TypeScript AI PR Reviewer: Catch Unsafe Types

This tutorial guides you through building a TypeScript pull-request reviewer called type-guardian. The reviewer combines Git diffs, TypeScript Compiler API diagnostics, local AST rules, and OpenAI structured output to provide local and contextual AI feedback while keeping compiler failures separate.

The key aspects include:

1. Defining strict compiler settings and shared types in tsconfig.json and src/types.ts, using TypeScript's strict options and specific finding categories such as explicit-any, unsafe-type-assertion, typescript-suppression, compiler-error, and ai-review.

2. Reading Git diffs to identify changed TypeScript files and running deterministic checks using the TypeScript Compiler API to obtain compiler diagnostics from the repository configuration.

3. Parsing the current working-tree source with the TypeScript parser and obtaining compiler diagnostics from the repository configuration.

4. Providing configurable options for the reviewer like baseRef, maxDiffChars, maxFiles, and includeAiReview, as well as generating a ReviewReport containing generated timestamps, baseRef, changedFiles count, compilerDiagnostics count, aiReviewIncluded status, findings, and more.

The tutorial emphasizes the importance of keeping compiler failures separate from contextual AI feedback, and avoiding silent code changes or becoming the sole merge gate. The model can explain potentially unsafe boundaries or spot context outside syntax rules, but should not override the compiler or serve as the sole merge gate.