Description

When a sub-agent completes its work and OpenClaw tries to auto-announce the completion back to the requester session in a Discord group chat (/channel), the delivery silently fails with source_reply_delivery_mode_mismatch.

This causes the main agent (and the user) to never receive sub-agent completion notifications. The user has to manually ask "did the sub-agent finish?" after every spawn.

Root Cause

In runs-DrbsiywK.js (~line 147):

if (options?.sourceReplyDeliveryMode === "message_tool_only" 
    && handle.sourceReplyDeliveryMode !== "message_tool_only") {
    diagnosticLogger.debug("queue message failed: ... reason=source_reply_delivery_mode_mismatch");
    return { kind: "complete", outcome: createQueueFailureOutcome(sessionId, "source_reply_delivery_mode_mismatch") };
}

Discord group chats use sourceReplyDeliveryMode: "message_tool_only" (see bot-D0mzNk0g.js:6915 — sourceReplyDeliveryMode: isRoomEvent ? "message_tool_only" : void 0). When the sub-agent completion event tries to deliver back to the parent session, the handle.sourceReplyDeliveryMode doesn't match "message_tool_only", and the delivery is quietly dropped.

Impact

This worked previously but broke at some point. The sessions_yield mechanism was a workaround (yield → wake on completion event), but even that has stopped working reliably in group chat contexts.

Each sub-agent spawn requires manual user check-in to verify completion. This defeats the purpose of automated multi-agent orchestration.

Steps to Reproduce

1. Be in a Discord group chat (not DM)
2. Spawn a sub-agent via sessions_spawn
3. Use sessions_yield to wait
4. Sub-agent completes
5. Neither the completion announcement nor the yield wake arrives
6. The sub-agent completion event is logged as source_reply_delivery_mode_mismatch

Suggested Fix

The delivery failure at line 147 should fall through to an alternative delivery path instead of failing silently. Options:

1. When source_reply_delivery_mode_mismatch occurs, deliver the completion as an internal systemEvent instead of dropping it
2. Allow the yield-wake path to work independently of the source reply delivery path
3. Add message_tool_only support to the session handle for group chat contexts

Environment

• OpenClaw gateway running on Linux
• Discord channel (#dev in guild)
• Multi-agent orchestration via sessions_spawn + sessions_yield

Found by: Josephur (user) & Brachyura McCrabface (main agent)