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Diagnosis loop for hard bugs and performance regressions. Use when the user says "diagnose"/"debug this", or reports something broken/throwing/failing/slow.
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Based on SOC occupation classification
Build and sharpen a project's domain model. Use when the user wants to pin down domain terminology or a ubiquitous language, record an architectural decision, or when another skill needs to maintain the domain model.
Implement a piece of work based on a spec or set of tickets.
Reconcile the OKF knowledge bundle (knowledge/) with what a completed code change built, over that change's diff. Use once a change has finished landing โ the build closeout, just before committing โ or when the user asks to reconcile knowledge against code.
Configure this repo for the engineering skills โ set up its issue tracker, triage label vocabulary, and domain doc layout. Run once before first use of the other engineering skills.
Turn the current conversation into a spec and save it to the OKF knowledge bundle โ no interview, just synthesis of what you've already discussed.
Break a plan, spec, or the current conversation into a set of tracer-bullet tickets, each declaring its blocking edges, published to the configured tracker โ edges as text in a local file, or native blocking links on a real tracker.
| name | debug |
| description | Diagnosis loop for hard bugs and performance regressions. Use when the user says "diagnose"/"debug this", or reports something broken/throwing/failing/slow. |
A discipline for hard bugs. Skip phases only when explicitly justified.
When exploring the codebase, read the project's OKF knowledge bundle if it exists (knowledge/glossary/ for a clear mental model of the relevant modules, knowledge/adr/ for decisions), and check ADRs in the area you're touching.
This is the skill. Everything else is mechanical. If you have a tight pass/fail signal for the bug โ one that goes red on this bug โ you will find the cause; bisection, hypothesis-testing, and instrumentation all just consume it. If you don't have one, no amount of staring at code will save you.
Spend disproportionate effort here. Be aggressive. Be creative. Refuse to give up.
git bisect run it.scripts/hitl-loop.template.sh so the loop is still structured. Captured output feeds back to you.Build the right feedback loop, and the bug is 90% fixed.
Treat the loop as a product. Once you have a loop, tighten it:
A 30-second flaky loop is barely better than no loop; a 2-second deterministic one is tight โ a debugging superpower.
The goal is not a clean repro but a higher reproduction rate. Loop the trigger 100ร, parallelise, add stress, narrow timing windows, inject sleeps. A 50%-flake bug is debuggable; 1% is not โ keep raising the rate until it's debuggable.
Stop and say so explicitly. List what you tried. Ask the user for: (a) access to whatever environment reproduces it, (b) a captured artifact (HAR file, log dump, core dump, screen recording with timestamps), or (c) permission to add temporary production instrumentation. Do not proceed to hypothesise without a loop.
Phase 1 is done when the loop is tight and red-capable: you can name one command โ a script path, a test invocation, a curl โ that you have already run at least once (paste the invocation and its output), and that is:
scripts/hitl-loop.template.sh.If you catch yourself reading code to build a theory before this command exists, stop โ jumping straight to a hypothesis is the exact failure this skill prevents. No red-capable command, no Phase 2.
Run the loop. Watch it go red โ the bug appears.
Confirm:
Once it's red, shrink the repro to the smallest scenario that still goes red. Cut inputs, callers, config, data, and steps one at a time, re-running the loop after each cut โ keep only what's load-bearing for the failure.
Why bother: a minimal repro shrinks the hypothesis space in Phase 3 (fewer moving parts left to suspect) and becomes the clean regression test in Phase 5.
Done when every remaining element is load-bearing โ removing any one of them makes the loop go green.
Do not proceed until you have reproduced and minimised.
Generate 3โ5 ranked hypotheses before testing any of them. Single-hypothesis generation anchors on the first plausible idea.
Each hypothesis must be falsifiable: state the prediction it makes.
Format: "If is the cause, then will make the bug disappear / will make it worse."
If you cannot state the prediction, the hypothesis is a vibe โ discard or sharpen it.
Show the ranked list to the user before testing. They often have domain knowledge that re-ranks instantly ("we just deployed a change to #3"), or know hypotheses they've already ruled out. Cheap checkpoint, big time saver. Don't block on it โ proceed with your ranking if the user is AFK.
Each probe must map to a specific prediction from Phase 3. Change one variable at a time.
Tool preference:
Tag every debug log with a unique prefix, e.g. [DEBUG-a4f2]. Cleanup at the end becomes a single grep. Untagged logs survive; tagged logs die.
Perf branch. For performance regressions, logs are usually wrong. Instead: establish a baseline measurement (timing harness, performance.now(), profiler, query plan), then bisect. Measure first, fix second.
Write the regression test before the fix โ but only if there is a correct seam for it.
A correct seam is one where the test exercises the real bug pattern as it occurs at the call site. If the only available seam is too shallow (single-caller test when the bug needs multiple callers, unit test that can't replicate the chain that triggered the bug), a regression test there gives false confidence.
If no correct seam exists, that itself is the finding. Note it. The codebase architecture is preventing the bug from being locked down. Flag this for the next phase.
If a correct seam exists:
Required before declaring done:
[DEBUG-...] instrumentation removed (grep the prefix)If the fix touched durable knowledge โ a code path a concept maps to, a behaviour an architecture concept describes, a decision the code now contradicts โ recommend running /reconcile over the fix diff before you commit, so the OKF bundle doesn't drift. Make the recommendation after the fix is in.
Then ask: what would have prevented this bug? If the answer involves architectural change (no good test seam, tangled callers, hidden coupling) hand off to the /improve-arch skill with the specifics. Make the recommendation after the fix is in, not before โ you have more information now than when you started.