prp-implement

name	prp-implement
description	Phase 3 of spec-driven development — generate tasks.md from plan.md. Executable [P]-parallelizable tasks, TDD-first, layer-ordered.
when_to_use	After /prp-plan produces plan.md. Produces a task checklist you can execute top-down.
argument-hint	<feature-slug>
allowed-tools	["Read","Write","Glob","Grep"]
model	opus

PRP Phase 3 — Executable Tasks

You turn plan.md into a TDD-ordered tasks.md that any agent can execute.

Input

$ARGUMENTS = <slug>. Reads specs/<slug>/plan.md.

Procedure

1. Verify specs/<slug>/plan.md exists and constitution-check passed.
2. Delegate to spec-writer subagent with phase=tasks.
3. The subagent:
   • Loads plan + .specify/templates/tasks.md.
   • Breaks each layer into a task sequence:
     • RED: failing test (must come before impl).
     • GREEN: minimum impl.
     • REFACTOR: cleanup.
     • INTEGRATION: wire into DI container.
   • Marks tasks [P] when they touch disjoint files and can run in parallel.
   • Groups tasks into milestones (layer-by-layer: domain → application → infra → interface).
   • Writes specs/<slug>/tasks.md.

tasks.md format

# Tasks — <slug>

## Milestone 1: Domain
- [ ] T-01 Write failing test `tests/unit/domain/test_foo_entity.py::test_bar`
- [ ] T-02 Implement `domain/entities/foo.py::Foo`
- [ ] T-03 [P] Write failing test `tests/unit/domain/test_foo_service.py`
- [ ] T-04 [P] Implement `domain/services/foo_service.py`

## Milestone 2: Application
- [ ] T-05 Write failing test `tests/unit/application/test_do_foo.py` (mock ports)
- [ ] T-06 Implement `application/use_cases/do_foo.py`

## Milestone 3: Infrastructure
- [ ] T-07 [P] Port ABC `domain/ports/foo_port.py`
- [ ] T-08 [P] Impl `infrastructure/foo/foo_adapter.py`
- [ ] T-09 Integration test `tests/integration/test_foo_adapter.py` (real PG)

## Milestone 4: Interface
- [ ] T-10 Route `interface/api/routes/foo.py`
- [ ] T-11 Wire DI `interface/api/container.py`
- [ ] T-12 API integration test

## Milestone 5: Gates
- [ ] T-13 Update `docs/TECH_DECISIONS.md` with TD-<next>
- [ ] T-14 Update `docs/CHANGELOG.md`
- [ ] T-15 Run full suite + lint

Guardrails

• Every impl task must have a preceding test task (TDD).
• [P] only when tasks touch disjoint files. Same-file edits serialize.
• No task may skip the test → impl → lint order.
• Target: each task ≤ 30 minutes of work. Split larger ones.