audio(win): filter choose_config to drivable formats (Codex B3/B5 re-review P3)

Codex's xhigh re-review of 306bc29 confirmed B3 sound and bounded_rate correct (no P1/P2), and caught one real P3: choose_config ranked supported config ranges by sample rate + channel count only, but the stream builders accept just F32/I16/U16 — cpal can also expose U8/I8/I32/U32/I64/U64/F64. An unsupported-format range (or a zero-channel range) could therefore out- rank a usable one, win selection, and then hard-fail in setup()'s `other => Err(unsupported sample format)` arm without trying another candidate. This was latent in the exact-48 kHz path too, not only B5's bounded case 3. Fix: a pure `format_supported` predicate + `usable_range` (nonzero channels AND a drivable format), applied as a filter in BOTH the exact-48 kHz `pick` and the bounded `pick_bounded`, so an undrivable range is never ranked. A zero-channel range can no longer be logged as "using bounded …" and then rejected by resolve. +1 unit test enumerating every cpal SampleFormat. Verified: windows-gnu cargo check --release --lib --tests --bins clean, no warnings; Linux paths untouched (cfg(windows)). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
audio(win): land the deferred cpal start-resilience items (B3 + B5)
2026-06-19 16:54:26 -04:00 · 2026-06-19 16:48:07 -04:00 · 2026-06-19 16:27:35 -04:00 · 2026-06-19 16:15:49 -04:00 · 2026-06-19 15:57:35 -04:00 · 2026-06-19 04:56:01 -04:00
27 changed files with 4349 additions and 556 deletions
@@ -0,0 +1,34 @@
+name: cargo-deny
+
+# Enforce the supply-chain policy in deny.toml (advisories / bans / licenses /
+# sources) on every push to main and every PR. Runs on a *locked* tree so the
+# pinned, vetted versions in Cargo.lock are exactly what get audited — see the
+# deny.toml header and VERSIONING.md. A new poisoned release of a dependency
+# cannot reach CI until Cargo.lock is deliberately updated.
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  cargo-deny:
+    runs-on: ubuntu-latest
+    # rust:1 provides the cargo toolchain that cargo-deny shells out to for
+    # `cargo metadata`. Adjust the runner label if your act_runner uses a
+    # different one.
+    container: rust:1
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install cargo-deny (pinned prebuilt)
+        run: |
+          set -euo pipefail
+          version=0.19.9
+          curl -sSfL \
+            "https://github.com/EmbarkStudios/cargo-deny/releases/download/${version}/cargo-deny-${version}-x86_64-unknown-linux-musl.tar.gz" \
+            | tar -xz -C /usr/local/bin --strip-components=1 --wildcards '*/cargo-deny'
+          cargo-deny --version
+
+      - name: cargo deny check
+        run: cargo deny --locked check
@@ -0,0 +1,85 @@
+name: windows-build
+
+# Milestone M1 of the Windows port (see docs/handoff windows-migration-plan):
+# prove the tree compiles for `x86_64-pc-windows-msvc` and the unit tests pass.
+# The audio backend is the Phase 0 `CpalBackend` stub for now — this job guards
+# the *compile* boundary (cfg gating, platform deps, the PlatformAudioBackend
+# alias) so a Unix-only assumption can't sneak back in and break Windows.
+#
+# RUNNER REQUIREMENT: this needs a Windows act_runner registered with the
+# `windows-latest` label (the Linux `cargo-deny` job's container approach does
+# NOT apply here — Windows jobs run on the host, not a Linux container). If your
+# runner advertises a different label, change `runs-on` below. Until a Windows
+# runner exists this workflow is simply skipped/queued, not a failure of the
+# Linux CI.
+#
+# BUILD-HOST REQUIREMENTS (validated by the opus spike, see
+# peerspeak-windows-opus-spike.md):
+#   - MSVC C toolchain (Visual Studio Build Tools) — to compile vendored libopus.
+#   - CMake on PATH — `audiopus_sys` builds libopus from source via cmake.
+#   - CMAKE_POLICY_VERSION_MINIMUM=3.5 (set below) — the vendored libopus declares
+#     an ancient `cmake_minimum_required` that CMake >= 4.0 refuses without it.
+# GitHub-hosted `windows-latest` images ship MSVC + CMake; a self-hosted runner
+# must provide both.
+
+on:
+  push:
+    # `main` plus the in-progress port branches, so the Windows path is exercised
+    # before merge rather than only after.
+    branches: [main, "windows-port-**"]
+  pull_request:
+  # Allow manual runs from the Gitea Actions UI.
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+env:
+  CARGO_TERM_COLOR: always
+  # The vendored libopus (audiopus_sys -> cmake) uses cmake_minimum_required < 3.5,
+  # which CMake 4.x rejects unless this is set. See the opus spike report.
+  CMAKE_POLICY_VERSION_MINIMUM: "3.5"
+
+jobs:
+  windows-build:
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust (MSVC, pinned to repo toolchain if present)
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: x86_64-pc-windows-msvc
+          components: clippy
+
+      - name: Show toolchain + build prerequisites
+        shell: bash
+        run: |
+          set -euo pipefail
+          rustc --version
+          cargo --version
+          # libopus is built from source via cmake; fail early with a clear
+          # message if the runner lacks it rather than deep in the opus build.
+          if ! command -v cmake >/dev/null 2>&1; then
+            echo "::error::cmake not found on PATH. The opus crate builds libopus from source via cmake; install CMake on this runner."
+            exit 1
+          fi
+          cmake --version
+
+      # Build on a *locked* tree so the pinned, vetted Cargo.lock versions are what
+      # get compiled — same supply-chain stance as the cargo-deny job.
+      - name: Build (all targets, msvc)
+        run: cargo build --all-targets --locked --target x86_64-pc-windows-msvc
+
+      # Unit (lib) tests only: the `transport_loopback` integration tests stand up
+      # real iroh/QUIC endpoints and need working loopback networking, which isn't
+      # guaranteed on a CI runner. Add `--tests` here once a networked Windows
+      # runner is confirmed.
+      - name: Unit tests (lib, msvc)
+        run: cargo test --lib --locked --target x86_64-pc-windows-msvc
+
+      # Informational for now (not `-D warnings`): the Windows tree may surface
+      # platform-specific lints we haven't triaged. Tighten to deny-warnings once
+      # it's clean.
+      - name: Clippy (msvc)
+        run: cargo clippy --all-targets --locked --target x86_64-pc-windows-msvc
@@ -105,6 +105,28 @@ version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"

+[[package]]
+name = "alsa"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed7572b7ba83a31e20d1b48970ee402d2e3e0537dcfe0a3ff4d6eb7508617d43"
+dependencies = [
+ "alsa-sys",
+ "bitflags 2.11.1",
+ "cfg-if",
+ "libc",
+]
+
+[[package]]
+name = "alsa-sys"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db8fee663d06c4e303404ef5f40488a53e062f89ba8bfed81f42325aafad1527"
+dependencies = [
+ "libc",
+ "pkg-config",
+]
+
 [[package]]
 name = "android-activity"
 version = "0.6.1"
@@ -114,12 +136,12 @@ dependencies = [
 "android-properties",
 "bitflags 2.11.1",
 "cc",
- "jni",
+ "jni 0.22.4",
 "libc",
 "log",
- "ndk",
+ "ndk 0.9.0",
 "ndk-context",
- "ndk-sys",
+ "ndk-sys 0.6.0+11769913",
 "num_enum",
 "thiserror 2.0.18",
 ]
@@ -712,6 +734,12 @@ dependencies = [
 "shlex",
 ]

+[[package]]
+name = "cesu8"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6d43a04d8753f35258c91f8ec639f792891f748a1edbd759cf1dcea3382ad83c"
+
 [[package]]
 name = "cexpr"
 version = "0.6.0"
@@ -1002,6 +1030,26 @@ dependencies = [
 "libm",
 ]

+[[package]]
+name = "coreaudio-rs"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "321077172d79c662f64f5071a03120748d5bb652f5231570141be24cfcd2bace"
+dependencies = [
+ "bitflags 1.3.2",
+ "core-foundation-sys",
+ "coreaudio-sys",
+]
+
+[[package]]
+name = "coreaudio-sys"
+version = "0.2.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9b4739a805a62757a83e5654fa3faabec0442666b263bb2287d5a8185bfd953"
+dependencies = [
+ "bindgen",
+]
+
 [[package]]
 name = "cosmic-text"
 version = "0.15.0"
@@ -1026,6 +1074,29 @@ dependencies = [
 "unicode-segmentation",
 ]

+[[package]]
+name = "cpal"
+version = "0.15.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "873dab07c8f743075e57f524c583985fbaf745602acbe916a01539364369a779"
+dependencies = [
+ "alsa",
+ "core-foundation-sys",
+ "coreaudio-rs",
+ "dasp_sample",
+ "jni 0.21.1",
+ "js-sys",
+ "libc",
+ "mach2",
+ "ndk 0.8.0",
+ "ndk-context",
+ "oboe",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "web-sys",
+ "windows 0.54.0",
+]
+
 [[package]]
 name = "cpufeatures"
 version = "0.2.17"
@@ -1228,6 +1299,12 @@ dependencies = [
 "syn",
 ]

+[[package]]
+name = "dasp_sample"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c87e182de0887fd5361989c677c4e8f5000cd9491d6d563161a8f3a5519fc7f"
+
 [[package]]
 name = "data-encoding"
 version = "2.11.0"
@@ -2227,7 +2304,7 @@ dependencies = [
 "http",
 "idna",
 "ipnet",
- "jni",
+ "jni 0.22.4",
 "rand 0.10.1",
 "rustls",
 "thiserror 2.0.18",
@@ -2247,7 +2324,7 @@ dependencies = [
 "data-encoding",
 "idna",
 "ipnet",
- "jni",
+ "jni 0.22.4",
 "once_cell",
 "prefix-trie",
 "rand 0.10.1",
@@ -2270,7 +2347,7 @@ dependencies = [
 "hickory-proto",
 "ipconfig",
 "ipnet",
- "jni",
+ "jni 0.22.4",
 "moka",
 "ndk-context",
 "once_cell",
@@ -3102,6 +3179,22 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"

+[[package]]
+name = "jni"
+version = "0.21.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a87aa2bb7d2af34197c04845522473242e1aa17c12f4935d5856491a7fb8c97"
+dependencies = [
+ "cesu8",
+ "cfg-if",
+ "combine",
+ "jni-sys 0.3.1",
+ "log",
+ "thiserror 1.0.69",
+ "walkdir",
+ "windows-sys 0.45.0",
+]
+
 [[package]]
 name = "jni"
 version = "0.22.4"
@@ -3463,6 +3556,15 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3d25b0e0b648a86960ac23b7ad4abb9717601dec6f66c165f5b037f3f03065f"

+[[package]]
+name = "mach2"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d640282b302c0bb0a2a8e0233ead9035e3bed871f0b7e81fe4a1ec829765db44"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "malloc_buf"
 version = "0.0.6"
@@ -3596,7 +3698,7 @@ dependencies = [
 "dispatch",
 "futures-channel",
 "futures-lite",
- "jni",
+ "jni 0.22.4",
 "ndk-context",
 "objc2 0.6.4",
 "objc2-app-kit 0.3.2",
@@ -3695,6 +3797,20 @@ dependencies = [
 "unicode-ident",
 ]

+[[package]]
+name = "ndk"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2076a31b7010b17a38c01907c45b945e8f11495ee4dd588309718901b1f7a5b7"
+dependencies = [
+ "bitflags 2.11.1",
+ "jni-sys 0.3.1",
+ "log",
+ "ndk-sys 0.5.0+25.2.9519653",
+ "num_enum",
+ "thiserror 1.0.69",
+]
+
 [[package]]
 name = "ndk"
 version = "0.9.0"
@@ -3704,7 +3820,7 @@ dependencies = [
 "bitflags 2.11.1",
 "jni-sys 0.3.1",
 "log",
- "ndk-sys",
+ "ndk-sys 0.6.0+11769913",
 "num_enum",
 "raw-window-handle",
 "thiserror 1.0.69",
@@ -3716,6 +3832,15 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "27b02d87554356db9e9a873add8782d4ea6e3e58ea071a9adb9a2e8ddb884a8b"

+[[package]]
+name = "ndk-sys"
+version = "0.5.0+25.2.9519653"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8c196769dd60fd4f363e11d948139556a344e79d451aeb2fa2fd040738ef7691"
+dependencies = [
+ "jni-sys 0.3.1",
+]
+
 [[package]]
 name = "ndk-sys"
 version = "0.6.0+11769913"
@@ -4466,6 +4591,29 @@ dependencies = [
 "objc2-foundation 0.2.2",
 ]

+[[package]]
+name = "oboe"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e8b61bebd49e5d43f5f8cc7ee2891c16e0f41ec7954d36bcb6c14c5e0de867fb"
+dependencies = [
+ "jni 0.21.1",
+ "ndk 0.8.0",
+ "ndk-context",
+ "num-derive",
+ "num-traits",
+ "oboe-sys",
+]
+
+[[package]]
+name = "oboe-sys"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c8bb09a4a2b1d668170cfe0a7d5bc103f8999fb316c98099b6a9939c9f2e79d"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.21.4"
@@ -4594,12 +4742,13 @@ checksum = "35fb2e5f958ec131621fdd531e9fc186ed768cbe395337403ae56c17a74c68ec"

 [[package]]
 name = "peerspeak"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
 "anyhow",
 "async-trait",
 "base64",
 "bytes",
+ "cpal",
 "dirs",
 "iced",
 "image",
@@ -5436,7 +5585,7 @@ checksum = "26d1e2536ce4f35f4846aa13bff16bd0ff40157cdb14cc056c7b14ba41233ba0"
 dependencies = [
 "core-foundation 0.10.1",
 "core-foundation-sys",
- "jni",
+ "jni 0.22.4",
 "log",
 "once_cell",
 "rustls",
@@ -5877,7 +6026,7 @@ dependencies = [
 "fastrand",
 "js-sys",
 "memmap2",
- "ndk",
+ "ndk 0.9.0",
 "objc2 0.6.4",
 "objc2-core-foundation",
 "objc2-core-graphics",
@@ -7162,7 +7311,7 @@ dependencies = [
 "log",
 "metal",
 "naga",
- "ndk-sys",
+ "ndk-sys 0.6.0+11769913",
 "objc",
 "once_cell",
 "ordered-float",
@@ -7247,6 +7396,16 @@ dependencies = [
 "thiserror 2.0.18",
 ]

+[[package]]
+name = "windows"
+version = "0.54.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9252e5725dbed82865af151df558e754e4a3c2c30818359eb17465f1346a1b49"
+dependencies = [
+ "windows-core 0.54.0",
+ "windows-targets 0.52.6",
+]
+
 [[package]]
 name = "windows"
 version = "0.58.0"
@@ -7254,7 +7413,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd04d41d93c4992d421894c18c8b43496aa748dd4c081bac0dc93eb0489272b6"
 dependencies = [
 "windows-core 0.58.0",
- "windows-targets",
+ "windows-targets 0.52.6",
 ]

 [[package]]
@@ -7278,6 +7437,16 @@ dependencies = [
 "windows-core 0.62.2",
 ]

+[[package]]
+name = "windows-core"
+version = "0.54.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "12661b9c89351d684a50a8a643ce5f608e20243b9fb84687800163429f161d65"
+dependencies = [
+ "windows-result 0.1.2",
+ "windows-targets 0.52.6",
+]
+
 [[package]]
 name = "windows-core"
 version = "0.58.0"
@@ -7288,7 +7457,7 @@ dependencies = [
 "windows-interface 0.58.0",
 "windows-result 0.2.0",
 "windows-strings 0.1.0",
- "windows-targets",
+ "windows-targets 0.52.6",
 ]

 [[package]]
@@ -7386,13 +7555,22 @@ dependencies = [
 "windows-strings 0.5.1",
 ]

+[[package]]
+name = "windows-result"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e383302e8ec8515204254685643de10811af0ed97ea37210dc26fb0032647f8"
+dependencies = [
+ "windows-targets 0.52.6",
+]
+
 [[package]]
 name = "windows-result"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1d1043d8214f791817bab27572aaa8af63732e11bf84aa21a45a78d6c317ae0e"
 dependencies = [
- "windows-targets",
+ "windows-targets 0.52.6",
 ]

 [[package]]
@@ -7411,7 +7589,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4cd9b125c486025df0eabcb585e62173c6c9eddcec5d117d3b6e8c30e2ee4d10"
 dependencies = [
 "windows-result 0.2.0",
- "windows-targets",
+ "windows-targets 0.52.6",
 ]

 [[package]]
@@ -7423,13 +7601,22 @@ dependencies = [
 "windows-link",
 ]

+[[package]]
+name = "windows-sys"
+version = "0.45.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75283be5efb2831d37ea142365f009c02ec203cd29a3ebecbc093d52315b66d0"
+dependencies = [
+ "windows-targets 0.42.2",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets",
+ "windows-targets 0.52.6",
 ]

 [[package]]
@@ -7441,20 +7628,35 @@ dependencies = [
 "windows-link",
 ]

+[[package]]
+name = "windows-targets"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e5180c00cd44c9b1c88adb3693291f1cd93605ded80c250a75d472756b4d071"
+dependencies = [
+ "windows_aarch64_gnullvm 0.42.2",
+ "windows_aarch64_msvc 0.42.2",
+ "windows_i686_gnu 0.42.2",
+ "windows_i686_msvc 0.42.2",
+ "windows_x86_64_gnu 0.42.2",
+ "windows_x86_64_gnullvm 0.42.2",
+ "windows_x86_64_msvc 0.42.2",
+]
+
 [[package]]
 name = "windows-targets"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
+ "windows_aarch64_gnullvm 0.52.6",
+ "windows_aarch64_msvc 0.52.6",
+ "windows_i686_gnu 0.52.6",
 "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows_i686_msvc 0.52.6",
+ "windows_x86_64_gnu 0.52.6",
+ "windows_x86_64_gnullvm 0.52.6",
+ "windows_x86_64_msvc 0.52.6",
 ]

 [[package]]
@@ -7466,18 +7668,36 @@ dependencies = [
 "windows-link",
 ]

+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "597a5118570b68bc08d8d59125332c54f1ba9d9adeedeef5b99b02ba2b0698f8"
+
 [[package]]
 name = "windows_aarch64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"

+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e08e8864a60f06ef0d0ff4ba04124db8b0fb3be5776a5cd47641e942e58c4d43"
+
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"

+[[package]]
+name = "windows_i686_gnu"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c61d927d8da41da96a81f029489353e68739737d3beca43145c8afec9a31a84f"
+
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
@@ -7490,24 +7710,48 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"

+[[package]]
+name = "windows_i686_msvc"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "44d840b6ec649f480a41c8d80f9c65108b92d89345dd94027bfe06ac444d1060"
+
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"

+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8de912b8b8feb55c064867cf047dda097f92d51efad5b491dfb98f6bbb70cb36"
+
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"

+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "26d41b46a36d453748aedef1486d5c7a85db22e56aff34643984ea85514e94a3"
+
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"

+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.42.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9aec5da331524158c6d1a4ac0ab1541149c0b9505fde06423b02f5ef0106b9f0"
+
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
@@ -7536,7 +7780,7 @@ dependencies = [
 "js-sys",
 "libc",
 "memmap2",
- "ndk",
+ "ndk 0.9.0",
 "objc2 0.5.2",
 "objc2-app-kit 0.2.2",
 "objc2-foundation 0.2.2",
@@ -1,7 +1,10 @@
 [package]
 name = "peerspeak"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2024"
+# Application crate, not a crates.io library — refuse `cargo publish` and let
+# cargo-deny's [licenses.private] skip the missing-license check.
+publish = false

