fix(server): stop idle private-memory growth from immortal parent spans

apps/server/src/auth/ServerSecretStore.ts

@@ -181,7 +181,7 @@ export const make = Effect.gen(function* () {
               }),
             ),
       ),
-      Effect.withSpan("ServerSecretStore.get"),
+      Effect.withTracerEnabled(false),
     );
 
   const set: ServerSecretStore["Service"]["set"] = (name, value) => {

apps/server/src/preview/PortScanner.ts

@@ -25,6 +25,7 @@ import * as Schedule from "effect/Schedule";
 import * as Scope from "effect/Scope";
 
 import * as ProcessRunner from "../processRunner.ts";
+import { withoutAmbientParentSpan } from "../serverActivation.ts";
 
 export class PortDiscovery extends Context.Service<
   PortDiscovery,
@@ -292,9 +293,8 @@ export const make = Effect.gen(function* PortDiscoveryMake() {
     yield* Effect.forEach(listeners, (listener) => listener(servers), { discard: true });
   });
 
-  const pollTick = Effect.fn("PortDiscovery.pollTick")(
+  const pollTickActive = Effect.fn("PortDiscovery.pollTick")(
     function* () {
-      if ((yield* Ref.get(stateRef)).retainCount <= 0) return;
       const next = yield* scanOnce();
       const changed = yield* Ref.modify(stateRef, (state) =>
         serversEqual(state.lastSnapshot, next)
@@ -308,10 +308,15 @@ export const make = Effect.gen(function* PortDiscoveryMake() {
     ),
   );
 
-  // Single layer-scoped polling fiber. Ticks are no-ops when no client is
-  // currently retained, so the cost is one Ref.get every POLL_INTERVAL.
-  yield* Effect.forkScoped(pollTick().pipe(Effect.repeat(Schedule.spaced(POLL_INTERVAL))));
+  // Idle early-return stays outside Effect.fn so no-op ticks create no span; detach ParentSpan (#5410).
+  const pollTick = Effect.gen(function* () {
+    if ((yield* Ref.get(stateRef)).retainCount <= 0) return;
+    yield* pollTickActive();
+  });
 
+  yield* Effect.forkScoped(
+    withoutAmbientParentSpan(pollTick.pipe(Effect.repeat(Schedule.spaced(POLL_INTERVAL)))),
+  );
   const acquireRetention = Effect.fn("PortDiscovery.retain")(function* () {
     const wasIdle = yield* Ref.modify(stateRef, (state) => [
       state.retainCount === 0,
@@ -320,7 +325,7 @@ export const make = Effect.gen(function* PortDiscoveryMake() {
     if (wasIdle) {
       // Run an immediate scan + broadcast so the new retainer doesn't have
       // to wait up to POLL_INTERVAL for the first emission.
-      yield* pollTick();
+      yield* pollTick;
     }
   });
 
@@ -385,6 +390,6 @@ export const make = Effect.gen(function* PortDiscoveryMake() {
     registerTerminalProcesses,
     unregisterTerminal,
   });
-}).pipe(Effect.withSpan("PortDiscovery.make"));
+});
 
 export const layer = Layer.effect(PortDiscovery, make);

apps/server/src/serverActivation.test.ts

@@ -1,8 +1,11 @@
 import { expect, it } from "@effect/vitest";
+import * as Context from "effect/Context";
 import * as Deferred from "effect/Deferred";
 import * as Effect from "effect/Effect";
+import * as Option from "effect/Option";
+import * as Tracer from "effect/Tracer";
 
-import { forkParked, ServerActivation } from "./serverActivation.ts";
+import { forkParked, ServerActivation, withoutAmbientParentSpan } from "./serverActivation.ts";
 
 it.effect("proves a root is parked before returning and releases it with one gate", () =>
   Effect.scoped(
@@ -21,3 +24,30 @@ it.effect("proves a root is parked before returning and releases it with one gat
     }),
   ),
 );
+
+it.effect("withoutAmbientParentSpan drops inherited ParentSpan for long-lived roots", () =>
+  Effect.gen(function* () {
+    const ambient = Tracer.externalSpan({
+      traceId: "00000000000000000000000000000001",
+      spanId: "0000000000000001",
+      sampled: true,
+    });
+
+    const sawParent = yield* Effect.serviceOption(Tracer.ParentSpan).pipe(
+      Effect.map(Option.isSome),
+      withoutAmbientParentSpan,
+      Effect.provideService(Tracer.ParentSpan, ambient),
+    );
+
+    expect(sawParent).toBe(false);
+
+    const stillHasParent = yield* Effect.serviceOption(Tracer.ParentSpan).pipe(
+      Effect.map(Option.isSome),
+      Effect.provideService(Tracer.ParentSpan, ambient),
+    );
+    expect(stillHasParent).toBe(true);
+
+    const stripped = Context.omit(Tracer.ParentSpan)(Context.make(Tracer.ParentSpan, ambient));
+    expect(Option.isNone(Context.getOption(stripped, Tracer.ParentSpan))).toBe(true);
+  }),
+);

apps/server/src/serverActivation.ts

@@ -2,25 +2,42 @@ import * as Context from "effect/Context";
 import * as Deferred from "effect/Deferred";
 import * as Effect from "effect/Effect";
 import type * as Scope from "effect/Scope";
+import * as Tracer from "effect/Tracer";
 
 export class ServerActivation extends Context.Reference<Effect.Effect<void> | undefined>(
   "t3/serverActivation",
   { defaultValue: () => undefined },
 ) {}
 
+// Clear inherited ParentSpan so long-lived forks don't pin short-lived startup spans (#5410).
+export const withoutAmbientParentSpan = <A, E, R>(
+  effect: Effect.Effect<A, E, R>,
+): Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan>> =>
+  Effect.updateContext(
+    effect,
+    (context) =>
+      Context.omit(Tracer.ParentSpan)(context) as Context.Context<
+        Exclude<NoInfer<R>, Tracer.ParentSpan>
+      >,
+  );
+
 /** Forks a long-running root before commit and proves it is parked at the activation boundary. */
 export const forkParked = <A, E, R>(
   effect: Effect.Effect<A, E, R>,
 ): Effect.Effect<void, never, Scope.Scope | R> =>
   Effect.gen(function* () {
     const activation = yield* ServerActivation;
+    const detached = withoutAmbientParentSpan(effect);
     if (activation === undefined) {
-      yield* Effect.forkScoped(effect);
+      yield* Effect.forkScoped(detached);
       return;
     }
     const parked = yield* Deferred.make<void>();
     yield* Effect.forkScoped(
-      Deferred.succeed(parked, undefined).pipe(Effect.andThen(activation), Effect.andThen(effect)),
+      Deferred.succeed(parked, undefined).pipe(
+        Effect.andThen(activation),
+        Effect.andThen(detached),
+      ),
     );
     yield* Deferred.await(parked);
   });