Debugging Agent Runs

Debugging agent runs

When the problem is the run, not the code: the agent keeps trying variations of the same thing, talks itself in circles, or acts on what it remembers instead of what's true. This skill is a recovery loop to break that. Be honest: it's a discipline you apply — it can't magically fix a stuck process.

Read first (always)

List learnings/ and read anything relevant — past failure modes specific to this project belong there.

Recognize the failure mode

| Symptom | Likely cause | |---|---| | Same action retried with slightly reworded prompts | Loop / no new information between attempts | | Output truncated, "forgetting" earlier context | Context overflow → compact or restart with a tighter scope | | Repeated 429 / timeouts | Rate limit → back off, batch, slow down | | Edits land on the wrong branch/files; conflicts | Branch / diff drift → re-verify git state | | Confident claims that don't match reality | Stale state → trusting memory over the world | | Scope keeps widening while nothing lands | Scope creep → shrink to one verifiable thing |

The recovery loop

Run these in order — most stuck runs are fixed by step 1–2:

1. Restate the real objective in one sentence. If you can't, that's the bug. Re-anchor to the user's actual goal, not the sub-task you spiraled into.
2. Verify world state — don't trust memory. Re-read the files, git status/diff, and the actual test/command output. The model's recollection is often stale; reality isn't.
3. Shrink the failing scope. Reduce to the smallest reproduction or the single failing unit. Big scope hides the cause.
4. Run one discriminating check — the single command/test whose result tells you which branch of the problem you're in. Don't guess; get one new bit of information.
5. Only then retry — and change the approach, not just the wording. If the new info didn't change your plan, you're still looping.

Anti-patterns

• Retrying the same action three times with reworded prompts (no new information = a loop).
• Trusting your memory of the code/state instead of re-reading it.
• Widening scope when stuck (the opposite of step 3).
• Fabricating that something "should now work" without a check that proves it.

When to stop and ask the human

After one full recovery pass with no progress — or on a budget/rate-limit wall — stop and surface it: the objective, what you verified, the one check you ran, and where it's blocked. A clear handoff beats more silent retries.

Capture a learning

If a project-specific failure mode or recovery trick shows up, append a learnings/YYYY-MM-DD-slug.md (or use /learn).

See also

• skills/fixing-bugs — once you've isolated a real code bug, switch to the reproduce-first fix workflow.
• skills/running-agent-loops — stop conditions and escalation for unattended loops.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Cristhianzl
• Source: Cristhianzl/claude-skills-czl
• License: MIT

Install and usage instructions live in the source repository linked above.