 [lib]
 name = "peerspeak"
@@ -27,17 +30,12 @@ bytes = "1.11.1"
 dirs = "6.0.0"
 iced = { version = "0.14.0", features = ["canvas", "image"] }
 # W4 custom avatars: decode/resize an arbitrary user image (png/jpeg only to keep
-# the codec surface small) and a native file picker (xdg-portal backend, no GTK).
+# the codec surface small). The matching native file picker (`rfd`) is platform-
+# gated below — its backend differs per OS (xdg-portal on Linux, Win32 on Windows).
 image = { version = "0.25", default-features = false, features = ["png", "jpeg"] }
-rfd = { version = "0.17", default-features = false, features = ["xdg-portal"] }
 iroh = "1.0.0-rc.0"
 iroh-gossip = "0.99.0"
 opus = "0.3.1"
-# v0_3_49 exposes `Buffer::requested()` (the graph's per-cycle quantum), used by
-# the playback RT callback to fill exactly what the device asks for instead of
-# pinning the buffer to a hard-coded 1024-frame quantum (crackle on non-1024
-# hardware). The field has existed in libpipewire since 0.3.49 (2022).
-pipewire = { version = "0.9", features = ["v0_3_49"] }
 rand = "0.10.1"
 ringbuf = "0.5.0"
 serde = { version = "1.0.228", features = ["derive"] }
@@ -45,3 +43,24 @@ serde_json = "1.0.150"
 thiserror = "2.0.18"
 tokio = { version = "1.52.3", features = ["full"] }
 tokio-stream = "0.1.18"
+
+# --- Platform-specific dependencies -----------------------------------------
+# Audio and the native file-picker backends differ per OS. Everything else in the
+# app talks to the `AudioBackend` trait and the `PlatformAudioBackend` alias (see
+# `src/audio/mod.rs`), so platform selection is confined to these few lines.
+
+[target.'cfg(target_os = "linux")'.dependencies]
+# Linux audio backend. v0_3_49 exposes `Buffer::requested()` (the graph's per-cycle
+# quantum), used by the playback RT callback to fill exactly what the device asks
+# for instead of a hard-coded 1024-frame quantum (crackle on non-1024 hardware).
+# The field has existed in libpipewire since 0.3.49 (2022).
+pipewire = { version = "0.9", features = ["v0_3_49"] }
+# Native file picker via the XDG desktop portal (no GTK) on Linux.
+rfd = { version = "0.17", default-features = false, features = ["xdg-portal"] }
+
+[target.'cfg(windows)'.dependencies]
+# Native file picker using the built-in Win32 dialog backend on Windows.
+rfd = { version = "0.17", default-features = false }
+# Windows audio backend: cpal drives WASAPI for capture/playback behind the
+# AudioBackend trait (src/audio/cpal_impl.rs). The Linux counterpart is pipewire.
+cpal = "0.15"
@@ -0,0 +1,51 @@
+# Security Review: `security-scan` branch (PeerSpeak)
+
+_Date: 2026-06-18_
+
+**Scope:** Protocol-versioning migration (`src/protocol.rs`, `versioned_topic`,
+ALPN/domain centralization, gossip topic namespacing) and the `deny.toml`
+supply-chain policy addition.
+
+## Result: No high-confidence security vulnerabilities found.
+
+Each plausible attack surface introduced by this branch was investigated and
+confirmed safe:
+
+### 1. `versioned_topic` XOR transform — topic secrecy preserved
+`src/protocol.rs:46`, used at `src/network/gossip.rs:255`
+
+The room `topic_id` is a uniformly random 32-byte secret (`rand::random()`,
+`src/core/mod.rs:1012`) acting as the room capability. XOR-ing it with the public
+constant `GOSSIP_PROTO.to_le_bytes()` cyclically is **bijective and
+entropy-preserving** — the result is still uniformly random; no byte becomes
+predictable and no entropy is lost. The room secret is no more recoverable by an
+observer than before the change (previously the raw `topic_id` was the on-wire
+topic; now it's a trivial public XOR of it). Bijectivity also preserves room
+distinctness, so isolation is not weakened. **Not a vulnerability.**
+
+### 2. Signature topic-binding — no raw/versioned confusion
+`src/network/gossip.rs`
+
+`active_topic_bytes` stores the **raw** `ticket.topic_id` (line 293), and both
+`sign_gossip` and `verify_gossip` bind against that raw value. Only the
+*subscribed* swarm topic (line 255) uses the versioned value. There is one swarm
+per join and every peer signs/verifies against the same raw topic, so no second
+topic exists to enable a raw↔versioned replay/confusion attack. Code matches
+VERSIONING.md's claim. **Not a vulnerability.**
+
+### 3. `GOSSIP_SIG_DOMAIN` — moved verbatim
+Value identical (`"peerspeak-gossip-v1"`, `src/protocol.rs:34`); cross-version
+cryptographic domain separation preserved. **Not a vulnerability.**
+
+### 4. ALPN changes — handshake compatibility only
+Audio `peerspeak-audio` → `peerspeak/audio/1`, friends `/0` → `/1`. No security
+check keys off the old ALPN strings (audio admission is gated by live room
+membership per S8, not the ALPN literal); no residual references to old strings
+in non-test code. **Not a vulnerability.**
+
+### 5. `deny.toml`
+Ignores only two *unmaintained* advisories (`RUSTSEC-2024-0436`,
+`RUSTSEC-2026-0150`) on compile-time/FFI-only crates — documented, and dependency
+advisories are out of scope. **Not a vulnerability.**
+
+The versioning migration is a clean, security-preserving change.
@@ -0,0 +1,139 @@
+# PeerSpeak Versioning Standard
+
+PeerSpeak is a full-mesh P2P voice app. Its "API contract" is not a library
+surface — it is the **wire protocol** two nodes use to talk. So versioning here
+tracks one question above all others:
+
+> **Can a node on build X talk to a node on build Y?**
+
+There are two distinct version layers. Keep them straight.
+
+---
+
+## Layer 1 — Release version (`Cargo.toml`)
+
+The human-facing label you put on a build ("install this one").
+
+**Scheme: SemVer, pre-1.0 (`0.MINOR.PATCH`).**
+
+While we are pre-1.0 (friends-only, no stability promise yet):
+
+| Change | Bump | Example |
+| --- | --- | --- |
+| **Breaking wire/protocol change** — peers on the old build can no longer interoperate; *everyone must update* | **MINOR** | `0.4.2 → 0.5.0` |
+| Compatible change — bug fix, internal refactor, or a feature that does **not** change the wire (UI, local-only behavior, additive logic that old peers ignore safely) | **PATCH** | `0.4.2 → 0.4.3` |
+
+- **Reaching `1.0.0`:** when PeerSpeak is first shared beyond the trusted-friends
+  circle (a "public" release), and we are willing to commit to wire stability.
+  After 1.0, MAJOR = wire break, MINOR = compatible feature, PATCH = fix (normal
+  SemVer).
+- Bump `version` in `Cargo.toml` as part of the change that warrants it, in the
+  same commit. The number in `Cargo.toml` is the source of truth; surface it in
+  the UI (e.g. an About/Settings line) so a user can read their build.
+
+**Rule of thumb:** if you find yourself writing "all peers must rebuild" or
+"breaking gossip wire change" in a commit message (as S2 and W4 did), that is a
+**MINOR** bump, and it must also bump the relevant protocol version in Layer 2.
+
+---
+
+## Layer 2 — Protocol compatibility (the one that actually breaks calls)
+
+Wire incompatibility must **fail fast and legibly** — never as a silent
+signature/decode error that looks like a bug or an attack. We achieve this by
+embedding a protocol version into each transport plane, so incompatible peers
+are rejected at connect/subscribe time instead of mid-conversation.
+
+PeerSpeak has **three independent planes**, each versioned **separately** — bump
+only the plane whose wire format actually changed (audio rarely changes; gossip
+changes often; they must not be forced to bump together).
+
+### ALPN naming convention
+
+All peerspeak ALPNs use the form **`peerspeak/<plane>/<N>`** where `<N>` is that
+plane's protocol version (an integer, starts at `1`). iroh refuses a connection
+whose ALPN does not match exactly, so two peers on different `<N>` for a plane
+simply cannot open that connection → we map that to a clean "peer is running an
+incompatible version" instead of garbage.
+
+| Plane | ALPN / mechanism | Bump when… |
+| --- | --- | --- |
+| **Audio** | ALPN `peerspeak/audio/<N>` | the Opus/datagram framing, sequencing, or audio-handshake changes |
+| **Friends/presence** | ALPN `peerspeak/friends/<N>` | the `ControlMsg` / presence ping-pong shape changes |
+| **Gossip** | *(see below — cannot use a custom ALPN)* | `GossipPayload` / `GossipMessage` / `PeerState` shape, signing, or freshness rules change |
+
+### Gossip is special
+
+The gossip plane runs over **iroh-gossip's own `GOSSIP_ALPN`**, which we do not
+control, so we cannot version it via the ALPN. Instead, the gossip protocol
+version is bound in **two** places:
+
+1. **Topic namespacing (primary, fail-fast):** the room's `topic_id` is a random
+   32 bytes carried in the ticket, but the topic we actually *subscribe* to is
+   `protocol::versioned_topic(topic_id)` — a deterministic, dependency-free
+   transform that folds `GOSSIP_PROTO` into the bytes. Peers on different gossip
+   versions therefore derive **different subscription topics from the same ticket**
+   and never share a swarm — the same isolation a versioned ALPN gives the other
+   planes. The ticket format and the room identity (`topic_id`) are unchanged; only
+   the subscribed topic is namespaced. (The transform is for *isolation*, not
+   security — cryptographic separation is the signature domain below.)
+2. **Signature domain (cryptographic separation):** the signing domain string
+   (`peerspeak-gossip-v<N>`, bound into every signed payload) carries the version,
+   so two versions that somehow met on a topic would fail each other's verification
+   rather than misread it.
+
+Bumping the gossip version = bump `protocol::GOSSIP_PROTO` (drives
+`versioned_topic`) **and** `protocol::GOSSIP_SIG_DOMAIN` together (a unit test in
+`protocol.rs` asserts the domain string matches `GOSSIP_PROTO`, so they can't drift).
+
+### Single source of truth for protocol versions
+
+All protocol versions, ALPNs, the gossip signature domain, and `versioned_topic`
+live in **`src/protocol.rs`**. Every call site derives from there (e.g.
+`crate::protocol::AUDIO_ALPN`); **never hand-write an ALPN literal inline.** A
+unit test asserts each ALPN/domain string matches its integer version so a bump
+can't half-apply.
+
+---
+
+## "I changed X — what do I bump?" (quick reference)
+
+| You changed… | Layer 2 (plane version) | Layer 1 (`Cargo.toml`) |
+| --- | --- | --- |
+| Opus framing / audio datagram layout | `peerspeak/audio/N` → `N+1` | MINOR |
+| `ControlMsg` / presence shape | `peerspeak/friends/N` → `N+1` | MINOR |
+| `GossipPayload`/`PeerState`/signing | `GOSSIP_PROTO_VERSION` + sig domain → next | MINOR |
+| UI, local config, recording, a fix that doesn't touch any wire | nothing | PATCH |
+| An *additive* gossip field that old peers safely ignore | judgement call — if old peers misbehave without it, treat as breaking (MINOR + gossip bump); if truly ignorable, PATCH | PATCH or MINOR |
+
+When in doubt about "is this additive-safe?", assume **breaking** and bump. A
+false MINOR bump costs a coordinated rebuild; a false PATCH costs silent broken
+calls in the field.
+
+---
+
+## Release checklist (per build handed to anyone)
+
+1. Decide MINOR vs PATCH from the table above; bump `Cargo.toml`.
+2. If MINOR for a wire reason, confirm the matching Layer-2 plane version(s) were
+   bumped in the same change.
+3. Note the version + "breaking?" in the commit / handoff.
+4. Tag the commit (`v0.x.y`) so a given binary maps to a known commit.
+5. Rebuild **every** peer that must interoperate (e.g. dopedart, staged friend
+   releases) when the bump was a MINOR/wire break.
+
+---
+
+## Current baseline (standard adopted + migrated, 2026-06-18, `0.2.0`)
+
+- `Cargo.toml`: **`0.2.0`** — the MINOR bump for the (deliberately breaking)
+  migration to this standard. **All peers must run ≥ `0.2.0` to interoperate**
+  (the ALPNs and gossip topics changed); the pre-standard `0.1.0`-era build
+  (e.g. an un-resynced dopedart) cannot talk to a `0.2.0` peer — by design, and it
+  now fails cleanly at the handshake instead of silently.
+- Protocol versions (all at `1`): `peerspeak/audio/1`, `peerspeak/friends/1`,
+  gossip `peerspeak-gossip-v1` + `versioned_topic`. All sourced from
+  `src/protocol.rs`.
+- **Remaining nicety (not blocking):** surface `env!("CARGO_PKG_VERSION")` in the
+  UI (an About/Settings line) and/or log it at startup, so a running build is
+  self-identifying in the field. Small follow-up.
@@ -0,0 +1,88 @@
+# cargo-deny policy for peerspeak
+#
+# Supersedes a bare `cargo audit` run. Enforce with:
+#     cargo install cargo-deny --locked
+#     cargo deny check
+#
+# In CI, run `cargo deny check` on a locked tree so the pinned, vetted
+# versions in Cargo.lock are what actually get audited.
+
+# ---------------------------------------------------------------------------
+# Advisories: RustSec database. Vulnerabilities and yanked crates are denied
+# by default. The two `ignore` entries below are *unmaintained* warnings only
+# (no known exploit); they are deep transitive deps we cannot remove. Pinning
+# them via Cargo.lock is our real protection — a future malicious release does
+# not reach us until we deliberately `cargo update`, so each update is a review
+# checkpoint. Revisit these if either advisory is upgraded to a vulnerability.
+# ---------------------------------------------------------------------------
+[advisories]
+ignore = [
+    # paste: unmaintained, compile-time proc-macro only (zero runtime surface),
+    # transitive via iroh/netdev/netlink and rav1e/image/iced. Maintained fork
+    # `pastey` is already in the tree; stragglers will follow upstream.
+    "RUSTSEC-2024-0436",
+    # audiopus_sys: unmaintained FFI bindings to the stable libopus C library,
+    # pulled in via our direct `opus 0.3.1` dep. No drop-in replacement.
+    "RUSTSEC-2026-0150",
+]
+
+# ---------------------------------------------------------------------------
+# Bans: shape of the dependency graph.
+# ---------------------------------------------------------------------------
+[bans]
+# Multiple versions of the same crate bloat the build; warn rather than fail
+# since transitive graphs (iroh, iced) routinely carry duplicates we can't fix.
+multiple-versions = "warn"
+# Wildcard ("*") version requirements are a supply-chain footgun: they accept
+# any future release, defeating the lockfile-as-review-checkpoint model.
+wildcards = "deny"
+# ...but our own intra-repo path deps may use "*"; don't penalize those.
+allow-wildcard-paths = true
+
+# Crates that may never appear in the graph. Add a maintained replacement's
+# predecessor here once you've migrated off it, to prevent regressions.
+deny = []
+
+# ---------------------------------------------------------------------------
+# Sources: where crates are allowed to come from. This is the core anti-hijack
+# control — only the official crates.io registry is trusted; arbitrary git
+# sources (a common vector for slipping in unaudited code) are rejected.
+# ---------------------------------------------------------------------------
+[sources]
+unknown-registry = "deny"
+unknown-git = "deny"
+allow-registry = ["https://github.com/rust-lang/crates.io-index"]
+# allow-git = []   # add a specific, pinned git repo here only if ever needed
+
+# ---------------------------------------------------------------------------
+# Licenses: permissive set covering the current graph. If `cargo deny check`
+# reports an unmatched license, vet it and add the SPDX id here (or add a
+# per-crate entry under [licenses.exceptions]) rather than widening blindly.
+# ---------------------------------------------------------------------------
+[licenses]
+allow = [
+    "MIT",
+    "Apache-2.0",
+    "Apache-2.0 WITH LLVM-exception",
+    "BSD-2-Clause",
+    "BSD-3-Clause",
+    "ISC",
+    "Zlib",
+    "MPL-2.0",
+    "Unicode-3.0",
+    "Unicode-DFS-2016",
+    "CC0-1.0",
+    "0BSD",
+    "Unlicense",
+    "BSL-1.0",
+    "NCSA",                 # University of Illinois/NCSA — BSD-like permissive
+    "CDLA-Permissive-2.0",  # Community Data License Agreement, permissive
+]
+confidence-threshold = 0.8
+exceptions = []
+
+# peerspeak itself has no `license` field and is not published, so skip the
+# "unlicensed" check for our own (private) crate. Add a license to Cargo.toml
+# if/when this is ever published.
+[licenses.private]
+ignore = true
@@ -0,0 +1,77 @@
+# 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.
+
+## What works today
+
+| Area | Status |
+|---|---|
+| GUI | Iced/wgpu builds and renders under Wine. |
+| Networking | Iroh QUIC transport and gossip compile on Windows. |
+| Audio backend | `cpal` drives WASAPI capture/playback behind `AudioBackend`. |
+| Codec | Opus remains 48 kHz mono, 20 ms frames. |
+| Identity | `ring` identity generation/load is platform-neutral. |
+| Chimes | Windows uses PowerShell `System.Media.SoundPlayer` for WAV playback. |
+
+Windows paths are resolved through `dirs`:
+
+- Config: `%APPDATA%\peerspeak\config.json`
+- Identity: `%APPDATA%\peerspeak\identity.key`
+- Log: `%LOCALAPPDATA%\peerspeak\peerspeak.log`
+
+## Building
+
+### Native Windows
+
+Install MSVC Build Tools and CMake, then build normally:
+
+```powershell
+cargo build --release
+```
+
+If CMake is 4.x or newer, the vendored `opus`/`libopus` build may need:
+
+```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.
+
+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.
+
+## 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`. |
+
+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.
@@ -2,7 +2,7 @@ use crate::core::{CoreController, messages::{CoreCommand, UiEvent}};
 use crate::network::PeerState;
 use crate::notify::{self, Sound};
 use crate::audio::eq::{EqSettings, EQ_GAIN_DB_MAX, EQ_GAIN_DB_MIN};
-use crate::audio::pw_cli::{AudioDevice, enumerate_audio_devices};
+use crate::audio::{AudioDevice, enumerate_audio_devices};
 use crate::config::{AppConfig, NetworkMode, RecordingMode, RoomLayout};
 use crate::hotkeys::{format_binding, HotkeyAction, HotkeyContext, KeyBinding};
 use crate::presence::PresenceMode;
@@ -32,6 +32,78 @@ pub enum Screen {
    Settings,
 }

+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SettingsCategory {
+    Audio,
+    Hotkeys,
+    Recording,
+    Profile,
+    Appearance,
+    Network,
+    Notifications,
+}
+
+impl SettingsCategory {
+    const ALL: [SettingsCategory; 7] = [
+        SettingsCategory::Audio,
+        SettingsCategory::Hotkeys,
+        SettingsCategory::Recording,
+        SettingsCategory::Profile,
+        SettingsCategory::Appearance,
+        SettingsCategory::Network,
+        SettingsCategory::Notifications,
+    ];
+
+    fn label(self) -> &'static str {
+        match self {
+            SettingsCategory::Audio => "Audio",
+            SettingsCategory::Hotkeys => "Hotkeys",
+            SettingsCategory::Recording => "Recording",
+            SettingsCategory::Profile => "Profile",
+            SettingsCategory::Appearance => "Appearance",
+            SettingsCategory::Network => "Network",
+            SettingsCategory::Notifications => "Notifications",
+        }
+    }
+
+    fn hint(self) -> &'static str {
+        match self {
+            SettingsCategory::Audio => "Devices, mic gate, echo",
+            SettingsCategory::Hotkeys => "Focused keyboard shortcuts",
+            SettingsCategory::Recording => "Mixed and stem capture",
+            SettingsCategory::Profile => "Avatar and identity",
+            SettingsCategory::Appearance => "Layout and theme",
+            SettingsCategory::Network => "Relay and privacy mode",
+            SettingsCategory::Notifications => "Chimes and sounds",
+        }
+    }
+}
+
+impl std::fmt::Display for SettingsCategory {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.label())
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum HomeLayoutMode {
+    FocusedEmpty,
+    ThreeColumn,
+    Stacked,
+}
+
+fn home_layout_mode(width: f32, has_recents: bool, has_friends: bool) -> HomeLayoutMode {
+    if width < 900.0 {
+        HomeLayoutMode::Stacked
+    } else if !has_recents && !has_friends {
+        HomeLayoutMode::FocusedEmpty
+    } else if width >= 1280.0 {
+        HomeLayoutMode::ThreeColumn
+    } else {
+        HomeLayoutMode::Stacked
+    }
+}
+
 /// One rendered room-chat line. `mine` distinguishes our own (locally echoed)
 /// messages from peers' for colouring.
 #[derive(Debug, Clone)]
@@ -175,6 +247,7 @@ pub enum AppMessage {
    EventOccurred(Event),
    NavigateToSettings,
    NavigateBack,
+    SelectSettingsCategory(SettingsCategory),
    ToggleNotifications(bool),
    ToggleEchoCancellation(bool),
    CustomSoundPathChanged(Sound, String),
@@ -298,6 +371,7 @@ pub struct AppState {
    ever_connected: HashSet<EndpointId>,
    controller: Arc<CoreController>,
    current_screen: Screen,
+    settings_category: SettingsCategory,
    /// Whether we're currently sharing our own screen (confirmed by the core).
    self_sharing: bool,
    /// Whether the `pixelpass` binary is available, gating the Share controls.
@@ -435,6 +509,7 @@ impl Default for AppState {
            ever_connected: HashSet::new(),
            controller,
            current_screen: Screen::Home,
+            settings_category: SettingsCategory::Audio,
            self_sharing: false,
            pixelpass_available,
            self_node_id: None,
@@ -478,11 +553,9 @@ pub fn run_gui() -> iced::Result {
            // the icon from the .desktop file matched by app_id instead).
            icon: window_icon(),
            // app_id must match the .desktop basename so Wayland compositors
-            // (e.g. KWin) attach our launcher icon to the window.
-            platform_specific: iced::window::settings::PlatformSpecific {
-                application_id: "peerspeak".to_string(),
-                ..Default::default()
-            },
+            // (e.g. KWin) attach our launcher icon to the window. The field is
+            // Linux-only in iced (X11/Wayland); see platform_specific_settings().
+            platform_specific: platform_specific_settings(),
            // We save the final size ourselves on CloseRequested, then exit.
            exit_on_close_request: false,
            ..Default::default()
@@ -490,6 +563,22 @@ pub fn run_gui() -> iced::Result {
        .run()
 }

+/// Window `PlatformSpecific` settings. `application_id` (used by X11/Wayland to
+/// match our `.desktop` launcher icon) only exists in iced on Linux, so it is
+/// set there and left at defaults on Windows.
+#[cfg(target_os = "linux")]
+fn platform_specific_settings() -> iced::window::settings::PlatformSpecific {
+    iced::window::settings::PlatformSpecific {
+        application_id: "peerspeak".to_string(),
+        ..Default::default()
+    }
+}
+
+#[cfg(not(target_os = "linux"))]
+fn platform_specific_settings() -> iced::window::settings::PlatformSpecific {
+    iced::window::settings::PlatformSpecific::default()
+}
+
 /// Build the window icon from an embedded 128×128 straight-RGBA blob rendered
 /// from `assets/icons/peerspeak.svg`. Using `from_rgba` (always available) keeps
 /// us off iced's heavy `image` feature — the blob is raw pixels, no decoder.
@@ -880,13 +969,15 @@ fn update(state: &mut AppState, message: AppMessage) -> Task<AppMessage> {
                    state.friend_presence.insert(id, presence);
                }
                UiEvent::PresenceModeReverted { mode } => {
-                    // The Discoverable time-box elapsed; core dropped us back to
-                    // `mode` (Normal) and stopped publishing. Mirror + persist so the
-                    // presence picker reflects it, and tell the user why it changed.
+                    // Core corrected the committed presence mode. Mirror + persist so
+                    // the picker reflects the discovery state the endpoint actually has.
                    state.config.presence_mode = mode;
                    state.config.save();
-                    state.status_message =
-                        "Discoverable timed out — back to Normal".to_string();
+                    state.status_message = if mode == PresenceMode::Normal {
+                        "Discoverable timed out — back to Normal".to_string()
+                    } else {
+                        format!("Presence mode stayed {mode}")
+                    };
                }
                UiEvent::ShutdownComplete => {
                    if state.closing {
@@ -1097,6 +1188,9 @@ fn update(state: &mut AppState, message: AppMessage) -> Task<AppMessage> {
            crate::recents::remove_recent(&mut state.config.recents, &ticket);
            state.config.save();
        }
+        AppMessage::SelectSettingsCategory(category) => {
+            state.settings_category = category;
+        }
        AppMessage::ToggleNotifications(enabled) => {
            state.config.notifications_enabled = enabled;
            state.config.save();
@@ -1270,12 +1364,28 @@ fn update(state: &mut AppState, message: AppMessage) -> Task<AppMessage> {
            // Defence in depth: only ever hand http(s) URLs to the opener. The
            // link span's href came from `linkify`, which only emits http/https,
            // but re-check here so this can't be widened into launching arbitrary
-            // schemes/args. `xdg-open` receives the URL as a single argv entry
-            // (no shell), so there's no injection surface.
-            if (url.starts_with("http://") || url.starts_with("https://"))
-                && let Err(e) = std::process::Command::new("xdg-open").arg(&url).spawn()
-            {
-                crate::log_msg(&format!("Failed to open URL {url:?}: {e}"));
+            // schemes/args. Each opener receives the URL as a single argv entry
+            // (no shell), so there's no injection surface:
+            //   - Unix: `xdg-open <url>`.
+            //   - Windows: `rundll32 url.dll,FileProtocolHandler <url>` — opens the
+            //     default browser without going through `cmd`/`start`, which would
+            //     otherwise re-parse `&` in query strings.
+            if url.starts_with("http://") || url.starts_with("https://") {
+                let spawned = {
+                    #[cfg(unix)]
+                    {
+                        std::process::Command::new("xdg-open").arg(&url).spawn()
+                    }
+                    #[cfg(windows)]
+                    {
+                        std::process::Command::new("rundll32")
+                            .args(["url.dll,FileProtocolHandler", &url])
+                            .spawn()
+                    }
+                };
+                if let Err(e) = spawned {
+                    crate::log_msg(&format!("Failed to open URL {url:?}: {e}"));
+                }
            }
        }
        AppMessage::ToggleMicTest(enabled) => {
@@ -1544,7 +1654,7 @@ fn connect_card(state: &AppState) -> Element<'_, AppMessage> {
        selection: color_blue,
    };

