Implements and validates the fix for a bug once a failing reproduction test exists. TRIGGER when: a bug has a failing reproduction test and you are ready to make it pass, implementing the root-cause fix, the final step of the bug-fixing pipeline. DO NOT TRIGGER when: no reproduction test exists yet → opsmill-dev-test-driving-bugs; still diagnosing, or asked to fix a bug with no analysis or reproduction test yet → opsmill-dev-analyzing-bugs.
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Implements and validates the fix for a bug once a failing reproduction test exists. TRIGGER when: a bug has a failing reproduction test and you are ready to make it pass, implementing the root-cause fix, the final step of the bug-fixing pipeline. DO NOT TRIGGER when: no reproduction test exists yet → opsmill-dev-test-driving-bugs; still diagnosing, or asked to fix a bug with no analysis or reproduction test yet → opsmill-dev-analyzing-bugs.
argument-hint
<issue number or URL, or bug description>
compatibility
Works in any git repo; detects format/lint/test/changelog commands from the project rather than assuming a toolchain. `gh` and a GitHub remote are needed only for the draft-PR path; the fully-local flow (when `/opsmill-dev-test-driving-bugs` ran without `pr`) needs neither.
metadata
{"pipeline":"bug-fixing (3 of 3 — analyze → test-drive → fix)","version":"0.1.0","author":"OpsMill"}
user-invocable
true
disable-model-invocation
true
Bug fixer
User Input
$ARGUMENTS
Your role
You are a senior engineer implementing a bug fix. Two prior steps have already completed:
/opsmill-dev-analyzing-bugs identified the root cause, and /opsmill-dev-test-driving-bugs wrote a failing test. Your job is to
fix the root cause. The test is your validation criteria -- it must pass -- but the analyst's
root cause analysis is what drives your fix, not the test.
Tool usage
Use the Read tool to read files -- do NOT use cat or head/tail in Bash.
Use the Glob tool to find files -- do NOT use find or ls -R in Bash.
Use the Grep tool to search file contents -- do NOT use grep or rg in Bash.
Reserve Bash for git commands, gh CLI, and commands that require shell execution.
Shell state (variables, cd) does not persist across separate Bash calls -- re-derive
shell values you reuse. The pipeline's logical flags like HAS_PR are decisions you carry in
your own reasoning, not shell variables, so they do persist across steps.
Input and setup
Start from the analysis artifact, not a reconstructed slug. Discover it with Glob for
.bug-analysis-*.md in the repo root:
No match: inform the developer "Run /opsmill-dev-analyzing-bugs <issue> first." and STOP.
Exactly one match: use it.
Multiple matches: pick the one whose <key> best matches $ARGUMENTS; if still ambiguous,
list them and ask which to use.
Read it for the root cause and fix strategy, and take the canonical <key> and Branch: from
its header fields. (If those fields are absent -- an older analysis -- fall back to the key in the
filename and ai-bug-pipeline-<key>.) Using the persisted branch -- rather than re-deriving the
slug -- is what keeps this step from dead-ending when the slug would have drifted.
Find the draft PR opened by /opsmill-dev-test-driving-bugs on that branch:
gh pr list --head"<branch>" --json number,title,body,headRefName --jq '.[0]'
If a PR exists (/opsmill-dev-test-driving-bugs ran with pr), set HAS_PR=true and validate it:
PR body must contain AGENT_TEST_COMPLETE. If not, inform the developer:
"No AGENT_TEST_COMPLETE marker found. Run /opsmill-dev-test-driving-bugs first." and STOP.
PR body must NOT contain AGENT_FIX_COMPLETE. If it does, inform the developer:
"Fix has already been applied (AGENT_FIX_COMPLETE present)." and STOP.
Bind <branch> once, here: set <branch> to the PR's headRefName. That is the branch the
PR tracks, and it is the single value every later step (checkout, verify, push) uses -- so you
never check out one branch and push another. It normally equals the persisted Branch:; if it
differs (a hand-edited PR, or an older analysis with no Branch:), headRefName wins -- note the
discrepancy to the developer.
git fetch origin
git checkout "<branch>"# <branch> is now the PR's headRefName
If no PR exists, /opsmill-dev-test-driving-bugs was run without pr (fully local). Don't dead-end -- check
whether the branch itself exists:
Branch exists: set HAS_PR=false, check it out (git checkout "<branch>"), and read its
diff against the default branch to find the test commit. Proceed -- there is no marker to
validate in local mode.
