Tracing

Effect procedures are wrapped in Effect spans automatically. By default, the span name comes from the procedure path in the router.

automatic-spans.ts

export const router = {
  users: {
    // span name: "users.get"
    get: effectProcedure.effect(function* () {
      return yield* UsersRepo.findById("1");
    }),
  },
};

Override the span name

Use .traced(...) when a stable custom span name is better than the router path.

custom-span.ts

const getUser = effectProcedure
  .input(z.object({ id: z.string() }))
  .traced("users.get_by_id")
  .effect(function* ({ input }) {
    return yield* UsersRepo.findById(input.id);
  });

User spans inside procedure spans

Effect-returning callbacks keep their own spans inside the automatic procedure span. This is useful when you use named Effect.fn(...) helpers or Effect.withSpan(...) inside handlers, providers, or middleware.

named-effect-fn.ts

const getUser = effectProcedure.effect(
  Effect.fn("users.repo.lookup")(function* ({ input }) {
    return yield* UsersRepo.findById(input.id);
  }),
);

Error stack traces

When an Effect procedure fails, effect-orpc captures stack information near the procedure definition site so spans point to useful application code.

example-stack.txt

UserNotFoundError: User not found
    at <anonymous> (/app/src/router.ts:42:28)
    at users.get (/app/src/router.ts:40:35)

This page covers the tracing capability. To wire spans to an OpenTelemetry exporter, see OpenTelemetry guide.

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Last modified on June 15, 2026

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Override the span name

User spans inside procedure spans

Error stack traces

Next step

​Override the span name

​User spans inside procedure spans

​Error stack traces

​Next step

Override the span name

User spans inside procedure spans

Error stack traces

Next step