-    let logo = text("PEERSPEAK").size(36).color(color_blue);
+    let logo = text("PEERSPEAK").size(38).color(color_blue);
    let subtitle = text("NAT-traversing full-mesh voice chat").size(16).color(color_subtext);

    let nickname_input = column![
@@ -1608,8 +1718,8 @@ fn connect_card(state: &AppState) -> Element<'_, AppMessage> {
        .align_x(iced::alignment::Horizontal::Center),
    )
    .style(c_style(color_mantle, color_surface, 12.0))
-    .padding(30)
-    .width(380)
+    .padding(32)
+    .width(420)
    .into()
 }

@@ -1653,50 +1763,51 @@ fn recents_card(state: &AppState) -> Element<'_, AppMessage> {
        }
    };

-    let now = std::time::SystemTime::now()
-        .duration_since(std::time::UNIX_EPOCH)
-        .map(|d| d.as_secs())
-        .unwrap_or(0);
-    let mut rows = column![].spacing(6).width(iced::Length::Fill);
-    if state.config.recents.is_empty() {
-        rows = rows.push(
-            text("No recent rooms yet — they'll appear here after you join one.")
-                .size(12)
-                .color(color_subtext),
-        );
-    }
-    for r in &state.config.recents {
-        let label = {
-            let n = crate::sanitize::sanitize_name(&r.name);
-            if n.is_empty() { "Untitled room".to_string() } else { n }
-        };
-        let when = crate::recents::relative_time(now, r.joined_at);
-        let entry = button(
-            row![
-                text(label).size(14).color(color_text),
-                horizontal_space(),
-                text(when).size(11).color(color_subtext),
-            ]
-            .align_y(iced::alignment::Vertical::Center),
-        )
-        .on_press(AppMessage::JoinRecent(r.ticket.clone()))
-        .style(b_style(color_crust, color_surface, color_text, 6.0))
-        .padding(8)
-        .width(iced::Length::Fill);
-        rows = rows.push(
-            row![
-                entry,
-                button(text("✕").size(12))
-                    .on_press(AppMessage::RemoveRecent(r.ticket.clone()))
-                    .style(b_style(color_surface, color_maroon, color_text, 6.0))
-                    .padding(8),
-            ]
-            .spacing(6)
-            .align_y(iced::alignment::Vertical::Center),
-        );
-    }
+    let empty = state.config.recents.is_empty();
+    let content: Element<'_, AppMessage> = if empty {
+        column![
+            text("RECENT ROOMS").size(14).color(color_subtext),
+            text("No recent rooms yet.").size(12).color(color_subtext),
+        ]
+        .spacing(4)
+        .into()
+    } else {
+        let now = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map(|d| d.as_secs())
+            .unwrap_or(0);
+        let mut rows = column![].spacing(6).width(iced::Length::Fill);
+        for r in &state.config.recents {
+            let label = {
+                let n = crate::sanitize::sanitize_name(&r.name);
+                if n.is_empty() { "Untitled room".to_string() } else { n }
+            };
+            let when = crate::recents::relative_time(now, r.joined_at);
+            let entry = button(
+                row![
+                    text(label).size(14).color(color_text),
+                    horizontal_space(),
+                    text(when).size(11).color(color_subtext),
+                ]
+                .align_y(iced::alignment::Vertical::Center),
+            )
+            .on_press(AppMessage::JoinRecent(r.ticket.clone()))
+            .style(b_style(color_crust, color_surface, color_text, 6.0))
+            .padding(8)
+            .width(iced::Length::Fill);
+            rows = rows.push(
+                row![
+                    entry,
+                    button(text("✕").size(12))
+                        .on_press(AppMessage::RemoveRecent(r.ticket.clone()))
+                        .style(b_style(color_surface, color_maroon, color_text, 6.0))
+                        .padding(8),
+                ]
+                .spacing(6)
+                .align_y(iced::alignment::Vertical::Center),
+            );
+        }

-    container(
        column![
            text("RECENT ROOMS").size(18).color(color_text),
            text("Rooms you've been in — click to hop back. Best-effort: only works while someone's still there.")
@@ -1705,11 +1816,14 @@ fn recents_card(state: &AppState) -> Element<'_, AppMessage> {
            vertical_space(10.0),
            rows,
        ]
-        .spacing(6),
-    )
-    .style(c_style(color_mantle, color_surface, 12.0))
-    .padding(24)
-    .width(380)
+        .spacing(6)
+        .into()
+    };
+
+    container(content)
+    .style(c_style(if empty { color_crust } else { color_mantle }, color_surface, 8.0))
+    .padding(if empty { 16 } else { 24 })
+    .width(if empty { 340 } else { 380 })
    .into()
 }

@@ -1725,6 +1839,7 @@ fn friends_panel(state: &AppState) -> Element<'_, AppMessage> {
    let color_red = pal.red;
    let color_maroon = pal.maroon;
    let color_green = pal.green;
+    let has_friends = !state.friends.list().is_empty();

    let c_style = move |bg: Color, b_color: Color, radius: f32| {
        move |_theme: &Theme| container::Style {
@@ -1763,9 +1878,9 @@ fn friends_panel(state: &AppState) -> Element<'_, AppMessage> {

    // The live friends list: status dot, inline rename, short id, remove.
    let mut friend_rows = column![].spacing(6).width(iced::Length::Fill);
-    if state.friends.list().is_empty() {
+    if !has_friends {
        friend_rows = friend_rows.push(
-            text("No friends yet — add one by their node ID below.")
+            text("No friends yet.")
                .size(12)
                .color(color_subtext),
        );
@@ -1868,28 +1983,34 @@ fn friends_panel(state: &AppState) -> Element<'_, AppMessage> {
    ]
    .spacing(4)
    .width(iced::Length::Fill);
+    let intro: Element<'_, AppMessage> = if has_friends {
+        text("Who's online — click Join to hop into a friend's room.")
+            .size(11)
+            .color(color_subtext)
+            .into()
+    } else {
+        column![].into()
+    };

    container(
        column![
-            text("FRIENDS").size(18).color(color_text),
-            text("Who's online — click Join to hop into a friend's room.")
-                .size(11)
-                .color(color_subtext),
-            vertical_space(10.0),
+            text("FRIENDS").size(if has_friends { 18 } else { 14 }).color(color_text),
+            intro,
+            vertical_space(if has_friends { 10.0 } else { 4.0 }),
            readonly_warning,
            friend_rows,
-            vertical_space(12.0),
+            vertical_space(if has_friends { 12.0 } else { 8.0 }),
            text("Add a friend").size(13).color(color_subtext),
            add_form,
-            vertical_space(14.0),
+            vertical_space(if has_friends { 14.0 } else { 10.0 }),
            text("Your presence").size(13).color(color_subtext),
            presence_picker,
        ]
        .spacing(6),
    )
    .style(c_style(color_mantle, color_surface, 12.0))
-    .padding(24)
-    .width(460)
+    .padding(if has_friends { 24 } else { 18 })
+    .width(if has_friends { 460 } else { 360 })
    .into()
 }

@@ -1959,19 +2080,23 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
        }
    };

-    let top_bar = row![
-        horizontal_space(),
-        tooltip(
-            button(icon(IconKind::Info, 18.0, color_text))
-                .on_press(AppMessage::OpenHotkeyInfo)
-                .style(b_style(color_surface, color_blue, color_text, 6.0))
-                .padding(8),
-            container(text("Hotkeys").size(11).color(color_text))
-                .padding(8)
-                .style(c_style(color_crust, color_surface, 6.0)),
-            iced::widget::tooltip::Position::Bottom,
-        )
-        .gap(8),
+    // The Hotkeys info button is always available (hotkeys are app-wide). The
+    // room-layout button is hidden on the Home screen, leaving only it + Settings.
+    let info_button = tooltip(
+        button(icon(IconKind::Info, 18.0, color_text))
+            .on_press(AppMessage::OpenHotkeyInfo)
+            .style(b_style(color_surface, color_blue, color_text, 6.0))
+            .padding(8),
+        container(text("Hotkeys").size(11).color(color_text))
+            .padding(8)
+            .style(c_style(color_crust, color_surface, 6.0)),
+        iced::widget::tooltip::Position::Bottom,
+    )
+    .gap(8);
+
+    let layout_button: Element<'_, AppMessage> = if state.current_screen == Screen::Home {
+        iced::widget::Space::new().width(0.0).height(0.0).into()
+    } else {
        tooltip(
            button(
                Canvas::new(LayoutIcon { fg: color_text })
@@ -1986,7 +2111,14 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                .style(c_style(color_crust, color_surface, 6.0)),
            iced::widget::tooltip::Position::Bottom,
        )
-        .gap(8),
+        .gap(8)
+        .into()
+    };
+
+    let top_bar = row![
+        horizontal_space(),
+        info_button,
+        layout_button,
        button(
            row![
                icon(IconKind::Settings, 15.0, color_text),
@@ -2404,9 +2536,8 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {

        // Presence + Friends moved to the home screen (see `friends_panel`).

-        let settings_content = scrollable(
-            column![
-                // --- Audio Devices ---
+        let settings_body: Element<'_, AppMessage> = match state.settings_category {
+            SettingsCategory::Audio => column![
                section_header("Audio Devices"),
                row![
                    column![
@@ -2435,26 +2566,46 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                    ].spacing(8).width(iced::Length::Fill),
                ].spacing(20).align_y(iced::alignment::Vertical::Top).width(iced::Length::Fill),
                vertical_space(section_gap),
-
-                // --- Microphone ---
                section_header("Microphone"),
                column![
                    mic_meter,
                    text("Drag the yellow handle to set the gate. While talking, place it just above your quiet-room level so silence is muted but your voice passes through.").size(11).color(color_subtext),
                    vertical_space(4.0),
-                    checkbox(state.config.echo_cancellation_enabled)
-                        .label("Echo cancellation")
-                        .on_toggle(AppMessage::ToggleEchoCancellation),
-                    text("Cancels speaker echo + suppresses noise (PipeWire). Takes effect on your next room join.").size(11).color(color_subtext),
+                    {
+                        let control: Element<'_, AppMessage> = {
+                            #[cfg(target_os = "linux")]
+                            {
+                                column![
+                                    checkbox(state.config.echo_cancellation_enabled)
+                                        .label("Echo cancellation")
+                                        .on_toggle(AppMessage::ToggleEchoCancellation),
+                                    text("Cancels speaker echo + suppresses noise (PipeWire). Takes effect on your next room join.").size(11).color(color_subtext),
+                                ].spacing(8).into()
+                            }
+                            #[cfg(not(target_os = "linux"))]
+                            {
+                                column![
+                                    checkbox(false)
+                                        .label("Echo cancellation"),
+                                    text("Echo cancellation is not available on Windows yet.").size(11).color(color_subtext),
+                                ].spacing(8).into()
+                            }
+                        };
+                        control
+                    },
                ].spacing(8).width(iced::Length::Fill),
-                vertical_space(section_gap),
-
-                // --- Hotkeys ---
+            ]
+            .spacing(10)
+            .width(iced::Length::Fill)
+            .into(),
+            SettingsCategory::Hotkeys => column![
                section_header("Hotkeys"),
                hotkey_section,
-                vertical_space(section_gap),
-
-                // --- Recording ---
+            ]
+            .spacing(10)
+            .width(iced::Length::Fill)
+            .into(),
+            SettingsCategory::Recording => column![
                section_header("Recording"),
                column![
                    mode_radio(RecordingMode::Mixed, "Mixed (single file)"),
@@ -2463,22 +2614,21 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                    vertical_space(2.0),
                    text("Hover an option for what it does. Saved to ~/peerspeak-recordings/ — Multitrack/Both as a timestamped folder of tracks, Mixed as a single file. Applies to your next recording.").size(11).color(color_subtext),
                ].spacing(8).width(iced::Length::Fill),
+            ]
+            .spacing(10)
+            .width(iced::Length::Fill)
+            .into(),
+            SettingsCategory::Profile => column![
+                section_header("Avatar"),
+                avatar_section,
                vertical_space(section_gap),
-
-                // --- Network & Privacy ---
-                section_header("Network & Privacy"),
-                column![
-                    pick_list(
-                        &NetworkMode::ALL[..],
-                        Some(state.config.network_mode),
-                        AppMessage::NetworkModeSelected,
-                    ).width(iced::Length::Fill),
-                    text(network_mode_hint(state.config.network_mode)).size(11).color(color_subtext),
-                    text("Takes effect on your next room join.").size(11).color(color_subtext),
-                ].spacing(4).width(iced::Length::Fill),
-                vertical_space(section_gap),
-
-                // --- Room Layout ---
+                section_header("Identity"),
+                identity_section,
+            ]
+            .spacing(10)
+            .width(iced::Length::Fill)
+            .into(),
+            SettingsCategory::Appearance => column![
                section_header("Room Layout"),
                column![
                    row![
@@ -2489,25 +2639,28 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                    text("How the in-call room is arranged. Applies live.").size(11).color(color_subtext),
                ].spacing(8).width(iced::Length::Fill),
                vertical_space(section_gap),
-
-                // --- Theme ---
                section_header("Theme"),
                theme_section,
-                vertical_space(section_gap),
-
-                // --- Avatar ---
-                section_header("Avatar"),
-                avatar_section,
-                vertical_space(section_gap),
-
-                // --- Identity ---
-                section_header("Identity"),
-                identity_section,
-                vertical_space(section_gap),
-
-                // (Presence + Friends now live on the home screen.)
-
-                // --- Notifications & Sounds ---
+            ]
+            .spacing(10)
+            .width(iced::Length::Fill)
+            .into(),
+            SettingsCategory::Network => column![
+                section_header("Network & Privacy"),
+                column![
+                    pick_list(
+                        &NetworkMode::ALL[..],
+                        Some(state.config.network_mode),
+                        AppMessage::NetworkModeSelected,
+                    ).width(iced::Length::Fill),
+                    text(network_mode_hint(state.config.network_mode)).size(11).color(color_subtext),
+                    text("Takes effect on your next room join.").size(11).color(color_subtext),
+                ].spacing(4).width(iced::Length::Fill),
+            ]
+            .spacing(10)
+            .width(iced::Length::Fill)
+            .into(),
+            SettingsCategory::Notifications => column![
                section_header("Notifications & Sounds"),
                column![
                    checkbox(state.config.notifications_enabled)
@@ -2535,9 +2688,92 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
            ]
            .spacing(10)
            .width(iced::Length::Fill)
-        )
-        .width(iced::Length::Fill)
-        .height(iced::Length::Fill);
+            .into(),
+        };
+
+        let category_button = |category: SettingsCategory| -> Element<'_, AppMessage> {
+            let selected = state.settings_category == category;
+            let label_color = if selected { color_blue } else { color_text };
+            let border_color = if selected { color_blue } else { Color::TRANSPARENT };
+            let bg = if selected { color_surface } else { Color::TRANSPARENT };
+            button(
+                container(
+                    column![
+                        text(category.label()).size(14).color(label_color),
+                        text(category.hint()).size(11).color(color_subtext),
+                    ]
+                    .spacing(2)
+                    .width(iced::Length::Fill),
+                )
+                .width(iced::Length::Fill),
+            )
+            .on_press(AppMessage::SelectSettingsCategory(category))
+            .style(move |_theme: &Theme, status: button::Status| {
+                let active_bg = match status {
+                    button::Status::Hovered if selected => color_surface,
+                    button::Status::Hovered => color_crust,
+                    _ => bg,
+                };
+                button::Style {
+                    background: Some(Background::Color(active_bg)),
+                    text_color: label_color,
+                    border: Border {
+                        color: border_color,
+                        width: if selected { 1.0 } else { 0.0 },
+                        radius: 8.0.into(),
+                    },
+                    ..Default::default()
+                }
+            })
+            .padding(10)
+            .width(iced::Length::Fill)
+            .into()
+        };
+
+        let mut settings_nav = column![
+            text("SETTINGS").size(11).color(color_subtext),
+        ]
+        .spacing(8)
+        .width(iced::Length::Fill);
+        for category in SettingsCategory::ALL {
+            settings_nav = settings_nav.push(category_button(category));
+        }
+        let settings_nav = container(settings_nav)
+            .padding(12)
+            .width(iced::Length::Fixed(220.0))
+            .height(iced::Length::Fill)
+            .style(c_style(color_crust, color_surface, 8.0));
+
+        let settings_content: Element<'_, AppMessage> = if state.window_size.width < 820.0 {
+            scrollable(
+                column![
+                    text("Category").size(12).color(color_subtext),
+                    pick_list(
+                        &SettingsCategory::ALL[..],
+                        Some(state.settings_category),
+                        AppMessage::SelectSettingsCategory,
+                    ).width(iced::Length::Fill),
+                    vertical_space(10.0),
+                    settings_body,
+                ]
+                .spacing(8)
+                .width(iced::Length::Fill),
+            )
+            .width(iced::Length::Fill)
+            .height(iced::Length::Fill)
+            .into()
+        } else {
+            row![
+                settings_nav,
+                scrollable(settings_body)
+                    .width(iced::Length::Fill)
+                    .height(iced::Length::Fill),
+            ]
+            .spacing(16)
+            .width(iced::Length::Fill)
+            .height(iced::Length::Fill)
+            .into()
+        };

        // Sticky header bar: stays fixed above the scrollable content so the Back
        // button is always reachable. The "Settings" title is centered by flanking
@@ -2597,29 +2833,44 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {

    if state.current_screen == Screen::Home {
        // --- HOME SCREEN ---
-        // Two cards: Connect (left) + the live Friends list (right). They sit
-        // side-by-side when the window is wide enough, and stack vertically on a
-        // narrow window so the Friends card never gets crushed — below ~860px the
-        // fixed-width Connect card would otherwise squeeze it until its node-ID
-        // field and remove button clip away. `responsive` measures the available
-        // width each layout pass and picks the orientation accordingly.
-        // Three cards: Recents | Connect | Friends, side-by-side when there's room.
-        // Three 380–460px cards need ~1280px to fit in a row, so below that the
-        // `responsive` measure stacks them in a column (Connect first — the primary
-        // action) rather than letting the row clip. Recents always shows (empty-
-        // state hint when no history) for parity with the Friends card.
+        // Keep Create/Join dominant on a fresh install. Once Recents or Friends
+        // has real content, the wider three-card layout returns.
+        let has_recents = !state.config.recents.is_empty();
+        let has_friends = !state.friends.list().is_empty();
        let body = responsive(move |size| {
-            let cards: Element<AppMessage> = if size.width < 1280.0 {
-                column![connect_card(state), recents_card(state), friends_panel(state)]
-                    .spacing(20)
-                    .align_x(iced::alignment::Horizontal::Center)
-                    .into()
-            } else {
-                row![recents_card(state), connect_card(state), friends_panel(state)]
+            let cards: Element<AppMessage> =
+                match home_layout_mode(size.width, has_recents, has_friends) {
+                    HomeLayoutMode::FocusedEmpty => row![
+                        connect_card(state),
+                        column![friends_panel(state), recents_card(state)]
+                            .spacing(16)
+                            .width(iced::Length::Fixed(360.0)),
+                    ]
+                    .spacing(22)
+                    .align_y(iced::alignment::Vertical::Top)
+                    .into(),
+                    HomeLayoutMode::ThreeColumn => row![
+                        recents_card(state),
+                        connect_card(state),
+                        friends_panel(state),
+                    ]
                    .spacing(20)
                    .align_y(iced::alignment::Vertical::Top)
-                    .into()
-            };
+                    .into(),
+                    HomeLayoutMode::Stacked => {
+                        let mut stack = column![connect_card(state)]
+                            .spacing(20)
+                            .align_x(iced::alignment::Horizontal::Center);
+                        if has_recents {
+                            stack = stack.push(recents_card(state));
+                        }
+                        stack = stack.push(friends_panel(state));
+                        if !has_recents {
+                            stack = stack.push(recents_card(state));
+                        }
+                        stack.into()
+                    }
+                };
            scrollable(container(cards).center_x(iced::Length::Fill))
                .width(iced::Length::Fill)
                .into()
@@ -3044,26 +3295,40 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                column![]
            },
            vertical_space(20.0),
-            // Echo cancellation — same flag + message as the Settings checkbox, so
-            // toggling here and there stay in sync automatically (single source of
-            // truth: config.echo_cancellation_enabled). Tooltip is explicit that it
-            // applies on the NEXT join (the PipeWire-module AEC is wired at join
-            // time, not hot-swappable mid-call).
-            tooltip(
-                checkbox(state.config.echo_cancellation_enabled)
-                    .label("Echo cancellation")
-                    .on_toggle(AppMessage::ToggleEchoCancellation),
-                container(
-                    text("Cancels speaker echo + suppresses noise. Applies on your next room join.")
-                        .size(11)
-                        .color(color_text),
-                )
-                .padding(8)
-                .max_width(260.0)
-                .style(c_style(color_crust, color_surface, 6.0)),
-                iced::widget::tooltip::Position::Top,
-            )
-            .gap(8),
+            {
+                // Echo cancellation is wired at join time on Linux; other
+                // targets show an inert status row instead of a dead toggle.
+                let control: Element<'_, AppMessage> = {
+                    #[cfg(target_os = "linux")]
+                    {
+                        tooltip(
+                            checkbox(state.config.echo_cancellation_enabled)
+                                .label("Echo cancellation")
+                                .on_toggle(AppMessage::ToggleEchoCancellation),
+                            container(
+                                text("Cancels speaker echo + suppresses noise. Applies on your next room join.")
+                                    .size(11)
+                                    .color(color_text),
+                            )
+                            .padding(8)
+                            .max_width(260.0)
+                            .style(c_style(color_crust, color_surface, 6.0)),
+                            iced::widget::tooltip::Position::Top,
+                        )
+                        .gap(8)
+                        .into()
+                    }
+                    #[cfg(not(target_os = "linux"))]
+                    {
+                        column![
+                            checkbox(false)
+                                .label("Echo cancellation"),
+                            text("Not available on Windows yet.").size(11).color(color_subtext),
+                        ].spacing(4).into()
+                    }
+                };
+                control
+            },
            vertical_space(20.0),
            {
                let (rec_kind, rec_label, rec_bg, rec_hover, rec_fg) = if state.recording {
@@ -4517,6 +4782,28 @@ mod tests {
        assert_eq!(format_duration(3661), "1:01:01");
        assert_eq!(format_duration(3725), "1:02:05");
    }
+
+    #[test]
+    fn settings_categories_are_stable_and_grouped_for_navigation() {
+        use super::SettingsCategory;
+        let labels: Vec<_> = SettingsCategory::ALL.iter().map(|c| c.label()).collect();
+        assert_eq!(
+            labels,
+            vec!["Audio", "Hotkeys", "Recording", "Profile", "Appearance", "Network", "Notifications"]
+        );
+        assert_eq!(SettingsCategory::Audio.hint(), "Devices, mic gate, echo");
+        assert_eq!(SettingsCategory::Profile.hint(), "Avatar and identity");
+    }
+
+    #[test]
+    fn home_layout_prioritizes_connect_on_empty_home() {
+        use super::{home_layout_mode, HomeLayoutMode};
+        assert_eq!(home_layout_mode(1280.0, false, false), HomeLayoutMode::FocusedEmpty);
+        assert_eq!(home_layout_mode(760.0, false, false), HomeLayoutMode::Stacked);
+        assert_eq!(home_layout_mode(1280.0, true, false), HomeLayoutMode::ThreeColumn);
+        assert_eq!(home_layout_mode(1100.0, true, true), HomeLayoutMode::Stacked);
+    }
+
    use super::{clamp_chat_height, clamp_participants_width, CHAT_MIN_H, PARTICIPANTS_MIN_W};

