Code Review: Bot Transport Layers

Scope

Matterbridge bot has resilient reconnect loop with exponential backoff and ping keepalive.
Matrix bot implements room allowlist, self-message filtering, shadow mode, and thread-aware replies.
Matrix bot persists sync tokens + dedupe state; avoids reprocessing on restarts.
Rate-limit handling respects M_LIMIT_EXCEEDED with retry/backoff.
Health endpoint exposes useful counters and sync timestamps.

Matterbridge message channel is unbounded for handlers
- messages buffered at 100; when full, messages drop. No metrics for drops or backpressure handling.
- Consider exposing drop count or increasing buffer if needed.
Matrix queue drops without marking dedupe
- When send queue is full, response is dropped but the event remains unmarked in dedupe store, so a later replay could re-trigger.
- Consider marking as processed on drop (or explicit retry queue sizing).
Matrix encrypted room handling is partial
- m.room.encryption events mark rooms as encrypted, but only after join. Encrypted rooms already in allowlist could still process early timeline events before encryption event arrives.
- Consider checking encryption state via /state or guarding on first sync for allowlisted rooms.
Matrix send loop has no shutdown drain
- sendLoop exits on context cancel without draining queued sends; may lose last responses on shutdown.
- Consider best-effort drain with timeout or log queue length on shutdown.
State store cleanup timer tied to MarkEventProcessed
- Cleanup only runs when processing messages, so long idle periods may keep stale entries. Low impact but worth noting.

The Matrix bot appropriately avoids E2EE rooms and invites, but could log a clear startup warning when any allowlisted room is encrypted.
Matterbridge bot closes connection on ping failure but doesn’t propagate to run loop; reconnect relies on read loop exiting.