audio: only FEC-recover a gap from its immediate successor packet

The jitter buffer's gap path fed the LOWEST buffered packet to
decode_fec regardless of position. Opus in-band FEC in packet N carries
a copy of frame N-1 and nothing else, so that reconstruction is only
correct when the smallest survivor is exactly next+1 (single loss).
On burst loss it spliced a later frame's audio into the wrong slot —
worse than concealment. Gate FEC on adjacency (new fec_covers_gap(),
wraparound-aware); everything else falls back to plain PLC.

Two new tests: the gate itself, and a burst-loss test proven to bite —
it compares bit-exact against a twin decoder and fails against the old
unconditional-FEC behavior (checked by mutation).

Fixes finding 3 of the 2026-07-16 full-codebase review.

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

.cargo/audit.toml

@@ -0,0 +1,11 @@
+# cargo-audit configuration. Keep the ignore list in sync with deny.toml,
+# which carries the full justification for each entry.
+[advisories]
+ignore = [
+    # quick-xml DoS advisories: build-time only, reached solely via the
+    # wayland-scanner proc-macro parsing trusted vendored protocol XML.
+    # Fix (0.41.0) is semver-incompatible with wayland-scanner's `^0.39`;
+    # drop once wayland-scanner bumps. See deny.toml.
+    "RUSTSEC-2026-0194",
+    "RUSTSEC-2026-0195",
+]

.gitea/workflows/cargo-deny.yml

@@ -1,34 +0,0 @@
-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

.gitea/workflows/ci.yml

@@ -36,7 +36,9 @@ jobs:
         run: cargo test --doc
 
       - name: cargo-deny (advisories, bans, licenses, sources)
-        run: cargo deny check
+        # --locked so the pinned, vetted versions in Cargo.lock are exactly
+        # what get audited (the lockfile-as-review-checkpoint model).
+        run: cargo deny --locked check
 
       - name: cargo-audit
         run: cargo audit

.gitea/workflows/windows-build.yml

@@ -7,11 +7,20 @@ name: windows-build
 # 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.
+# `windows-latest` label (a Linux-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.
+#
+# MANUAL-ONLY until that runner exists: with push/PR triggers enabled, every
+# push queued a run no runner could claim and Gitea auto-cancelled it ~24h
+# later, littering the Actions page with cancelled runs. Restore the push/PR
+# triggers when a Windows runner is registered:
+#
+#   on:
+#     push:
+#       branches: [main, "windows-port-**"]
+#     pull_request:
+#     workflow_dispatch:
 #
 # BUILD-HOST REQUIREMENTS (validated by the opus spike, see
 # peerspeak-windows-opus-spike.md):
@@ -23,12 +32,7 @@ name: windows-build
 # 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.
+  # Manual runs from the Gitea Actions UI only — see the header comment.
   workflow_dispatch:
 
 permissions:

Cargo.lock

@@ -1207,9 +1207,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.18"
+version = "0.9.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+checksum = "2d6914041f254d6e9176c01941b21115dcfb7089e55135a35411081bd106ef3f"
 dependencies = [
  "crossbeam-utils",
 ]

deny.toml

@@ -24,6 +24,19 @@ ignore = [
     # 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",
+    # ttf-parser: unmaintained, transitive via iced/cosmic-text (font parsing
+    # for the GUI). Inputs are system + embedded fonts, not network data. No
+    # upstream migration yet; revisit when iced moves off it.
+    "RUSTSEC-2026-0192",
+    # quick-xml 0.39.4 DoS advisories (quadratic dup-attr check; unbounded
+    # namespace allocation). Build-time only: quick-xml is reached solely via
+    # the wayland-scanner PROC-MACRO, which parses the wayland protocol XML
+    # files vendored inside the wayland-* crates at compile time. Attacker
+    # input never reaches it and it is not in the shipped binary. The fix
+    # (0.41.0) is semver-incompatible with wayland-scanner 0.31.x's `^0.39`
+    # requirement; drop both ignores once wayland-scanner releases a bump.
+    "RUSTSEC-2026-0194",
+    "RUSTSEC-2026-0195",
 ]
 