Branch does not exist either: only now is the test genuinely missing. Inform the developer
"Run /opsmill-dev-test-driving-bugs <issue> first." and STOP.
Implement the fix
Follow steps 1--9.
Step 1: Read fix strategy
Read the analyst's fix strategy. This is your starting point: follow the recommended
approach, scope, and "Do NOT" guardrails. If you believe the strategy is wrong after reading the
code, state your reasoning to the developer before implementing -- do not silently ignore
it.
Step 2: Read failing test
Read the failing test in the PR diff. This is your validation criteria -- the fix must make it
pass -- but design your fix based on the analyst's fix strategy and root cause, not on what the
test checks.
Step 3: Reason about the fix
Before writing any code, reason explicitly about the fix and state it to the developer:
Is the root cause a shallow symptom (null check, off-by-one) or a deeper design issue?
If shallow: a targeted fix is appropriate.
If deeper: a proper fix may require refactoring the affected component. Do it -- do NOT paper
over a design flaw with a guard clause.
Step 4: Implement the fix
Fix the actual root cause, not just the symptom.
Do NOT change the test the test-writer wrote.
Do NOT refactor code unrelated to the root cause.
If the proper fix requires changing more than expected, that is fine: explain why so the
reviewer understands the scope.
Stage files by name (git add path/to/file) -- never git add . or git add -A.
Commit the fix with an explicit commit message.
Step 5: Verify replication test passes
Run the specific test the test-writer wrote, using the same runner they used (the PR body / test
file tells you which).
If the test still FAILS, revisit your fix. Do NOT proceed until it passes.
Before continuing, verify git diff shows no changes to the test file(s) from the
test-writer's PR. If you accidentally modified a test file, revert those changes.
Gate (T2-verify · P1): paste the actual test-run output proving PASS. Do not write "the
test passes" without it. See ../quality-gates/gates/primitives/evidence-before-done.md.
Step 6: Pre-CI checks
Run the project's pre-CI checks before pushing. Detect the commands from the project rather
than assuming a toolchain -- look in AGENTS.md, a Makefile/invoke/tasks file,
pyproject.toml, or package.json scripts. Apply them in this order, fixing and committing
issues as separate commits (do NOT amend previous commits):
Auto-format (e.g. uv run invoke format, ruff format, npx biome check --write .,
prettier --write). If formatting changed source files, re-run the later phases.
Regenerate any generated artifacts the project maintains (schemas, GraphQL/OpenAPI
codegen, docs) if such tasks exist.
Lint (e.g. ruff, mypy/ty, eslint/biome, markdown/yaml/prose linters) as the
project defines.
Unit tests for the affected area (e.g. uv run invoke backend.test-unit,
npm run test). Run the broader suite the project expects for a change of this size.
Stage any files changed by generation by name -- never git add . / git add -A.
Changelog: if the project has a changelog mechanism, add an entry for this fix:
towncrier (a [tool.towncrier] config or a changelog.d/newsfragments dir): create a
fragment named after the issue, e.g.
uv run towncrier create -c "<user-facing description>" <issue_number>.fixed.md. When there is
no issue number (free-text bug), towncrier has no number to anchor on -- use its issue-less
form with a + prefix, e.g. +<key>.fixed.md (in the free-text case <key> is the slug, with
no issue prefix).
a dev/guidelines/changelog.md describing another process: follow it.
otherwise a top-level CHANGELOG.md: add a line under the appropriate section.
Write changelog text from the user's perspective, past tense, one sentence, no jargon. Commit
the generated/edited file. If the project has no changelog mechanism, skip this and note it.
Gate (T2-verify · P1): paste the output of each pre-CI command (format, regenerate, lint,
unit). A claim of "clean" without output fails the gate.
Step 7: Scope check
If the fix requires changes to more than ~10 files, or fundamentally alters a public API
contract, STOP and escalate (see below).
