---
name: test-driven-implementation
user-invocable: false
description: Use whenever code is about to be written or modified as part of a spec-driven implementation — whole-system or subsystem. Trigger on phrases like "実装する", "コードを書く", "TDD で進めて", "テスト先に書く", "implement this", "write the code", "let's TDD this". This skill is a REQUIRED SUB-SKILL of `spec-coexist:implementing-from-spec` and `spec-coexist:revising` and MUST halt if a failing test does not exist before production code is written. Carves out legacy/spike/notebook/config/docs via `references/negative-triggers.md`.
---

# test-driven-implementation

Conformance keywords follow [RFC 2119](https://www.rfc-editor.org/rfc/rfc2119) / [RFC 8174](https://www.rfc-editor.org/rfc/rfc8174).

## Independence

This skill **MUST NOT** invoke or delegate to any `superpowers:*` skill, including `superpowers:test-driven-development`. It is a self-contained project-local TDD discipline skill and **MUST** be used from within the spec-coexist suite only.

## Purpose

Enforce the spec-coexist Iron Law: within a spec-driven implementation, production code **MUST NOT** be added or modified unless a failing test already exists and that failure has been recorded as evidence. This skill translates the superpowers TDD discipline into spec-coexist's bilingual, evidence-anchored, RFC 2119 style — it is not imported.

## Hard Constraints (RFC 2119)

- A failing test **MUST** exist before any in-scope production code change (see `references/iron-law.md`).
- The RED failure **MUST** be recorded via `scripts/record_red_phase.sh`, which delegates to `../_shared/scripts/write_evidence.sh` with `proof-type: tdd-red`.
- The GREEN pass **MUST** be recorded via `scripts/record_green_phase.sh` with `proof-type: tdd-green`.
- If production code is discovered without a prior RED record, the change **MUST** be reverted and re-done test-first, OR an explicit waiver **MUST** be recorded per `references/iron-law.md` §Waivers.
- Scope exclusions in `references/negative-triggers.md` **MAY** skip RED, but the exclusion reason **MUST** be recorded as evidence.
- The agent **MUST NOT** rationalize a skip. See `references/rationalization-table.md`.

## References

- `references/iron-law.md` — scoped Iron Law, application boundary, waiver procedure.
- `references/red-green-refactor.md` — the three phases in spec-coexist vocabulary.
- `references/rationalization-table.md` — 20+ bilingual excuse → rebuttal rows.
- `references/tdd-evidence-protocol.md` — exact evidence format and `write_evidence.sh` invocation.
- `references/negative-triggers.md` — what is out of scope for the Iron Law.
- `references/failure-patterns.md` — 7+ common TDD failure modes.

## Scripts

- `scripts/record_red_phase.sh <slug> -- <test-cmd>` — runs the test, asserts failure, writes a `tdd-red` evidence record.
- `scripts/record_green_phase.sh <slug> -- <test-cmd>` — runs the test, asserts pass, writes a `tdd-green` record correlated by slug.
- `scripts/verify_test_first.sh <base-ref>` — walks `git log <base-ref>..HEAD` and flags production-code commits not preceded by a test-adding commit.

## Procedure

1. Confirm the caller is `implementing-from-spec` or `revising`. If not, HALT — this is a sub-skill.
2. Check `references/negative-triggers.md`. If fully excluded, record the waiver and exit.
3. Write the smallest failing test for the next acceptance bullet.
4. Run `scripts/record_red_phase.sh` — HALT on unexpected pass.
5. Write the minimal production code that turns the test green.
6. Run `scripts/record_green_phase.sh` — HALT on failure.
7. Refactor under the safety net, then re-run the suite.
8. Run `scripts/verify_test_first.sh` before returning — HALT on violation.
9. Report the RED and GREEN evidence paths to the caller.

## Flow

```mermaid
flowchart TD
    Start([Caller invokes]) --> Scope{Spec-driven<br/>change?}
    Scope -- No --> Halt([HALT])
    Scope -- Yes --> Neg{Matches<br/>negative-triggers?}
    Neg -- Yes --> Waiver[Record waiver] --> Done([Return])
    Neg -- No --> Red[Write failing test]
    Red --> RedRec[record_red_phase.sh]
    RedRec --> Impl[Minimal production code]
    Impl --> GreenRec[record_green_phase.sh]
    GreenRec --> Ref[Refactor]
    Ref --> Verify[verify_test_first.sh]
    Verify --> Done
```