Summary

Queue drain uses typeof threadId === "number" which silently drops Slack's string thread_ts, causing queued replies to leak to the main channel instead of the thread.

lobster-biscuit

Repro Steps

1. Configure Slack with replyToMode: all
2. Send 2+ messages while agent is processing
3. Queued response appears in channel, not thread

Root Cause

src/auto-reply/reply/queue/drain.ts uses typeof threadId === "number" in 3 places. Telegram uses numeric topic IDs (passes check), Slack uses string thread_ts like "1770474140.187459" (fails check). The type in queue/types.ts was updated to string | number when Slack threading was added, but drain.ts was not updated.

Behavior Changes

• String thread IDs (Slack thread_ts) now preserved during queue drain
• Empty string "" treated as absent (prevents spurious thread grouping if any provider normalizes missing values to "")
• No change for numeric thread IDs (Telegram)

Codebase and GitHub Search

• Searched: originatingThreadId, typeof.*number.*threadId, thread_ts.*queue
• Found 3 prior PRs with same fix but missing empty-string edge case (fix: handle string thread_ts from Slack properly #4389, fix: handle string thread IDs in queue drain for Slack #4749, [Slack] fix: preserve thread context for string threadId in queue drain #5245)
• Reviewer on fix: handle string thread_ts from Slack properly #4389 (Greptile) flagged the empty-string gap — this PR addresses it

Tests

3 new cases in queue.collect-routing.test.ts:

• ✅ Collects messages with matching string thread_ts (same Slack thread)
• ✅ Separates messages with different string thread_ts (different threads)
• ✅ Treats empty string threadId same as absent

pnpm test src/auto-reply/reply/queue.collect-routing.test.ts
 ✓ 9 tests passed

Sign-Off

• Models used: Claude Opus 4 (via OpenClaw)
• Submitter effort: AI-assisted, fully tested, code reviewed
• Agent notes: Fix addresses empty-string edge case missed by fix: handle string thread_ts from Slack properly #4389, fix: handle string thread IDs in queue drain for Slack #4749, [Slack] fix: preserve thread context for string threadId in queue drain #5245. Verified no other typeof === "number" checks on threadId exist in codebase.

Fixes #11195
Related PRs (same fix, but without empty-string edge case protection):

• fix: handle string thread_ts from Slack properly #4389 — uses threadId == null without !== "" check. Greptile flagged this gap at Confidence 4/5.
• fix: handle string thread IDs in queue drain for Slack #4749 — identical diff to fix: handle string thread_ts from Slack properly #4389, same gap.
• [Slack] fix: preserve thread context for string threadId in queue drain #5245 — adds comments but same != null without empty-string guard.

This PR adds \&\& threadId !== "" to all 3 locations, addressing the edge case Greptile identified. Also includes 3 new tests (string thread_ts collection, different threads separation, empty-string handling) which the other PRs lack.

Related issues: #4380, #4424, #5615

Greptile Overview

Greptile Summary

This PR fixes follow-up queue drain routing so Slack thread replies don't lose their thread_ts context during "collect" drains.

The drain logic previously treated originatingThreadId as present only when it was a number, which works for Telegram topic IDs but drops Slack's string thread_ts values. The change updates the routing key computation and the collected-batch originatingThreadId selection to treat any non-empty string | number as a valid thread id, while treating "" as absent to avoid creating spurious thread groups. New tests in queue.collect-routing.test.ts cover same-thread collection, different-thread separation, and empty-string behavior.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk.
• Changes are narrowly scoped to queue drain routing, align with existing FollowupRun.originatingThreadId: string | number typing, and are covered by targeted unit tests for Slack thread_ts string handling and empty-string edge cases.
• No files require special attention

_{Greptile review restored manually after accidental body overwrite.}