| name | migrate |
| description | Move code, callers, data, configuration, or dependencies from an old contract to a new one with explicit compatibility and rollback decisions. Use for API, schema, framework, dependency, or storage migrations. Do not use for a simple isolated replacement with no consumers. |
Migrate
Converge on the target state without leaving an accidental permanent compatibility layer.
Inventory
Define the old and target contracts. Find all callers, persisted forms, generated artifacts, deployment dependencies, and external consumers. Classify each as migrated, compatible, blocked, or unknown.
When domain meaning changes, inventory the bounded contexts and owners that use each term. Preserve or deliberately migrate aggregate and transaction boundaries, translation layers, and published event semantics. Use an anticorruption layer when a legacy or external model must coexist without becoming the target domain model.
Choose the transition
Decide whether the change can be atomic or requires staged coexistence. State the compatibility window, rollback point, data transformation, observability, and deletion condition. Do not preserve the old path when no real compatibility requirement exists.
For a security-sensitive version, credential, or signing-key migration, define the minimum safe version, revoke the retired authority, prove that old access no longer works, and prevent rollback or recovery from reviving a vulnerable artifact or credential. Give every temporary compatibility bypass an owner and deletion deadline or condition.
Sequence
Order work so every stage is deployable and verifiable. For a staged migration, introduce the new read or write path, validate real traffic or data, move consumers, then remove the old path. Make repeated operations idempotent when retries are possible.
Verify
Check caller coverage, transformed data, mixed-version behavior, rollback, and absence of stale uses. Use authoritative counts or queries where data is involved.
Boundaries
Require confirmation only for destructive production-data operations that could cause material, difficult-to-recover harm and are not already explicitly authorized. Treat an explicit migration or deployment request as authorization for its ordinary in-scope production writes. Report unknown external consumers rather than assuming none exist.
Output
Return the target state, inventory, transition sequence, checkpoints, rollback strategy, deletion condition, and evidence.
