Build

Execute implementation plan tasks with TDD workflow, auto-commit, and phase gates. Use when user says "build it", "start building", "execute plan", "implemen...

This skill is self-contained — follow the task loop, TDD rules, and completion flow below instead of delegating to external build/execution skills (superpowers, etc.).

Execute tasks from an implementation plan. Finds plan.md (in docs/plan/), picks the next unchecked task, implements it with TDD workflow, commits, and updates progress.

When to use

After /plan has created a track with spec.md + plan.md. This is the execution engine.

Pipeline: /plan → /build → /deploy → /review

MCP Tools (use if available)

• session_search(query) — find how similar problems were solved before
• project_code_search(query, project) — find reusable code across projects
• codegraph_query(query) — check file dependencies, imports, callers

If MCP tools are not available, fall back to Glob + Grep + Read.

Pre-flight Checks

1. Detect context — find where plan files live:

   • Check docs/plan/*/plan.md — standard location
   • Use whichever exists.
   • DO NOT search for conductor/ or any other directory — only docs/plan/.

2. Load workflow config from docs/workflow.md (if exists):

   • TDD strictness (strict / moderate / none)
   • Commit strategy (conventional commits format)
   • Verification checkpoint rules
   • Integration Testing section — if present, run the specified CLI commands after completing tasks that touch the listed paths If docs/workflow.md missing: use defaults (moderate TDD, conventional commits).

3. Verify git hooks are installed:

   Read the stack YAML (templates/stacks/{stack}.yaml) — the pre_commit field tells you which system and what it runs:

   • husky + lint-staged → JS/TS stacks (eslint + prettier + tsc)
   • pre-commit → Python stacks (ruff + ruff-format + ty)
   • lefthook → mobile stacks (swiftlint/detekt + formatter)

   Then verify the hook system is active:

   # husky
   [ -f .husky/pre-commit ] && git config core.hooksPath | grep -q husky && echo "OK" || echo "NOT ACTIVE"
   # pre-commit (Python)
   [ -f .pre-commit-config.yaml ] && [ -f .git/hooks/pre-commit ] && echo "OK" || echo "NOT ACTIVE"
   # lefthook
   [ -f lefthook.yml ] && lefthook version >/dev/null 2>&1 && echo "OK" || echo "NOT ACTIVE"
   

   If not active — install before first commit:

   • husky: pnpm prepare (or npm run prepare)
   • pre-commit: uv run pre-commit install
   • lefthook: lefthook install

   Don't use --no-verify on commits — if hooks fail, fix the issue and commit again.

Track Selection

If $ARGUMENTS contains a track ID:

• Validate: {plan_root}/{argument}/plan.md exists (check docs/plan/).
• If not found: search docs/plan/*/plan.md for partial matches, suggest corrections.

If $ARGUMENTS contains --task X.Y:

• Jump directly to that task in the active track.

If no argument:

1. Search for plan.md files in docs/plan/.
2. Read each plan.md, find tracks with uncompleted tasks.
3. If multiple, ask via AskUserQuestion.
4. If zero tracks: "No plans found. Run /plan first."

Context Loading

Step 1 — Architecture overview (if MCP available)

codegraph_explain(project="{project name}")

Returns: stack, languages, directory layers, key patterns, top dependencies, hub files — one call instead of exploring the tree manually.

Step 2 — Essential docs (parallel reads)

1. docs/plan/{trackId}/plan.md — task list (REQUIRED)
2. docs/plan/{trackId}/spec.md — acceptance criteria (REQUIRED)
3. docs/workflow.md — TDD policy, commit strategy (if exists)
4. CLAUDE.md — architecture, Do/Don't
5. .solo/pipelines/progress.md — running docs from previous iterations (if exists, pipeline-specific). Contains what was done in prior pipeline sessions: stages completed, commit SHAs, last output lines. Use this to avoid repeating completed work.

Do NOT read source code files at this stage. Only docs. Source files are loaded per-task in the execution loop (step 3 below).

Resumption

If a task is marked [~] in plan.md:

Resuming: {track title}
Last task: Task {X.Y}: {description} [in progress]

1. Continue from where we left off
2. Restart current task
3. Show progress summary first

Ask via AskUserQuestion, then proceed.

