[KevinEdry]

Summary

Closes #106.

When a @Query/@Mutation/@Subscription has no explicit output schema, the CLI generator now infers the procedure's output type from the resolver method's return type, instead of falling back to any. This brings nestjs-trpc closer to native tRPC ergonomics and removes the need to duplicate service return types as decorator schemas.

Approach

The generated file imports the router class with import type and casts the placeholder resolver to Awaited<ReturnType<RouterClass["method"]>>:

import type { FolderRouter } from "<...>/folder.router";

list: publicProcedure
  .query(async () => "PLACEHOLDER_DO_NOT_REMOVE" as unknown as Awaited<ReturnType<FolderRouter["list"]>>)

Inference is deferred to the consumer's tsc, so it works through arbitrary business logic and resolves referenced types transitively — the CLI never needs to be a type checker. import type is fully erased, so there's no runtime/bundle impact.

Behavior

• Explicit output schema always wins — existing behavior is unchanged when output is provided.
• Inference applies only to named-export routers. Non-exported and default-exported routers fall back to any, since they can't be referenced by name from the generated file.
• Runtime is unchanged — tRPC already infers output natively at runtime when .output() is omitted; this only closes the codegen gap for the generated AppRouter type.

Tests

• New output-inference fixture + snapshot covering inferred, explicit-override, and object-literal-return cases.
• A validation test runs tsc over the generated file to prove the ReturnType<> references compile and types flow through correctly.
• non-exported-router fixture asserts the any fallback.
• The validation harness now stubs bare-package modules (e.g. nestjs-trpc) imported by the router files that are now type-checked transitively.

All CLI tests pass; clippy (-D warnings) and rustfmt are clean.

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Project	Deployment	Actions	Updated (UTC)
nestjs-trpc-docs	Ready	Preview, Comment	Jun 18, 2026 5:52pm