 # ---------------------------------------------------------------------------

docs/chat-hardening-plan.md

@@ -0,0 +1,385 @@
+# Chat hardening — ephemeral implementation plan
+
+**Status (2026-07-15):** PLANNED, not started. This is a temporary scope
+contract for hardening the existing room chat. Update the checkboxes and decision
+log as work lands, then delete this file when the work is complete. Do not add
+link previews as part of this effort.
+
+## Goal
+
+Strengthen the current encrypted, signed, session-only room chat without changing
+its product model: plain selectable text, clickable web links, and peer-to-peer
+attachments over the existing gossip and files planes. The work should make chat
+resistant to identity spoofing, replay, spam, oversized input, expensive rendering,
+and attachment-driven memory/bandwidth pressure while preserving normal Unicode
+conversation and the existing full-mesh architecture.
+
+## Existing foundation to preserve
+
+- Gossip payloads are signed by the claimed `EndpointId`, bound to the raw room
+  topic and protocol domain, and checked before dispatch.
+- The signed envelope timestamp is admitted only within the two-minute gossip
+  freshness window.
+- Inbound gossip frames are capped at 128 KiB before JSON deserialization. This
+  larger plane-wide cap must remain because `Announce` may contain a custom avatar.
+- Chat history is session-only and capped at 300 entries.
+- Only `http://` and `https://` links are opened, as a single process argument
+  without a shell.
+- Attachment descriptors are signed with the chat payload; attachment bytes use
+  the encrypted files plane, have a 25 MiB per-file cap, and are keyed by both
+  author and attachment id.
+- Image bytes are decoded defensively and automatic image fetches already have a
+  four-task concurrency limit.
+
+## Working design decisions
+
+These are the implementation defaults unless code inspection or tests reveal a
+concrete reason to adjust them. Record any adjustment in the decision log.
+
+1. **No wire change.** Keep `GossipMessage::Chat` unchanged and do not bump
+   `GOSSIP_PROTO`. The redundant wire `name` and inner `Chat.ts` remain serialized
+   for compatibility but are not trusted. Remove them only during a future planned
+   gossip-version bump.
+2. **Roster identity is authoritative.** A chat line is admitted only for an
+   authenticated identity already known to the current room (including the
+   reconnect grace state). Its displayed name comes from the sanitized roster
+   state, never from `GossipMessage::Chat.name`.
+3. **Body Unicode remains expressive.** Do not apply the short-label sanitizer to
+   the message body; it strips format characters used by some languages and emoji.
+   Continue neutralizing controls and whitespace, while treating author labels,
+   filenames, and URLs more strictly because those are spoof-sensitive surfaces.
+4. **Bounds apply at every trust boundary.** UI input is bounded while editing,
+   outgoing text is normalized before signing, and incoming text is byte-checked
+   and normalized before it leaves the gossip layer. UI-only truncation is not an
+   adequate ingress defense.
+5. **Automatic network work is stricter than manual work.** Keep the 25 MiB manual
+   attachment ceiling, but auto-fetch only small images. Larger images remain
+   available behind an explicit Load/Download action.
+6. **Caches are bounded by cost, not only entry count.** Count encoded bytes and
+   estimated decoded image bytes. A count cap remains as a secondary bound.
+7. **Rate limiting degrades quietly.** Drop excess/replayed peer messages with a
+   rate-limited log entry. Do not let a spammer produce a second UI-notification
+   flood.
+
+## Proposed policy constants
+
+Keep these together near the code that enforces them and cover them with boundary
+tests. Values are starting points, not a compatibility contract.
+
+| Policy | Initial value | Reason |
+| --- | ---: | --- |
+| Chat body characters | 2,000 | Preserves current UI behavior |
+| Chat body UTF-8 bytes | 8 KiB | Covers 2,000 four-byte scalars with small headroom |
+| Live input characters/bytes | Same as body | Prevent oversized paste/edit state |
+| Clickable links per message | 8 | Bounds spans and opener targets |
+| Retained chat text | 512 KiB plus 300 entries | Bounds redraw and selection work |
+| Per-author chat limiter | Burst 8, refill 1/second | Allows normal bursts, stops sustained spam |
+| Room-wide chat limiter | Burst 32, refill 8/second | Protects shared event/UI queues |
+| Exact-chat replay cache | 1,024 digests, 2-minute TTL | Covers freshness window with a hard bound |
+| Auto-fetch image encoded size | 4 MiB | Limits unsolicited bandwidth and allocations |
+| Attachment cache encoded budget | 128 MiB | Allows several ordinary files without GiB growth |
+| Attachment cache decoded-preview budget | 64 MiB | Bounds renderer-side image pressure |
+| Served attachment budget | 256 MiB plus a count cap | Bounds sender memory for a long session |
+| Inline preview longest side | 1,600 px | Chat renders near 260 px; full 4K decode is wasteful |
+| Decoded source image pixels | 16 megapixels maximum | Adds a total-pixel bound to per-side bounds |
+
+## Phase 1 — Shared text policy and live-input bounds
+
+**Target:** downstream layers never receive or retain an unexpectedly large or
+unsafe chat string.
+
+- [ ] Move chat constants and `sanitize_chat` from `src/app/mod.rs` into
+  `src/sanitize.rs` (or a narrowly scoped shared chat-policy module if that keeps
+  the API clearer).
+- [ ] Implement a single-pass sanitizer that:
+  - maps control characters to spaces;
+  - collapses whitespace and trims ends;
+  - enforces both the character and UTF-8 byte ceilings without splitting a scalar;
+  - returns empty for content with no visible text.
+- [ ] Add `cap_chat_input` for live editing. It must preserve the user's current
+  whitespace while enforcing character and byte ceilings; normalization remains a
+  submit/ingress operation so typing does not visibly jump.
+- [ ] Apply `cap_chat_input` in `AppMessage::ChatInputChanged`, covering keyboard,
+  clipboard, primary-selection, and context-menu paste paths through the controlled
+  input widget.
+- [ ] Sanitize outgoing text immediately before local echo and `CoreCommand` send.
+- [ ] Sanitize again before `GossipMessage::Chat` is signed, so a future non-UI
+  caller cannot bypass policy.
+- [ ] At gossip ingress, reject raw chat text over the byte ceiling before doing
+  downstream sanitization; sanitize accepted text before creating `RoomEvent`.
+- [ ] Keep attachment-only messages when the sanitized caption is empty; drop a
+  chat with neither visible text nor a valid attachment.
+- [ ] Stop sanitizing an incoming chat `name` with the body sanitizer. Phase 2
+  replaces it with the roster-bound name.
+
+### Phase 1 tests
+
+- [ ] ASCII, multibyte Unicode, emoji, whitespace, NUL/CR/LF/TAB/ESC, empty input.
+- [ ] Exact character and byte boundaries, including a four-byte scalar at the
+  cutoff.
+- [ ] Oversized paste never makes `state.chat_input` exceed either ceiling.
