---
name: plan
description: "Generate an implementation plan from a specification. Phase 2 of Spec Kit workflow."
argument-hint: "<path to specification file>"
allowed-tools: Read, Glob, Grep, Write, Edit, Skill, Task
---

# Generate Implementation Plan

Generate an implementation design document from a canonical specification.

## Workflow

1. **Load Specification**
   - Read the specification file from provided path
   - If no path provided, search `.specs/` for recent specifications
   - Parse requirements and acceptance criteria

2. **Analyze Codebase**
   - Explore existing codebase for:
     - Existing patterns and conventions
     - Related components and modules
     - Integration points
     - Technology stack

3. **Generate Design**
   - Create implementation approach
   - Identify components to create/modify
   - Define data models (if applicable)
   - Design API contracts (if applicable)
   - Document alternatives considered
   - Map design elements to requirements

4. **Validate Coverage**
   - Verify design addresses all requirements
   - Check alignment with codebase conventions
   - Identify risks and mitigation strategies

5. **Save Design**
   - Save to `.specs/{feature-name}/design.md`
   - Update specification with design reference
   - Report design summary

## Arguments

- `$ARGUMENTS` - Path to specification file

## Examples

```bash
# From specification file
/spec-driven-development:plan .specs/user-auth/spec.md

# Auto-detect recent specification
/spec-driven-development:plan
```

## Design Document Structure

```markdown
# Design: {Feature Name}

## Overview
[High-level implementation approach]

## Components

### {Component 1}
- **Responsibility:** [What it does]
- **Location:** [File path]
- **Interfaces:** [How it connects]

## Data Model
[Entity definitions if applicable]

## API Design
[Endpoint specifications if applicable]

## Alternatives Considered
[Other approaches and why rejected]

## Requirements Coverage
| Requirement | Covered By |
| --- | --- |
| FR-1 | Component A |
| FR-2 | Component B |
```

## Related Commands

- `/spec-driven-development:specify` - Generate specification (Phase 1)
- `/spec-driven-development:tasks` - Generate task breakdown (Phase 3)
- `/spec-driven-development:implement` - Guide implementation (Phase 4)