fix(cli): isolate server request traces (#37395)

packages/cli/src/commands/handlers/serve.ts

@@ -5,7 +5,7 @@ import { ServerProcess } from "../../server-process"
 
 export default Runtime.handler(
   Commands.commands.serve,
-  Effect.fn("cli.serve")(function* (input) {
+  Effect.fnUntraced(function* (input) {
     if (input.service && input.stdio) return yield* Effect.fail(new Error("--service and --stdio cannot be combined"))
     return yield* ServerProcess.run({
       mode: input.service ? "service" : input.stdio ? "stdio" : "default",

packages/cli/src/server-process.ts

@@ -24,13 +24,14 @@ export type Options = {
   readonly port?: number
 }
 
-export const run = Effect.fn("cli.server-process.run")((options: Options) =>
-  processEffect(options).pipe(
+// The process effect lives until server shutdown; tracing it would parent every request to one process-lifetime trace.
+export const run = Effect.fnUntraced(function* (options: Options) {
+  return yield* processEffect(options).pipe(
     Effect.provide(Updater.layer),
     Effect.provide(AppNodeBuilder.build(LayerNode.group([Global.node, AppProcess.node]))),
     Effect.provide(NodeServices.layer),
-  ),
-)
+  )
+})
 
 const processEffect = Effect.fnUntraced(function* (options: Options) {
   if (options.mode === "service") yield* Effect.sync(() => process.chdir(Global.Path.home))

packages/server/src/process.ts

@@ -10,6 +10,7 @@ import { HttpMiddleware, HttpRouter, HttpServer, HttpServerRequest, HttpServerRe
 import { createServer } from "node:http"
 import { ServerAuth } from "./auth"
 import { authorizedRequest } from "./middleware/authorization"
+import { withoutParentSpan } from "./request-tracing"
 import { createRoutes } from "./routes"
 import { ServerInfo } from "./server-info"
 import { Status } from "./service-status"
@@ -39,7 +40,10 @@ export const start = Effect.fn("ServerProcess.start")(function* <E, R>(options:
   })
   const bound = yield* listen(options)
   const application = yield* Ref.make(Option.none<App>())
-  yield* bound.http.serve(dispatch(options.password, status, application, shutdown), HttpMiddleware.logger)
+  // Request fibers may continue inbound trace context, but must not inherit the server startup parent.
+  yield* bound.http
+    .serve(dispatch(options.password, status, application, shutdown), HttpMiddleware.logger)
+    .pipe(withoutParentSpan)
   if (options.service) yield* options.service.onListen(bound.http.address)
 
   const parentScope = yield* Scope.Scope

packages/server/src/request-tracing.ts

@@ -0,0 +1,6 @@
+import { Context, Effect, Scope, Tracer } from "effect"
+
+export const withoutParentSpan = <A, E>(effect: Effect.Effect<A, E, Scope.Scope>) =>
+  effect.pipe(
+    Effect.updateContext((context: Context.Context<Scope.Scope>) => Context.omit(Tracer.ParentSpan)(context)),
+  )

packages/server/test/request-tracing.test.ts

@@ -0,0 +1,48 @@
+import { expect, test } from "bun:test"
+import { Effect, Option, Scope, Tracer } from "effect"
+import { HttpMiddleware, HttpServerRequest, HttpServerResponse } from "effect/unstable/http"
+import { withoutParentSpan } from "../src/request-tracing"
+
+test("requests ignore ambient parents and continue inbound trace context", async () => {
+  const spans: Tracer.NativeSpan[] = []
+  const tracer = Tracer.make({
+    span(options) {
+      const span = new Tracer.NativeSpan(options)
+      spans.push(span)
+      return span
+    },
+  })
+  const app = Effect.gen(function* () {
+    yield* Scope.Scope
+    return yield* HttpMiddleware.tracer(Effect.succeed(HttpServerResponse.empty()))
+  })
+  const request = (traceparent?: string) =>
+    app.pipe(
+      Effect.provideService(
+        HttpServerRequest.HttpServerRequest,
+        HttpServerRequest.fromWeb(
+          new Request("http://localhost/trace", {
+            headers: traceparent === undefined ? undefined : { traceparent },
+          }),
+        ),
+      ),
+      withoutParentSpan,
+    )
+
+  await Effect.runPromise(
+    Effect.gen(function* () {
+      yield* request()
+      yield* request()
+      yield* request("00-11111111111111111111111111111111-2222222222222222-01")
+      yield* Effect.yieldNow
+    }).pipe(Effect.withSpan("fixture.lifecycle"), Effect.provideService(Tracer.Tracer, tracer), Effect.scoped),
+  )
+
+  const requests = spans.filter((span) => span.kind === "server")
+  expect(requests).toHaveLength(3)
+  expect(requests[0]?.traceId).not.toBe(requests[1]?.traceId)
+  expect(Option.getOrUndefined(requests[0]?.parent ?? Option.none())).toBeUndefined()
+  expect(Option.getOrUndefined(requests[1]?.parent ?? Option.none())).toBeUndefined()
+  expect(requests[2]?.traceId).toBe("11111111111111111111111111111111")
+  expect(Option.getOrUndefined(requests[2]?.parent ?? Option.none())?.spanId).toBe("2222222222222222")
+})