- Slack/Identity: thread agent outbound identity (`chat:write.customize` overrides) through the channel reply delivery path so per-agent username, icon URL, and icon emoji are applied to all Slack replies including media messages. (#27134) Thanks @hou-rong.

- Slack/Threading: resolve `replyToMode` per incoming message using chat-type-aware account config (`replyToModeByChatType` and legacy `dm.replyToMode`) so DM/channel reply threading honors overrides instead of always using monitor startup defaults. (#24717) Thanks @dbachelder.

- Slack/Threading: track bot participation in message threads (per account/channel/thread) so follow-up messages in those threads can be handled without requiring repeated @mentions, while preserving mention-gating behavior for unrelated threads. (#29165) Thanks @luijoc.

- Agents/Subagents delivery: refactor subagent completion announce dispatch into an explicit queue/direct/fallback state machine, recover outbound channel-plugin resolution in cold/stale plugin-registry states across announce/message/gateway send paths, finalize cleanup bookkeeping when announce flow rejects, and treat Telegram sends without `message_id` as delivery failures (instead of false-success `"unknown"` IDs). (#26867, #25961, #26803, #25069, #26741) Thanks @SmithLabsLLC and @docaohieu2808.

- Telegram/Webhook: pre-initialize webhook bots, switch webhook processing to callback-mode JSON handling, and preserve full near-limit payload reads under delayed handlers to prevent webhook request hangs and dropped updates. (#26156)

- Slack/Session threads: prevent oversized parent-session inheritance from silently bricking new thread sessions, surface embedded context-overflow empty-result failures to users, and add configurable `session.parentForkMaxTokens` (default `100000`, `0` disables). (#26912) Thanks @markshields-tl.