+- [ ] Outgoing, incoming, and direct core/network paths converge on the same
+  normalized result.
+- [ ] Empty captions are retained only when a valid attachment remains.
+
+## Phase 2 — Admission, identity binding, replay, and spam control
+
+**Target:** only current authenticated room members can create chat UI work, and a
+member cannot impersonate another participant or monopolize the control/UI queues.
+
+- [ ] Change the core event task's chat roster from a bare `HashSet<EndpointId>` to
+  a bounded map containing each member's latest sanitized display name (or retain a
+  parallel name map if less invasive).
+- [ ] Insert/update the map on `PeerJoined`/`PeerUpdated`, retain it during transient
+  reconnect grace, and remove it on graceful or terminal eviction.
+- [ ] Before attachment handling or UI forwarding, reject `RoomEvent::ChatMessage`
+  whose author is not present in that authoritative roster.
+- [ ] Replace the embedded wire name with the roster map's name before constructing
+  `UiEvent::ChatMessage`. The UI may keep storing a name snapshot so old chat lines
+  remain labeled after a peer leaves.
+- [ ] Add a lightweight early known-author gate in the gossip loop using its live
+  and disconnected-peer sets. Keep the core roster gate as defense in depth and as
+  the final authority.
+- [ ] Validate that the inner `Chat.ts` equals the signed envelope timestamp, or
+  ignore it entirely. Do not use the inner timestamp for replay or ordering.
+- [ ] Add exact-chat replay suppression after signature verification and before
+  event-channel send:
+  - hash the canonical signed bytes, not raw JSON formatting;
+  - use BLAKE3 (make it a direct dependency if needed; it is already in the iroh
+    dependency graph) or an equally collision-resistant existing primitive;
+  - store a `HashSet` plus FIFO/TTL order for bounded lookup and eviction;
+  - prune by both the gossip freshness window and the hard entry cap.
+- [ ] Add a bounded token bucket per admitted author and a room-wide bucket before
+  awaiting `event_tx.send`. Limiter state must be removed with roster eviction and
+  remain bounded by the roster cap.
+- [ ] Ensure duplicate messages are dropped before consuming rate-limit tokens, so
+  a replay cannot starve a legitimate new message from that author.
+- [ ] Rate-limit rejection logging per author/reason.
+- [ ] Consider applying the same local submit policy to accidental rapid Enter or
+  button activation, without routing chat through the coalescing command path.
+
+### Phase 2 tests
+
+- [ ] Valid roster author is admitted; never-announced, post-leave, forged, and
+  stale authors are rejected.
+- [ ] A peer sending `name = "Victim"` renders under its own roster name.
+- [ ] A name update affects future messages without rewriting history.
+- [ ] Reconnect grace continues accepting the known author; terminal eviction does
+  not.
+- [ ] The same signed chat is displayed once; distinct chats created in the same
+  millisecond are both admitted.
+- [ ] Replay-cache TTL/cap pruning cannot grow without bound.
+- [ ] Per-author burst/refill and room-wide burst/refill boundaries.
+- [ ] Excess chat cannot prevent a subsequent `Leave` or `Announce` from reaching
+  the event loop in a deterministic channel-pressure test.
+
+## Phase 3 — Attachment transfer and memory hardening
+
+**Target:** neither peers nor long local sessions can turn chat attachments into
+unbounded memory, bandwidth, decoder, or task pressure.
+
+### 3A. Cache and image cost
+
+- [ ] Extend `AttachmentCache` with encoded-byte and decoded-preview-byte counters.
+  Preserve the count cap, but evict oldest entries until all three budgets fit.
+- [ ] Give every entry an explicit weight. Replacement must subtract the old
+  weight before checking/inserting the new one.
+- [ ] Decide behavior for a single entry larger than the cache budget: service an
+  immediate pending Save/Play request without retaining it, then expose it as
+  evicted/unavailable rather than exceeding the budget.
+- [ ] Add a total-pixel limit to `validate_image_bytes` in addition to the existing
+  width/height limit.
+- [ ] Build a downscaled inline preview handle with a maximum 1,600 px side. Keep
+  original bytes only for Save; do not hand a full-resolution 4K image to the
+  renderer merely to display it at chat width.
+- [ ] Count estimated RGBA preview cost (`width * height * 4`) against the decoded
+  budget even if iced internally copies or uploads it.
+- [ ] Strip the same bidi/zero-width spoofing characters used for display labels
+  from attachment filenames, while preserving ordinary Unicode filenames.
+
+### 3B. Automatic download policy and state
+
+- [ ] Auto-fetch only roster-authored images whose declared size is at or below
+  `MAX_AUTO_IMAGE_BYTES`; keep the existing `(author,id)` dedup and four-permit
+  concurrency bound.
+- [ ] Add per-author and session byte/request budgets for automatic fetches so a
+  peer cannot drain bandwidth sequentially after each permit is released.
+- [ ] Represent `NotFetched`, `Loading`, `Ready`, `Failed`, and `Evicted` distinctly
+  enough for the UI to avoid an indefinite “loading…” label when auto-fetch was
+  skipped or the cache evicted an item.
+- [ ] Render a Load image button for large/skipped images. A manual click may use
+  the 25 MiB file cap but still observes cache/decoder budgets.
+- [ ] Ensure a repeated click cannot create duplicate unguarded fetch tasks.
+- [ ] Keep non-image attachments manual-only.
+
+### 3C. Exact transfers, local reads, and served files
+
+- [ ] In `IrohTransport::fetch_blob`, require `bytes.len() as u64 == declared_size`.
+  Reject empty, short, and overlong transfers with a concise local error.
+- [ ] Replace the file picker's unbounded `FileHandle::read()` with a helper that
+  reads at most `MAX_ATTACHMENT_BYTES + 1`. Check metadata first where available,
+  but retain the bounded read because metadata can race or be unavailable through
+  a portal.
+- [ ] Avoid duplicating a full attachment across UI, command queue, and serve store.
+  Prefer `Arc<Vec<u8>>`/`Arc<[u8]>` through `AttachmentState`, `CoreCommand`, and
+  `serve_attachment`, subject to iced handle API constraints.
+- [ ] Replace the unbounded session `served_files` map with a count- and byte-
+  budgeted FIFO store. Evicted ids should produce the existing “sender no longer
+  has the file” response rather than stale or aliased data.
+- [ ] Keep attachment ids keyed by author on receipt and preserve all existing
+  request-length, timeout, filename, and decoder checks.
+
+### Phase 3 tests
+
+- [ ] Byte-budget eviction, count eviction, replacement accounting, clear/reset,
+  and an individually overweight entry.
+- [ ] Decoded-preview budget and downscale dimensions for wide, tall, square, and
+  boundary images.
+- [ ] Image with valid per-side dimensions but excessive total pixels is rejected.
+- [ ] A declared 4 MiB image auto-fetches; the first byte over the limit requires a
+  click.
+- [ ] Per-author/session auto-fetch budgets recover according to their policy and
+  never exceed task concurrency.
+- [ ] Short, exact, and overlong file responses.
