implement

Implement

A structured five-step loop for turning a specification (PRD, issue, or design doc) into committed, reviewed code. Complements tdd-workflow (which focuses on the Red→Green→Refactor micro-cycle) and verification-before-completion (which enforces proof before claiming done). This skill governs the macro flow: from spec to commit.

When to Use

• You have a PRD, issue, or spec and need a repeatable path from "start" to "merged"
• You want to enforce /review and type-checking as gates before every commit
• You need a structured sequence that doesn't skip test coverage or review under deadline pressure

When NOT to Use

Instead of implement	Use
Red→Green micro-cycle for a single function	tdd-workflow
Verifying a claim before saying "done"	verification-before-completion
Full sprint across multiple features	sprint-workflow

Prerequisites

• A PRD, spec file, or set of linked issues is available and understood
• Test framework installed and runnable (npm test, pytest, cargo test, etc.)
• Type checker available when the language supports it (tsc --noEmit, mypy, etc.)

The Five-Step Loop

Step 1: TDD — Write a Failing Test First

Before touching implementation, write the test that will prove the spec is met.

> Write a failing test for [behavior from PRD]. Keep it to the thinnest observable behavior.

Run it and confirm it fails:

# JavaScript / TypeScript
npm test -- --testPathPattern="<target>"

# Python
pytest tests/test_<target>.py

# Rust
cargo test <test_name>

If no test framework exists yet, create the simplest one before writing any source code.

Step 2: Implement — Minimal Code to Pass

Write the minimum code to turn the failing test green. Do not add features beyond the test.

[Autopilot Mode]
> Implement the minimum code to pass the test in step 1.