Strict TypeScript Migration Assistant

The problem

Migrating large JavaScript or permissive TypeScript codebases to strict mode often results in a "wall of errors" that halts productivity. Developers frequently struggle to balance type safety with runtime stability, leading to unsafe assertions or hidden regressions.

What it does

• Analyzes current tsconfig settings and source files to identify typing weaknesses and high-risk boundaries.
• Maps every point where untrusted runtime data (APIs, DBs, JSON) enters the typed system.
• Generates a sequenced, multi-wave migration plan that prioritizes leaf modules before domain services.
• Recommends specific compiler option stages (e.g., noImplicitAny before strictNullChecks) to prevent build failures.
• Classifies all 'any' usages and type assertions to determine if they need schemas, generics, or unknown wrappers.

Frameworks & tools

TypeScript, Node.js, and any frontend framework. Works with tsconfig.json configurations and project references.

Why this beats prompting it yourself

Most LLMs will suggest a broad "fix all" approach that breaks builds and ignores runtime validation. This skill enforces a strict rubric that separates static type safety from runtime contract verification, ensuring your migration doesn't hide logic changes.

Use cases

• Transitioning a legacy JavaScript repository to TypeScript without a total rewrite.
• Enabling strict mode in a production application while maintaining a rollback path.
• Replacing widespread 'any' usage with validated runtime guards and unknown types.
• Reviewing a migration proposal to ensure external API contracts remain intact.

Known limitations

Does not execute builds, tests, or codemods. Requires manual implementation of the generated plan.