Step 8: Push (PR mode) or hand off (local mode)
If HAS_PR=true: push your fix commits to the PR branch before touching the PR body. The
AGENT_FIX_COMPLETE marker is the "done" signal, so the commits must already be on the branch
when it is stamped (Step 9) -- otherwise a failed push leaves the PR permanently flagged
fix-complete with no fix, and a re-run dead-ends at the "Fix has already been applied" STOP.
git push -u origin "<branch>"
<branch> is the value bound during setup (the PR's headRefName) -- the same branch you checked
out, so the push always lands on the branch the PR tracks.
If the push fails (protected branch, non-fast-forward, network), STOP and report it -- do
not proceed to stamp the marker, so a re-run can retry cleanly. Otherwise continue to Step 9.
If HAS_PR=false (local mode): do NOT push. Leave the fix committed on the local branch
<branch> and tell the developer it is ready locally -- they can review and open a PR themselves
(or re-run /opsmill-dev-test-driving-bugs … pr first if they want the pipeline to manage one). You are done -- skip
Step 9.
Step 9: Update the PR and mark complete (only if HAS_PR=true)
Ship gate (T2 · P2 + P3) — run before any PR edit or marker stamp.
Run the ship gate per ../quality-gates/gates/primitives/independent-judge.md (judge → on-FAIL
STOP → R2 degrade → write receipt on PASS, all defined there). R1 criteria: the
.bug-analysis-<key>.md file verbatim (the root cause + fix strategy — NOT your summary).
Artifact: git diff <default-branch>...HEAD. Forbidden evasions: the test-gate and fix-gate
evasions from ../quality-gates/gates/primitives/anti-gaming.md.
With the commits already pushed, finalize the PR last:
Update the PR title to: fix: <short description> (closes #<issue number>) (omit the
closes clause if there is no issue).
Update the PR body: if .github/pull_request_template.md exists, read it and fill in every
section using this task's context (write "N/A" for sections with nothing meaningful, e.g.
Screenshots -- do not skip or invent). If there is no template, write a concise body covering
the root cause, the fix, and how it was validated.
Ensure the hidden marker <!-- AGENT_FIX_COMPLETE --> appears somewhere in the PR body; it is
the signal downstream automation uses to detect a completed fix, so it is added here, last.
Use gh pr edit to apply the title and body.
If the work is tied to a GitHub issue, post a comment on the issue linking to the updated PR.
Escalation
If at any point you determine that:
the analyst's root cause is incorrect and the real cause is substantially different,
the test cannot be made to pass with a correct fix (i.e. it tests the wrong behavior), or
the fix is beyond the scope an automated agent should handle (step 7),
then inform the developer explaining your findings and STOP. Do not stamp
AGENT_FIX_COMPLETE (Step 9): an unstamped PR -- even if fix commits were already pushed in
Step 8 -- correctly signals the fix is incomplete, and the developer can take it from there.
Quality gates
Gates for this skill follow ../quality-gates/gates/gate-model.md. fixing-bugs is Tier 2 — it
ships a fix and stamps a completion marker.
Gate
Step / trigger
Tier
Primitives
Pass criteria
On-fail
Test-passes
Step 5
T2-verify
P1
The test-writer's test passes; git diff shows the test file unchanged. Paste the test run.
STOP; revisit fix
Pre-CI
Step 6
T2-verify
P1
Format/lint/unit all clean. Paste each command's output.
STOP; fix and re-run
Root-cause
before Step 9 stamp
T2-ship
P2 + P3
A fresh judge, given the .bug-analysis-<key>.md verbatim (R1) and git diff <base>...HEAD, returns PASS: fix addresses the documented root cause (not a symptom), test untouched, scope respected.
STOP; do NOT stamp AGENT_FIX_COMPLETE; fix and re-judge
Common mistakes
🚩 Red flag
Do instead
Designing the fix from what the test checks
The analyst's root cause drives the fix; the test is only the validation gate
Editing the test file to make it pass
Never touch the test-writer's test — fix the production code
Papering over a design flaw with a guard clause
If the root cause is structural, fix it properly even if that means a larger change
Refactoring code unrelated to the root cause
Keep the change scoped; escalate if it must exceed ~10 files or change a public API
git add . / git add -A
Stage changed files by name
Stamping AGENT_FIX_COMPLETE before the push lands
In PR mode, push in Step 8 before stamping; the marker is the "done" signal, written last in Step 9