Task Execution Loop

Makefile convention: If Makefile exists in project root, always prefer make targets over raw commands. Use make test instead of pnpm test, make lint instead of pnpm lint, make build instead of pnpm build, etc. Run make help (or read Makefile) to discover available targets. If a make integration or similar target exists, use it for integration testing after pipeline-related tasks.

IMPORTANT — All-done check: Before entering the loop, scan plan.md for ANY - [ ] or - [~] tasks. If ALL tasks are [x] — skip the loop entirely and jump to Completion section below to run final verification and output <solo:done/>.

For each incomplete task in plan.md (marked [ ]), in order:

1. Find Next Task

Parse plan.md for first line matching - [ ] Task X.Y: (or - [~] Task X.Y: if resuming).

2. Start Task

• Update plan.md: [ ] → [~] for current task.
• Announce: "Starting Task X.Y: {description}"

3. Research (smart, before coding)

Do NOT grep the entire project or read all source files. Load only what this specific task needs.

If MCP available (preferred):

1. project_code_search(query="{task keywords}", project="{name}") — find relevant code in the project. Read only the top 2-3 results.
2. session_search("{task keywords}") — check if you solved this before.
3. codegraph_query("MATCH (f:File {project: '{name}'})-[:IMPORTS]->(dep) WHERE f.path CONTAINS '{module}' RETURN dep.path") — check imports/dependencies of files you'll modify.

If MCP unavailable (fallback):

1. Read ONLY the files explicitly mentioned in the task description (file paths).
2. Glob for the specific module directory the task targets (e.g., src/auth/**/*.ts), not the entire project.
3. If the task doesn't mention files, use Grep with a narrow pattern on src/ or app/ — never **/*.

Never do: Grep "keyword" . across the whole project. This dumps hundreds of lines into context for no reason. Be surgical.

Python-Specific Quality Tools

When the project uses a Python stack (detected by pyproject.toml or stack YAML), run the full Astral toolchain:

1. Ruff — linting + formatting (always):

   uv run ruff check --fix .
   uv run ruff format .
   

2. ty — type-checking (if ty in dev dependencies or stack YAML):

   uv run ty check .
   

   ty is Astral's type-checker (extremely fast, replaces mypy/pyright). Fix type errors before committing.

3. Hypothesis — property-based testing (if hypothesis in dependencies):

   • Use @given(st.from_type(MyModel)) to auto-generate Pydantic model inputs.
   • Use @given(st.text(), st.integers()) for edge-case coverage on parsers/validators.
   • Hypothesis tests go in the same test files alongside regular pytest tests.

4. Pre-commit — run all hooks before committing:

   uv run pre-commit run --all-files
   

Run these checks after each task implementation, before git commit. If any fail, fix before proceeding.

JS/TS-Specific Quality Tools

When the project uses a JS/TS stack (detected by package.json or stack YAML):

1. ESLint — linting (always):

   pnpm lint --fix
   

2. Prettier — formatting (always):

   pnpm format
   

3. tsc --noEmit — type-checking (strict mode):

   pnpm tsc --noEmit
   

   Fix type errors before committing. Strict mode should be on in tsconfig.json.

4. Knip — dead code detection (if in devDependencies, run periodically):

   pnpm knip
   

   Finds unused files, exports, and dependencies. Run after significant refactors.

5. Pre-commit — husky + lint-staged runs ESLint + Prettier + tsc on staged files.

iOS/Android-Specific Quality Tools

When the project uses a mobile stack:

iOS (Swift):

swiftlint lint --strict
swift-format format --in-place --recursive Sources/

Android (Kotlin):

./gradlew detekt
./gradlew ktlintCheck

Both use lefthook for pre-commit hooks (language-agnostic, no Node.js required).

4. TDD Workflow (if TDD enabled in workflow.md)

Red — write failing test:

• Create/update test file for the task functionality.
• Run tests to confirm they fail.

Green — implement:

• Write minimum code to make the test pass.
• Run tests to confirm pass.

Refactor:

• Clean up while tests stay green.
• Run tests one final time.

