Loop Diagnosis

Diagnose and fix stalled agent coding loops. This skill covers the diagnostic CLI, common failure modes, and the observability patterns that prevent silent stalls.

Quick Commands

# Diagnose all active loops at once
joelclaw loop diagnose all -c

# Diagnose a specific loop
joelclaw loop diagnose <loop-id> -c

# Diagnose AND auto-fix
joelclaw loop diagnose all -c --fix

# Full JSON output (for detailed inspection)
joelclaw loop diagnose <loop-id>

What Diagnosis Checks

The diagnose command runs 6 checks in order:

1. Redis state — PRD stories (pass/skip/pending), progress entries, active claims
2. Worktree — exists? commits? uncommitted changes? .out files?
3. Inngest runs — running/failed agent-loop-* functions, recent plan runs
4. Agent processes — any claude/codex processes still alive?
5. Worker health — function_count from localhost:3111/api/inngest
6. Diagnosis — pattern-matches the above into a root cause

Failure Modes & Fixes

When to Use (vs Other Skills)

• loop-diagnosis → Loop is stuck/stalled, need to figure out why and fix it
• loop-nanny → Loop is running, need to monitor progress and clean up after
• agent-loop → Need to START a new loop

The Event Chain

Understanding the chain helps diagnose WHERE it broke:

agent/loop.started
  → plan (picks story, dispatches test-writer)
    → agent/loop.story.dispatched
      → test-writer (writes acceptance tests)
        → agent/loop.tests.written
          → implement (codex/claude writes code)
            → agent/loop.story.implemented
              → review (runs tests, typecheck, claude review)
                → agent/loop.story.reviewed
                  → judge (pass/fail/retry decision)
                    → agent/loop.story.passed  ←── feeds back to plan
                    → agent/loop.story.failed  ←── feeds back to plan
                    → agent/loop.story.retry   ←── feeds back to implement

Most common break point: judge → plan. The agent/loop.story.passed event fires but plan never picks it up. This happens when:

• Inngest is restarting during the event
• Worker was restarted between judge and plan
• k8s pod restart dropped the event

Observability Patterns

Passive: Failure Events

Every loop function should emit failure events via onFailure handlers (being added by harden loop). These fire agent/loop.function.failed which gets logged to slog.

Active: Watchdog (Future)

A periodic Inngest function (system/loop-watchdog) that:

1. Scans all loops in Redis with pending stories
2. Checks if any events were emitted in the last 10 minutes
3. If not → auto-runs diagnose + fix
4. Logs to slog + daily log

Manual: The Diagnostic Session

When an agent needs to debug loops manually, follow this sequence:

# 1. Quick overview
joelclaw loop diagnose all -c

# 2. If fix needed
joelclaw loop diagnose all -c --fix

# 3. Verify fix worked (wait ~30s for plan to fire)
joelclaw loop status <loop-id> -c

# 4. If still stuck, check worker
curl -s localhost:3111/api/inngest | python3 -c "import json,sys; print(json.load(sys.stdin)['function_count'])"

# 5. Nuclear option: full restart
joelclaw loop restart <loop-id>

Making Loops More Resilient

The root cause of most stalls is lost events in the judge→plan chain. Solutions being implemented:

1. onFailure handlers — every function gets one, logs failure + emits diagnostic event
2. Loop watchdog — periodic check for silent stalls
3. Debounce on content-sync — prevents event storms that can crowd out loop events
4. Singleton on backfill — prevents resource contention during loops

Cross-References

• agent-loop skill — starting loops
• loop-nanny skill — monitoring + cleanup
• joelclaw skill — full CLI reference
• ADR-0028 — reliability patterns