+- [ ] Local file reader stops at cap + 1 instead of allocating the full source.
+- [ ] Served-file FIFO/byte eviction and replacement accounting.
+- [ ] Same attachment id from two authors remains isolated throughout fetch, cache,
+  save, and display.
+
+## Phase 4 — URL and rendering resilience
+
+**Target:** keep clickable links without making malformed/deceptive input or many
+small spans an unnecessary UI/launcher surface.
+
+- [ ] Make `url` a direct dependency (already present transitively) and validate
+  link candidates with `url::Url`.
+- [ ] A clickable URL must have an `http` or `https` scheme and a valid host.
+- [ ] Treat URLs containing username/password syntax as plain text, or require an
+  explicit confirmation that shows the parsed destination host. Prefer plain text
+  for the first implementation.
+- [ ] Preserve the existing defense-in-depth validation in `AppMessage::OpenUrl`;
+  replace prefix checks with the shared parsed-URL policy.
+- [ ] Cap clickable candidates at eight per message. Remaining content stays
+  selectable plain text and must still round-trip exactly.
+- [ ] Refactor linkification to return borrowed ranges/offsets or cache link ranges
+  in `ChatEntry`, avoiding allocation and rescanning on every redraw.
+- [ ] Bound retained history by total sanitized text bytes as well as 300 entries.
+  Eviction must keep attachment bookkeeping coherent and should not invalidate an
+  open Save/Play operation.
+- [ ] Do not add metadata fetching, remote images, Markdown, or link previews.
+
+### Phase 4 tests
+
+- [ ] Valid HTTP/HTTPS, malformed host, empty host, mixed case, Unicode path/query,
+  punctuation, credentials/userinfo, and non-web schemes.
+- [ ] Eight-link boundary and many-link adversarial input.
+- [ ] Segment/range reconstruction exactly reproduces the sanitized message.
+- [ ] Entry-count and total-text-budget history eviction.
+- [ ] Opener policy cannot launch a non-web scheme even if called directly.
+
+## Phase 5 — Honest local send status
+
+**Target:** never present a locally echoed message as successfully broadcast when
+the core rejected it or gossip broadcast failed.
+
+- [ ] Add a local-only message id and `Pending`/`Broadcast`/`Failed` state to local
+  chat entries. Do not put this id or state on the wire.
+- [ ] Carry the local id through `CoreCommand::SendChat`/`SendChatFile` and return a
+  `UiEvent` result after the local gossip broadcast call succeeds or fails.
+- [ ] If the core is not in an active session, return failure instead of silently
+  doing nothing.
+- [ ] Show failure compactly with a retry action. A successful local broadcast must
+  not be labeled “delivered” or “read”; PeerSpeak has no peer acknowledgements.
+- [ ] Retry creates one new signed broadcast while retaining replay correctness and
+  attachment serving state.
+
+### Phase 5 tests
+
+- [ ] Local echo starts pending, becomes broadcast on success, and becomes failed
+  on no-session/channel/gossip error.
+- [ ] Results update only the matching local entry, including after history
+  eviction or room reset.
+- [ ] Retry does not duplicate served bytes or mutate an unrelated entry.
+
+## Compatibility and versioning
+
+- The planned implementation changes validation, local data structures, and
+  internal `CoreCommand`/`UiEvent` shapes only. Keep the serialized
+  `GossipMessage::Chat` and file request/response formats unchanged.
+- Therefore do **not** bump `GOSSIP_PROTO`, `FILES_PROTO`, or the pre-1.0 MINOR
+  solely for this plan. The eventual release is a compatible PATCH unless scope
+  expands into a wire change.
+- If implementation requires removing/adding serialized fields, changing
+  attachment request framing, or introducing acknowledgements on the wire, stop
+  and revise this section before coding that part. Follow `VERSIONING.md` and use
+  the appropriate protocol plus release MINOR bump.
+
+## Verification gates
+
+Run after each phase, with focused tests first and the full gates before handoff:
+
+```text
+cargo fmt --check
+cargo test --lib
+cargo test --all-targets
+cargo clippy --all-targets -- -D warnings
+```
+
+Also retain the existing ignored/loopback coverage where the environment supports
+it; do not make ordinary unit tests depend on external network access.
+
+### Two-machine field test
+
+- [ ] Ordinary ASCII/Unicode conversation, rapid short burst, long boundary text,
+  and oversized paste.
+- [ ] Rename during a room: new lines use the new roster name; old lines retain
+  their snapshot.
+- [ ] Disconnect/reconnect grace and post-leave chat admission behavior.
+- [ ] Multiple normal images, one image above the auto threshold, a malformed
+  “image”, and a maximum-size manual file.
+- [ ] Download/save after cache eviction; clear failure state and no runaway
+  memory across repeated attachments.
+- [ ] Observe process RSS and UI responsiveness during a bounded spam/attachment
+  stress run; verify leave/reconnect controls remain responsive.
+- [ ] Linux and Windows URL opening for valid links; malformed/userinfo links remain
+  selectable but do not launch.
+
+## Completion criteria
+
+The plan is complete when:
+
+1. Only active/grace-rostered authenticated authors reach chat UI state.
+2. Chat identity is roster-bound and cannot be overridden by the embedded wire
+   name.
+3. Exact replay and sustained spam are bounded before shared event queues.
+4. Live input, inbound/outbound body size, history text, attachment caches,
+   automatic transfers, served files, and decoded previews all have tested hard
+   bounds.
+5. File transfer length and image decoding/display costs are validated.
+6. Clickable links pass a shared parsed-URL policy and rendering work is bounded.
+7. Local broadcast failure is visible without claiming peer delivery.
+8. Unit/all-target/clippy gates and the two-machine field test pass.
+9. Relevant durable docs (`README.md`, `docs/FEATURES.md`, `CHANGELOG.md`, security
+   notes, and comments) describe the final behavior.
+10. This ephemeral plan is deleted after its useful status/history is transferred
+    to durable documentation.
+
+## Out of scope
+
+- Link previews, metadata fetches, or remote thumbnail requests.
+- Persistent/offline chat history or server-side message storage.
+- Markdown, rich embeds, reactions, editing, deletion, threads, or search.
+- Read receipts or peer delivery acknowledgements.
+- Moderation UI, kicking, blocking, or trust-list redesign.
+- Antivirus/malware scanning of user-requested downloaded files.
+- A new application-layer group-encryption protocol or a broader cryptographic
+  redesign. If PeerSpeak makes a formal end-to-end-encryption product claim, audit
+  and document the exact iroh/gossip/relay threat model as a separate project.
+
+## Decision log
+
+- **2026-07-15:** Chose hardening over automatic link previews because receiving a
+  message should not trigger third-party web requests or weaken PeerSpeak's
+  privacy-oriented design.
+- **2026-07-15:** Initial scope keeps all wire formats stable; hardening is local
+  admission, validation, resource accounting, and honest UI state.