5. Non-TDD Workflow (if TDD is "none" or "moderate" and task is simple)

• Implement the task directly.
• Run existing tests to check nothing broke.
• For "moderate": write tests for business logic and API routes, skip for UI/config.

5.5. Integration Testing (CLI-First)

If the task touches core business logic (pipeline, algorithms, agent tools), run make integration (or the integration command from docs/workflow.md). The CLI exercises the same code paths as the UI without requiring a browser. If make integration fails, fix before committing.

5.6. Visual Verification (if browser/simulator/emulator available)

After implementation, run a quick visual smoke test if tools are available:

Web projects (Playwright MCP or browser tools): If you have Playwright MCP tools or browser tools available:

1. Start the dev server if not already running (check stack YAML for dev_server.command)
2. Navigate to the page affected by the current task
3. Check the browser console for errors (hydration mismatches, uncaught exceptions, 404s)
4. Take a screenshot to verify the visual output matches expectations
5. If the task affects responsive layout, resize to mobile viewport (375px) and check

iOS projects (simulator): If instructed to use iOS Simulator in the pipeline prompt:

1. Build for simulator: xcodebuild -scheme {Name} -sdk iphonesimulator build
2. Install on booted simulator: xcrun simctl install booted {app-path}
3. Launch and take screenshot: xcrun simctl io booted screenshot /tmp/sim-screenshot.png
4. Check simulator logs: xcrun simctl spawn booted log stream --style compact --timeout 10

Android projects (emulator): If instructed to use Android Emulator in the pipeline prompt:

1. Build debug APK: ./gradlew assembleDebug
2. Install: adb install -r app/build/outputs/apk/debug/app-debug.apk
3. Take screenshot: adb exec-out screencap -p > /tmp/emu-screenshot.png
4. Check logcat: adb logcat '*:E' --format=time -d 2>&1 | tail -20

Graceful degradation: If browser/simulator/emulator tools are not available or fail — skip visual checks entirely. Visual testing is a bonus, never a blocker. Log that it was skipped and continue with the task.

6. Complete Task

Commit (following commit strategy):

git add {specific files changed}
git commit -m "<type>(<scope>): <description>"

Types: feat, fix, refactor, test, docs, chore, perf, style

Capture SHA after commit:

git rev-parse --short HEAD

SHA annotation in plan.md. After every task commit:

1. Mark task done: [~] → [x]
2. Append commit SHA inline: - [x] Task X.Y: description <!-- sha:abc1234 -->

Without a SHA, there's no traceability and no revert capability. If a task required multiple commits, record the last one.

7. Phase Completion Check

After each task, check if all tasks in current phase are [x].

If phase complete:

1. SHA audit — scan all [x] tasks in this phase. If any are missing <!-- sha:... -->, capture their SHA now from git log and add it. Every [x] task MUST have a SHA.
2. Run verification steps listed under ### Verification for the phase.
3. Run full test suite.
4. Run linter.
5. Mark verification checkboxes in plan.md: - [ ] → - [x].
6. Commit plan.md progress: git commit -m "chore(plan): complete phase {N}".
7. Capture checkpoint SHA and append to phase heading in plan.md: ## Phase N: Title <!-- checkpoint:abc1234 -->.
8. Report results and continue:

Phase {N} complete! <!-- checkpoint:abc1234 -->

  Tasks:  {M}/{M}
  Tests:  {pass/fail}
  Linter: {pass/fail}
  Verification:
    - [x] {check 1}
    - [x] {check 2}

  Revert this phase: git revert abc1234..HEAD

Proceed to the next phase automatically. No approval needed.

Error Handling

Test Failure

Tests failing after Task X.Y:
  {failure details}

1. Attempt to fix
2. Rollback task changes (git checkout)
3. Pause for manual intervention

Ask via AskUserQuestion. Do NOT automatically continue past failures.

