Agent Skills: Verify Gate

Verify Gate

Machine verification gate between implementation and quality review. Runs the project's compile, test, and lint commands. If any fail, enters a fix loop. If all pass, unblocks simplify-and-harden.

This is the inner loop's verify step. Without it, the agent hands off code with zero machine signal about whether it actually works.

When to Use

• After any implementation work completes, before signaling "done"
• Before running simplify-and-harden
• After fixing audit findings from agent-teams-simplify-and-harden
• Any time you want a machine-verified green signal

Pipeline Position

[implementation] → verify-gate → simplify-and-harden → self-improvement
                   ↻ fix loop

Step 1: Discover Project Commands

Read the project's configuration to find verification commands. Check these sources in order:

1. CLAUDE.md — look for a ## Verification or ## Test Commands section
2. package.json — scripts.test, scripts.lint, scripts.typecheck, scripts.build. Also check for a bun.lock / bun.lockb alongside it → prefer bun run <script> over npm run <script> when present. Check for pnpm-lock.yaml → prefer pnpm run. Check for yarn.lock → prefer yarn.
3. Makefile / Justfile — test, lint, check, build targets
4. Cargo.toml — cargo build, cargo test, cargo clippy
5. pyproject.toml / setup.cfg — pytest, mypy, ruff
6. go.mod — go build ./..., go test ./..., go vet ./...
7. deno.json / deno.jsonc — deno task <name> for any defined tasks

If no commands are discoverable, ask the user once and suggest they add a ## Verification section to CLAUDE.md for future sessions:

## Verification

- Build: `npm run build`
- Test: `npm test`
- Lint: `npm run lint`
- Type check: `npx tsc --noEmit`

Step 2: Run Verification

Run discovered commands in this order. Stop at the first failure category.

Phase 1: Compile / Type Check

Run the build or type-check command. These catch structural errors before wasting time on tests.

Exit 0 → proceed to Phase 2
Exit non-zero → enter fix loop with compiler output

Phase 2: Tests

Run the test command. Scope to changed files if the test runner supports it.

Exit 0 → proceed to Phase 3
Exit non-zero → enter fix loop with test output

Phase 3: Lint (optional, skippable with --skip-lint)

Run the lint command. Lint failures are lower severity but still worth catching.

Exit 0 → all phases green, gate passes
Exit non-zero → enter fix loop with lint output

Step 3: Fix Loop

When a phase fails:

1. Read the output. Parse the error output for actionable diagnostics — file paths, line numbers, error messages.
2. Scope the fix. Only fix what the verification caught. Do not refactor, improve, or touch unrelated code.
3. Apply the fix. Make the minimal change to resolve the failure.
4. Re-run the failed phase. Not all phases — just the one that failed.
5. If it passes, continue to the next phase.
6. If it fails again, increment the attempt counter.

Fix Loop Limits

• Default max attempts: 3 per phase (configurable via --fix-limit N)
• Counter increments on every attempt, even if the error changes. Fixing Error A and uncovering Error B counts as attempt 2, not attempt 1. The counter tracks fix attempts, not unique errors.
• If limit reached: Stop. Report what failed, what was tried, and the remaining error output. Do not guess further — signal to the user that manual intervention is needed.
• Total budget: The fix loop should not exceed 20% of the original implementation effort. If fixes are snowballing, stop and report.

Step 4: Gate Signal

When all phases pass:

## Verify Gate: PASSED

- Build: passed
- Tests: passed (N tests, M suites)
- Lint: passed (or skipped)

Ready for simplify-and-harden.

When the fix loop is exhausted:

## Verify Gate: BLOCKED

- Build: passed
- Tests: FAILED (attempt 3/3)
  - [file:line] error description
  - [file:line] error description
- Lint: not reached

Fix loop exhausted. Manual intervention needed before quality review.

Integration with Other Skills

skill-pipeline

verify-gate should run at every pipeline depth except Trivial:

| Task size | Pipeline | |-----------|----------| | Trivial | None | | Small | verify-gate → simplify-and-harden | | Medium | intent-framed-agent + verify-gate → simplify-and-harden | | Large | Full pipeline with verify-gate before quality pass |

agent-teams-simplify-and-harden

agent-teams already has compile + tests embedded in Step 4. verify-gate can replace that embedded logic for consistency — the team lead spawns verify-gate instead of running ad-hoc compile/test commands.

self-improvement

If the fix loop resolves an error that was non-obvious, log it:

• Pattern: what broke and why
• Fix: what resolved it
• Prevention: what convention or check would have caught it earlier

What This Skill Does NOT Do

• Does not review code quality (that's simplify-and-harden)
• Does not check security (that's harden-auditor)
• Does not verify spec compliance (that's spec-auditor)
• Does not modify test files or add new tests
• Does not run tests for code it didn't change (unless the test runner doesn't support scoping)

Configuration

If the project has a .verify-gate.yml or a verify-gate section in CLAUDE.md:

verify-gate:
  build: npm run build
  test: npm test
  lint: npm run lint
  type_check: npx tsc --noEmit
  fix_limit: 3
  skip_lint: false
  test_scope: changed  # changed | all

If no configuration exists, discover commands automatically (Step 1) and suggest persisting them.

Custom Verification Tools (mcp-scripts) — Extension Point

These are examples of what's possible with gh-aw mcp-scripts, not features shipped with this plugin. Projects define their own scripts.

Projects with custom invariants can define inline verification tools using gh-aw's mcp-scripts. These run as additional phases after the standard compile/test/lint checks.

Example — a project that needs API schema validation and legacy import checks:

# In .github/workflows/verify-gate-ci.md or plugin config
mcp-scripts:
  verify-api-schema:
    lang: shell
    description: "Validate API schema matches implementation"
    run: |
      python scripts/validate_schema.py --strict

  check-no-legacy-imports:
    lang: shell
    description: "Ensure no imports from deprecated legacy/ directory"
    run: |
      ! grep -r "from legacy" src/ --include="*.py"

  verify-rate-limits:
    lang: javascript
    description: "All API routes must have rate limiting middleware"
    run: |
      const routes = require('./src/routes');
      const missing = routes.filter(r => !r.middleware.includes('rateLimit'));
      if (missing.length) { console.error('Missing rate limit:', missing); process.exit(1); }

When mcp-scripts are defined, verify-gate runs them as Phase 4 after lint. Each script's exit code determines pass/fail. Failed scripts enter the same fix loop as standard phases.

This moves project-specific invariants from "knowledge in your head" to "knowledge in the harness" — exactly where the agent can reach it.