Phase 3 of docs/chat-hardening-plan.md — attachments can no longer turn
into unbounded memory, bandwidth, decoder, or task pressure (S15 closed;
S14's filename half closed).
Cache and image cost (3A): AttachmentCache now carries encoded- and
decoded-byte budgets (96 MiB / 64 MiB) on top of the count cap, with
per-entry weights, replacement accounting, and oldest-first eviction; an
individually over-budget fetch services any pending Save/Play from the
bytes in hand and is exposed as Evicted instead of retained.
validate_image_bytes prechecks header dimensions (per-side AND a new
14 MP total-pixel limit) before any decode; the renderer only ever
receives a ≤1600 px downscaled RGBA preview whose w*h*4 cost counts
against the decoded budget — originals stay encoded-only for Save.
sanitize_filename strips the bidi/zero-width spoofing set (RTL-override
extension spoof).
Download policy and state (3B): images auto-fetch only when roster-
authored AND declared ≤4 MiB, gated by a new deterministic
AutoFetchBudget (per-author and session request+byte token buckets,
check-then-take, bounded author map) alongside the existing dedup and
four-permit bound. Attachment state is now explicit — absence/Loading/
Ready/Failed/Evicted — driven by a new AttachmentFetchStarted event, so
skipped or evicted images render a "Load image" button instead of an
indefinite "loading…", and repeated clicks can never spawn duplicate
fetch tasks.
Exact transfers and serve store (3C): fetch_blob requires the received
length to equal the declared size (short = local error, overlong =
bounded-read reject, empty keeps meaning "sender no longer has it");
the file picker's unbounded read is replaced by a metadata-prechecked
cap+1 bounded reader; one Arc<Vec<u8>> now backs the UI cache, command
queue, and serve store; served_files is a count- and byte-budgeted FIFO
ServeStore (16 entries / 128 MiB).
37 new tests (568 lib total) including a real two-endpoint loopback
exercising exact/short/overlong/unknown-id transfers. Plan checkboxes
ticked and constant deviations decision-logged. Tests-green-only: the
plan's two-machine field-test section remains open.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Chat-hardening plan Phase 2 — only current authenticated room members can
create chat UI work, impersonation via the wire name is structurally closed,
and no member can monopolize the event channel:
- core: new ChatRoster (bounded id -> sanitized-name map, shared) replaces the
event task's bare HashSet; upserted on PeerJoined/PeerUpdated, removed on
graceful PeerLeft AND terminal grace-expiry eviction (both timer paths).
Non-roster chat is dropped before attachment handling; the rendered author
label is the roster-bound name — the sender-claimed wire name is never read.
- gossip: ChatIngressGate after verify_gossip, before any sanitize work or
event send: early known-author gate (live + mid-reconnect peers), exact-
replay suppression keyed on the deterministic Ed25519 signature (1024-entry
cap + freshness-window TTL, zero new deps vs the plan's BLAKE3 option), then
per-author (8 burst, 1/s) and room-wide (32 burst, 8/s) token buckets.
Replays are detected before tokens are consumed; a room-bucket reject
refunds the author token; rejection logging is squelched per author.
- The inner Chat.ts is now ignored entirely; RoomEvent carries the signed
envelope timestamp.
550 lib tests (+18), reconnect_eviction +1 (grace keeps chat authority,
terminal eviction revokes it), clippy --all-targets -D warnings clean.
Tests-green-only: the plan's two-machine field-test section remains open.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Chat-hardening plan Phase 1. The chat body policy (2,000-char + 8 KiB
ceilings, single-pass control/whitespace normalization) moves from the UI
layer into src/sanitize.rs and is now enforced at every trust boundary:
cap_chat_input bounds the live input (oversized paste), the gossip sign
point re-sanitizes so non-UI callers can't bypass policy, and gossip
ingress rejects oversized raw text before sanitizing (admit_chat_text)
and drops messages with neither visible text nor an attachment. The
incoming chat author label now uses the strict name sanitizer until
Phase 2 roster-binds it. +8 tests (532 lib green).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
GPT-5.6's 5-phase plan for the chat identity/replay/rate-limit cluster
(2026-07-16 review findings 5-8): roster-bound display names, replay
dedup, quiet rate limiting, bidi-aware sanitization, attachment size
checks. Self-describes as temporary — delete when the work completes.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
molluskandClaude Fable 5