Summary

Subagent completion announcements (via sessions_spawn) always land in the main Slack DM instead of the originating thread. The threadId is correctly passed through the entire announce pipeline (sendSubagentAnnounceDirectly → callGateway({method: "send"}) → deliverOutboundPayloads) but the Slack channel extension's outbound sendText and sendMedia functions do not destructure threadId from the delivery context.

Root Cause

In extensions/slack/src/channel.ts, the outbound sendText function:

sendText: async ({ to, text, accountId, deps, replyToId, cfg }) => {
  // ...
  const result = await send(to, text, {
    threadTs: replyToId ?? undefined,  // ❌ only uses replyToId, ignores threadId
  });
}

The delivery context carries threadId (set from deliveryContext.threadId of the requester session), but it is never destructured or used. Only replyToId is mapped to threadTs.

Fix

sendText: async ({ to, text, accountId, deps, replyToId, threadId, cfg }) => {
  // ...
  const result = await send(to, text, {
    threadTs: replyToId ?? threadId ?? undefined,  // ✅ falls back to threadId
  });
}

Same fix needed for sendMedia.

Steps to Reproduce

1. Open a Slack DM with OpenClaw bot
2. Start a thread on any message
3. From within the thread, have the agent call sessions_spawn(task="test")
4. Wait for subagent completion
5. Expected: Announce appears in the thread
6. Actual: Announce appears in the main DM (top-level)

Debug Evidence

Added logging to sendMessageSlack — confirmed threadTs=NONE despite threadId being present throughout the announce flow:

[ANNOUNCE-FLOW-START] threadId="1771478217.865789" ✅
[COMPLETION-PATH] threadId="1771478217.865789" ✅  
[SLACK-SEND] threadTs=NONE ❌

After fix:

[SLACK-SEND] threadTs=1771478217.865789 ✅

Environment

• OpenClaw 2026.2.19-2
• Slack channel (non-assistant-app, regular DM threads)
• Linux x64

Related Issues

• [Bug]: Subagent announce doesn't preserve Slack assistant app thread context #17731 — Similar symptom but different root cause (assistant app thread sessions)
• Sub-agent announce drops threadId for depth≥1 requesters — completions post to channel instead of thread #22118 — Different: depth≥1 sub-agent chain threadId loss