    #[test]
@@ -56,12 +56,60 @@ pub trait AudioBackend: Send + Sync {
    fn stop(&self) -> Result<(), AudioError>;
 }

-pub mod echo_cancel;
 pub mod eq;
 pub mod gate;
 pub mod limiter;
 pub mod multitrack;
 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(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;
+
+/// A selectable audio device for the input/output pickers. `name` is the stable
+/// identifier the backend uses to request the device (`target_node`);
+/// `description` is the human-facing label shown in the UI. The two may be equal
+/// (cpal/WASAPI) or differ (PipeWire node name vs. description).
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct AudioDevice {
+    pub name: String,
+    pub description: String,
+    pub is_input: bool,
+}
+
+impl std::fmt::Display for AudioDevice {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.description)
+    }
+}
+
+// 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;
+
+/// The audio backend implementation for the current platform.
+///
+/// The whole app constructs and threads this alias (via
+/// `PlatformAudioBackend::new()`) rather than any concrete backend type, so
+/// platform selection lives entirely here. Both implementations satisfy the
+/// [`AudioBackend`] trait, which is the only interface the core talks to.
+///
+/// - Linux → PipeWire ([`pipewire_impl::PipeWireBackend`]).
+/// - Windows → cpal/WASAPI ([`cpal_impl::CpalBackend`]).
+#[cfg(target_os = "linux")]
+pub type PlatformAudioBackend = pipewire_impl::PipeWireBackend;
+#[cfg(windows)]
+pub type PlatformAudioBackend = cpal_impl::CpalBackend;
@@ -1,18 +1,6 @@
+use super::AudioDevice;
 use std::process::Command;

-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct AudioDevice {
-    pub name: String,
-    pub description: String,
-    pub is_input: bool,
-}
-
-impl std::fmt::Display for AudioDevice {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self.description)
-    }
-}
-
 pub fn enumerate_audio_devices() -> Vec<AudioDevice> {
    let output = Command::new("pw-cli")
        .arg("list-objects")
@@ -0,0 +1,307 @@
+//! Dep-free linear-interpolation resamplers for the Windows/cpal backend (W4).
+//!
+//! The pipeline runs internally at 48 kHz (Opus + the 20 ms frame), but a WASAPI
+//! endpoint may run at a different rate (commonly 44.1 kHz) and/or a non-stereo
+//! channel layout. These convert at the device boundary so such a device plays and
+//! captures instead of hard-erroring (the W4 limitation in the Windows port).
+//!
+//! ## Where each is used
+//! - [`PushResampler`] (single channel) converts **capture** from the device rate
+//!   to 48 kHz on the capture drain thread — off the RT callback.
+//! - [`StereoPullResampler`] converts **playback** from the internal 48 kHz stereo
+//!   bus to the device rate inside the output RT callback, pulling internal frames
+//!   from the ring on demand. It allocates nothing in `next`, so it is RT-safe.
+//!
+//! ## Quality
+//! This is plain linear interpolation with no anti-aliasing filter: correct,
+//! allocation-free, and adequate for speech, but it adds some aliasing when
+//! downsampling. The seam is intentionally tiny so a higher-quality polyphase/FIR
+//! resampler (e.g. the `rubato` crate, pending a supply-chain decision) can later
+//! replace the internals without touching the cpal backend. The matching-rate /
+//! matching-layout path in the backend bypasses these entirely and stays bit-exact.
+
+/// Linear interpolation between `a` and `b` at fractional position `frac` in `[0, 1)`.
+#[inline]
+fn lerp(a: f32, b: f32, frac: f32) -> f32 {
+    a + (b - a) * frac
+}
+
+/// Stateful single-channel **push** resampler: feed input samples at `in_rate`,
+/// receive output samples at `out_rate` through an `emit` callback. It carries the
+/// fractional read position and the previous input sample across calls, so feeding
+/// the stream block-by-block joins seamlessly. Neither [`push`](Self::push) nor
+/// [`process`](Self::process) allocates.
+pub struct PushResampler {
+    /// Input samples consumed per output sample (`in_rate / out_rate`).
+    step: f64,
+    /// Position of the next output sample, in input-sample units, measured from the
+    /// index of `prev` (the most recent input). Always advanced to stay `< 1.0`
+    /// after each input is consumed.
+    next: f64,
+    /// The previous input sample (left edge of the current interpolation segment).
+    prev: f32,
+    /// Whether any input has been seen yet (anchors the first output at input[0]).
+    started: bool,
+}
+
+impl PushResampler {
+    /// Build a resampler from `in_rate` to `out_rate` (both in Hz). Rates are
+    /// clamped to `>= 1` so `step` is always finite and non-zero: a zero `step`
+    /// would make [`push`](Self::push)'s `while self.next < 1.0` loop forever. The
+    /// cpal backend's `resolve()` also rejects such rates up front, so this is
+    /// belt-and-suspenders against a future caller (review W7).
+    pub fn new(in_rate: u32, out_rate: u32) -> Self {
+        Self {
+            step: in_rate.max(1) as f64 / out_rate.max(1) as f64,
+            next: 0.0,
+            prev: 0.0,
+            started: false,
+        }
+    }
+
+    /// Feed one input sample; `emit` is called for each output sample produced
+    /// (zero or more, depending on the rate ratio).
+    pub fn push(&mut self, cur: f32, mut emit: impl FnMut(f32)) {
+        if !self.started {
+            // First sample: just establish the left edge. Linear interpolation
+            // needs the next input as the right edge, so the first output is
+            // produced on the next push. This gives exact alignment
+            // (`output[k] == input[k]` at equal rates) with one input-sample of
+            // latency — negligible (~20 µs at 48 kHz).
+            self.started = true;
+            self.prev = cur;
+            self.next = 0.0;
+            return;
+        }
+        // `prev` sits at position 0 of this segment and `cur` at position 1; emit
+        // every output whose position falls in [0, 1).
+        while self.next < 1.0 {
+            emit(lerp(self.prev, cur, self.next as f32));
+            self.next += self.step;
+        }
+        self.next -= 1.0;
+        self.prev = cur;
+    }
+
+    /// Convenience for tests / batch callers: push a whole slice.
+    pub fn process(&mut self, input: &[f32], mut emit: impl FnMut(f32)) {
+        for &s in input {
+            self.push(s, &mut emit);
+        }
+    }
+}
+
+/// Stateful stereo **pull** resampler: produce output frames at `out_rate` by
+/// pulling input frames at `in_rate` from a closure on demand. Call
+/// [`next`](Self::next) once per output frame; it pulls as many input frames as the
+/// ratio requires and returns the interpolated `(left, right)`, or `None` when the
+/// puller runs dry (an underrun). Allocates nothing, so it is safe in an RT output
+/// callback.
+pub struct StereoPullResampler {
+    /// Input frames consumed per output frame (`in_rate / out_rate`).
+    step: f64,
+    /// Position of the next output frame within `[prev, cur)`, in `[0, 1)`.
+    frac: f64,
+    /// Left edge of the current interpolation segment.
+    prev: (f32, f32),
+    /// Right edge of the current interpolation segment.
+    cur: (f32, f32),
+    /// Whether `prev`/`cur` have been primed from the puller yet.
+    primed: bool,
+}
+
+impl StereoPullResampler {
+    /// Build a resampler from `in_rate` to `out_rate` (both in Hz). Rates are
+    /// clamped to `>= 1` so `step` is finite and non-zero — otherwise
+    /// [`next`](Self::next)'s `while self.frac >= 1.0` could spin (review W7).
+    pub fn new(in_rate: u32, out_rate: u32) -> Self {
+        Self {
+            step: in_rate.max(1) as f64 / out_rate.max(1) as f64,
+            frac: 0.0,
+            prev: (0.0, 0.0),
+            cur: (0.0, 0.0),
+            primed: false,
+        }
+    }
+
+    /// Produce the next output frame, pulling input frames via `pull` as needed.
+    /// Returns `None` if `pull` returns `None` before the frame can be formed
+    /// (underrun); the caller should substitute silence for that frame.
+    pub fn next(&mut self, mut pull: impl FnMut() -> Option<(f32, f32)>) -> Option<(f32, f32)> {
+        if !self.primed {
+            // Prime both edges from two pulls so the first output frame aligns
+            // exactly with the first input frame (`out[0] == in[0]` at equal
+            // rates). Needs two frames available to start, which the prefilled
+            // playback ring always has.
+            self.prev = pull()?;
+            self.cur = pull()?;
+            self.primed = true;
+            self.frac = 0.0;
+        }
+        // Advance the segment until the read position lands inside [prev, cur).
+        while self.frac >= 1.0 {
+            self.prev = self.cur;
+            self.cur = pull()?;
+            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));
+        self.frac += self.step;
+        Some(out)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Equal rates align exactly: `output[k] == input[k]`. The final input lands on
+    /// the next push (one-sample streaming latency), so we get `n - 1` outputs.
+    #[test]
+    fn push_identity_when_rates_match() {
+        let mut r = PushResampler::new(48_000, 48_000);
+        let input = [0.0, 0.1, 0.2, 0.3, 0.4];
+        let mut out = Vec::new();
+        r.process(&input, |s| out.push(s));
+        assert_eq!(out.len(), input.len() - 1);
+        for (a, b) in out.iter().zip(input.iter()) {
+            assert!((a - b).abs() < 1e-6, "{a} vs {b}");
+        }
+    }
+
+    /// Upsampling 2x roughly doubles the output count and the midpoints interpolate.
+    #[test]
+    fn push_upsample_2x_interpolates_midpoints() {
+        let mut r = PushResampler::new(24_000, 48_000); // step = 0.5
+        let input = [0.0, 1.0, 2.0, 3.0];
+        let mut out = Vec::new();
+        r.process(&input, |s| out.push(s));
+        // (n - 1) segments at 2 outputs each = 6.
+        assert_eq!(out.len(), 6, "out {out:?}");
+        // A half-step between 1.0 and 2.0 must appear near 1.5.
+        assert!(
+            out.iter().any(|&s| (s - 1.5).abs() < 1e-3),
+            "expected a ~1.5 midpoint in {out:?}"
+        );
+    }
+
+    /// Downsampling drops the rate: fewer outputs than inputs, monotonic ramp preserved.
+    #[test]
+    fn push_downsample_reduces_count() {
+        let mut r = PushResampler::new(48_000, 44_100); // step ~1.088
+        let input: Vec<f32> = (0..441).map(|i| i as f32).collect();
+        let mut out = Vec::new();
+        r.process(&input, |s| out.push(s));
+        // 441 in @ 48k -> ~405 out @ 44.1k.
+        assert!(
+            (390..=410).contains(&out.len()),
+            "expected ~405 outputs, got {}",
+            out.len()
+        );
+        // Output stays within the input's value range and is non-decreasing.
+        for w in out.windows(2) {
+            assert!(w[1] >= w[0] - 1e-3, "ramp should not reverse: {w:?}");
+        }
+        assert!(*out.last().unwrap() <= 440.0 + 1e-3);
+    }
+
+    /// Pull resampler at equal rates returns each input frame in order, aligned.
+    /// Two-pull priming uses one frame of lookahead, so `n` inputs yield `n - 1`
+    /// outputs (the last frame emits once a successor arrives).
+    #[test]
+    fn pull_identity_when_rates_match() {
+        let mut r = StereoPullResampler::new(48_000, 48_000);
+        let frames = [(0.0, 9.0), (1.0, 8.0), (2.0, 7.0), (3.0, 6.0)];
+        let mut idx = 0;
+        let mut out = Vec::new();
+        while let Some(f) = r.next(|| {
+            let v = frames.get(idx).copied();
+            idx += 1;
+            v
+        }) {
+            out.push(f);
+        }
+        assert_eq!(out.len(), frames.len() - 1, "out {out:?}");
+        for (got, want) in out.iter().zip(frames.iter()) {
+            assert!((got.0 - want.0).abs() < 1e-6 && (got.1 - want.1).abs() < 1e-6);
+        }
+    }
+
+    /// Pull resampler reports underrun (`None`) once the source is exhausted.
+    #[test]
+    fn pull_returns_none_on_underrun() {
+        let mut r = StereoPullResampler::new(48_000, 44_100); // step ~1.088 -> pulls >1 per out
+        let frames = [(0.0, 0.0), (1.0, -1.0)];
+        let mut idx = 0;
+        let mut pull = || {
+            let v = frames.get(idx).copied();
+            idx += 1;
+            v
+        };
+        // First frame primes + emits; subsequent calls eventually exhaust the source.
+        let mut produced = 0;
+        let mut hit_none = false;
+        for _ in 0..10 {
+            if r.next(&mut pull).is_some() {
+                produced += 1;
+            } else {
+                hit_none = true;
+                break;
+            }
+        }
+        assert!(produced >= 1, "should produce at least the primed frame");
+        assert!(hit_none, "should report underrun once the puller is dry");
+    }
+
+    /// Downsampling via pull consumes more input frames than it emits output frames.
+    #[test]
+    fn pull_downsample_consumes_more_than_it_emits() {
+        let mut r = StereoPullResampler::new(48_000, 24_000); // step = 2.0
+        let input: Vec<(f32, f32)> = (0..100).map(|i| (i as f32, -(i as f32))).collect();
+        let mut idx = 0;
+        let mut emitted = 0;
+        for _ in 0..40 {
+            let f = r.next(|| {
+                let v = input.get(idx).copied();
+                idx += 1;
+                v
+            });
+            if f.is_some() {
+                emitted += 1;
+            } else {
+                break;
+            }
+        }
+        // At step 2.0 we consume ~2 input frames per output frame.
+        assert!(idx > emitted, "consumed {idx} input, emitted {emitted} output");
+    }
+
+    /// A zero rate must not produce a zero `step` (which would spin `push`'s inner
+    /// `while self.next < 1.0` forever). Clamping makes the call terminate (W7).
+    #[test]
+    fn push_zero_rate_does_not_spin() {
+        let mut r = PushResampler::new(0, 48_000);
+        let mut count = 0usize;
+        // Feed two samples; with a clamped non-zero step this returns promptly.
+        r.push(0.0, |_| count += 1);
+        r.push(1.0, |_| count += 1);
+        // Reaching here at all is the assertion (no hang); some output is produced.
+        assert!(count >= 1);
+    }
+
+    /// A zero output rate must not make the pull resampler's segment-advance loop
+    /// spin. Clamping keeps `step` finite so `next` terminates (W7).
+    #[test]
+    fn pull_zero_out_rate_does_not_spin() {
+        let mut r = StereoPullResampler::new(48_000, 0);
+        let frames = [(0.0, 0.0), (1.0, 1.0), (2.0, 2.0)];
+        let mut idx = 0;
+        let got = r.next(|| {
+            let v = frames.get(idx).copied();
+            idx += 1;
+            v
+        });
+        // Terminates and yields the primed frame instead of hanging.
+        assert!(got.is_some());
+    }
+}
@@ -1,11 +1,11 @@
 //! Audio playout diagnostic probe.
 //!
-//! Drives a phase-continuous sine tone through the *real* PipeWire playback path
-//! (`PipeWireBackend::start_playback`), using the *same* fill-paced production
-//! the production mixer uses (`core/mod.rs`): generate a frame only while the
+//! Drives a phase-continuous sine tone through the *real* playback path
+//! (PipeWire on Linux, cpal/WASAPI on Windows), using the *same* fill-paced
+//! production the production mixer uses (`core/mod.rs`): generate a frame only while the
 //! playback ring is below `PLAYBACK_TARGET_SAMPLES`, so production tracks the
-//! PipeWire hardware clock. No network, no microphone — this isolates the local
-//! output path so we can confirm the clock-paced playout is glitch-free.
+//! hardware clock. No network, no microphone — this isolates the local output
+//! path so we can confirm the clock-paced playout is glitch-free.
 //!
 //! Use your ears on the tone (any click/pop is a glitch) together with the
 //! `playout-health:` lines tailed to stdout:
@@ -17,105 +17,235 @@
 //!
 //! Run:  cargo run --bin audio_probe -- [freq_hz] [seconds] [target_node]
 //!   e.g. cargo run --release --bin audio_probe -- 440 30
+//!
+//! This probe exercises the platform playback backend directly: PipeWire on Linux
+//! and cpal/WASAPI on Windows. Other targets use a stub that explains the limitation.

-use std::io::{BufRead, BufReader, Seek, SeekFrom};
-use std::sync::Arc;
-use std::sync::atomic::AtomicUsize;
-use std::sync::mpsc;
-use std::time::Duration;
-
-use peerspeak::audio::AudioBackend;
-use peerspeak::audio::pipewire_impl::PipeWireBackend;
-use peerspeak::core::jitter::FRAME_SAMPLES; // 960 mono frames = 20ms @ 48kHz
-
-const SAMPLE_RATE: f32 = 48_000.0;
-
-#[tokio::main]
-async fn main() {
-    let mut args = std::env::args().skip(1);
-    let freq: f32 = args.next().and_then(|s| s.parse().ok()).unwrap_or(440.0);
-    let secs: u64 = args.next().and_then(|s| s.parse().ok()).unwrap_or(30);
-    let target_node: Option<String> = args.next();
-
-    // The playout-health logger is quiet in normal operation (it only logs
-    // glitches); ask it for the full once-per-second heartbeat so the probe can
-    // show the steady-state numbers.
-    // SAFETY: set before any playback thread starts, so no concurrent env read.
-    unsafe { std::env::set_var("PEERSPEAK_AUDIO_VERBOSE", "1") };
-
-    println!("audio_probe: {freq} Hz tone for {secs}s through the real playback path.");
-    println!("Listen for clicks/pops; watch the playout-health lines below.\n");
-
-    // Tail the app log (where playout-health lines land) to stdout in the
-    // background so it's all in one terminal.
-    spawn_log_tailer();
-
-    let backend = PipeWireBackend::new();
-    let (tx, rx) = mpsc::channel::<Vec<i16>>();
-    let ring_fill = Arc::new(AtomicUsize::new(0));
-    if let Err(e) = backend.start_playback(rx, target_node, ring_fill.clone()) {
-        eprintln!("failed to start playback: {e}");
-        return;
-    }
-
-    // Phase-continuous sine, generated one 20ms frame at a time, fill-paced
-    // exactly like the production mixer: only produce while the ring is below
-    // target, so production tracks the PipeWire hardware clock.
-    use std::sync::atomic::Ordering;
-    let deadline = tokio::time::Instant::now() + Duration::from_secs(secs);
-    let mut n: u64 = 0; // running sample index keeps phase continuous across frames
-    while tokio::time::Instant::now() < deadline {
-        if ring_fill.load(Ordering::Relaxed) >= peerspeak::audio::PLAYBACK_TARGET_SAMPLES {
-            tokio::time::sleep(Duration::from_millis(2)).await;
-            continue;
-        }
-        let mut frame = Vec::with_capacity(FRAME_SAMPLES * peerspeak::audio::PLAYBACK_CHANNELS);
-        for _ in 0..FRAME_SAMPLES {
-            let t = n as f32 / SAMPLE_RATE;
-            // 0.25 amplitude: clearly audible but not harsh.
-            let sample = (0.25 * i16::MAX as f32 * (2.0 * std::f32::consts::PI * freq * t).sin()) as i16;
-            // Stereo playback bus: duplicate the probe tone to L/R.
-            frame.push(sample);
-            frame.push(sample);
-            n += 1;
-        }
-        if tx.send(frame).is_err() {
-            eprintln!("playback channel closed early");
-            break;
-        }
-    }
-
-    // Let the ring drain, then stop.
-    tokio::time::sleep(Duration::from_millis(300)).await;
-    let _ = backend.stop();
-    println!("\naudio_probe: done.");
+#[cfg(target_os = "linux")]
+fn main() {
+    unix_probe::run();
 }

