Code Migration Planner

Create a comprehensive code migration plan for the following transition: Migration Context: - From: {{source_stack}} (e.g., React 17 + Redux, PHP Laravel 8, Python 3.8 Django) - To: {{target_stack}} (e.g., Next.js 15 App Router, Node.js Express, Python FastAPI) - Codebase size: {{codebase_size}} (e.g., ~50 files, 20k LOC, monolith with 5 modules) - Team size: {{team_size}} - Deadline/timeline: {{timeline}} - Critical requirements: {{critical_requirements}} (e.g., zero downtime, maintain SEO, preserve user sessions) Deliver: 1. **Executive Summary** — whats changing and why 2. **Risk Assessment** — top 5 risks with severity (High/Medium/Low) and mitigation 3. **Pre-migration checklist** — audit steps before writing a single line 4. **Phased migration plan** — minimum 3 phases with clear milestones and success criteria 5. **Testing strategy** — how to validate each phase without breaking production 6. **Rollback plan** — specific steps to revert if a phase fails 7. **Post-migration cleanup** — deprecating old code, updating docs, team training 8. **Estimated timeline** — breakdown by phase Format as a structured technical document.