src/app/mod.rs

@@ -6239,7 +6239,11 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                         // Rendered only while the audio link is live — the
                         // Connecting/Reconnecting indicator covers the rest.
                         if let Some(info) = state.conn_stats.get(peer_id) {
-                            let dot_color = if info.relay { color_yellow } else { color_green };
+                            let dot_color = if info.relay {
+                                color_yellow
+                            } else {
+                                color_green
+                            };
                             let badge = row![
                                 text("●").size(9).color(dot_color),
                                 text(conn_badge_label(info)).size(11).color(color_subtext),
@@ -6248,7 +6252,9 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                             .align_y(iced::alignment::Vertical::Center);
                             let detail = column![
                                 text(conn_tooltip_path(info)).size(11).color(color_text),
-                                text(conn_loss_label(info.loss_pct)).size(11).color(color_subtext),
+                                text(conn_loss_label(info.loss_pct))
+                                    .size(11)
+                                    .color(color_subtext),
                                 text(format!(
                                     "↑ {}   ↓ {}",
                                     conn_rate_label(info.up_kbps),
@@ -6261,9 +6267,11 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                             name_col = name_col.push(
                                 tooltip(
                                     badge,
-                                    container(detail)
-                                        .padding(8)
-                                        .style(c_style(color_crust, color_surface, 6.0)),
+                                    container(detail).padding(8).style(c_style(
+                                        color_crust,
+                                        color_surface,
+                                        6.0,
+                                    )),
                                     iced::widget::tooltip::Position::Bottom,
                                 )
                                 .gap(6),

src/core/jitter.rs

@@ -202,15 +202,20 @@ impl JitterBuffer {
                     None
                 } else {
                     // Gap with later packets already buffered: a packet was lost
-                    // or reordered out of window. First try Opus in-band FEC from
-                    // the next packet; if unavailable, fall back to plain PLC.
+                    // or reordered out of window. Try Opus in-band FEC from the
+                    // packet right after the gap; if that packet isn't buffered
+                    // (burst loss) or FEC fails, fall back to plain PLC.
                     self.next_seq = Some(next.wrapping_add(1));
                     self.note_disruption();
-                    let next_payload = self.packets.values().next().expect("non-empty");
+                    let (&smallest, next_payload) = self.packets.iter().next().expect("non-empty");
+                    if fec_covers_gap(next, smallest) {
                         self.decoder
                             .decode_fec(next_payload)
                             .or_else(|_| self.decoder.decode(None))
                             .ok()
+                    } else {
+                        self.decoder.decode(None).ok()
+                    }
                 }
             }
         }
@@ -222,6 +227,15 @@ impl JitterBuffer {
     }
 }
 
+/// Opus in-band FEC in packet N carries a low-fidelity copy of frame N-1 and
+/// nothing else — a lost frame `next` is FEC-recoverable solely from packet
+/// `next+1`. Any later successor's FEC data is a different frame's audio, and
+/// splicing it into this gap plays sound from the wrong position; the caller
+/// must conceal with plain PLC instead.
+fn fec_covers_gap(next: u32, smallest_buffered: u32) -> bool {
+    smallest_buffered == next.wrapping_add(1)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -379,6 +393,77 @@ mod tests {
         );
     }
 
