now() + Duration::from_secs(3)).await;
+    let received = count_audio(
+        &conn2,
+        25,
+        tokio::time::Instant::now() + Duration::from_secs(3),
+    )
+    .await;
     assert!(
         received >= 20,
         "audio should resume after reconnecting via the retained address; got {received} frames"