Fix bug
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npx -y skills add gabriel-f-santos/coding-agents --skill fix-bugAssembled from the repository path, not quoted from the project. Check it against their README if it does not work.
2 things to look at
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What its author says it does
Copied from the file, not written here
Fix a bug the disciplined way — reproduce, write a FAILING regression test, then fix until green. Use when the user reports a bug or asks to fix/debug something — "tem um bug", "corrige esse erro", "fix this bug", "isso deveria retornar X mas retorna Y", "debug isso", "não está funcionando", "reproduz e corrige". Enforces TDD red-green for bugs: reproduce deterministically, write a regression test that asserts the CORRECT behavior and fails on the current code (confirm Red), make the smallest root-cause fix, confirm the test passes (Green), then run the full suite so nothing regressed. Hard rule: never declare it fixed without a test that reproduced the bug now passing. Runs the tests when a runner exists, else writes the test + fix and flags it unverified. Do not use to add a new feature (use implement-phase) or for pure code review (use review-*).
The file declares its own license as MIT. That is the author’s claim about this one file, and it is not the same thing as the license GitHub reports for the repository, which is listed with the other numbers below.
SKILL.md
4.4 KB, as published. Nobody here has run it
fix-bug — reproduce → red test → fix → green
Fix bugs with TDD's Red-Green-Refactor, not by vibes. The point is an objective oracle: a test that reproduced the bug and now passes. Without that, "fixed" is just a claim.
References
| Open when you need to… | Read |
|---|---|
| reproduce & isolate deterministically (scientific debugging) | references/reproduce-and-isolate.md |
| write a good failing regression test (per-ecosystem, confirm Red) | references/regression-test.md |
The loop (follow in order — don't skip)
1. Understand & reproduce
Pin down the expected vs actual behavior and the exact inputs/conditions that trigger it. Build
a deterministic, minimal reproduction (a failing command, request, or input). → reproduce-and-isolate.md
- You cannot fix what you cannot reproduce. If it's flaky/unreproducible, stop and gather more (logs, the failing input, env) before touching code.
2. Locate (just enough)
Form a hypothesis about the root cause — bisect, add a probe/log, narrow to the smallest suspect region. Don't over-investigate before the test; the test will confirm you found it.
3. Write a failing test (🔴 Red)
Write a regression test that asserts the correct behavior, at the right layer (unit if the
bug is in a function; integration/e2e if it's a flow). → references/regression-test.md
- Run it and confirm it FAILS — for the right reason (the bug, not a setup/import error).
- A test that passes before the fix doesn't test the bug. If it passes, it's wrong — fix the test.
- Reuse the project's testing guide/conventions if present (e.g. a
testing-guide-*skill).
4. Fix (root cause, smallest change)
Make the smallest change that fixes the root cause — not a symptom patch. If the real cause is upstream of where it surfaced, fix it there.
5. Green + regression
- Run the new test → it passes (🟢). If not, iterate on the fix (not the test).
- Run the full test suite (or at least the affected modules) → confirm nothing regressed.
- Reproduce the original symptom manually one more time → confirm it's gone.
6. Report
- Root cause (one line — what was actually wrong, not just where).
- The test added (path + what it asserts) — it stays forever as protection.
- The fix (the diff, scoped).
- Verification: test went Red→Green; full suite green; original repro gone.
Hard rules (the discipline)
- Never declare fixed without a previously-failing test now passing. This is the whole skill.
- The regression test must fail before the fix (you saw the Red). If you didn't, you don't know it catches the bug.
- Don't weaken, skip, or delete the test to get green; don't assert the buggy behavior.
- Fix the cause, not the symptom — green on a symptom patch with the cause alive is a fail.
- Run the full suite before done — a fix that breaks three other tests isn't a fix.
When you can't run tests
If there's no runner / you can't execute (sandbox, missing deps): still write the failing test + the fix, explain how to run them, and flag the result as UNVERIFIED — say plainly you did not observe Red→Green. Never claim a verified fix you didn't run.
Pairs with
The regression test feeds CI (github-actions/greenfield-monorepo) so the bug can't return;
review-functionality checks the fix against the contract; implement-phase for new features.