-/// Open the app log, seek to the end, and echo new lines (the `playout-health:`
-/// reports) to stdout once they appear.
-fn spawn_log_tailer() {
-    let path = peerspeak::log_file_path();
-    std::thread::spawn(move || {
-        // Wait for the file to exist (first log_msg creates it).
-        let file = loop {
-            if let Ok(f) = std::fs::File::open(&path) {
-                break f;
+#[cfg(windows)]
+fn main() {
+    win_probe::run();
+}
+
+#[cfg(not(any(target_os = "linux", windows)))]
+fn main() {
+    eprintln!(
+        "audio_probe is only supported on Linux and Windows builds (it drives the platform playback backend directly)."
+    );
+}
+
+#[cfg(target_os = "linux")]
+mod unix_probe {
+    use std::io::{BufRead, BufReader, Seek, SeekFrom};
+    use std::sync::Arc;
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::mpsc;
+    use std::time::Duration;
+
+    use peerspeak::audio::AudioBackend;
+    use peerspeak::audio::pipewire_impl::PipeWireBackend;
+    use peerspeak::core::jitter::FRAME_SAMPLES; // 960 mono frames = 20ms @ 48kHz
+
+    const SAMPLE_RATE: f32 = 48_000.0;
+
+    #[tokio::main]
+    pub async fn run() {
+        let mut args = std::env::args().skip(1);
+        let freq: f32 = args.next().and_then(|s| s.parse().ok()).unwrap_or(440.0);
+        let secs: u64 = args.next().and_then(|s| s.parse().ok()).unwrap_or(30);
+        let target_node: Option<String> = args.next();
+
+        // The playout-health logger is quiet in normal operation (it only logs
+        // glitches); ask it for the full once-per-second heartbeat so the probe can
+        // show the steady-state numbers.
+        // SAFETY: set before any playback thread starts, so no concurrent env read.
+        unsafe { std::env::set_var("PEERSPEAK_AUDIO_VERBOSE", "1") };
+
+        println!("audio_probe: {freq} Hz tone for {secs}s through the real playback path.");
+        println!("Listen for clicks/pops; watch the playout-health lines below.\n");
+
+        // Tail the app log (where playout-health lines land) to stdout in the
+        // background so it's all in one terminal.
+        spawn_log_tailer();
+
+        let backend = PipeWireBackend::new();
+        let (tx, rx) = mpsc::channel::<Vec<i16>>();
+        let ring_fill = Arc::new(AtomicUsize::new(0));
+        if let Err(e) = backend.start_playback(rx, target_node, ring_fill.clone()) {
+            eprintln!("failed to start playback: {e}");
+            return;
+        }
+
+        // Phase-continuous sine, generated one 20ms frame at a time, fill-paced
+        // exactly like the production mixer: only produce while the ring is below
+        // target, so production tracks the PipeWire hardware clock.
+        use std::sync::atomic::Ordering;
+        let deadline = tokio::time::Instant::now() + Duration::from_secs(secs);
+        let mut n: u64 = 0; // running sample index keeps phase continuous across frames
+        while tokio::time::Instant::now() < deadline {
+            if ring_fill.load(Ordering::Relaxed) >= peerspeak::audio::PLAYBACK_TARGET_SAMPLES {
+                tokio::time::sleep(Duration::from_millis(2)).await;
+                continue;
            }
-            std::thread::sleep(Duration::from_millis(100));
-        };
-        let mut reader = BufReader::new(file);
-        let _ = reader.seek(SeekFrom::End(0));
-        loop {
-            let mut line = String::new();
-            match reader.read_line(&mut line) {
-                Ok(0) => std::thread::sleep(Duration::from_millis(150)),
-                Ok(_) => {
-                    if line.contains("playout-health:") {
-                        print!("{line}");
-                    }
+            let mut frame = Vec::with_capacity(FRAME_SAMPLES * peerspeak::audio::PLAYBACK_CHANNELS);
+            for _ in 0..FRAME_SAMPLES {
+                let t = n as f32 / SAMPLE_RATE;
+                // 0.25 amplitude: clearly audible but not harsh.
+                let sample =
+                    (0.25 * i16::MAX as f32 * (2.0 * std::f32::consts::PI * freq * t).sin()) as i16;
+                // Stereo playback bus: duplicate the probe tone to L/R.
+                frame.push(sample);
+                frame.push(sample);
+                n += 1;
+            }
+            if tx.send(frame).is_err() {
+                eprintln!("playback channel closed early");
+                break;
+            }
+        }
+
+        // Let the ring drain, then stop.
+        tokio::time::sleep(Duration::from_millis(300)).await;
+        let _ = backend.stop();
+        println!("\naudio_probe: done.");
+    }
+
+    /// Open the app log, seek to the end, and echo new lines (the `playout-health:`
+    /// reports) to stdout once they appear.
+    fn spawn_log_tailer() {
+        let path = peerspeak::log_file_path();
+        std::thread::spawn(move || {
+            // Wait for the file to exist (first log_msg creates it).
+            let file = loop {
+                if let Ok(f) = std::fs::File::open(&path) {
+                    break f;
                }
-                Err(_) => std::thread::sleep(Duration::from_millis(150)),
+                std::thread::sleep(Duration::from_millis(100));
+            };
+            let mut reader = BufReader::new(file);
+            let _ = reader.seek(SeekFrom::End(0));
+            loop {
+                let mut line = String::new();
+                match reader.read_line(&mut line) {
+                    Ok(0) => std::thread::sleep(Duration::from_millis(150)),
+                    Ok(_) => {
+                        if line.contains("playout-health:") {
+                            print!("{line}");
+                        }
+                    }
+                    Err(_) => std::thread::sleep(Duration::from_millis(150)),
+                }
+            }
+        });
+    }
+}
+
+#[cfg(windows)]
+mod win_probe {
+    use std::io::{BufRead, BufReader, Seek, SeekFrom};
+    use std::sync::Arc;
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::mpsc;
+    use std::time::Duration;
+
+    use peerspeak::audio::AudioBackend;
+    use peerspeak::audio::cpal_impl::CpalBackend;
+    use peerspeak::core::jitter::FRAME_SAMPLES; // 960 mono frames = 20ms @ 48kHz
+
+    const SAMPLE_RATE: f32 = 48_000.0;
+
+    #[tokio::main]
+    pub async fn run() {
+        let mut args = std::env::args().skip(1);
+        let freq: f32 = args.next().and_then(|s| s.parse().ok()).unwrap_or(440.0);
+        let secs: u64 = args.next().and_then(|s| s.parse().ok()).unwrap_or(30);
+        let target_node: Option<String> = args.next();
+
+        // The playout-health logger is quiet in normal operation (it only logs
+        // glitches); ask it for the full once-per-second heartbeat so the probe can
+        // show the steady-state numbers.
+        // SAFETY: set before any playback thread starts, so no concurrent env read.
+        unsafe { std::env::set_var("PEERSPEAK_AUDIO_VERBOSE", "1") };
+
+        println!("audio_probe: {freq} Hz tone for {secs}s through the real playback path.");
+        println!("Listen for clicks/pops; watch the playout-health lines below.\n");
+
+        // Tail the app log (where playout-health lines land) to stdout in the
+        // background so it's all in one terminal.
+        spawn_log_tailer();
+
+        let backend = CpalBackend::new();
+        let (tx, rx) = mpsc::channel::<Vec<i16>>();
+        let ring_fill = Arc::new(AtomicUsize::new(0));
+        if let Err(e) = backend.start_playback(rx, target_node, ring_fill.clone()) {
+            eprintln!("failed to start playback: {e}");
+            return;
+        }
+
+        // Phase-continuous sine, generated one 20ms frame at a time, fill-paced
+        // exactly like the production mixer: only produce while the ring is below
+        // target, so production tracks the cpal/WASAPI hardware clock.
+        use std::sync::atomic::Ordering;
+        let deadline = tokio::time::Instant::now() + Duration::from_secs(secs);
+        let mut n: u64 = 0; // running sample index keeps phase continuous across frames
+        while tokio::time::Instant::now() < deadline {
+            if ring_fill.load(Ordering::Relaxed) >= peerspeak::audio::PLAYBACK_TARGET_SAMPLES {
+                tokio::time::sleep(Duration::from_millis(2)).await;
+                continue;
+            }
+            let mut frame = Vec::with_capacity(FRAME_SAMPLES * peerspeak::audio::PLAYBACK_CHANNELS);
+            for _ in 0..FRAME_SAMPLES {
+                let t = n as f32 / SAMPLE_RATE;
+                // 0.25 amplitude: clearly audible but not harsh.
+                let sample =
+                    (0.25 * i16::MAX as f32 * (2.0 * std::f32::consts::PI * freq * t).sin()) as i16;
+                // Stereo playback bus: duplicate the probe tone to L/R.
+                frame.push(sample);
+                frame.push(sample);
+                n += 1;
+            }
+            if tx.send(frame).is_err() {
+                eprintln!("playback channel closed early");
+                break;
            }
        }
-    });
+
+        // Let the ring drain, then stop.
+        tokio::time::sleep(Duration::from_millis(300)).await;
+        let _ = backend.stop();
+        println!("\naudio_probe: done.");
+    }
+
+    /// Open the app log, seek to the end, and echo new lines (the `playout-health:`
+    /// reports) to stdout once they appear.
+    fn spawn_log_tailer() {
+        let path = peerspeak::log_file_path();
+        std::thread::spawn(move || {
+            // Wait for the file to exist (first log_msg creates it).
+            let file = loop {
+                if let Ok(f) = std::fs::File::open(&path) {
+                    break f;
+                }
+                std::thread::sleep(Duration::from_millis(100));
+            };
+            let mut reader = BufReader::new(file);
+            let _ = reader.seek(SeekFrom::End(0));
+            loop {
+                let mut line = String::new();
+                match reader.read_line(&mut line) {
+                    Ok(0) => std::thread::sleep(Duration::from_millis(150)),
+                    Ok(_) => {
+                        if line.contains("playout-health:") {
+                            print!("{line}");
+                        }
+                    }
+                    Err(_) => std::thread::sleep(Duration::from_millis(150)),
+                }
+            }
+        });
+    }
 }
@@ -124,11 +124,10 @@ pub enum UiEvent {
    /// 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 },
-    /// The Discoverable time-box elapsed (W7 P6): the core auto-reverted our presence
-    /// posture to the carried `mode` (always `Normal`) and stopped publishing. The
-    /// GUI must mirror + persist this so its presence picker stops showing
-    /// Discoverable. Distinct from a user-driven change so the GUI knows to update
-    /// without having issued the command itself.
+    /// Core corrected the committed presence posture. Usually the Discoverable
+    /// 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 },
    /// Core finished orderly app shutdown and the GUI can exit.
    ShutdownComplete,
@@ -1,7 +1,7 @@
 pub mod messages;
 pub mod jitter;

-use crate::audio::{AudioBackend, pipewire_impl::PipeWireBackend};
+use crate::audio::{AudioBackend, PlatformAudioBackend};
 use crate::audio::eq::{Eq, EqSettings};
 use crate::codec::{AudioEncoder, opus_impl::OpusEncoder};
 use crate::core::jitter::{JitterBuffer, FRAME_SAMPLES};
@@ -13,6 +13,7 @@ use crate::network::{
 use crate::core::messages::{CoreCommand, UiEvent};

 use crate::config::{NetworkMode, RecordingMode};
+use crate::presence::PresenceMode;
 use crate::audio::multitrack::MultitrackRecorder;
 use iroh::{Endpoint, EndpointAddr, EndpointId, RelayMode, SecretKey, endpoint::presets, protocol::Router};
 use iroh_gossip::net::Gossip;
@@ -64,6 +65,32 @@ impl CoreController {
 /// clears from the room promptly.
 const RECONNECT_GRACE: Duration = Duration::from_secs(45);

+/// Opus frames sent by our encoder are one 20 ms mono frame, normally far below
+/// this. 4000 bytes still leaves room for large valid Opus packets (well above a
+/// 48 kHz / 60 ms frame) while bounding malicious datagram copy/decode churn.
+const MAX_OPUS_PAYLOAD: usize = 4000;
+
+/// If the Discoverable time-box tries to revert but discovery service reconfiguration
+/// fails, retry soon while keeping the UI in the still-possible publishing state.
+const DISCOVERY_REVERT_RETRY: Duration = Duration::from_secs(60);
+
+fn audio_datagram_len_ok(len: usize) -> bool {
+    (4..=4 + MAX_OPUS_PAYLOAD).contains(&len)
+}
+
+fn arm_discovery_retry(
+    discovery_deadline: &mut Option<tokio::time::Instant>,
+    now: tokio::time::Instant,
+) {
+    let retry_deadline = now + DISCOVERY_REVERT_RETRY;
+    if discovery_deadline
+        .map(|current| current > retry_deadline)
+        .unwrap_or(true)
+    {
+        *discovery_deadline = Some(retry_deadline);
+    }
+}
+
 /// Per-peer reconnect grace timers (see [`RECONNECT_GRACE`]). Shared between the
 /// room-event task (which arms one on a transient drop and cancels it on a
 /// gossip rejoin) and the conn-event task (which cancels it when the audio link
@@ -110,6 +137,7 @@ fn arm_grace_timer(
    let handle = tokio::spawn(async move {
        tokio::time::sleep(grace).await;
        crate::log_msg(&format!("Reconnect grace expired; evicting peer {:?}", peer_id));
+        transport_evict.remove_audio_sender(peer_id);
        transport_evict.disconnect_peer(peer_id).await;
        jitter_evict.lock().await.remove(&peer_id);
        // Scrub our internal state *before* announcing the eviction, so anything
@@ -209,7 +237,7 @@ fn run_mic_monitor(
 /// Stops a standalone mic monitor if one is running. MUST NOT be called while a
 /// room session is active — `backend.stop()` would also tear down the call's
 /// capture/playback. Monitor and session are mutually exclusive by construction.
-fn stop_mic_monitor(backend: &PipeWireBackend, monitor: Option<MicMonitor>) {
+fn stop_mic_monitor(backend: &PlatformAudioBackend, monitor: Option<MicMonitor>) {
    if let Some(m) = monitor {
        let _ = backend.stop();
        let _ = m.thread.join();
@@ -343,6 +371,7 @@ impl ConnEventHandler {
                // until the grace timer or the slow gossip Leave.
                cancel_grace_timer(&self.grace_timers, &id);
                self.seen_connected.lock().unwrap().remove(&id);
+                self.transport.remove_audio_sender(id);
                self.transport.disconnect_peer(id).await;
                self.jitter.lock().await.remove(&id);
                let _ = self.ui_tx.send(UiEvent::PeerLeft { id }).await;
@@ -361,6 +390,7 @@ struct ActiveSession {
    grace_timers: GraceTimers,
    transport: Arc<IrohTransport>,
    /// Loaded PipeWire echo-cancel module (if enabled); unloads on drop.
+    #[cfg(target_os = "linux")]
    echo_cancel: Option<crate::audio::echo_cancel::EchoCancelGuard>,
    /// Our pixelpass screen-share host child while sharing (`kill_on_drop`, so it
    /// also dies if the session is dropped without an explicit stop).
@@ -371,7 +401,7 @@ struct ActiveSession {
 }

 impl ActiveSession {
-    async fn shutdown(mut self, audio_backend: Arc<PipeWireBackend>) {
+    async fn shutdown(mut self, audio_backend: Arc<PlatformAudioBackend>) {
        crate::log_msg("ActiveSession::shutdown started");
        // Tear down any screen-share children first so the host stops streaming
        // promptly (kill_on_drop is the backstop, but kill explicitly so viewers
@@ -402,6 +432,7 @@ impl ActiveSession {

        // Unload the echo-cancel module now that the audio streams releasing its
        // virtual nodes have stopped. (Dropping the guard runs `pactl unload`.)
+        #[cfg(target_os = "linux")]
        drop(self.echo_cancel);

        crate::log_msg("Leaving room...");
@@ -457,12 +488,11 @@ impl NetStack {
 /// `DnsAddressLookup`, mirroring the `N0` preset) is added when `plan.resolver`; the
 /// n0 DNS *publisher* (`PkarrPublisher`) when `plan.publisher`.
 ///
-/// Idempotent and reversible: it clears the whole service set and reinstalls exactly
-/// what the plan wants, so flipping `publisher` off simply drops the publisher (its
-/// republish task ends when the last clone is dropped, and the already-published
-/// record TTL-expires within ~30s) without an endpoint rebuild and without disturbing
-/// resolution. The brief clear→re-add window is a few synchronous calls; presence
-/// toggles are rare, so a concurrent dial racing it is not a practical concern.
+/// Idempotent and reversible: it builds the replacement services first, then clears
+/// the service set and reinstalls exactly what the plan wants. Flipping `publisher`
+/// off drops the publisher (its republish task ends when the last clone is dropped,
+/// and the already-published record TTL-expires within ~30s) without an endpoint
+/// rebuild and without disturbing resolution.
 fn apply_discovery(
    endpoint: &Endpoint,
    memory_lookup: &iroh::address_lookup::memory::MemoryLookup,
@@ -473,16 +503,34 @@ fn apply_discovery(
        pkarr::{PkarrPublisher, PkarrResolver},
    };
    let services = endpoint.address_lookup()?;
+    let pkarr_resolver = if plan.resolver {
+        Some(PkarrResolver::n0_dns().into_address_lookup(endpoint)?)
+    } else {
+        None
+    };
+    let dns_resolver = if plan.resolver {
+        Some(DnsAddressLookup::n0_dns().into_address_lookup(endpoint)?)
+    } else {
+        None
+    };
+    let publisher = if plan.publisher {
+        Some(PkarrPublisher::n0_dns().into_address_lookup(endpoint)?)
+    } else {
+        None
+    };
+
    services.clear();
    // Always keep the local, server-free lookup (this is what ticket/gossip dialing
    // depends on — it must survive every posture, including DirectOnly).
    services.add(memory_lookup.clone());
-    if plan.resolver {
-        services.add(PkarrResolver::n0_dns().into_address_lookup(endpoint)?);
-        services.add(DnsAddressLookup::n0_dns().into_address_lookup(endpoint)?);
+    if let Some(pkarr_resolver) = pkarr_resolver {
+        services.add(pkarr_resolver);
    }
-    if plan.publisher {
-        services.add(PkarrPublisher::n0_dns().into_address_lookup(endpoint)?);
+    if let Some(dns_resolver) = dns_resolver {
+        services.add(dns_resolver);
+    }
+    if let Some(publisher) = publisher {
+        services.add(publisher);
    }
    Ok(())
 }
@@ -538,7 +586,7 @@ async fn build_net_stack(
    // report) is injected via `friends_handler`.
    let router = Router::builder(endpoint.clone())
        .accept(iroh_gossip::net::GOSSIP_ALPN, gossip.clone())
-        .accept(b"peerspeak-audio", audio_router.clone())
+        .accept(crate::protocol::AUDIO_ALPN, audio_router.clone())
        .accept(
            crate::presence_net::FRIENDS_ALPN,
            crate::presence_net::FriendsProtocol::new(friends_handler),
@@ -634,7 +682,7 @@ async fn probe_friends_once(
        let ep = endpoint.clone();
        set.spawn(async move {
            match crate::presence_net::probe(&ep, addr).await {
-                Ok(reply) => crate::presence::interpret_pong(&reply).map(|p| (id, p)),
+                Ok((from, reply)) => crate::presence::interpret_pong(&reply, from).map(|p| (id, p)),
                Err(_) => None,
            }
        });
@@ -685,7 +733,7 @@ async fn run_core_loop(
    let known_peers: Arc<std::sync::Mutex<HashMap<String, HashMap<EndpointId, EndpointAddr>>>> =
        Arc::new(std::sync::Mutex::new(HashMap::new()));

-    let audio_backend = Arc::new(PipeWireBackend::new());
+    let audio_backend = Arc::new(PlatformAudioBackend::new());

    let is_muted = Arc::new(AtomicBool::new(false));
    let is_deafened = Arc::new(AtomicBool::new(false));
@@ -842,22 +890,64 @@ async fn run_core_loop(
            // W7 P6 time-box: Discoverable auto-reverts to Normal after DISCOVERY_TIMEBOX
            // so a publish beacon never stands indefinitely. The branch is disabled
            // (`if` guard) unless a deadline is armed; `unwrap_or_else` is unreachable
-            // belt-and-braces. On fire: stop publishing, drop to Normal, tell the GUI.
+            // belt-and-braces. On fire: stop publishing first, then commit Normal only
+            // if the endpoint's discovery services accepted the non-publishing plan.
            _ = tokio::time::sleep_until(
                discovery_deadline.unwrap_or_else(tokio::time::Instant::now),
            ), if discovery_deadline.is_some() => {
-                discovery_deadline = None;
-                *presence_mode.lock().unwrap() = crate::presence::PresenceMode::Normal;
-                let plan = crate::discovery::lookup_plan(network_mode, false);
-                if let Err(e) = apply_discovery(&net.endpoint, &net.memory_lookup, plan) {
-                    crate::log_msg(&format!("discovery: time-box revert failed: {e:#}"));
+                let previous_mode = *presence_mode.lock().unwrap();
+                if previous_mode != PresenceMode::Discoverable {
+                    discovery_deadline = None;
+                    continue;
+                }
+
+                let requested_mode = PresenceMode::Normal;
+                let now = tokio::time::Instant::now();
+                let plan = crate::discovery::lookup_plan(
+                    network_mode,
+                    requested_mode.publishes_to_discovery(),
+                );
+                let apply_result = apply_discovery(&net.endpoint, &net.memory_lookup, plan);
+                let (committed_mode, transition_error) =
+                    crate::discovery::resolve_presence_transition(
+                        previous_mode,
+                        requested_mode,
+                        apply_result.is_ok(),
+                    );
+                *presence_mode.lock().unwrap() = committed_mode;
+                discovery_deadline = if committed_mode == PresenceMode::Discoverable {
+                    Some(now + DISCOVERY_REVERT_RETRY)
+                } else {
+                    None
+                };
+
+                match apply_result {
+                    Ok(()) => {
+                        crate::log_msg(
+                            "discovery: Discoverable time-box elapsed → reverting to Normal",
+                        );
+                        let _ = ui_tx
+                            .send(UiEvent::PresenceModeReverted {
+                                mode: PresenceMode::Normal,
+                            })
+                            .await;
+                    }
+                    Err(e) => {
+                        crate::log_msg(&format!("discovery: time-box revert failed: {e:#}"));
+                        if committed_mode != requested_mode {
+                            let _ = ui_tx
+                                .send(UiEvent::PresenceModeReverted {
+                                    mode: committed_mode,
+                                })
+                                .await;
+                        }
+                        if let Some(message) = transition_error {
+                            let _ = ui_tx
+                                .send(UiEvent::Error(format!("{message} ({e:#})")))
+                                .await;
+                        }
+                    }
                }
-                crate::log_msg("discovery: Discoverable time-box elapsed → reverting to Normal");
-                let _ = ui_tx
-                    .send(UiEvent::PresenceModeReverted {
-                        mode: crate::presence::PresenceMode::Normal,
-                    })
-                    .await;
                continue;
            }
        };
@@ -923,7 +1013,12 @@ async fn run_core_loop(
                let ticket_str = if ticket.trim().is_empty() || ticket == "create" {
                    let topic_id: [u8; 32] = rand::random();
                    let host_addr = endpoint.addr();
-                    crate::log_msg(&format!("Creating room. host_addr={:?}, topic_id={:?}", host_addr, topic_id));
+                    crate::log_msg(&format!(
+                        "Creating room. host_id={}, host_addrs={}, topic={}",
+                        crate::short_id(&host_addr.id.to_string()),
+                        host_addr.addrs.len(),
+                        crate::short_bytes_hex(&topic_id)
+                    ));
                    // The creator's chosen cosmetic label rides in the ticket so
                    // every joiner inherits it; sanitize it before it leaves here.
                    let label = crate::sanitize::sanitize_name(&room_name);
@@ -931,7 +1026,10 @@ async fn run_core_loop(
                    ticket.to_string()
                } else {
                    let ticket_str = ticket.trim().to_string();
-                    crate::log_msg(&format!("Joining room with existing ticket={}", ticket_str));
+                    crate::log_msg(&format!(
+                        "Joining room with existing ticket={}",
+                        crate::redact_for_log(&ticket_str)
+                    ));
                    ticket_str
                };

