The Code Migration Planner

# SITUATION
A codebase needs to migrate from one technology to another. This is a high-stakes operation — wrong sequencing can introduce bugs, break production, or leave the codebase in a half-migrated state that's worse than the original.

Migration details:
- From: {{FROM_TECH}}
- To: {{TO_TECH}}
- Codebase size and structure: {{CODEBASE_DESC}}
- Business constraints: {{CONSTRAINTS}}

# PURPOSE
Produce a migration plan that a team can execute incrementally without a big-bang rewrite. The plan must minimize risk, maintain a deployable state at every step, and identify the highest-danger phases upfront.

# EXPECTED OUTPUT
A structured migration plan with these sections:

## 1. Migration Assessment
- Compatibility analysis: what translates directly, what requires rewriting, what has no equivalent
- Tooling available: automated migration tools, codemods, type checkers, or compatibility layers
- Estimated effort by component (rough ranges: hours / days / weeks)

## 2. Migration Strategy
State the chosen strategy and why:
- **Strangler Fig** (new system gradually replaces old) vs. **Parallel Run** (both systems active during transition) vs. **Batch Migration** (coordinated switch)
Justify the choice based on the constraints provided.

## 3. Phased Execution Plan
Break the migration into phases. Each phase must:
- Have a clear definition of done
- Leave the codebase in a deployable state
- Be independently revertible if something breaks
List phases as numbered steps with dependencies between them.

## 4. Risk Register
Top 5 risks ranked by severity. For each: what can go wrong, how likely, and the specific mitigation.

## 5. Validation Strategy
How to verify correctness at each phase: test coverage requirements, canary deployments, feature flags, or comparison checks.

# CONTEXT
- Assume a team of 2-5 developers
- Prioritize correctness over speed
- If automated tooling exists for this migration path, call it out explicitly with usage notes

# STYLE
Technical, direct, no hedging. This is an engineering document — opinions should be stated clearly with reasoning. No filler about "the importance of migration" or "challenges inherent in software evolution." Get to the plan.