+    #[test]
+    fn fec_covers_gap_only_for_the_immediate_successor() {
+        // Packet next+1 is the only one whose in-band FEC describes frame `next`.
+        assert!(fec_covers_gap(4, 5));
+        // A burst gap: the smallest survivor's FEC is some other frame's audio.
+        assert!(!fec_covers_gap(3, 5));
+        assert!(!fec_covers_gap(3, 3_000));
+        // Sequence wraparound still counts as adjacent.
+        assert!(fec_covers_gap(u32::MAX, 0));
+    }
+
+    #[test]
+    fn burst_gap_falls_back_to_plc_not_wrong_position_fec() {
+        let mut enc = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
+        enc.apply_params(&OpusParams {
+            bitrate: 20_000,
+            inband_fec: true,
+            packet_loss_perc: 60,
+            dtx: false,
+        })
+        .unwrap();
+
+        // Frames 0..=6; 3 and 4 are lost as a burst, so when playout reaches
+        // seq 3 the smallest buffered packet is 5 — whose FEC data is frame 4,
+        // NOT frame 3. The buffer must conceal 3 with plain PLC rather than
+        // splice frame 4's audio into the wrong position.
+        let packets: Vec<Vec<u8>> = (0..7).map(|seq| tone_frame(&mut enc, 8_000, seq)).collect();
+
+        // Twin decoder replaying the exact call sequence the jitter buffer
+        // should make for seq 3: decode 0,1,2 then a plain PLC conceal.
+        let mut twin = OpusDecoder::new(48000, Channels::Mono, FRAME_SAMPLES).unwrap();
+        for packet in packets.iter().take(3) {
+            twin.decode(Some(packet)).unwrap();
+        }
+        let expected_plc = twin.decode(None).unwrap();
+
+        let mut jb = JitterBuffer::new().unwrap();
+        for (seq, packet) in packets.iter().enumerate() {
+            if seq != 3 && seq != 4 {
+                jb.insert(seq as u32, packet.clone());
+            }
+        }
+
+        for _ in 0..3 {
+            assert_eq!(jb.pop_frame().map(|frame| frame.len()), Some(FRAME_SAMPLES));
+        }
+
+        // Seq 3: burst gap — bit-exact PLC (same decoder state, same inputs),
+        // which decode_fec(packet 5) could never produce.
+        let concealed = jb.pop_frame().expect("gap should be concealed");
+        assert_eq!(concealed, expected_plc, "burst gap must use plain PLC");
+
+        // Seq 4: packet 5 IS the immediate successor, so its FEC data is
+        // frame 4's audio — the correctly-positioned recovery still applies.
+        let recovered = jb
+            .pop_frame()
+            .expect("adjacent gap should be reconstructed");
+        let mut fec_twin = OpusDecoder::new(48000, Channels::Mono, FRAME_SAMPLES).unwrap();
+        for packet in packets.iter().take(3) {
+            fec_twin.decode(Some(packet)).unwrap();
+        }
+        fec_twin.decode(None).unwrap();
+        let expected_fec = fec_twin.decode_fec(&packets[5]).unwrap();
+        assert_eq!(recovered, expected_fec, "adjacent gap should still use FEC");
+
+        // Then 5 and 6 play normally.
+        assert_eq!(jb.pop_frame().map(|frame| frame.len()), Some(FRAME_SAMPLES));
+        assert_eq!(jb.pop_frame().map(|frame| frame.len()), Some(FRAME_SAMPLES));
+        assert!(jb.pop_frame().is_none());
+    }
+
     #[test]
     fn drops_packets_already_played() {
         let mut enc = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();

src/core/mod.rs

@@ -888,6 +888,103 @@ async fn build_net_stack(
     })
 }
 
+/// Retry policy for a live net-stack replacement, generic over the builder so
+/// it is unit-testable without binding sockets: build for `requested`; if that
+/// fails, build for `live` (the posture the old stack was actually running) so
+/// a bad posture change degrades to the previous posture instead of leaving no
+/// stack at all. When `requested == live` the second attempt is a plain retry.
+///
+/// `Ok((stack, mode, primary_err))` — a stack is up on `mode`; `primary_err`
+/// is `Some` when the first attempt failed. `Err((primary, fallback))` — both
+/// attempts failed and networking is gone.
+async fn rebuild_with_fallback<T, E, F, Fut>(
+    mut build: F,
+    requested: NetworkMode,
+    live: NetworkMode,
+) -> Result<(T, NetworkMode, Option<E>), (E, E)>
+where
+    F: FnMut(NetworkMode) -> Fut,
+    Fut: std::future::Future<Output = Result<T, E>>,
+{
+    match build(requested).await {
+        Ok(stack) => Ok((stack, requested, None)),
+        Err(primary) => match build(live).await {
+            Ok(stack) => Ok((stack, live, Some(primary))),
+            Err(fallback) => Err((primary, fallback)),
+        },
+    }
+}
+
+/// Tear down `old` and stand up a replacement stack for `requested_mode`.
+///
+/// A build failure here is rare (only the local socket bind can fail; the
+/// relay handshake is backgrounded), but it used to propagate straight out of
+/// `run_core_loop` with no `UiEvent`, silently killing every future command —
+/// the app looked alive and did nothing. Instead, fall back to `live_mode`
+/// via `rebuild_with_fallback`, tell the UI when the requested change did not
+/// stick, and return the mode the new stack actually runs so the caller can
+/// keep its state honest. `Err` only when both builds fail: networking is
+/// gone (already reported to the UI as fatal) and the caller should exit.
+#[allow(clippy::too_many_arguments)]
+async fn replace_net_stack(
+    old: NetStack,
+    what: &str,
+    secret_key: &SecretKey,
+    requested_mode: NetworkMode,
+    live_mode: NetworkMode,
+    friends_handler: &crate::presence_net::Handler,
+    publish: bool,
+    ui_tx: &mpsc::Sender<UiEvent>,
+) -> Result<(NetStack, NetworkMode), anyhow::Error> {
+    let lookup = old.memory_lookup.clone();
+    old.shutdown().await;
+    let outcome = rebuild_with_fallback(
+        |mode| {
+            build_net_stack(
+                secret_key.clone(),
+                mode,
+                lookup.clone(),
+                friends_handler.clone(),
+                publish,
+            )
+        },
+        requested_mode,
+        live_mode,
+    )
+    .await;
+    match outcome {
+        Ok((stack, mode, None)) => Ok((stack, mode)),
+        Ok((stack, mode, Some(primary))) => {
+            if mode == requested_mode {
+                // Same-posture retry succeeded — everything the user asked for
+                // is in effect, so log it rather than raising a UI error.
+                crate::log_msg(&format!(
+                    "{what}: net stack build failed once ({primary:#}); retry succeeded"
+                ));
+            } else {
+                let _ = ui_tx
+                    .send(UiEvent::Error(format!(
+                        "{what} failed ({primary:#}); staying on the previous \
+                         network mode for this session"
+                    )))
+                    .await;
+            }
+            Ok((stack, mode))
+        }
+        Err((primary, fallback)) => {
+            let _ = ui_tx
+                .send(UiEvent::Error(format!(
+                    "Networking lost: {primary:#} (recovery attempt also failed: \
+                     {fallback:#}). Restart PeerSpeak to reconnect."
+                )))
+                .await;
+            Err(anyhow::anyhow!(
+                "net stack rebuild failed: {primary:#}; fallback: {fallback:#}"
+            ))
+        }
+    }
+}
+
 /// Maximum number of *automatic* chat-attachment fetches in flight at once.
 ///
 /// Auto-fetch (inline image preview) is triggered by an untrusted peer's chat
@@ -1335,6 +1432,10 @@ async fn run_core_loop(
     // rebuilt on the next Leave (or before the next Join), preserving the old
     // "applies on next join" semantics while keeping the endpoint up while idle.
     let mut net_rebuild_pending = false;
+    // The posture the live stack was actually built with. Trails `network_mode`
+    // while a rebuild is pending, and is the fallback posture when a rebuild
+    // fails (see `replace_net_stack`).
+    let mut net_mode = network_mode;
 
