implement

name	implement
description	Implement a feature following the Spec-Driven Development workflow. Reads specs, requirements, and TDD tests to guide implementation.
user-invocable	true
argument-hint	[feature-slug]
allowed-tools	Read, Grep, Glob, Edit, Write, Bash

/implement — Implement a Feature

Pick a feature from the spec index, read its full specification, and generate an implementation plan.

Workflow

1. Read the feature index:

   • Open specs/.devx/features.json
   • Find the first feature with "status": "not-started", or ask the user which feature to implement
   • Note the feature slug

2. Read the full specification:

   • Open specs/<slug>/specs.md
   • Understand the Summary, Key Features, Functional Requirements, and User Scenarios
   • Do not skip any section

3. Read the requirements checklist:

   • Open specs/<slug>/requirements.md
   • This is the acceptance criteria — every item must be satisfied

4. Read the TDD test specifications:

   • Open specs/<slug>/tdd-tests.md
   • For each acceptance criterion, follow the Red-Green-Refactor cycle: a. Red: Write a failing test that maps to the criterion b. Green: Write the minimum production code to make the test pass c. Refactor: Clean up while keeping all tests green
   • Do not proceed to the next criterion until the current one is fully green

5. Create an implementation plan:

   • Break the work into concrete steps based on the requirements
   • Identify files to create or modify
   • Identify dependencies between requirements
   • Present the plan to the user for approval

6. Implement one requirement at a time:

   • Follow the spec exactly — do not add features not described
   • After each requirement, verify it against requirements.md
   • Ensure all TDD tests pass before moving to the next requirement

7. After all requirements are complete:

   • Review the full requirements.md checklist
   • Verify all user scenarios from specs.md work correctly
   • Update features.json status to "done"

Rules

• Do not deviate from the specification. If the spec is wrong, update it first.
• One requirement at a time. Complete and validate before moving on.
• Requirements are the source of truth for what "done" means.
• Follow TDD strictly. No production code before a failing test exists.
• No gold-plating. Do not add features beyond what the spec describes.