@@ -970,7 +1068,17 @@ async fn run_core_loop(
                    .map(|peers| peers.values().cloned().collect())
                    .unwrap_or_default();

-                crate::log_msg(&format!("Attempting room_state.join with self_state={:?}, extra_bootstrap={:?}", self_state, extra_bootstrap.iter().map(|a| a.id).collect::<Vec<_>>()));
+                let extra_bootstrap_ids = extra_bootstrap
+                    .iter()
+                    .map(|a| crate::short_id(&a.id.to_string()))
+                    .collect::<Vec<_>>();
+                crate::log_msg(&format!(
+                    "Attempting room_state.join self_id={}, self_name={:?}, sharing={}, extra_bootstrap={:?}",
+                    crate::short_id(&self_state.addr.id.to_string()),
+                    self_state.name,
+                    self_state.sharing.is_some(),
+                    extra_bootstrap_ids
+                ));
                if let Err(e) = room_state.join(&ticket_str, self_state.clone(), extra_bootstrap).await {
                    crate::log_msg(&format!("Error room_state.join failed: {:?}", e));
                    let _ = ui_tx.send(UiEvent::Error(format!("Failed to join room: {}", e))).await;
@@ -989,7 +1097,9 @@ async fn run_core_loop(
                // The guard unloads the module on drop — including the early-return
                // paths below, since it's a local until moved into the session. On
                // any failure, warn and fall back to the direct devices.
+                #[cfg(target_os = "linux")]
                let mut echo_cancel_guard = None;
+                #[cfg(target_os = "linux")]
                let (capture_target, playback_target) = if echo_cancellation {
                    match crate::audio::echo_cancel::enable(
                        input_device.as_deref(),
@@ -1016,6 +1126,10 @@ async fn run_core_loop(
                } else {
                    (input_device.clone(), output_device.clone())
                };
+                #[cfg(not(target_os = "linux"))]
+                let _ = echo_cancellation;
+                #[cfg(not(target_os = "linux"))]
+                let (capture_target, playback_target) = (input_device.clone(), output_device.clone());

                if let Err(e) = audio_backend.start_capture(capture_tx, capture_target) {
                    let _ = ui_tx.send(UiEvent::Error(format!("Failed to start capture: {}", e))).await;
@@ -1135,8 +1249,12 @@ async fn run_core_loop(
                    };

                    while let Some((from_peer, bytes)) = datagram_rx.recv().await {
-                        if bytes.len() < 4 {
-                            continue; // malformed: missing sequence header
+                        if !transport_recv.audio_sender_admitted(from_peer) {
+                            continue;
+                        }
+                        if !audio_datagram_len_ok(bytes.len()) {
+                            // Malformed (< sequence header) or oversized Opus payload.
+                            continue;
                        }
                        let seq = u32::from_le_bytes([bytes[0], bytes[1], bytes[2], bytes[3]]);
                        let payload = bytes[4..].to_vec();
@@ -1368,6 +1486,7 @@ async fn run_core_loop(
                                // A (re)join means the peer is back — cancel any
                                // pending reconnect grace timer before re-adding it.
                                cancel_grace_timer(&grace_timers_events, &peer_id);
+                                transport_events.admit_audio_sender(peer_id);
                                // Establish the audio connection as soon as the peer
                                // is known (the transport dedupes the full-mesh race).
                                // Hand over the full address so reconnects can dial
@@ -1419,6 +1538,7 @@ async fn run_core_loop(
                                {
                                    peers.remove(&peer_id);
                                }
+                                transport_events.remove_audio_sender(peer_id);
                                transport_events.disconnect_peer(peer_id).await;
                                jitter_events.lock().await.remove(&peer_id);
                                let _ = ui_tx_events.send(UiEvent::PeerLeft { id: peer_id }).await;
@@ -1431,6 +1551,7 @@ async fn run_core_loop(
                                // it. Idempotent: an ordinary mute/unmute update just
                                // re-records the same address.
                                cancel_grace_timer(&grace_timers_events, &peer_id);
+                                transport_events.admit_audio_sender(peer_id);
                                transport_events.connect_peer(state.addr.clone()).await;
                                // Auto-heal a friend's saved address (W7) on the
                                // re-announce too — this is the path that catches a
@@ -1472,6 +1593,7 @@ async fn run_core_loop(
                                // hasn't recovered within RECONNECT_GRACE. A gossip
                                // rejoin (PeerJoined/PeerUpdated) or a transport
                                // reconnect (ConnEvent::Connected) cancels it first.
+                                transport_events.keep_audio_sender_for_reconnect_grace(peer_id);
                                let _ = ui_tx_events.send(UiEvent::PeerConnecting { id: peer_id }).await;
                                arm_grace_timer(
                                    &grace_timers_events,
@@ -1518,6 +1640,7 @@ async fn run_core_loop(
                    conn_event_task,
                    grace_timers,
                    transport: transport.clone(),
+                    #[cfg(target_os = "linux")]
                    echo_cancel: echo_cancel_guard,
                    screenshare_host: None,
                    screenshare_viewers: Vec::new(),
@@ -1693,17 +1816,26 @@ async fn run_core_loop(
            }

            CoreCommand::SetNetworkMode(mode) => {
-                network_mode = mode;
-                // Rebuild the persistent stack to the new posture immediately if
-                // idle; if a call is active, defer to the next Leave/Join so the
-                // live call isn't disrupted (preserves "applies on next join").
-                if active_session.is_none() {
-                    let lookup = net.memory_lookup.clone();
-                    net.shutdown().await;
-                    let publish = presence_mode.lock().unwrap().publishes_to_discovery();
-                    net = build_net_stack(secret_key.clone(), network_mode, lookup, friends_handler.clone(), publish).await?;
-                } else {
-                    net_rebuild_pending = true;
+                // Skip when the posture is unchanged. The GUI re-sends the saved
+                // network mode as part of its startup config-sync, and that mode
+                // usually already matches the freshly-built stack — rebuilding the
+                // iroh endpoint for an identical posture just churns the network
+                // and adds a needless ~1s teardown+rebuild bounce at every launch
+                // (seen on both Linux and Windows/Wine). A real change still
+                // rebuilds exactly as before.
+                if mode != network_mode {
+                    network_mode = mode;
+                    // Rebuild the persistent stack to the new posture immediately if
+                    // idle; if a call is active, defer to the next Leave/Join so the
+                    // live call isn't disrupted (preserves "applies on next join").
+                    if active_session.is_none() {
+                        let lookup = net.memory_lookup.clone();
+                        net.shutdown().await;
+                        let publish = presence_mode.lock().unwrap().publishes_to_discovery();
+                        net = build_net_stack(secret_key.clone(), network_mode, lookup, friends_handler.clone(), publish).await?;
+                    } else {
+                        net_rebuild_pending = true;
+                    }
                }
            }

@@ -1770,22 +1902,60 @@ async fn run_core_loop(
            }

            CoreCommand::SetPresenceMode(mode) => {
-                *presence_mode.lock().unwrap() = mode;
-                // W7 P6: re-apply n0 DNS discovery for the new posture (publish on iff
-                // Discoverable). Runtime — no endpoint rebuild; clears + reinstalls the
-                // address-lookup services. The resolver stays on regardless so we can
-                // still look up moved friends.
-                let plan = crate::discovery::lookup_plan(network_mode, mode.publishes_to_discovery());
-                if let Err(e) = apply_discovery(&net.endpoint, &net.memory_lookup, plan) {
-                    crate::log_msg(&format!("discovery: apply failed: {e:#}"));
+                let previous_mode = *presence_mode.lock().unwrap();
+                let now = tokio::time::Instant::now();
+
+                if previous_mode == mode {
+                    // Same-mode requests are no-ops for discovery wiring, but keep the
+                    // existing UX: re-selecting Discoverable restarts the clock.
+                    discovery_deadline = if mode == PresenceMode::Discoverable {
+                        Some(now + crate::discovery::DISCOVERY_TIMEBOX)
+                    } else {
+                        None
+                    };
+                    continue;
                }
-                // Arm (Discoverable) or cancel (any other posture) the auto-revert
-                // time-box. Re-selecting Discoverable restarts the clock.
-                discovery_deadline = if mode == crate::presence::PresenceMode::Discoverable {
-                    Some(tokio::time::Instant::now() + crate::discovery::DISCOVERY_TIMEBOX)
+
+                // W7 P6/S11: re-apply n0 DNS discovery for the requested posture
+                // first, then commit the presence mode only if the endpoint accepted
+                // that discovery plan. This keeps the UI truthful when dropping the
+                // publisher fails.
+                let plan =
+                    crate::discovery::lookup_plan(network_mode, mode.publishes_to_discovery());
+                let apply_result = apply_discovery(&net.endpoint, &net.memory_lookup, plan);
+                let (committed_mode, transition_error) =
+                    crate::discovery::resolve_presence_transition(
+                        previous_mode,
+                        mode,
+                        apply_result.is_ok(),
+                    );
+                *presence_mode.lock().unwrap() = committed_mode;
+
+                if committed_mode == PresenceMode::Discoverable {
+                    if apply_result.is_ok() && mode == PresenceMode::Discoverable {
+                        discovery_deadline = Some(now + crate::discovery::DISCOVERY_TIMEBOX);
+                    } else {
+                        arm_discovery_retry(&mut discovery_deadline, now);
+                    }
                } else {
-                    None
-                };
+                    discovery_deadline = None;
+                }
+
+                if let Err(e) = apply_result {
+                    crate::log_msg(&format!("discovery: apply failed: {e:#}"));
+                    if committed_mode != mode {
+                        let _ = ui_tx
+                            .send(UiEvent::PresenceModeReverted {
+                                mode: committed_mode,
+                            })
+                            .await;
+                    }
+                    if let Some(message) = transition_error {
+                        let _ = ui_tx
+                            .send(UiEvent::Error(format!("{message} ({e:#})")))
+                            .await;
+                    }
+                }
            }

            CoreCommand::SetRecordingMode(mode) => {
@@ -1987,8 +2157,8 @@ async fn run_core_loop(
 #[cfg(test)]
 mod tests {
    use super::{
-        apply_volume, frame_level, mix_frames, mix_stereo_frames, stereo_to_mono, MicLevelMeter,
-        MIC_LEVEL_REPORT_SAMPLES,
+        apply_volume, audio_datagram_len_ok, frame_level, mix_frames, mix_stereo_frames,
+        stereo_to_mono, MicLevelMeter, MAX_OPUS_PAYLOAD, MIC_LEVEL_REPORT_SAMPLES,
    };

    /// A frame of constant amplitude with the given sample count.
@@ -2005,6 +2175,15 @@ mod tests {
        assert!(m.push(&frame(1000, MIC_LEVEL_REPORT_SAMPLES)).is_some());
    }

+    #[test]
+    fn audio_datagram_length_gate_preserves_header_and_caps_payload() {
+        assert!(!audio_datagram_len_ok(0));
+        assert!(!audio_datagram_len_ok(3));
+        assert!(audio_datagram_len_ok(4));
+        assert!(audio_datagram_len_ok(4 + MAX_OPUS_PAYLOAD));
+        assert!(!audio_datagram_len_ok(5 + MAX_OPUS_PAYLOAD));
+    }
+
    #[test]
    fn mic_meter_holds_the_peak_across_the_window() {
        let mut m = MicLevelMeter::new();
@@ -8,14 +8,19 @@
 //! The model (from `docs/contacts-plan.md` P6, decided 2026-06-16):
 //! - **Resolving is always allowed on relay-capable modes** — a stationary friend
 //!   (typically in `Normal`) must be able to look up a friend who moved networks. A
-//!   resolve is a DNS query to n0 that publishes nothing; it only fires when a saved
-//!   address is stale and the dial falls through to discovery.
+//!   resolve is a DNS query to n0 that publishes nothing, but still exposes query
+//!   timing/source metadata to n0; it only fires when a saved address is stale and
+//!   the dial falls through to discovery.
 //! - **Publishing is gated on `Discoverable`** and asymmetric: only the mover
 //!   publishes their address to n0 DNS; everyone else just looks it up.
+//! - **Stopping publishing removes the local publisher service**; iroh does not
+//!   expose an explicit unpublish call here, so already-published pkarr records can
+//!   linger until their default ~30s TTL expires.
 //! - **`DirectOnly` is the explicit no-server posture** — neither resolve nor publish
 //!   ever touches n0 there, regardless of the Discoverable toggle.

 use crate::config::NetworkMode;
+use crate::presence::PresenceMode;
 use std::time::Duration;

 /// How long `Discoverable` stays on before auto-reverting to `Normal`. Discovery is
@@ -46,12 +51,43 @@ pub fn lookup_plan(network_mode: NetworkMode, want_publish: bool) -> LookupPlan
    match network_mode {
        // The explicit serverless posture: no n0 contact at all, even to resolve.
        // A Discoverable toggle here is intentionally inert.
-        NetworkMode::DirectOnly => LookupPlan { resolver: false, publisher: false },
+        NetworkMode::DirectOnly => LookupPlan {
+            resolver: false,
+            publisher: false,
+        },
        // Relay-capable: always resolve (so a stationary friend can find a mover);
        // publish only when the user opted into Discoverable.
-        NetworkMode::RelayNoDiscovery | NetworkMode::N0Full => {
-            LookupPlan { resolver: true, publisher: want_publish }
-        }
+        NetworkMode::RelayNoDiscovery | NetworkMode::N0Full => LookupPlan {
+            resolver: true,
+            publisher: want_publish,
+        },
+    }
+}
+
+/// Decide which presence mode may be committed after attempting to apply discovery
+/// services for `requested`.
+///
+/// On failure, keep the previous mode: it is the only locally truthful state because
+/// the endpoint's discovery services may still reflect the old posture. Same-mode
+/// requests are no-ops from a presence-truth perspective and do not surface an error.
+pub fn resolve_presence_transition(
+    previous: PresenceMode,
+    requested: PresenceMode,
+    apply_ok: bool,
+) -> (PresenceMode, Option<String>) {
+    if previous == requested {
+        return (previous, None);
+    }
+
+    if apply_ok {
+        (requested, None)
+    } else {
+        (
+            previous,
+            Some(format!(
+                "Couldn't update discovery mode; keeping {previous}."
+            )),
+        )
    }
 }

@@ -64,12 +100,18 @@ mod tests {
        for mode in [NetworkMode::RelayNoDiscovery, NetworkMode::N0Full] {
            assert_eq!(
                lookup_plan(mode, false),
-                LookupPlan { resolver: true, publisher: false },
+                LookupPlan {
+                    resolver: true,
+                    publisher: false
+                },
                "{mode:?}: resolve always on, no publish when not Discoverable"
            );
            assert_eq!(
                lookup_plan(mode, true),
-                LookupPlan { resolver: true, publisher: true },
+                LookupPlan {
+                    resolver: true,
+                    publisher: true
+                },
                "{mode:?}: Discoverable adds publish on top of resolve"
            );
        }
@@ -79,12 +121,18 @@ mod tests {
    fn direct_only_never_touches_n0_even_when_discoverable() {
        assert_eq!(
            lookup_plan(NetworkMode::DirectOnly, false),
-            LookupPlan { resolver: false, publisher: false }
+            LookupPlan {
+                resolver: false,
+                publisher: false
+            }
        );
        // The serverless posture overrides the Discoverable request entirely.
        assert_eq!(
            lookup_plan(NetworkMode::DirectOnly, true),
-            LookupPlan { resolver: false, publisher: false }
+            LookupPlan {
+                resolver: false,
+                publisher: false
+            }
        );
    }

@@ -92,4 +140,42 @@ mod tests {
    fn timebox_is_thirty_minutes() {
        assert_eq!(DISCOVERY_TIMEBOX, Duration::from_secs(1800));
    }
+
+    #[test]
+    fn presence_transition_commits_requested_mode_after_successful_apply() {
+        assert_eq!(
+            resolve_presence_transition(PresenceMode::Normal, PresenceMode::Discoverable, true),
+            (PresenceMode::Discoverable, None)
+        );
+    }
+
+    #[test]
+    fn presence_transition_keeps_previous_mode_when_apply_fails() {
+        let (mode, err) =
+            resolve_presence_transition(PresenceMode::Normal, PresenceMode::Discoverable, false);
+
+        assert_eq!(mode, PresenceMode::Normal);
+        assert!(err.unwrap().contains("keeping Normal"));
+    }
+
+    #[test]
+    fn presence_transition_keeps_discoverable_when_off_transition_fails() {
+        let (mode, err) =
+            resolve_presence_transition(PresenceMode::Discoverable, PresenceMode::Normal, false);
+
+        assert_eq!(mode, PresenceMode::Discoverable);
+        assert!(err.unwrap().contains("keeping Discoverable"));
+    }
+
+    #[test]
+    fn presence_transition_same_mode_is_noop_without_error() {
+        assert_eq!(
+            resolve_presence_transition(
+                PresenceMode::Discoverable,
+                PresenceMode::Discoverable,
+                false
+            ),
+            (PresenceMode::Discoverable, None)
+        );
+    }
 }
@@ -2,6 +2,7 @@ pub mod audio;
 pub mod codec;
 pub mod dsp;
 pub mod network;
+pub mod protocol;
 pub mod core;
 pub mod app;
 pub mod config;
@@ -18,9 +19,16 @@ pub mod recents;
 pub mod discovery;
 pub mod hotkeys;

-use std::path::PathBuf;
+use std::fs::File;
+use std::path::{Path, PathBuf};
 use std::sync::OnceLock;

+const LOG_MAX_BYTES: u64 = 5 * 1024 * 1024;
+// Owner-only log permissions are a Unix concept (mode bits); on Windows the log
+// inherits the directory's default ACL. Only referenced under `cfg(unix)`.
+#[cfg(unix)]
+const LOG_MODE: u32 = 0o600;
+
 /// Resolves the log file path once: `$XDG_STATE_HOME/peerspeak/peerspeak.log`
 /// (via `dirs::state_dir`), falling back to the system temp dir. Computed lazily
 /// so we never hardcode a per-user path.
@@ -43,6 +51,74 @@ pub fn log_file_path() -> PathBuf {
    log_path().clone()
 }

+/// Short, human-matchable id prefix for diagnostics. Never use this where the
+/// full value is needed for protocol behavior.
+pub fn short_id(id: &str) -> String {
+    id.chars().take(8).collect()
+}
+
+/// Redact a capability-bearing value for logs while keeping a tiny prefix for
+/// support correlation. Tickets and endpoint addresses are bearer capabilities:
+/// logging the full string is equivalent to leaking the room/share.
+pub fn redact_for_log(value: &str) -> String {
+    let value = value.trim();
+    if value.is_empty() {
+        "<redacted:empty>".to_string()
+    } else {
+        format!("<redacted:{}...>", short_id(value))
+    }
+}
+
+pub fn short_bytes_hex(bytes: &[u8]) -> String {
+    bytes.iter()
+        .take(6)
+        .map(|b| format!("{b:02x}"))
+        .collect::<Vec<_>>()
+        .join("")
+}
+
+fn rotated_log_path(path: &Path) -> PathBuf {
+    let file_name = path.file_name().and_then(|n| n.to_str()).unwrap_or("peerspeak.log");
+    path.with_file_name(format!("{file_name}.1"))
+}
+
+fn prepare_log_file(path: &Path) -> std::io::Result<File> {
+    prepare_log_file_with_limit(path, LOG_MAX_BYTES)
+}
+
+fn prepare_log_file_with_limit(path: &Path, max_bytes: u64) -> std::io::Result<File> {
+    if let Some(parent) = path.parent() {
+        let _ = std::fs::create_dir_all(parent);
+    }
+
+    if std::fs::metadata(path).is_ok_and(|m| m.len() > max_bytes) {
+        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 mut opts = std::fs::OpenOptions::new();
+    opts.create(true).append(true);
+    // The log can carry capability-bearing values (redacted, but still): keep it
+    // owner-only on Unix via the open mode. Windows has no mode bits; it inherits
+    // the directory ACL, so this hardening is Unix-only.
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::OpenOptionsExt;
+        opts.mode(LOG_MODE);
+    }
+    let file = opts.open(path)?;
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        // Re-assert the mode in case the file pre-existed with looser perms.
+        let _ = std::fs::set_permissions(path, std::fs::Permissions::from_mode(LOG_MODE));
+    }
+    Ok(file)
+}
+
 pub fn log_msg(msg: &str) {
    // Format the whole line into one buffer first, then emit it with a single
    // `write_all`. The file is opened with `O_APPEND`, so a lone `write()` is
@@ -52,12 +128,65 @@ pub fn log_msg(msg: &str) {
        Ok(time) => format!("[{}.{:03}] {}\n", time.as_secs(), time.subsec_millis(), msg),
        Err(_) => format!("{}\n", msg),
    };
-    if let Ok(mut file) = std::fs::OpenOptions::new()
-        .create(true)
-        .append(true)
-        .open(log_path())
-    {
+    if let Ok(mut file) = prepare_log_file(log_path()) {
        use std::io::Write;
        let _ = file.write_all(line.as_bytes());
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Write;
+    #[cfg(unix)]
+    use std::os::unix::fs::PermissionsExt;
+
+    fn temp_log_dir() -> PathBuf {
+        let stamp = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos();
+        std::env::temp_dir().join(format!("peerspeak-log-test-{}-{stamp}", std::process::id()))
+    }
+
+    #[test]
+    fn redaction_keeps_only_a_short_prefix() {
+        let secret = "abcdefghijklmnopqrstuvwxyz";
+        let redacted = redact_for_log(secret);
+        assert!(redacted.contains("abcdefgh"));
+        assert!(!redacted.contains("ijklmnopqrstuvwxyz"));
+        assert_eq!(redact_for_log("   "), "<redacted:empty>");
+    }
+
+    // Owner-only log perms are a Unix concept; on Windows the file inherits the
+    // directory ACL and there's no mode to assert.
+    #[cfg(unix)]
+    #[test]
+    fn log_file_is_created_private() {
+        let dir = temp_log_dir();
+        let path = dir.join("peerspeak.log");
+        let _file = prepare_log_file(&path).unwrap();
+
+        let mode = std::fs::metadata(&path).unwrap().permissions().mode() & 0o777;
+        assert_eq!(mode, LOG_MODE);
+        let _ = std::fs::remove_dir_all(dir);
+    }
+
+    #[test]
+    fn oversized_log_is_rotated_on_open() {
+        let dir = temp_log_dir();
+        std::fs::create_dir_all(&dir).unwrap();
+        let path = dir.join("peerspeak.log");
+        {
+            let mut file = std::fs::File::create(&path).unwrap();
+            file.write_all(b"oversized").unwrap();
+        }
+
+        let _file = prepare_log_file_with_limit(&path, 4).unwrap();
+        let rotated = rotated_log_path(&path);
+
+        assert_eq!(std::fs::read_to_string(rotated).unwrap(), "oversized");
+        assert_eq!(std::fs::metadata(&path).unwrap().len(), 0);
+        let _ = std::fs::remove_dir_all(dir);
+    }
+}
@@ -12,7 +12,7 @@ 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.
-const GOSSIP_SIG_DOMAIN: &str = "peerspeak-gossip-v1";
+use crate::protocol::GOSSIP_SIG_DOMAIN;

