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name: speckit-plan description: Generate technical implementation plans from feature specifications. Use after creating a spec to define architecture, tech stack, and implementation phases. Creates plan.md with detailed technical design. compatibility: Requires spec-kit project structure with .specify/ directory metadata: author: github-spec-kit source: templates/commands/plan.md

Speckit Plan Skill

User Input

$ARGUMENTS

You MUST consider the user input before proceeding (if not empty).

Outline

1. Setup: Run .specify/scripts/powershell/setup-plan.ps1 -Json from repo root and parse JSON for FEATURE_SPEC, IMPL_PLAN, SPECS_DIR, BRANCH. For single quotes in args like "I'm Groot", use escape syntax: e.g 'I'''m Groot' (or double-quote if possible: "I'm Groot").

2. Load context: Read FEATURE_SPEC and .specify/memory/constitution.md. Load IMPL_PLAN template (already copied).

3. Execute plan workflow: Follow the structure in IMPL_PLAN template to:

   • Fill Technical Context (mark unknowns as "NEEDS CLARIFICATION")
   • Fill Constitution Check section from constitution
   • Evaluate gates (ERROR if violations unjustified)
   • Phase 0: Generate research.md (resolve all NEEDS CLARIFICATION)
   • Phase 1: Generate data-model.md, contracts/, quickstart.md
   • Phase 1: Update agent context by running the agent script
   • Re-evaluate Constitution Check post-design

4. Stop and report: Command ends after Phase 2 planning. Report branch, IMPL_PLAN path, and generated artifacts.

Phases

Phase 0: Outline & Research

1. Extract unknowns from Technical Context above:

   • For each NEEDS CLARIFICATION → research task
   • For each dependency → best practices task
   • For each integration → patterns task

2. Generate and dispatch research agents:

   For each unknown in Technical Context:
     Task: "Research {unknown} for {feature context}"
   For each technology choice:
     Task: "Find best practices for {tech} in {domain}"
   

3. Consolidate findings in research.md using format:

   • Decision: [what was chosen]
   • Rationale: [why chosen]
   • Alternatives considered: [what else evaluated]

Output: research.md with all NEEDS CLARIFICATION resolved

Phase 1: Design & Contracts

Prerequisites: research.md complete

1. Extract entities from feature spec → data-model.md:

   • Entity name, fields, relationships
   • Validation rules from requirements
   • State transitions if applicable

2. Define interface contracts (if project has external interfaces) → /contracts/:

   • Identify what interfaces the project exposes to users or other systems
   • Document the contract format appropriate for the project type
   • Examples: public APIs for libraries, command schemas for CLI tools, endpoints for web services, grammars for parsers, UI contracts for applications
   • Skip if project is purely internal (build scripts, one-off tools, etc.)

3. Agent context update:

   • Run .specify/scripts/powershell/update-agent-context.ps1 -AgentType codex
   • These scripts detect which AI agent is in use
   • Update the appropriate agent-specific context file
   • Add only new technology from current plan
   • Preserve manual additions between markers

Output: data-model.md, /contracts/*, quickstart.md, agent-specific file

Key rules

• Use absolute paths
• ERROR on gate failures or unresolved clarifications