Bug

Sub-agents spawned via sessions_spawn are accepted but never announce completion back to the parent session. This affects ALL providers — not model-specific.

Structured Test (Mar 19, 2026)

Spawned 3 sub-agents simultaneously with identical tasks (simple generation + file read + computation) to isolate whether this is model-specific or systemic:

All three returned {"status": "accepted"} with valid session keys. None announced completion after 2+ hours.

Additional Observations

1. subagents list shows nothing — no active, no recent (even within 30min of spawn)
2. sessions_history on child sessions returns forbidden — Session history visibility is restricted to the current session tree
3. sessions_list with kinds: ["subagent"] returns 0 results
4. A 4th sub-agent (GPT 5.4, spawned ~15min earlier for a coding task) also failed identically — accepted, never completed

This Is a Regression

Sub-agents worked reliably as recently as Mar 17-18. Multiple GPT 5.4 sub-agents completed successfully (Bybit logger fix, bot code reviews). Something changed between Mar 18 and Mar 19.

Possibly Related

• [Bug] Subagent announce completion fails consistently on v2026.3.7+ — lane wait times up to 60min #45075 — Sub-agent announce completion fails due to lane wait times. However, that bug described delayed announces (minutes), not permanent silent failure.
• The earlier GPT 5.4 coding sub-agent (ac720778) showed status: failed with runtime of 396ms — suggesting it crashed immediately rather than running and failing to announce.

Impact

Sub-agents are a core workflow for us — code reviews, parallel research, bot audits, coding tasks. With 4/4 spawns failing silently, the feature is effectively broken.

Environment

• OpenClaw: 2026.3.13 (61d171a)
• Channel: Telegram
• Parent model: Claude Opus 4 (also tested from GPT 5.4 session)
• Sub-agent models tested: Opus, Sonnet, GPT 5.4
• Host: macOS, M1 Ultra

Expected

Sub-agents should either:

1. Complete and announce results back to parent, OR
2. Fail with a visible error in the parent session

Actual

Sub-agents accept the spawn, then vanish. No completion, no error, no trace. Parent session has no way to know what happened.