 /// How far a payload's sender-stamped timestamp may differ from local time
 /// before it's rejected as stale (replayed) or implausibly future. Bounds the
@@ -43,7 +43,7 @@ impl std::fmt::Debug for GossipPayload {
        f.debug_struct("GossipPayload")
            .field("author", &self.author)
            .field("ts", &self.ts)
-            .field("msg", &self.msg)
+            .field("msg_kind", &gossip_message_kind(&self.msg))
            .finish_non_exhaustive()
    }
 }
@@ -79,6 +79,58 @@ enum GossipReject {
    BadSignature,
    /// Timestamp outside the freshness window — stale (replay) or implausibly future.
    OutOfWindow,
+    /// A signed Announce advertised an address for a different node id.
+    AnnounceAddressMismatch,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+enum StateMutationKind {
+    Announce,
+    Leave,
+}
+
+fn gossip_message_kind(msg: &GossipMessage) -> &'static str {
+    match msg {
+        GossipMessage::Announce(_) => "Announce",
+        GossipMessage::Leave => "Leave",
+        GossipMessage::Chat { .. } => "Chat",
+    }
+}
+
+fn state_mutation_kind(msg: &GossipMessage) -> Option<StateMutationKind> {
+    match msg {
+        GossipMessage::Announce(_) => Some(StateMutationKind::Announce),
+        GossipMessage::Leave => Some(StateMutationKind::Leave),
+        GossipMessage::Chat { .. } => None,
+    }
+}
+
+fn admit_state_mutation(
+    seen: &mut HashMap<(EndpointId, StateMutationKind), u64>,
+    author: EndpointId,
+    msg: &GossipMessage,
+    ts: u64,
+) -> bool {
+    let Some(kind) = state_mutation_kind(msg) else {
+        return true;
+    };
+    let key = (author, kind);
+    if seen.get(&key).is_some_and(|last_ts| ts <= *last_ts) {
+        return false;
+    }
+    seen.insert(key, ts);
+    true
+}
+
+fn peer_state_for_log(state: &PeerState) -> String {
+    format!(
+        "name={:?}, muted={}, addr_id={}, addrs={}, sharing={}",
+        state.name,
+        state.is_muted,
+        crate::short_id(&state.addr.id.to_string()),
+        state.addr.addrs.len(),
+        state.sharing.is_some()
+    )
 }

 /// Authenticate a received payload against the room topic and local clock. The
@@ -99,6 +151,10 @@ fn verify_gossip(
    if now_ms.abs_diff(payload.ts) > window_ms {
        return Err(GossipReject::OutOfWindow);
    }
+    if let GossipMessage::Announce(state) = &payload.msg
+        && state.addr.id != payload.author {
+        return Err(GossipReject::AnnounceAddressMismatch);
+    }
    Ok(())
 }

@@ -185,11 +241,25 @@ impl RoomState for IrohGossipState {
        self_state: PeerState,
        extra_bootstrap: Vec<EndpointAddr>,
    ) -> Result<(), NetError> {
-        crate::log_msg(&format!("RoomState::join: self_id={:?}, self_name={:?}, ticket={}", self_state.addr.id, self_state.name, ticket_str));
+        crate::log_msg(&format!(
+            "RoomState::join: self_id={}, self_name={:?}, ticket={}",
+            crate::short_id(&self_state.addr.id.to_string()),
+            self_state.name,
+            crate::redact_for_log(ticket_str)
+        ));
        let ticket = ticket_str.parse::<PeerSpeakTicket>()?;
-        let topic_id = TopicId::from_bytes(ticket.topic_id);
+        // Version-namespace the subscribed topic (VERSIONING.md): peers on a
+        // different gossip protocol version derive a different topic from the same
+        // ticket and never share a swarm. The raw ticket.topic_id stays the room
+        // identity (and what signatures bind, below).
+        let topic_id = TopicId::from_bytes(crate::protocol::versioned_topic(ticket.topic_id));

-        crate::log_msg(&format!("Parsed ticket. host_id={:?}, host_addrs={:?}, topic={:?}", ticket.host_addr.id, ticket.host_addr.addrs, topic_id));
+        crate::log_msg(&format!(
+            "Parsed ticket. host_id={}, host_addrs={}, topic={}",
+            crate::short_id(&ticket.host_addr.id.to_string()),
+            ticket.host_addr.addrs.len(),
+            crate::short_bytes_hex(&ticket.topic_id)
+        ));

        // Stop any currently running topic
        let _ = self.leave().await;
@@ -236,6 +306,7 @@ impl RoomState for IrohGossipState {

        let handle = tokio::spawn(async move {
            crate::log_msg(&format!("Spawned gossip topic loop for self_id={:?}", self_id));
+            let mut state_mutations_seen = HashMap::new();

            // Broadcast initial state
            let initial_payload = {
@@ -285,7 +356,26 @@ impl RoomState for IrohGossipState {
                                    continue;
                                }

-                                crate::log_msg(&format!("Gossip Event::Received from author={:?}, payload={:?}", payload.author, payload.msg));
+                                if !admit_state_mutation(
+                                    &mut state_mutations_seen,
+                                    payload.author,
+                                    &payload.msg,
+                                    payload.ts,
+                                ) {
+                                    crate::log_msg(&format!(
+                                        "Gossip dropped replayed state mutation author={}, kind={}, ts={}",
+                                        crate::short_id(&payload.author.to_string()),
+                                        gossip_message_kind(&payload.msg),
+                                        payload.ts
+                                    ));
+                                    continue;
+                                }
+
+                                crate::log_msg(&format!(
+                                    "Gossip Event::Received author={}, kind={}",
+                                    crate::short_id(&payload.author.to_string()),
+                                    gossip_message_kind(&payload.msg)
+                                ));

                                match payload.msg {
                                    GossipMessage::Announce(mut state) => {
@@ -299,6 +389,10 @@ impl RoomState for IrohGossipState {
                                        // monogram, so a malformed/oversized/bomb
                                        // image can't crash or exhaust us (W4).
                                        state.avatar = state.avatar.sanitize_incoming();
+                                        // 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);
                                        let (is_new, state_changed) = {
                                            let mut peer_map = peers.lock().unwrap();
                                            let is_new = !peer_map.contains_key(&payload.author);
@@ -310,11 +404,19 @@ impl RoomState for IrohGossipState {
                                        };

                                        if is_new {
-                                            crate::log_msg(&format!("Gossip new peer joined: {:?}, state: {:?}", payload.author, state));
+                                            crate::log_msg(&format!(
+                                                "Gossip new peer joined: {}, state: {}",
+                                                crate::short_id(&payload.author.to_string()),
+                                                peer_state_for_log(&state)
+                                            ));
                                            address_lookup.add_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: {:?}", payload.author, state));
+                                            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;
                                        }
                                    }
@@ -390,7 +492,10 @@ impl RoomState for IrohGossipState {
    }

    async fn update_self_state(&self, self_state: PeerState) -> Result<(), NetError> {
-        crate::log_msg(&format!("RoomState::update_self_state: state={:?}", self_state));
+        crate::log_msg(&format!(
+            "RoomState::update_self_state: state: {}",
+            peer_state_for_log(&self_state)
+        ));
        *self.self_state.lock().unwrap() = Some(self_state.clone());

        let sender_opt = self.active_sender.lock().unwrap().clone();
@@ -489,11 +594,10 @@ mod tests {
    use super::*;
    use crate::network::PeerState;
    use iroh::SecretKey;
+    use std::collections::HashMap;

-    fn sample_peer_state() -> PeerState {
-        let secret = SecretKey::generate();
-        let public = secret.public();
-        let addr = iroh::EndpointAddr::from(public);
+    fn sample_peer_state_for(id: EndpointId) -> PeerState {
+        let addr = iroh::EndpointAddr::from(id);
        PeerState {
            name: "TestPeerGossip".to_string(),
            is_muted: true,
@@ -563,7 +667,7 @@ mod tests {
    fn test_gossip_payload_announce_round_trip() {
        let secret = SecretKey::generate();
        let topic = [9u8; 32];
-        let peer_state = sample_peer_state();
+        let peer_state = sample_peer_state_for(secret.public());
        let payload = sign_gossip(&secret, &topic, 1000, GossipMessage::Announce(peer_state.clone()));

        let serialized = serde_json::to_string(&payload).unwrap();
@@ -732,5 +836,60 @@ mod tests {
        // Within the window (clock skew tolerance) → accepted.
        assert!(verify_gossip(&p, &topic, 1_000_000 + GOSSIP_FRESHNESS_MS - 1, GOSSIP_FRESHNESS_MS).is_ok());
    }
-}

+    #[test]
+    fn verify_rejects_announce_with_address_for_another_identity() {
+        let signer = SecretKey::generate();
+        let advertised = SecretKey::generate();
+        let topic = [6u8; 32];
+        let state = sample_peer_state_for(advertised.public());
+        let p = sign_gossip(&signer, &topic, 5_000, GossipMessage::Announce(state));
+
+        assert_eq!(
+            verify_gossip(&p, &topic, 5_000, GOSSIP_FRESHNESS_MS),
+            Err(GossipReject::AnnounceAddressMismatch)
+        );
+    }
+
+    #[test]
+    fn state_mutation_replay_gate_drops_replayed_leave_and_announce() {
+        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));
+
+        let announce = GossipMessage::Announce(sample_peer_state_for(author));
+        assert!(admit_state_mutation(&mut seen, author, &announce, 10));
+        assert!(!admit_state_mutation(&mut seen, author, &announce, 10));
+        assert!(!admit_state_mutation(&mut seen, author, &announce, 9));
+        assert!(admit_state_mutation(&mut seen, author, &announce, 12));
+    }
+
+    #[test]
+    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 };
+        let earlier_chat = GossipMessage::Chat { name: "A".into(), text: "earlier".into(), ts: 100 };
+
+        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");
+    }
+
+    #[test]
+    fn state_mutation_replay_gate_is_per_author_and_kind() {
+        let author = fresh_id();
+        let other = fresh_id();
+        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, &announce, 5));
+        assert!(admit_state_mutation(&mut seen, other, &GossipMessage::Leave, 5));
+    }
+}
@@ -5,11 +5,11 @@ use bytes::Bytes;
 use tokio::sync::mpsc;
 use tokio::sync::mpsc::Receiver;
 use std::sync::{Arc, Mutex as StdMutex};
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::time::Duration;
 use async_trait::async_trait;

-const AUDIO_ALPN: &[u8] = b"peerspeak-audio";
+use crate::protocol::AUDIO_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.
@@ -56,6 +56,10 @@ struct Shared {
    /// supervisor inserts its connection when the link comes up and removes it
    /// when the link dies.
    live_conns: StdMutex<HashMap<EndpointId, Connection>>,
+    /// Core-owned audio admission snapshot for this room session. It mirrors the
+    /// verified gossip roster plus peers still inside reconnect grace; transport
+    /// connections alone never mutate this set.
+    admitted_audio: StdMutex<HashSet<EndpointId>>,
    incoming_tx: mpsc::Sender<(EndpointId, Bytes)>,
    /// Best-effort link-state notifications for the UI (connecting / connected).
    conn_events_tx: mpsc::Sender<ConnEvent>,
@@ -112,6 +116,16 @@ impl Shared {
            crate::log_msg(&format!("Transport: stopped supervising peer {:?}", peer_id));
        }
    }
+
+    fn audio_sender_admitted(&self, peer_id: EndpointId) -> bool {
+        let roster = self.admitted_audio.lock().unwrap();
+        audio_sender_admitted(peer_id, &roster)
+    }
+
+    fn apply_audio_admission(&self, peer_id: EndpointId, event: AudioAdmissionEvent) {
+        let mut roster = self.admitted_audio.lock().unwrap();
+        apply_audio_admission_event(&mut roster, peer_id, event);
+    }
 }

 /// Why a peer's live-link wait woke up.
@@ -135,6 +149,41 @@ fn is_graceful_leave(err: &ConnectionError) -> bool {
    matches!(err, ConnectionError::ApplicationClosed(frame) if frame.error_code == VarInt::from_u32(GOODBYE_CODE))
 }

+/// Pure S8 membership decision: iroh already authenticated `remote` as the
+/// connection's endpoint id, so audio admission is exactly live roster membership.
+pub(crate) fn audio_sender_admitted(remote: EndpointId, roster: &HashSet<EndpointId>) -> bool {
+    roster.contains(&remote)
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum AudioAdmissionEvent {
+    /// A signed gossip Announce/Update says the peer is in the live room roster.
+    RosterPresent,
+    /// Gossip reported a transient drop; keep admission during reconnect grace.
+    TransientDropGrace,
+    /// Graceful leave, transport Left eviction, or reconnect-grace expiry.
+    Remove,
+}
+
+pub(crate) fn apply_audio_admission_event(
+    roster: &mut HashSet<EndpointId>,
+    peer_id: EndpointId,
+    event: AudioAdmissionEvent,
+) {
+    match event {
+        AudioAdmissionEvent::RosterPresent => {
+            roster.insert(peer_id);
+        }
+        AudioAdmissionEvent::TransientDropGrace => {
+            // Grace is not an authority to add membership; it only preserves an
+            // already-admitted peer until either rejoin or grace expiry.
+        }
+        AudioAdmissionEvent::Remove => {
+            roster.remove(&peer_id);
+        }
+    }
+}
+
 /// Owns a single peer's connection lifecycle for as long as the peer is in the
 /// room: obtain a link, run the send/read loops, and on loss obtain a new one —
 /// with capped backoff on the dialing side. The deterministic-initiator rule
@@ -333,10 +382,17 @@ impl iroh::protocol::ProtocolHandler for AudioRouter {
            if shared.self_id.to_string() < peer_id.to_string() {
                return Ok(());
            }
+            if !shared.audio_sender_admitted(peer_id) {
+                crate::log_msg(&format!(
+                    "Transport: rejected inbound audio from non-member {}",
+                    crate::short_id(&peer_id.to_string())
+                ));
+                return Ok(());
+            }
            // Route the connection to this peer's supervisor (creating it if the
-            // inbound link beat the gossip join event). try_send keeps the
-            // protocol handler from ever blocking; a full queue only happens if
-            // links are churning, and the supervisor will get the next one.
+            // inbound link arrives after the signed gossip Announce admitted it).
+            // try_send keeps the protocol handler from ever blocking; a full queue
+            // 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));
@@ -369,6 +425,7 @@ impl IrohTransport {
            addrs: StdMutex::new(HashMap::new()),
            peers: tokio::sync::Mutex::new(HashMap::new()),
            live_conns: StdMutex::new(HashMap::new()),
+            admitted_audio: StdMutex::new(HashSet::new()),
            incoming_tx,
            conn_events_tx,
        });
@@ -397,11 +454,35 @@ impl IrohTransport {
        }
        self.shared.senders.lock().unwrap().clear();
        self.shared.addrs.lock().unwrap().clear();
+        self.shared.admitted_audio.lock().unwrap().clear();
        // Give the CONNECTION_CLOSE frames a moment to flush before the caller
        // shuts the endpoint/router down (the `conns` clones are still alive
        // here, so the endpoint can still transmit them).
        tokio::time::sleep(Duration::from_millis(150)).await;
    }
+
+    /// Admit a peer to this session's audio plane. Core calls this from verified
+    /// gossip roster events; the transport never derives membership on its own.
+    pub fn admit_audio_sender(&self, peer_id: EndpointId) {
+        self.shared
+            .apply_audio_admission(peer_id, AudioAdmissionEvent::RosterPresent);
+    }
+
+    /// Preserve an already-admitted peer through the reconnect grace window.
+    pub fn keep_audio_sender_for_reconnect_grace(&self, peer_id: EndpointId) {
+        self.shared
+            .apply_audio_admission(peer_id, AudioAdmissionEvent::TransientDropGrace);
+    }
+
+    /// Remove a peer from audio admission before tearing down transport/jitter state.
+    pub fn remove_audio_sender(&self, peer_id: EndpointId) {
+        self.shared
+            .apply_audio_admission(peer_id, AudioAdmissionEvent::Remove);
+    }
+
+    pub fn audio_sender_admitted(&self, peer_id: EndpointId) -> bool {
+        self.shared.audio_sender_admitted(peer_id)
+    }
 }

 #[async_trait]
@@ -443,3 +524,85 @@ impl NetworkTransport for IrohTransport {
            .ok_or_else(|| NetError::Other("Connection events already subscribed".to_string()))
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use iroh::SecretKey;
+
+    fn endpoint_id() -> EndpointId {
+        SecretKey::generate().public()
+    }
+
+    #[test]
+    fn audio_sender_admission_accepts_roster_member() {
+        let member = endpoint_id();
+        let roster = HashSet::from([member]);
+
+        assert!(audio_sender_admitted(member, &roster));
+    }
+
+    #[test]
+    fn audio_sender_admission_rejects_unknown_sender() {
+        let member = endpoint_id();
+        let stranger = endpoint_id();
+        let roster = HashSet::from([member]);
+
+        assert!(!audio_sender_admitted(stranger, &roster));
+    }
+
+    #[test]
+    fn audio_sender_admission_rejects_former_member_after_roster_removal() {
+        let former = endpoint_id();
+        let mut roster = HashSet::from([former]);
+        assert!(audio_sender_admitted(former, &roster));
+
+        roster.remove(&former);
+
+        assert!(!audio_sender_admitted(former, &roster));
+    }
+
+    #[test]
+    fn audio_sender_admission_waits_for_mid_join_announce() {
+        let joining_peer = endpoint_id();
+        let mut roster = HashSet::new();
+
+        assert!(!audio_sender_admitted(joining_peer, &roster));
+
+        roster.insert(joining_peer);
+
+        assert!(audio_sender_admitted(joining_peer, &roster));
+    }
+
+    #[test]
+    fn audio_admission_lifecycle_keeps_peer_through_transient_grace() {
+        let peer = endpoint_id();
+        let mut roster = HashSet::new();
+
+        apply_audio_admission_event(&mut roster, peer, AudioAdmissionEvent::RosterPresent);
+        assert!(audio_sender_admitted(peer, &roster));
+
+        apply_audio_admission_event(&mut roster, peer, AudioAdmissionEvent::TransientDropGrace);
+        assert!(audio_sender_admitted(peer, &roster));
+    }
+
+    #[test]
+    fn audio_admission_lifecycle_does_not_add_unknown_peer_on_grace_event() {
+        let peer = endpoint_id();
+        let mut roster = HashSet::new();
+
+        apply_audio_admission_event(&mut roster, peer, AudioAdmissionEvent::TransientDropGrace);
+
+        assert!(!audio_sender_admitted(peer, &roster));
+    }
+
+    #[test]
+    fn audio_admission_lifecycle_removes_peer_on_leave_or_grace_expiry() {
+        let peer = endpoint_id();
+        let mut roster = HashSet::from([peer]);
+
+        apply_audio_admission_event(&mut roster, peer, AudioAdmissionEvent::Remove);
+
+        assert!(!audio_sender_admitted(peer, &roster));
+    }
+}
@@ -3,11 +3,12 @@
 //!
 //! The WAVs are embedded in the binary (`include_bytes!`) so a deployed single
 //! binary is self-contained — no asset directory to ship alongside it. On first
-//! use each sound is written once to a temp file, then played fire-and-forget
-//! via `pw-play` (PipeWire-native; falls back to `paplay`/`aplay`). Playback runs
-//! on a detached thread that waits on the child, so it never blocks the UI and
-//! never leaves a zombie. Any failure (no player, no audio) is silent by design —
-//! a missing chime should never disrupt a call.
+//! use each sound is written once to a temp file, then played fire-and-forget.
+//! Linux uses `pw-play` (PipeWire-native; falls back to `paplay`/`aplay`);
+//! Windows uses PowerShell's `System.Media.SoundPlayer`. Playback runs on a
+//! detached thread that waits on the child, so it never blocks the UI and never
+//! leaves a zombie. Any failure (no player, no audio) is silent by design — a
+//! missing chime should never disrupt a call.

 use std::collections::HashMap;
 use std::path::{Path, PathBuf};
@@ -202,8 +203,14 @@ fn cached_path(sound: Sound) -> Option<PathBuf> {
    Some(path)
 }

+#[cfg(any(windows, test))]
+fn escape_powershell_single_quoted(s: &str) -> String {
+    s.replace('\'', "''")
+}
+
 /// Try each available player in turn, waiting on the first that starts (which
 /// reaps the child). Runs on a detached thread, so the wait is harmless.
+#[cfg(not(windows))]
 fn spawn_player(path: &Path) {
    for player in ["pw-play", "paplay", "aplay"] {
        let started = Command::new(player)
@@ -221,6 +228,23 @@ fn spawn_player(path: &Path) {
    }
 }

+/// Play through Windows' built-in WAV player. Runs on a detached thread, so
+/// `PlaySync()` blocking for the sound duration is fine.
+#[cfg(windows)]
+fn spawn_player(path: &Path) {
+    let path = escape_powershell_single_quoted(&path.display().to_string());
+    let command = format!("(New-Object System.Media.SoundPlayer '{path}').PlaySync()");
+    let _ = Command::new("powershell")
+        .arg("-NoProfile")
+        .arg("-NonInteractive")
+        .arg("-Command")
+        .arg(command)
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .status();
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;
@@ -234,6 +258,18 @@ mod tests {
        assert!(!should_play(false, false));
    }

+    #[test]
+    fn test_powershell_single_quote_escape() {
+        assert_eq!(
+            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"
+        );
+    }
+
    #[test]
    fn test_sound_indices_unique_and_match_all() {
        // `index()` must be a 0..COUNT bijection in `ALL` order, or the flag
@@ -110,26 +110,32 @@ pub enum FriendPresence {
    InRoom { name: String, ticket: String },
 }

