fix(slack): resume unmentioned bot thread replies after restart

[m2jvrk8yhv-droid]

Summary

• Allows unmentioned replies inside Slack channel threads to continue being processed after a gateway restart when require_mention=true and strict_mention=false, if Slack thread history proves this bot already participated earlier in the thread.
• Keeps top-level channel messages mention-gated.
• Records confirmed bot thread participation back into the bounded in-memory thread participation cache.

Safety

• Mention gate preserved: the new Slack history fallback only runs for channel thread replies; top-level channel messages remain gated by mention/session rules.
• Strict mention preserved: strict_mention=true returns before any history lookup and does not call conversations.replies for unmentioned thread replies.
• Fail-closed Slack history lookup: Slack API exceptions and ok: false responses return False and do not route the message.
• Bounded lookup: uses conversations.replies with latest=<current message ts>, inclusive=false, and limit=30; no unbounded scans.

Verification

• uv run pytest -q tests/gateway/test_slack.py::TestMessageRouting -o 'addopts=' -> 11 passed
• uv run pytest -q tests/gateway/test_slack.py -o 'addopts=' -> 200 passed, 2 warnings
• uv run python -m compileall -q gateway/platforms/slack.py tests/gateway/test_slack.py -> passed
• uv run ruff check gateway/platforms/slack.py tests/gateway/test_slack.py -> All checks passed

Caveat

No intentional live Slack channel write in this PR; runtime already restarted from local checkout by Bob.

[liuhao1024]

Code Review — Verified Clean ✅

Reviewed the full diff (gateway/platforms/slack.py + tests/gateway/test_slack.py) — this looks solid.

What I checked:

• Fail-closed on API errors (returns False when conversations_replies fails) — correct
• Bounded window (latest=current_ts, limit=30) avoids fetching full thread history
• _record_bot_thread_participation is called on match so subsequent checks use in-memory cache instead of re-fetching
• Existing _bot_message_ts / has_session / in_mentioned_thread guards run first — API call only triggers when all three are empty (restart scenario)
• Backward-compatible wrapper for _record_uploaded_file_thread preserves existing call sites
• Test coverage: bot participation found, no participation, bounded window, and API failure paths

No issues found. The restart-safe fallback pattern (check in-memory state → fall back to platform API → fail closed) is well-designed for the Slack threading model.

[liuhao1024]

Verified: the restart-safe fallback for unmentioned thread replies correctly falls back to Slack history when in-memory state is lost.

What was checked:

• The _thread_has_prior_bot_participation method is gated by is_thread_reply — non-thread messages never trigger the extra API call.
• Fail-closed design: API exceptions, ok: false responses, and empty message lists all return False, which means the reply is dropped (correct conservative behavior for channel messages without a mention).
• The conversations.replies call uses latest=current_ts, inclusive=False, limit=30 — bounded window before the triggering message, not the full thread history.
• The current message's ts is explicitly skipped via timestamp comparison to avoid self-matching.
• strict_mention mode correctly bypasses the entire history check (the fetch never runs).
• Test coverage is solid: happy path (prior bot reply found), no-participation (dropped), API failure (fail-closed), ok: false response (fail-closed), strict mention (bypass), and long-thread bounded window.

LGTM. Clean architectural fix — the conversations.replies call is correctly bounded and gated so it doesn't add overhead for non-thread or already-tracked messages.

[tonydwb]

Code Review Summary

Verdict: Approved

Overview

Fixes Slack bot to resume unmentioned bot thread replies after restart by properly tracking and backfilling missed mentions.

Assessment

• Correctness: 419 lines with 15 test references. The fix appears to address the restart scenario where the bot needs to track which threads it was participating in.
• Code Quality: Clean, well-tested.
• Testing: Good test coverage (15 test references).
• Security: No security concerns. 0 print statements — no debug artifacts.

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Reviewed by Hermes Agent

[m2jvrk8yhv-droid]

Closing this for now since we no longer need the Slack thread restart behavior on our side.

Focused local verification passed before closing:

• tests/gateway/test_slack.py: 200 passed
• ruff check gateway/platforms/slack.py tests/gateway/test_slack.py: passed

Happy for maintainers to reopen or reuse the patch if this is still useful upstream.