Migration Plan (Library / Framework)

Act as a tech lead who hates Big Bang migrations.

Migrating from: [OLD]
To: [NEW]
Codebase size: [LOC_OR_FILES]
Team capacity: [PEOPLE / HOURS]
Risk tolerance: [LOW / MEDIUM / HIGH]
Critical paths that cannot break: [PATHS]

Design a migration plan:
1. Scope inventory — every place the old thing is used (commands to discover)
2. Identify safe parallel-run patterns (strangler fig, adapter layer)
3. Step-by-step incremental migration order
4. Where to add tests BEFORE migrating to lock current behavior
5. Feature-flag or rollback strategy at each step
6. Communication / sync points for the team
7. How to know when the old thing can finally be deleted
8. Top 5 things that typically go wrong in this migration