-/// Interpret a peer's reply defensively. Only a `Pong` is a reply (a `Ping` is
-/// not, so it yields `None`). When the peer reports a room, we **sanitize the
-/// peer-supplied name** and **only surface it as joinable if the ticket actually
-/// parses** as a [`crate::network::PeerSpeakTicket`] — a garbage or hostile
-/// ticket downgrades the friend to plain `Online` rather than offering a dead /
-/// dangerous Join button. (We still never auto-join; the user clicks.)
-pub fn interpret_pong(msg: &ControlMsg) -> Option<FriendPresence> {
+/// Interpret a peer's reply defensively. `from` must be the connection's
+/// authenticated remote id, not any value carried in the payload. Only a `Pong`
+/// is a reply (a `Ping` is not, so it yields `None`). When the peer reports a
+/// room, we **sanitize the peer-supplied name** and **only surface it as joinable
+/// if the ticket actually parses** as a [`crate::network::PeerSpeakTicket`] and
+/// points back at the replying friend. A garbage/redirect ticket downgrades the
+/// friend to plain `Online` rather than offering a dead or attacker-controlled
+/// Join button. (We still never auto-join; the user clicks.)
+pub fn interpret_pong(msg: &ControlMsg, from: EndpointId) -> Option<FriendPresence> {
    match msg {
        ControlMsg::Ping => None,
        ControlMsg::Pong { room: None } => Some(FriendPresence::Online),
        ControlMsg::Pong { room: Some(r) } => {
-            if r.ticket.parse::<crate::network::PeerSpeakTicket>().is_ok() {
-                Some(FriendPresence::InRoom {
-                    name: crate::sanitize::sanitize_name(&r.name),
-                    ticket: r.ticket.clone(),
-                })
-            } else {
+            let Ok(ticket) = r.ticket.parse::<crate::network::PeerSpeakTicket>() else {
                // Online, but the advertised room is unusable — don't offer Join.
-                Some(FriendPresence::Online)
+                return Some(FriendPresence::Online);
+            };
+            if ticket.host_addr.id != from {
+                // Online, but the advertised room redirects away from the friend
+                // who authenticated this Pong — don't offer a phishing Join.
+                return Some(FriendPresence::Online);
            }
+            Some(FriendPresence::InRoom {
+                name: crate::sanitize::sanitize_name(&r.name),
+                ticket: r.ticket.clone(),
+            })
        }
    }
 }
@@ -206,21 +212,22 @@ mod tests {

    #[test]
    fn interpret_ping_is_not_a_reply() {
-        assert_eq!(interpret_pong(&ControlMsg::Ping), None);
+        assert_eq!(interpret_pong(&ControlMsg::Ping, id()), None);
    }

    #[test]
    fn interpret_pong_online_and_inroom() {
+        let friend = id();
        // No room -> Online.
        assert_eq!(
-            interpret_pong(&ControlMsg::Pong { room: None }),
+            interpret_pong(&ControlMsg::Pong { room: None }, friend),
            Some(FriendPresence::Online)
        );
        // Valid ticket -> InRoom with a sanitized name.
-        let t = valid_ticket(id());
+        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 }));
    }

@@ -230,17 +237,29 @@ mod tests {
        // 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());
+        assert_eq!(got, Some(FriendPresence::Online));
+    }
+
+    #[test]
+    fn interpret_pong_rejects_ticket_for_a_different_host() {
+        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);
        assert_eq!(got, Some(FriendPresence::Online));
    }

    #[test]
    fn interpret_pong_sanitizes_a_hostile_room_name() {
        // Control/bidi characters in a peer-supplied name are stripped.
-        let t = valid_ticket(id());
+        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);
        match got {
            Some(FriendPresence::InRoom { name, .. }) => {
                assert!(!name.contains('\u{202e}'), "bidi override must be stripped");
@@ -31,7 +31,7 @@ use std::time::Duration;

 /// ALPN for the friends presence/control plane. Separate from the audio/gossip
 /// ALPNs so a control dial never lands on a bare room endpoint and vice versa.
-pub const FRIENDS_ALPN: &[u8] = b"peerspeak/friends/0";
+pub const FRIENDS_ALPN: &[u8] = crate::protocol::FRIENDS_ALPN;

 /// Upper bound on a single control message — generous for a Pong carrying a
 /// member ticket (~300 chars), but rejects a peer trying to make us buffer a
@@ -49,16 +49,17 @@ fn decode(bytes: &[u8]) -> Result<ControlMsg> {
    serde_json::from_slice(bytes).context("failed to decode control message")
 }

-/// Probe `peer` for presence: send a `Ping`, return their `Pong`. An error means
-/// no usable reply (offline / unreachable / refused / 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<ControlMsg> {
+/// Probe `peer` for presence: send a `Ping`, return their authenticated id and
+/// `Pong`. An error means no usable reply (offline / unreachable / refused /
+/// 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)> {
    let conn = tokio::time::timeout(IO_TIMEOUT, endpoint.connect(peer, FRIENDS_ALPN))
        .await
        .context("timed out connecting to peer")?
        .context("failed to connect to peer")?;
+    let from = conn.remote_id();

    let io = async {
        let (mut send, mut recv) = conn.open_bi().await.context("failed to open control stream")?;
@@ -77,7 +78,7 @@ pub async fn probe(endpoint: &Endpoint, peer: impl Into<EndpointAddr>) -> Result
        .await
        .context("timed out awaiting pong")?;
    conn.close(VarInt::from_u32(0), b"done");
-    result
+    result.map(|msg| (from, msg))
 }

 /// A reply policy: given the *authenticated* remote id, decide whether and how to
@@ -110,6 +111,10 @@ async fn handle(incoming: Incoming, handler: Handler) -> Result<()> {
 async fn exchange(conn: &iroh::endpoint::Connection, handler: &Handler) -> Result<()> {
    // The authenticated remote id — NOT anything the peer puts in the payload.
    let from = conn.remote_id();
+    let Some(reply) = handler(from) else {
+        conn.close(VarInt::from_u32(0), b"not authorized");
+        return Ok(());
+    };

    let io = async {
        let (mut send, mut recv) = conn.accept_bi().await.context("failed to accept stream")?;
@@ -118,13 +123,9 @@ async fn exchange(conn: &iroh::endpoint::Connection, handler: &Handler) -> Resul
            ControlMsg::Ping => {}
            other => bail!("expected a ping, got {other:?}"),
        }
-        // Ask the policy what to send. None -> answer nothing (stranger / invisible):
-        // finish the stream with no bytes so the prober sees an empty (unusable) reply.
-        if let Some(reply) = handler(from) {
-            send.write_all(&encode(&reply)?)
-                .await
-                .context("failed to write pong")?;
-        }
+        send.write_all(&encode(&reply)?)
+            .await
+            .context("failed to write pong")?;
        send.finish().context("failed to finish reply stream")?;
        Ok::<_, anyhow::Error>(())
    };
@@ -220,10 +221,11 @@ mod tests {
        let serve_task = tokio::spawn(async move { serve(server_ep, handler).await });

        // The allowed prober gets a Pong with the room.
-        let pong = tokio::time::timeout(Duration::from_secs(15), probe(&prober, server_addr.clone()))
+        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"),
            other => panic!("expected Pong with a room, got {other:?}"),
@@ -0,0 +1,82 @@
+//! Single source of truth for PeerSpeak's on-wire protocol versions and the
+//! per-plane ALPNs / gossip constants derived from them.
+//!
+//! See `VERSIONING.md`. The rule: each transport plane is versioned independently
+//! (audio rarely changes, gossip changes often), and incompatible peers must fail
+//! fast — never as a silent decode/signature error. iroh refuses a mismatched
+//! ALPN at the QUIC handshake, so the audio/friends planes are self-isolating;
+//! gossip can't use a custom ALPN (it rides iroh-gossip's `GOSSIP_ALPN`), so its
+//! version is bound into the subscribed topic ([`versioned_topic`]) and the
+//! signature domain ([`GOSSIP_SIG_DOMAIN`]).
+//!
+//! **Never hand-write an ALPN literal elsewhere — derive it here.** Bumping a
+//! plane's protocol version is a breaking wire change → also bump `Cargo.toml`
+//! MINOR (see `VERSIONING.md`).
+
+/// Audio datagram plane version (Opus framing / sequencing). Bump on any audio
+/// wire change. Mirrored in [`AUDIO_ALPN`].
+pub const AUDIO_PROTO: u32 = 1;
+/// Friends/presence plane version (`ControlMsg` ping-pong shape). Bump on any
+/// change. Mirrored in [`FRIENDS_ALPN`].
+pub const FRIENDS_PROTO: u32 = 1;
+/// Gossip plane version (`GossipPayload`/`GossipMessage`/`PeerState`, signing,
+/// freshness). Bump on any change. Mirrored in [`GOSSIP_SIG_DOMAIN`] and folded
+/// into [`versioned_topic`].
+pub const GOSSIP_PROTO: u32 = 1;
+
+/// ALPN for the audio datagram plane: `peerspeak/audio/<AUDIO_PROTO>`.
+pub const AUDIO_ALPN: &[u8] = b"peerspeak/audio/1";
+/// ALPN for the friends/presence plane: `peerspeak/friends/<FRIENDS_PROTO>`.
+pub const FRIENDS_ALPN: &[u8] = b"peerspeak/friends/1";
+/// ed25519 gossip signature domain: `peerspeak-gossip-v<GOSSIP_PROTO>`. Carries
+/// the gossip protocol version into every signed payload — a version mismatch
+/// fails verification (cryptographic separation between gossip versions).
+pub const GOSSIP_SIG_DOMAIN: &str = "peerspeak-gossip-v1";
+
+/// Version-namespace a room topic so peers on different gossip protocol versions
+/// derive **different subscription topics from the same ticket** and therefore
+/// never share a swarm — the gossip analog of a versioned ALPN. The room's raw
+/// `topic_id` (random 32 bytes, carried in the ticket) is the room identity and
+/// is unchanged; only the *subscribed* topic is namespaced.
+///
+/// Deterministic and dependency-free; bijective for a fixed version, so distinct
+/// rooms stay distinct after namespacing. This transform is for *isolation*, not
+/// security — cryptographic separation between versions comes from
+/// [`GOSSIP_SIG_DOMAIN`].
+pub fn versioned_topic(topic_id: [u8; 32]) -> [u8; 32] {
+    let v = GOSSIP_PROTO.to_le_bytes();
+    let mut out = topic_id;
+    for (i, b) in out.iter_mut().enumerate() {
+        *b ^= v[i % v.len()];
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// The ALPN/domain strings must stay in lock-step with the integer versions
+    /// 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!(GOSSIP_SIG_DOMAIN, format!("peerspeak-gossip-v{GOSSIP_PROTO}"));
+    }
+
+    #[test]
+    fn versioned_topic_is_deterministic_and_room_distinct() {
+        let a = [9u8; 32];
+        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");
+    }
+
+    #[test]
+    fn versioned_topic_actually_namespaces_for_current_version() {
+        // Guards against a no-op transform: GOSSIP_PROTO=1 must change the topic.
+        assert_ne!(versioned_topic([0u8; 32]), [0u8; 32]);
+    }
+}
@@ -25,6 +25,20 @@ use tokio::process::{Child, Command};
 /// points elsewhere.
 const PIXELPASS_BIN: &str = "pixelpass";

+#[cfg(windows)]
+fn pixelpass_path_candidates(dir: &Path) -> [PathBuf; 2] {
+    [dir.join(PIXELPASS_BIN), dir.join("pixelpass.exe")]
+}
+
+#[cfg(not(windows))]
+fn pixelpass_path_candidates(dir: &Path) -> [PathBuf; 1] {
+    [dir.join(PIXELPASS_BIN)]
+}
+
+/// Pixelpass endpoint tickets are normally ~140 chars. Leave headroom for format
+/// growth, but reject unbounded gossip payloads before the UI offers "Watch".
+const MAX_TICKET_LEN: usize = 512;
+
 /// How long to wait for the host to emit its ticket / the viewer to connect
 /// before giving up and killing the child. Startup is normally sub-second; this
 /// is only a safety net so a hung pixelpass can't wedge the caller forever.
@@ -108,6 +122,19 @@ pub fn viewer_args(ticket: &str) -> Vec<String> {
    ]
 }

+/// Sanitize a peer-advertised pixelpass ticket at the gossip boundary. Peerspeak
+/// intentionally does not depend on pixelpass/iroh-tickets, so this validates the
+/// stable CLI ticket envelope we consume: bounded ASCII endpoint tickets beginning
+/// with `endpoint`. Invalid input becomes `None`, which removes the Watch button.
+pub fn sanitize_ticket(ticket: String) -> Option<String> {
+    let ticket = ticket.trim();
+    let valid_len = !ticket.is_empty() && ticket.len() <= MAX_TICKET_LEN;
+    let valid_shape = ticket.starts_with("endpoint")
+        && ticket.len() > "endpoint".len()
+        && ticket.bytes().all(|b| b.is_ascii_alphanumeric());
+    (valid_len && valid_shape).then(|| ticket.to_string())
+}
+
 /// Resolve the pixelpass binary: an explicit config override (used only if it
 /// points at an existing file), otherwise the first `pixelpass` found on
 /// `$PATH`. `None` means it isn't installed — a normal, handled state. An
@@ -126,7 +153,7 @@ pub fn pixelpass_path(config_override: Option<&str>) -> Option<PathBuf> {
    }
    let path_var = std::env::var_os("PATH")?;
    std::env::split_paths(&path_var)
-        .map(|dir| dir.join(PIXELPASS_BIN))
+        .flat_map(|dir| pixelpass_path_candidates(&dir))
        .find(|c| c.is_file())
 }

@@ -267,12 +294,29 @@ where
    tokio::spawn(async move {
        while let Ok(Some(line)) = lines.next_line().await {
            if let Some(ev) = parse_pixelpass_event(&line) {
-                crate::log_msg(&format!("pixelpass {role}: {ev:?}"));
+                crate::log_msg(&format!("pixelpass {role}: {}", event_for_log(&ev)));
            }
        }
    });
 }

+fn event_for_log(ev: &PixelpassEvent) -> String {
+    match ev {
+        PixelpassEvent::Ticket(ticket) => format!("ticket {}", crate::redact_for_log(ticket)),
+        PixelpassEvent::Connected(_) => "connected".to_string(),
+        PixelpassEvent::ViewerJoined { active, max } => {
+            format!("viewer_joined active={active} max={max}")
+        }
+        PixelpassEvent::ViewerLeft { active, max } => {
+            format!("viewer_left active={active} max={max}")
+        }
+        PixelpassEvent::Refused(reason) => format!("viewer_refused reason={reason:?}"),
+        PixelpassEvent::CaptureStarted => "capture_started".to_string(),
+        PixelpassEvent::CaptureStopped => "capture_stopped".to_string(),
+        PixelpassEvent::Other => "other".to_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.
@@ -340,6 +384,27 @@ mod tests {
        );
    }

+    #[test]
+    fn sanitize_ticket_accepts_pixelpass_endpoint_ticket_shape() {
+        let ticket = "endpointaabwxjexzensznfvuudiapn5tyzws3angd2merarm";
+        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("endpointabc-def".into()), None);
+    }
+
+    #[test]
+    fn event_log_redacts_ticket_values() {
+        let ticket = "endpointaabwxjexzensznfvuudiapn5tyzws3angd2merarm".to_string();
+        let log = event_for_log(&PixelpassEvent::Ticket(ticket.clone()));
+        assert!(log.contains("endpoint"));
+        assert!(!log.contains(&ticket["endpoint".len() + 8..]));
+    }
+
    #[test]
    fn parses_ticket() {
        assert_eq!(
@@ -458,4 +523,14 @@ mod tests {
        // only assert it doesn't return the empty path as a match.
        assert_ne!(pixelpass_path(Some("   ")).as_deref(), Some(Path::new("")));
    }
+
+    #[test]
+    fn pixelpass_path_candidates_are_platform_specific() {
+        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")]);
+        #[cfg(not(windows))]
+        assert_eq!(candidates, vec![dir.join("pixelpass")]);
+    }
 }
@@ -1,81 +0,0 @@
-# Codex task report - 2026-06-16
-
-## W2 - Per-peer EQ
-
- Added `src/audio/eq.rs`: a 3-band listener-side RBJ biquad EQ (low shelf, mid peaking, high shelf) with per-peer state and flat bypass.
- Added local config persistence in `AppConfig.peer_eq`, keyed by peer node id string.
- Added local `CoreCommand::SetPeerEq` and mixer-side per-peer `Eq` state. EQ is applied after local volume and before pan/mix; raw multitrack stems remain pre-volume/pre-EQ.
- Added participant-card controls for Low/Mid/High gain sliders (-12 dB to +12 dB). Changes apply live and persist on slider release.
- Tests added for flat identity, low/high boost energy, coefficient finiteness, clamping, and hot-signal processing.
-
-Unverified: subjective voice quality and zipper/noise behavior on real devices.
-
-## W1 - Per-listener pan / stereo playback
-
- Added `src/audio/pan.rs`: constant-power `pan_gains()` with tests, plus playback gains that preserve the legacy default dual-mono center.
- Converted playback mix to interleaved stereo in `src/core/mod.rs`.
- Switched PipeWire playback output to 2-channel S16LE and adjusted ring target/capacity/stride accounting in `src/audio/pipewire_impl.rs`.
- Kept capture, Opus encode/decode, jitter buffers, and network audio mono.
- Limiter now receives the interleaved stereo bus; shared limiter gain ducks both channels consistently.
- Mixed WAV and multitrack convenience mix fold the listener stereo mix back to mono before writing. Per-peer stems remain raw mono.
- Updated `audio_probe` to send dual-mono stereo frames.
- Added tests for exact center dual-mono behavior, hard-left pan contribution, and stereo fold-down.
-
-Decision for senior sanity-check: pure pan law is constant-power, but playback scales it by sqrt(2) so pan=0 is exactly the old mono signal in both ears. This satisfies the "default behavior unchanged" guardrail at the cost of louder hard-panned extremes, which the existing limiter catches.
-
-Unverified: real PipeWire stereo playback, underrun behavior on actual hardware, and recorded WAV listening checks.
-
-## W5 - Focused hotkeys + info popup
-
- Added `src/hotkeys.rs`: serializable `KeyBinding`, `HotkeyAction`, `HotkeyMap`, parse/format/lookup, tier checks, and duplicate conflict detection.
- Added `AppConfig.hotkeys` with defaults: F9 mute, F10 deafen, F2 Settings, Space push-to-talk, Leave unset.
- Replaced the hard-coded PTT key capture with config-backed binding capture.
- Added Settings hotkey editor with Set/Clear per action and live conflict warnings.
- Added top-right hotkey info popup that lists every action and current binding, showing `unset` for unbound actions.
- Routed focused iced key events through the map. App-wide actions can fire from any screen while focused; room-only actions require an active call. PTT press/release still uses `SetPttActive`.
- Tests added for unset formatting, duplicate detection, room-tier lookup, defaults, and character parse/format.
-
-Unverified: manual keyboard interaction in the GUI. No OS-global hooks were added.
-
-## W3 - PipeWire pro-routing plan (not implemented)
-
-I stopped at design for W3. The current backend already supports simple target-node routing through PipeWire stream property `node.target`, but true "pro routing" (explicit ports / manual graph links / no-autoconnect patching) would require backend changes that are not safely verifiable offline.
-
-Proposed future scope:
-
- Expose two advanced route targets: capture source node and playback sink node, with optional future per-port routing.
- Enumerate available nodes with the existing `pw-cli list-objects Node` parser. For port-level routing, add a separate parser for `pw-cli list-objects Port` collecting `object.id`, `node.id`, `port.name`, direction, and channel position.
- For node-level routing, continue using PipeWire stream property `node.target` on stream creation. This is the low-risk path and matches current backend behavior.
- For explicit port routing, do not use `AUTOCONNECT`; instead capture the created PeerSpeak stream node/port ids from the PipeWire registry, then link with PipeWire-native APIs or `pw-link <source-port-id> <sink-port-id>`. Degrade by falling back to `node.target` autoconnect if any selected node/port is missing.
- Offline tests should cover pure routing-plan decisions: selected node exists/missing, selected port exists/missing, capture/playback direction mismatch, and fallback choice. Real-device tests still need a PipeWire graph.
-
-Reason for not implementing: the current `run_playback` / `run_capture` code does not retain stream node or port ids, and changing `AUTOCONNECT` behavior plus adding manual `pw-link` calls could destabilize the working audio path. That matches the assignment's "bail if risky" instruction.
-
-## Backlog A21/A22 - correctness fixes
-
- Fixed A21 in `src/core/jitter.rs`: implausibly large sequence discontinuities now reset the per-peer jitter stream instead of being treated as ordinary late packets or packet loss.
- The reset threshold is `500` frames, about 10 seconds at 20 ms/frame. That covers both same-identity sender restart back to sequence 0 and a faulty/malicious jump far ahead that would otherwise force a long PLC run.
- Added jitter regression tests for both far-behind restart and far-ahead jump cases.
- Fixed A22 in `src/audio/recorder.rs`: `WavWriter` now tracks data bytes as `u64`, checks additions before writing, and rejects data that cannot fit both the RIFF size field and the `data` chunk size field.
- Added a WAV overflow regression test that exercises the limit without creating a huge file.
-
-Unverified: the same-identity peer restart has not been exercised in a live 2-machine call; the WAV fix is counter/size-field tested, not a real >12h recording.
-
-## Backlog A14 - orderly window-close shutdown
-
- Added `CoreCommand::Shutdown` and `UiEvent::ShutdownComplete`.
- Window close now saves config, marks the GUI as closing, asynchronously queues `Shutdown`, and exits only after the core acknowledges completion or after a 5-second fallback timeout.
- Core shutdown finalizes active mixed/multitrack recordings before session teardown, stops the standalone mic monitor, runs `ActiveSession::shutdown()` for active calls, clears room presence/routing, closes the persistent network stack, sends `ShutdownComplete`, and ends the core loop.
- The shutdown command is queued with an awaited `mpsc::Sender::send` task instead of the best-effort `try_send`, so a full command queue does not immediately drop the close command.
-
-Unverified: actual GUI window-close behavior during a live call/recording still needs a manual run; tests/builds only prove the path compiles and existing unit coverage still passes.
-
-## Verification
-
- `cargo check` passed.
- `cargo test --lib` passed: 288 passed, 0 failed, 2 ignored.
- `cargo clippy --all-targets` passed.
- `cargo build --release` passed.
- Formatted the touched Rust files with `rustfmt --edition 2024`; I did not run repo-wide `cargo fmt` to avoid unrelated formatting churn.
-
-No new dependencies were added. Runtime/manual/field verification is still pending for audio-device and 2-machine behavior.
@@ -169,6 +169,9 @@ async fn loopback_sequenced_audio_reaches_peer_and_decodes() {
    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);

    // Subscribe to incoming datagrams on B before any are sent.
    let mut b_rx = b.transport.receive_datagrams().await.expect("subscribe B");