Symptom

User-sent Discord messages stop being processed in a channel even though the gateway is healthy and other channels work. Diagnostic log emits repeatedly:

lane wait exceeded: lane=session:agent:main:discord:channel:<id> waitedMs=<>200000 queueAhead=0|1

with no concurrent LLM activity (per-session <sessionId>.jsonl mtime is 5+ minutes stale, gateway CPU low). Manually deleting the session entry from agents/main/sessions/sessions.json and restarting unblocks the channel; new messages then process normally.

Repro hypothesis

Lane release path appears to miss a branch when a run completes via cron / heartbeat / system-event entry rather than a user-initiated reply. Multiple paths in the bundled dist do call sessionLock.release() (e.g. compact, wait-for-idle-before-flush, transcript-rewrite, selection), but at least one terminal path leaves the in-memory lock held without an exception/abort. Fresh user messages then pile up behind a lane that thinks it is still processing.

Concrete observation: in a 24h window we saw lane wait exceeded entries for 3 distinct Discord channels with queueAhead=0 (head-of-queue stuck) and waitedMs ranging 220s–600s, with the per-session jsonl untouched for the entire wait period.

Environment

• OpenClaw 2026.4.24 (homebrew)
• Node 25.9.0
• macOS arm64
• Discord plugin, multiple guilds/channels, several main-session crons feeding through

Repro steps (best-effort)

1. Configure several payload.kind=systemEvent crons targeted at sessionTarget=main plus current-bound agentTurn jobs that share Discord channel session keys.
2. Run for hours.
3. Eventually one channel goes silent: queued user messages don't trigger a reply, gateway is otherwise healthy.

I have not been able to produce a tight unit-test repro — it appears to be a race between a run terminating and the lock-release callback in certain delivery paths.

Workaround

cp ~/.openclaw/agents/main/sessions/sessions.json{,.bak}
python3 - <<'PY'
import json
p = '<sessions.json path>'
d = json.load(open(p))
del d['agent:main:discord:channel:<channel-id>']
json.dump(d, open(p,'w'), indent=2)
PY
openclaw gateway restart

I've shipped a detection-only watchdog on my side that scans the diagnostic log for lane wait exceeded and alerts to a Discord ops channel — happy to PR that as a CLI subcommand if useful.

What would help

1. Confirm whether sessionLock.release() is invoked from every terminal path of runAgentTurn / processSystemEvent — particularly the cron-delivered and heartbeat-delivered branches.
2. Add a defensive watchdog inside the gateway: any lane held >N minutes with no in-flight LLM call should be auto-released (with a warning log).
3. Expose lane state via openclaw status --lanes for easier diagnosis.

Happy to provide gateway logs / sessions.json snapshots privately if helpful.