Track Completion

When all phases and tasks are [x]:

1. Final Verification

• Run local build — must pass before deploy:
  • Next.js: pnpm build
  • Python: uv build or uv run python -m py_compile src/**/*.py
  • Astro: pnpm build
  • Cloudflare: pnpm build
  • iOS: xcodebuild -scheme {Name} -sdk iphonesimulator build
  • Android: ./gradlew assembleDebug
• Run full test suite.
• Run linter + type-checker.
• Visual smoke test (if tools available):
  • Web: start dev server, navigate to main page, check console for errors, take screenshot
  • iOS: build + install on simulator, launch, take screenshot, check logs
  • Android: build APK + install on emulator, launch, take screenshot, check logcat
  • Skip if tools unavailable — not a blocker for completion
• Check acceptance criteria from spec.md.

2. Update plan.md header

Change **Status:** [ ] Not Started → **Status:** [x] Complete at the top of plan.md.

3. Signal completion

Output pipeline signal ONLY if pipeline state directory (.solo/states/) exists:

<solo:done/>

Do NOT repeat the signal tag elsewhere in the response. One occurrence only.

4. Summary

Track complete: {title} ({trackId})

  Phases: {N}/{N}
  Tasks:  {M}/{M}
  Tests:  All passing

  Phase checkpoints:
    Phase 1: abc1234
    Phase 2: def5678
    Phase 3: ghi9012

  Revert entire track: git revert abc1234..HEAD

Next:
  /build {next-track-id}  — continue with next track
  /plan "next feature"    — plan something new

Reverting Work

SHA comments in plan.md enable surgical reverts:

Revert a single task:

# Find SHA from plan.md: - [x] Task 2.3: ... <!-- sha:abc1234 -->
git revert abc1234

Then update plan.md: [x] → [ ] for that task.

Revert an entire phase:

# Find checkpoint from phase heading: ## Phase 2: ... <!-- checkpoint:def5678 -->
# Find previous checkpoint: ## Phase 1: ... <!-- checkpoint:abc1234 -->
git revert abc1234..def5678

Then update plan.md: all tasks in that phase [x] → [ ].

Never use git reset --hard — always git revert to preserve history.

Progress Tracking (TodoWrite)

At the start of a build session, create a task list from plan.md so progress is visible:

1. On session start: Read plan.md, find all incomplete tasks ([ ] and [~]).
2. Create TaskCreate for each phase with its tasks as description.
3. TaskUpdate as you work: in_progress when starting a task, completed when done.
4. This gives the user (and pipeline) real-time visibility into progress.

Rationalizations Catalog

These thoughts mean STOP — you're about to cut corners:

Thought	Reality
"This is too simple to test"	Simple code breaks too. Write the test.
"I'll add tests later"	Tests written after pass immediately — they prove nothing.
"I already tested it manually"	Manual tests don't persist. Automated tests do.
"The test framework isn't set up"	Set it up. That's part of the task.
"This is just a config change"	Config changes break builds. Verify.
"I'm confident this works"	Confidence without evidence is guessing. Run the command.
"Let me just try changing X"	Stop. Investigate root cause first.
"Tests are passing, ship it"	Tests passing ≠ acceptance criteria met. Check spec.md.
"I'll fix the lint later"	Fix it now. Tech debt compounds.
"It works on my machine"	Run the build. Verify in the actual environment.

Critical Rules

1. Run phase checkpoints — verify tests + linter pass before moving to next phase.
2. STOP on failure — do not continue past test failures or errors.
3. Keep plan.md updated — task status must reflect actual progress at all times.
4. Commit after each task — atomic commits with conventional format.
5. Research before coding — 30 seconds of search saves 30 minutes of reimplementation.
6. One task at a time — finish current task before starting next.
7. Keep test output concise — when running tests, pipe through head -50 or use --reporter=dot / -q flag. Thousands of test lines pollute context. Only show failures in detail.
8. Verify before claiming done — run the actual command, read the full output, confirm success BEFORE marking a task complete. Never say "should work now".

Common Issues

"No plans found"

Cause: No plan.md exists in docs/plan/. Fix: Run /plan "your feature" first to create a track.

Tests failing after task

Cause: Implementation broke existing functionality. Fix: Use the error handling flow — attempt fix, rollback if needed, pause for user input. Never skip failing tests.

Phase checkpoint failed

Cause: Tests or linter failed at phase boundary. Fix: Fix failures before proceeding. Re-run verification for that phase.