1. Get Parameters

From command invocation:

Testing Request:
- Module: auth
- Layer: infrastructure
- Playbook: docs/playbook.md (optional)
- Coverage Target: 100% (optional)

From natural invocation: Ask user for module, layer, playbook path (optional), coverage target (optional).

2. Get Testing Strategy

If playbook provided:

Read(${PLAYBOOK_PATH})

If no playbook: Ask user to choose:

If user picks 1-3: Use template from skills/layer-testing/templates/

If user picks 4: Ask:

• Coverage target? (100%/80%/70%)
• What to test? (business logic only / all code)
• What to skip? (types, schemas, mocks, configs)
• Build strategy from answers

Store strategy for agent use.

3. Run Coverage First

Check for existing tests:

find src/modules/${MODULE}/${LAYER} -name "*.test.*" -o -path "*/__tests__/*"

If NO tests: Skip to step 4

If tests exist:

Detect framework and run coverage (run these checks in parallel):

if [[ -f "vitest.config.ts" ]] || grep -q "vitest" package.json; then
  pnpm test src/modules/${MODULE}/${LAYER} --coverage --reporter=json-summary
elif [[ -f "jest.config.js" ]] || grep -q "jest" package.json; then
  pnpm test -- src/modules/${MODULE}/${LAYER} --coverage --coverageReporters=json-summary
fi

Parse coverage/coverage-summary.json:

TOTAL_COV=$(jq '.total.lines.pct' coverage/coverage-summary.json)

If 100% coverage:

✅ Already at 100% coverage!

Options:
1. Exit (nothing to do)
2. Verify test quality
3. Enhance tests

Choose (1-3):

If user picks 1, exit successfully.

If < 100%: Continue to Step 4

4. Analyze Files

Find all files:

find src/modules/${MODULE}/${LAYER} -name "*.ts" ! -name "*.test.*" ! -path "*/__tests__/*"

Categorize using strategy:

• Testable (matches "what to test" patterns)
• Skip (matches "what to skip" patterns)

Cross-reference with coverage (if available):

• Fully covered (100%)
• Partially covered (<100%, extract uncovered lines)
• Not tested (0% or not in coverage)

5. Present Analysis & Ask User

Show results:

📊 ${MODULE}/${LAYER}

Coverage: ${TOTAL_COV}% (target: ${TARGET}%)
Gap: ${GAP}%

✅ Fully Covered:
  - File1.ts (100%)

⚠️ Partially Covered:
  - File2.ts (45%, lines 10-20, 30-40 uncovered)

❌ Not Tested:
  - File3.ts (0%)

⊘ Skip:
  - schema.ts (per strategy)

Which files to test?
1. All gaps
2. Untested only
3. Partial only
4. Custom selection

Wait for user response.

6. Create Worktree

BRANCH="test/${MODULE}-${LAYER}-coverage"
git worktree add ../worktree-${BRANCH} -b ${BRANCH}

7. Spawn Testing Agent

Task({
  subagent_type: 'general-purpose',
  description: 'Test ${MODULE}/${LAYER}',
  prompt: `
Test the ${LAYER} layer of ${MODULE} module.

Strategy: Read ${PLAYBOOK_PATH}
Files: ${SELECTED_FILES}
Target: ${COVERAGE_TARGET}%
Working directory: ${WORKTREE_PATH}

Follow strategy principles.
Write comprehensive tests.
Never modify production code.
Create single commit when done.

Report:
- Coverage achieved
- Tests created
- Any issues
`
})

Wait for agent completion.

8. Verify Results

# 1. Tests pass
pnpm test ${FILES}

# 2. Coverage meets target
pnpm test ${FILES} --coverage
# Parse and verify >= target

# 3. No production code changes
git diff --name-only | grep -v test | wc -l  # Should be 0

# 4. Type check passes
pnpm typecheck

# 5. Lint passes
pnpm lint

✅ Testing Complete: ${MODULE}/${LAYER}

Coverage: ${BEFORE}% → ${AFTER}% (+${DELTA}%)
Tests: ${COUNT} new tests
Files: ${FILES_TESTED}
Commit: ${COMMIT_HASH}

Quality Gates:
✅ All tests passing
✅ Coverage target met
✅ No production changes
✅ Type check passing
✅ Lint passing

Next steps:
- Review tests in worktree
- Merge: git rebase ${BRANCH}
- Or: Continue testing other layers