refactor(ios): share the discovery-pending retry loop

packages/platform-apple/src/snapshot-observability.ts

@@ -7,7 +7,7 @@ import type { PlatformRuntimeHost } from '@agent-device/contracts/platform-runti
 import type { DeviceInfo } from '@agent-device/kernel/device';
 import type { SimulatorSnapshotSource } from './snapshot-source-facade.ts';
 import {
-  isSimulatorTargetDiscoveryPending,
+  resolveSimulatorTargetJoiningDiscovery,
   type SimulatorSnapshotTarget,
   type SimulatorSnapshotTargetResolver,
 } from './snapshot-target.ts';
@@ -111,12 +111,19 @@ async function resolveLaunchedTarget(
   appBundleId: string,
   signal: AbortSignal,
 ): Promise<SimulatorSnapshotTarget | undefined> {
-  for (;;) {
-    try {
-      return await resolveTarget(device, appBundleId, signal);
-    } catch (error) {
-      signal.throwIfAborted();
-      if (!isSimulatorTargetDiscoveryPending(error)) return undefined;
-    }
+  try {
+    return await resolveSimulatorTargetJoiningDiscovery(
+      resolveTarget,
+      device,
+      appBundleId,
+      signal,
+      () => {
+        signal.throwIfAborted();
+        return true;
+      },
+    );
+  } catch {
+    signal.throwIfAborted();
+    return undefined;
   }
 }

packages/platform-apple/src/snapshot-route.ts

@@ -29,7 +29,7 @@ import {
 } from './snapshot-observability.ts';
 import {
   createSimulatorSnapshotTargetResolver,
-  isSimulatorTargetDiscoveryPending,
+  resolveSimulatorTargetJoiningDiscovery,
   type SimulatorSnapshotTarget,
   type SimulatorSnapshotTargetResolver,
 } from './snapshot-target.ts';
@@ -236,15 +236,14 @@ async function resolveTargetForObservation(
   signal: AbortSignal,
 ): Promise<SimulatorSnapshotTarget> {
   const appBundleId = input.options!.appBundleId!;
-  for (;;) {
-    try {
-      return await resolveTarget(device, appBundleId, signal);
-    } catch (error) {
-      if (!isSimulatorTargetDiscoveryPending(error)) throw error;
-      const execution = { requestId: input.execution?.requestId };
-      if (await host.appleApplications.hasLiveRunnerSession(device, execution)) throw error;
-    }
-  }
+  const execution = { requestId: input.execution?.requestId };
+  return await resolveSimulatorTargetJoiningDiscovery(
+    resolveTarget,
+    device,
+    appBundleId,
+    signal,
+    async () => !(await host.appleApplications.hasLiveRunnerSession(device, execution)),
+  );
 }
 
 function isEligible(device: DeviceInfo, input: CaptureSnapshotInput): boolean {

packages/platform-apple/src/snapshot-target.ts

@@ -73,10 +73,34 @@ export function createSimulatorSnapshotTargetResolver(): SimulatorSnapshotTarget
  * Whether a resolver failure only says the discovery is still running. The discovery keeps going
  * under its own deadline, so asking again joins it rather than starting another.
  */
-export function isSimulatorTargetDiscoveryPending(error: unknown): boolean {
+function isSimulatorTargetDiscoveryPending(error: unknown): boolean {
   return error instanceof AppError && error.details?.reason === TARGET_DISCOVERY_PENDING;
 }
 
+/**
+ * Resolves `resolveTarget`, re-asking it for as long as the only thing standing in the way is a
+ * discovery still in flight: the discovery's own deadline, or `resolveTarget` itself observing the
+ * request signal, is what eventually turns that into a real answer or a non-pending failure, which
+ * this always rethrows at once. `keepWaiting` is the one thing callers differ on: whether riding
+ * the discovery out is still worth it before the next wait slice.
+ */
+export async function resolveSimulatorTargetJoiningDiscovery(
+  resolveTarget: SimulatorSnapshotTargetResolver,
+  device: DeviceInfo,
+  appBundleId: string,
+  signal: AbortSignal,
+  keepWaiting: () => Promise<boolean> | boolean,
+): Promise<SimulatorSnapshotTarget> {
+  for (;;) {
+    try {
+      return await resolveTarget(device, appBundleId, signal);
+    } catch (error) {
+      if (!isSimulatorTargetDiscoveryPending(error)) throw error;
+      if (!(await keepWaiting())) throw error;
+    }
+  }
+}
+
 async function resolveSimulatorSnapshotTarget(
   device: DeviceInfo,
   appBundleId: string,