     // When Discoverable is on, the instant it auto-reverts to Normal (W7 P6 time-box).
     // `None` = not Discoverable, no pending revert. Set on SetPresenceMode(Discoverable),
@@ -1552,17 +1653,24 @@ async fn run_core_loop(
                 // active, rebuild the persistent stack now — after the old session is
                 // gone, before the new one binds — so this join uses the new posture.
                 if net_rebuild_pending {
-                    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(),
+                    let (stack, live) = replace_net_stack(
+                        net,
+                        "Applying deferred network settings",
+                        &secret_key,
                         network_mode,
-                        lookup,
-                        friends_handler.clone(),
+                        net_mode,
+                        &friends_handler,
                         publish,
+                        &ui_tx,
                     )
                     .await?;
+                    net = stack;
+                    net_mode = live;
+                    // If the new posture failed and we fell back, keep the mode
+                    // state honest (and re-attemptable) rather than pretending
+                    // the change applied. The join proceeds on the live stack.
+                    network_mode = live;
                     net_rebuild_pending = false;
                 }
 
@@ -2594,17 +2702,21 @@ async fn run_core_loop(
                 // Apply any network-mode / identity change that was deferred while we
                 // were in the call (rebuild while idle keeps the endpoint reachable).
                 if net_rebuild_pending {
-                    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(),
+                    let (stack, live) = replace_net_stack(
+                        net,
+                        "Applying deferred network settings",
+                        &secret_key,
                         network_mode,
-                        lookup,
-                        friends_handler.clone(),
+                        net_mode,
+                        &friends_handler,
                         publish,
+                        &ui_tx,
                     )
                     .await?;
+                    net = stack;
+                    net_mode = live;
+                    network_mode = live;
                     net_rebuild_pending = false;
                 }
             }
@@ -2750,17 +2862,21 @@ async fn run_core_loop(
                     // 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(),
+                        let (stack, live) = replace_net_stack(
+                            net,
+                            "Network mode change",
+                            &secret_key,
                             network_mode,
-                            lookup,
-                            friends_handler.clone(),
+                            net_mode,
+                            &friends_handler,
                             publish,
+                            &ui_tx,
                         )
                         .await?;
+                        net = stack;
+                        net_mode = live;
+                        network_mode = live;
                     } else {
                         net_rebuild_pending = true;
                     }
@@ -2798,17 +2914,22 @@ async fn run_core_loop(
                 // key unchanged, so a rebuild would be pointless churn).
                 if regenerated {
                     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(),
+                        // Same mode both attempts — the fallback is a plain
+                        // retry under the (already persisted) new key.
+                        let (stack, live) = replace_net_stack(
+                            net,
+                            "Endpoint restart after identity change",
+                            &secret_key,
                             network_mode,
-                            lookup,
-                            friends_handler.clone(),
+                            net_mode,
+                            &friends_handler,
                             publish,
+                            &ui_tx,
                         )
                         .await?;
+                        net = stack;
+                        net_mode = live;
                     } else {
                         net_rebuild_pending = true;
                     }
@@ -3322,10 +3443,10 @@ fn replace_viewer_index<T>(viewers: &[(String, T)], ticket: &str) -> Option<usiz
 mod tests {
     use super::{
         KnownPeers, MAX_OPUS_PAYLOAD, MAX_RETAINED_PEERS, MIC_LEVEL_REPORT_SAMPLES, MicLevelMeter,
-        PLAYBACK_HANDOFF_QUEUE_FRAMES, PeerSpeakTicket, admit_retained, apply_peer_volume,
-        apply_volume, audio_datagram_len_ok, coalesce_insert, coalesce_pop, frame_level,
-        mix_frames, mix_stereo_frames, next_game_change, replace_viewer_index, send_playback_frame,
-        should_auto_fetch, stereo_to_mono,
+        NetworkMode, PLAYBACK_HANDOFF_QUEUE_FRAMES, PeerSpeakTicket, admit_retained,
+        apply_peer_volume, apply_volume, audio_datagram_len_ok, coalesce_insert, coalesce_pop,
+        frame_level, mix_frames, mix_stereo_frames, next_game_change, rebuild_with_fallback,
+        replace_viewer_index, send_playback_frame, should_auto_fetch, stereo_to_mono,
     };
     use crate::core::messages::{CoalesceKey, CoreCommand, coalesce_key};
     use std::collections::{HashMap, HashSet};
@@ -3349,6 +3470,101 @@ mod tests {
         assert_eq!(replace_viewer_index::<u8>(&[], "ticket-A"), None);
     }
 
