Codex Spec Driven Development

TL;DR

Use before $prototype, MVP, fullstack, or high-ambiguity feature work. Write .codex/specs/<slug>/SPEC.md first, then plan, delegate, implement, and validate against acceptance criteria.

Activation

1. Activate on $spec, $prototype, "spec-driven", "MVP", "fullstack prototype", "from scratch", or "build whole app".
2. Activate when a task spans frontend + backend, data, QA, or deployment concerns.
3. Activate when requirements are ambiguous enough that coding first would create rework.

Hard Rules

• Do not implement prototype/fullstack work before a spec exists.
• Specs must include requirements, non-goals, acceptance criteria, FE/BE/data/QA impact, and validation plan.
• Specs must include Schema-Version: 1.0, AC IDs such as AC-001, and a traceability table mapping changed files to AC IDs and validation commands.
• Keep specs project-local under .codex/specs/; do not always load every spec.
• Use check_spec.py after code changes when .codex/specs/ exists.
• Treat spec checks as advisory in quality gate unless the user makes spec compliance mandatory.

Commands

python "<SKILLS_ROOT>/codex-spec-driven-development/scripts/init_spec.py" --project-root <path> --title "<title>"
python "<SKILLS_ROOT>/codex-spec-driven-development/scripts/check_spec.py" --project-root <path> --changed-files <csv>

Output Contract

• init_spec.py returns JSON with status, spec_path, and slug.
• check_spec.py returns JSON with schema_version, overall, matched_specs, matched_acceptance_criteria, unmapped_files, and suggested_actions.

Prototype Flow

1. Run $hook to detect domains and readiness.
2. Run $init-profile if profile is missing.
3. Run $genome and $init-docs if context/docs are missing.
4. Run $spec to lock requirements and acceptance criteria.
5. Run $plan, then $sdd or inline execution.
6. Run $check-full and update role docs/handoff.

Reference Files

• references/spec.schema.json: required spec markdown contract and traceability fields.