docs: add channel unification checklist

docs/refactor/channel-unify.md

@@ -0,0 +1,103 @@
+---
+summary: "Checklist for unifying messaging channel logic"
+read_when:
+  - Planning refactors across channel implementations
+  - Standardizing shared message handling behavior
+---
+# Channel unification checklist
+
+Purpose: centralize repeated messaging logic so core + extensions stay consistent, testable, and easier to evolve.
+
+## Ack reactions (already centralized)
+- [x] Shared gating helper for core channels.
+- [x] Shared gating helper for extensions.
+- [x] WhatsApp-specific gating helper (direct/group/mentions) aligned with activation.
+- [ ] Optional: centralize “remove after reply” behavior (see below).
+
+## Ack reaction removal (after reply)
+Problem: duplicated logic across Discord, Slack, Telegram, BlueBubbles.
+- [ ] Create `channel.reactions.removeAfterReply()` helper that accepts:
+  - `removeAckAfterReply` flag
+  - ack promise + result boolean
+  - channel-specific remove fn + ids
+- [ ] Wire in:
+  - `src/discord/monitor/message-handler.process.ts`
+  - `src/slack/monitor/message-handler/dispatch.ts`
+  - `src/telegram/bot-message-dispatch.ts`
+  - `extensions/bluebubbles/src/monitor.ts`
+- [ ] Add unit tests for the helper (success + ack-failed paths).
+
+## Pending history buffering + flush
+Problem: repeated “record pending history”, “prepend pending history”, and “clear history” patterns.
+- [ ] Identify shared flow in:
+  - `src/discord/monitor/message-handler.preflight.ts`
+  - `src/discord/monitor/message-handler.process.ts`
+  - `src/slack/monitor/message-handler/prepare.ts`
+  - `src/telegram/bot-message-context.ts`
+  - `src/signal/monitor/event-handler.ts`
+  - `src/imessage/monitor/monitor-provider.ts`
+  - `extensions/mattermost/src/mattermost/monitor.ts`
+  - `src/web/auto-reply/monitor/group-gating.ts`
+- [ ] Add helper(s) to `src/auto-reply/reply/history.ts`:
+  - `recordPendingIfBlocked()` (accepts allowlist/mention gating reason)
+  - `mergePendingIntoBody()` (returns combined body)
+  - `clearPendingHistory()` (wrapper to standardize historyKey, limits)
+- [ ] Ensure per-channel metadata (sender label, timestamps, messageId) preserved.
+- [ ] Add tests for helper(s); keep per-channel smoke tests.
+
+## Typing lifecycle
+Problem: inconsistent typing start/stop handling and error logging.
+- [ ] Add a shared typing adapter in core (ex: `src/channels/typing.ts`) that accepts:
+  - `startTyping` / `stopTyping` callbacks
+  - `onReplyStart` / `onReplyIdle` hooks from dispatcher
+  - TTL + interval config (reuse `auto-reply/reply/typing` machinery)
+- [ ] Wire in:
+  - Discord (`src/discord/monitor/typing.ts`)
+  - Slack (`src/slack/monitor/message-handler/dispatch.ts`)
+  - Telegram (dispatch flow)
+  - Signal (`src/signal/monitor/event-handler.ts`)
+  - Matrix (`extensions/matrix/src/matrix/monitor/handler.ts`)
+  - Mattermost (`extensions/mattermost/src/mattermost/monitor.ts`)
+  - BlueBubbles (`extensions/bluebubbles/src/monitor.ts`)
+  - MS Teams (`extensions/msteams/src/reply-dispatcher.ts`)
+- [ ] Add helper tests for start/stop and error handling.
+
+## Reply dispatcher wiring
+Problem: channels hand-roll dispatcher glue; varies in error handling and typing.
+- [ ] Add a shared wrapper that builds:
+  - reply dispatcher
+  - response prefix context
+  - table mode conversion
+- [ ] Adopt in:
+  - Discord, Slack, Telegram (core)
+  - BlueBubbles, Matrix, Mattermost (extensions)
+- [ ] Keep per-channel delivery adapter (send message / chunking).
+
+## Session meta + last route updates
+Problem: repeated patterns for `recordSessionMetaFromInbound` and `updateLastRoute`.
+- [ ] Add helper `channel.session.recordInbound()` that accepts:
+  - `storePath`, `sessionKey`, `ctx`
+  - optional `channel/accountId/target` for `updateLastRoute`
+- [ ] Wire in:
+  - Discord, Slack, Telegram, Matrix, BlueBubbles
+
+## Control command gating patterns
+Problem: similar gating flow per channel (allowlists + commands).
+- [ ] Add a helper that merges:
+  - allowlist checks
+  - command gating decisions
+  - mention bypass evaluation
+- [ ] Keep channel-specific identity/user resolution separate.
+
+## Error + verbose logging
+Problem: inconsistent message formats across channels.
+- [ ] Define canonical log helpers:
+  - `logInboundDrop(reason, meta)`
+  - `logAckFailure(meta)`
+  - `logTypingFailure(meta)`
+- [ ] Apply to all channel handlers.
+
+## Docs + SDK
+- [ ] Expose new helpers through `src/plugin-sdk/index.ts` + plugin runtime.
+- [ ] Update `docs/tools/reactions.md` if ack semantics expand.
+- [ ] Add `read_when` hints if new cross-cutting helpers are introduced.