+    // --- rebuild_with_fallback: the retry policy behind replace_net_stack ---
+    // The builder is injected, so these cover the policy without sockets. The
+    // closure does its bookkeeping synchronously and returns a ready future.
+
+    #[tokio::test]
+    async fn rebuild_keeps_requested_posture_on_first_success() {
+        let calls = std::cell::RefCell::new(Vec::new());
+        let out = rebuild_with_fallback(
+            |mode| {
+                calls.borrow_mut().push(mode);
+                std::future::ready(Ok::<u8, String>(7))
+            },
+            NetworkMode::DirectOnly,
+            NetworkMode::N0Full,
+        )
+        .await;
+        assert_eq!(out, Ok((7, NetworkMode::DirectOnly, None)));
+        // No second build: the live posture is only a fallback.
+        assert_eq!(*calls.borrow(), vec![NetworkMode::DirectOnly]);
+    }
+
+    #[tokio::test]
+    async fn rebuild_falls_back_to_the_live_posture_when_the_requested_one_fails() {
+        let calls = std::cell::RefCell::new(Vec::new());
+        let out = rebuild_with_fallback(
+            |mode| {
+                calls.borrow_mut().push(mode);
+                std::future::ready(if mode == NetworkMode::DirectOnly {
+                    Err("bind failed".to_string())
+                } else {
+                    Ok(7u8)
+                })
+            },
+            NetworkMode::DirectOnly,
+            NetworkMode::N0Full,
+        )
+        .await;
+        // A stack is up on the OLD posture and the caller learns both that it
+        // fell back (mode) and why (the primary error) — no silent zombie.
+        assert_eq!(
+            out,
+            Ok((7, NetworkMode::N0Full, Some("bind failed".to_string())))
+        );
+        assert_eq!(
+            *calls.borrow(),
+            vec![NetworkMode::DirectOnly, NetworkMode::N0Full]
+        );
+    }
+
+    #[tokio::test]
+    async fn rebuild_reports_both_errors_when_networking_is_gone() {
+        let out = rebuild_with_fallback(
+            |_| std::future::ready(Err::<u8, String>("bind failed".to_string())),
+            NetworkMode::DirectOnly,
+            NetworkMode::N0Full,
+        )
+        .await;
+        assert_eq!(
+            out,
+            Err(("bind failed".to_string(), "bind failed".to_string()))
+        );
+    }
+
+    #[tokio::test]
+    async fn rebuild_with_equal_postures_is_a_plain_retry() {
+        // RegenerateIdentity rebuilds under the same mode: the fallback is a
+        // second attempt with identical parameters, not a posture change.
+        let calls = std::cell::Cell::new(0u8);
+        let out = rebuild_with_fallback(
+            |mode| {
+                calls.set(calls.get() + 1);
+                assert_eq!(mode, NetworkMode::RelayNoDiscovery);
+                std::future::ready(if calls.get() == 1 {
+                    Err("transient".to_string())
+                } else {
+                    Ok(7u8)
+                })
+            },
+            NetworkMode::RelayNoDiscovery,
+            NetworkMode::RelayNoDiscovery,
+        )
+        .await;
+        // Succeeded on the requested posture, so the caller treats the change
+        // as applied (the Some(err) is logged, not surfaced as a UI error).
+        assert_eq!(
+            out,
+            Ok((
+                7,
+                NetworkMode::RelayNoDiscovery,
+                Some("transient".to_string())
+            ))
+        );
+        assert_eq!(calls.get(), 2);
+    }
+
     #[test]
     fn admit_retained_rejects_only_new_ids_at_the_cap() {
         // Below the cap, a brand-new identity is retained.

src/screenshare/mod.rs

@@ -374,7 +374,11 @@ pub async fn spawn_host(
     // Log the exact argv we hand pixelpass so a field log can confirm which
     // encode/quality flags (e.g. --bitrate) actually reached the host — these
     // are local flags with no ticket/secret, so logging them verbatim is safe.
-    crate::log_msg(&format!("pixelpass host spawn: {} {}", bin.display(), args.join(" ")));
+    crate::log_msg(&format!(
+        "pixelpass host spawn: {} {}",
+        bin.display(),
+        args.join(" ")
+    ));
     let mut child = Command::new(bin)
         .args(&args)
         .stdin(Stdio::null())

src/widget/context_input.rs

@@ -766,7 +766,11 @@ where
                 }
             }
             MenuAction::Paste => {
-                let clip = sanitize_clip(&clipboard.read(clipboard::Kind::Standard).unwrap_or_default());
+                let clip = sanitize_clip(
+                    &clipboard
+                        .read(clipboard::Kind::Standard)
+                        .unwrap_or_default(),
+                );
                 let edit = paste(self.value, start, end, &clip);
 
                 self.publish_paste(edit, shell);

tests/transport_loopback.rs

@@ -304,7 +304,9 @@ async fn connection_stats_report_a_direct_path_with_live_counters() {
     assert_eq!(info.remote_addr, s2.remote_addr);
     assert!(info.rtt_ms < 1000, "localhost RTT should be sane");
     assert!(
-        info.up_kbps.expect("same path + positive window has a rate") > 0.0,
+        info.up_kbps
+            .expect("same path + positive window has a rate")
+            > 0.0,
         "audio was flowing, so the upstream rate must be non-zero"
     );
 }