[NestJS] Add controller route resolver

[Yashasvi2229]

Target branch: code-graph-preview

Dependency

The TypeScript extractor is already available on code-graph-preview. No language-extractor issue blocks this resolver.

Goal

Add a bounded NestJS resolver that connects decorator-defined controller routes to their handler methods. The first version should focus only on HTTP controller routes that can be identified confidently from source.

Scope

• Detect NestJS through @nestjs/common in dependencies or dev dependencies.
• Recognize classes decorated with @Controller().
• Recognize methods decorated with @Get, @Post, @Put, @Patch, @Delete, @Options, @Head, or @All.
• Combine the controller prefix and method path into a normalized route name such as GET /users/:id.
• Emit a route node and a function_ref reference to the controller method.
• Resolve an unambiguous route reference to the matching method node, preferring the same file/class context.
• Preserve unresolved or ambiguous references rather than guessing.

Required changes

• Add src/graph/resolution/frameworks/nestjs.ts implementing FrameworkResolver.
• Register and export it from src/graph/resolution/frameworks/index.ts.
• Add a minimal NestJS controller fixture.
• Add focused detection, extraction, resolution, and ambiguity tests.

Acceptance criteria

• Positive and negative NestJS detection are tested.
• Controller and method paths are normalized without losing dynamic parameter text.
• Tests cover at least two HTTP methods, a controller prefix, an empty method path, and a parameterized path.
• Route nodes use stable ids and TypeScript-family language ids.
• Same-file methods resolve with confidence only when unambiguous.
• Duplicate handler names or missing methods remain unresolved.
• The resolver is additive and does not change the frozen interface.
• npm run typecheck, npm test, and npm run build pass.

Out of scope

• Dependency-injection graph edges.
• Guards, pipes, interceptors, middleware, gateways, GraphQL, or microservices.
• Runtime decorator evaluation.
• Changes to the TypeScript extractor or graph core.

Contributor references

• Extending the code graph
• src/graph/resolution/frameworks/express.ts
• src/graph/__tests__/resolver-express.test.ts

Contributor workflow

git switch code-graph-preview
git pull
git switch -c feat/nestjs-route-resolver

Open the pull request with base branch code-graph-preview.

[abhinav-phi]

Hi @Yashasvi2229,

I'd like to work on this issue. If it's still available, could you please assign it to me?

Thanks!

[Yashasvi2229]

Hi @abhinav-phi , yes it's available, assigned it to you. Good to go!