implement-spec

name	implement-spec
description	Implements a specification file phase-by-phase with progress tracking. Activates when: implementing a spec, building from a spec, starting a spec phase, or when user mentions: implement spec, spec file, implement phase, build spec, start phase.
argument-hint	["spec file path","e.g. specs/octane-store-isolation.md"]

Implement Spec

Implements a specification file phase-by-phase, tracking progress directly in the spec file.

When to Use This Skill

Use this skill when:

• Implementing a feature described in a specs/*.md file
• The user asks to "implement this spec" or "start the next phase"
• Continuing work on a partially implemented spec

Workflow Overview

Read spec -> Identify phases -> Implement phase -> Check off tasks -> Log findings -> Verify -> Next phase -> Final verification -> Create PR

Step 1: Read and Understand the Spec

1. Read the full spec file to understand the complete feature scope.
2. Locate the implementation section — look for ## Implementation.
3. Identify phases — look for ### Phase N: headings within the implementation section.
4. Determine the current phase — the first phase with unchecked - [ ] tasks is the next to implement.

Specs Without Phases

Some specs don't have explicit phases — they describe a single focused change. In this case, treat the entire spec as a single phase.

Step 2: Implement the Current Phase

For each phase:

1. Read all relevant existing files before writing any code.
2. Raise any open questions from the spec's Open Questions section that affect this phase. Don't make assumptions — ask the user. After the user answers, move it from ## Open Questions to ## Resolved Questions with the decision and rationale.
3. Implement each task described in the phase.
4. Check off each task (- [x]) in the spec file as you complete it.
5. Write tests for all new functionality — happy paths, failure paths, and edge cases.
6. Run Pint on changed files:

   vendor/bin/pint --dirty --format agent
   

7. Run the phase tests to confirm they pass:

   vendor/bin/phpunit tests/RelevantTest.php
   

8. Log notes in the Findings section — record any design decisions, deviations from the spec, or discovered issues.

Do NOT run PHPStan, Rector, or the full test suite between phases. They are slow and only run at Final Verification (Step 3) after all phases are complete.

Between Phases

After each phase, ask the user if they want to:

• Continue to the next phase
• Review the changes first
• Stop for now

Step 3: Final Verification (After All Phases Complete)

Once all task checkboxes are checked, use the backend-quality skill (Tier 2: full checks).

All checks must pass with 0 errors/failures. Fix any issues and re-run until clean.

Step 4: Clean Up

After final verification passes, the spec file can be removed as part of PR creation or kept for reference — ask the user.

Guidelines

• One phase at a time. Never implement multiple phases in a single pass.
• Spec is the source of truth. Follow the spec's design decisions. If you disagree with a design choice, raise it with the user before deviating.
• Check off tasks as you go. The - [x] checkboxes in the spec are the single source of progress. Don't leave them for the end of a phase.
• Log findings. When you make a design decision, deviate from the spec, or discover something unexpected, add a note to the ## Findings section.
• Tests are mandatory. Every phase must have test coverage before it can be considered complete.
• Progress must be accurate. Never check off a task if its tests are failing.
• Don't skip verification. The final verification gate exists to catch cross-phase regressions. Run every step.
• Open questions in the spec should be raised with the user before implementing the affected section. Don't make assumptions.
• Future/deferred phases (marked Priority: LOW) should be skipped unless the user explicitly requests them.