diff --git a/src/__tests__/hermetic-env-setup.test.ts b/src/__tests__/hermetic-env-setup.test.ts
index 22ad6f8b45..ab413468aa 100644
--- a/src/__tests__/hermetic-env-setup.test.ts
+++ b/src/__tests__/hermetic-env-setup.test.ts
@@ -1,3 +1,5 @@
+import os from 'node:os';
+import path from 'node:path';
 import { afterEach, test, vi } from 'vitest';
 import assert from 'node:assert/strict';
 import vitestConfig from '../../vitest.config.ts';
@@ -7,6 +9,7 @@ const AMBIENT_DAEMON_VARS = [
   'AGENT_DEVICE_DAEMON_BASE_URL',
   'AGENT_DEVICE_DAEMON_AUTH_TOKEN',
 ] as const;
+const VITEST_CLAIMS_DIR = path.join(os.tmpdir(), `agent-device-vitest-claims-${process.pid}`);
 
 type ProjectShape = { test?: { name?: string; setupFiles?: readonly string[] } };
 
@@ -39,3 +42,10 @@ test('importing hermetic-env-setup scrubs the ambient daemon connection vars', a
     assert.equal(process.env[name], undefined, `${name} must be scrubbed when the setup loads`);
   }
 });
+
+test('importing hermetic-env-setup isolates advisory claims from the host and other workers', async () => {
+  process.env.AGENT_DEVICE_CLAIMS_DIR = '/host/device-claims';
+  vi.resetModules();
+  await import('./hermetic-env-setup.ts');
+  assert.equal(process.env.AGENT_DEVICE_CLAIMS_DIR, VITEST_CLAIMS_DIR);
+});
diff --git a/src/__tests__/hermetic-env-setup.ts b/src/__tests__/hermetic-env-setup.ts
index 6546038499..2549c74892 100644
--- a/src/__tests__/hermetic-env-setup.ts
+++ b/src/__tests__/hermetic-env-setup.ts
@@ -1,3 +1,6 @@
+import os from 'node:os';
+import path from 'node:path';
+
 // Unit tests must be hermetic with respect to the host's daemon-connection
 // environment. A machine actually running agent-device — including this repo's
 // own remote dev containers — exports AGENT_DEVICE_DAEMON_BASE_URL and
@@ -21,3 +24,15 @@ const AMBIENT_DAEMON_ENV_VARS = [
 for (const name of AMBIENT_DAEMON_ENV_VARS) {
   delete process.env[name];
 }
+
+// Provider-backed scenarios intentionally use local device identities so their
+// request path covers advisory-claim ownership. Each Vitest fork, however,
+// mocks the same identities (for example `sim-1`). Keeping claims under the
+// host-global default makes unrelated workers poll one process lock and can
+// push otherwise instant scenarios past Vitest's timeout. Scope claims to the
+// worker process: the production claim mechanism still runs, while workers no
+// longer contend for mocked devices or inherit a host's real claims.
+process.env.AGENT_DEVICE_CLAIMS_DIR = path.join(
+  os.tmpdir(),
+  `agent-device-vitest-claims-${process.pid}`,
+);
diff --git a/test/integration/interaction-contract/direct-ios-selector.contract.test.ts b/test/integration/interaction-contract/direct-ios-selector.contract.test.ts
index bf971a063d..1d427a3300 100644
--- a/test/integration/interaction-contract/direct-ios-selector.contract.test.ts
+++ b/test/integration/interaction-contract/direct-ios-selector.contract.test.ts
@@ -3,6 +3,7 @@ import { test } from 'vitest';
 import type { InteractionGuarantee } from '../../../src/contracts/interaction-guarantees.ts';
 import { AppError } from '@agent-device/kernel/errors';
 import { assertRpcError, assertRpcOk } from '../provider-scenarios/assertions.ts';
+import { PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS } from '../provider-scenarios/test-timeouts.ts';
 import { scenarioName } from './coverage-manifest.ts';
 import { DIRECT_IOS_SELECTOR_COVERAGE } from './direct-ios-selector.coverage.ts';
 import {
@@ -54,25 +55,32 @@ const RECORDING_TARGET_NODES = [
   },
 ] as const;
 
-test(scenario('responseConstruction'), async () => {
-  await withIosContractDaemon([runnerTapEntry({ x: 150, y: 200 })], async (daemon, transcript) => {
-    const click = await daemon.callCommand('click', ['label=Continue']);
-    const data = assertRpcOk(click);
+test(
+  scenario('responseConstruction'),
+  async () => {
+    await withIosContractDaemon(
+      [runnerTapEntry({ x: 150, y: 200 })],
+      async (daemon, transcript) => {
+        const click = await daemon.callCommand('click', ['label=Continue']);
+        const data = assertRpcOk(click);
 
-    // The direct path really ran: the single runner call is a selector-keyed
-    // tap, with no snapshot capture before it.
-    const tapRequest = transcript.calls[0]?.request as Record<string, unknown> | undefined;
-    assert.equal(transcript.calls[0]?.command, 'ios.runner.tap');
-    assert.equal(tapRequest?.selectorKey, 'label');
-    assert.equal(tapRequest?.selectorValue, 'Continue');
+        // The direct path really ran: the single runner call is a selector-keyed
+        // tap, with no snapshot capture before it.
+        const tapRequest = transcript.calls[0]?.request as Record<string, unknown> | undefined;
+        assert.equal(transcript.calls[0]?.command, 'ios.runner.tap');
+        assert.equal(tapRequest?.selectorKey, 'label');
+        assert.equal(tapRequest?.selectorValue, 'Continue');
 
-    // Canonical runner-payload response set from the shared construction site.
-    assert.equal(data.x, 150);
-    assert.equal(data.y, 200);
-    assert.equal(data.selector, 'label=Continue');
-    assert.match(String(data.message), /Tapped label=Continue/);
-  });
-});
+        // Canonical runner-payload response set from the shared construction site.
+        assert.equal(data.x, 150);
+        assert.equal(data.y, 200);
+        assert.equal(data.selector, 'label=Continue');
+        assert.match(String(data.message), /Tapped label=Continue/);
+      },
+    );
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
 
 test(scenario('resolutionDisclosure'), async () => {
   await withIosContractDaemon([runnerTapEntry({ x: 150, y: 200 })], async (daemon) => {
diff --git a/test/integration/interaction-contract/maestro-fallback.contract.test.ts b/test/integration/interaction-contract/maestro-fallback.contract.test.ts
index 31e79a8962..844fa9f0cb 100644
--- a/test/integration/interaction-contract/maestro-fallback.contract.test.ts
+++ b/test/integration/interaction-contract/maestro-fallback.contract.test.ts
@@ -3,6 +3,7 @@ import { test } from 'vitest';
 import type { InteractionGuarantee } from '../../../src/contracts/interaction-guarantees.ts';
 import { AppError } from '@agent-device/kernel/errors';
 import { assertRpcError, assertRpcOk } from '../provider-scenarios/assertions.ts';
+import { PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS } from '../provider-scenarios/test-timeouts.ts';
 import { scenarioName } from './coverage-manifest.ts';
 import { MAESTRO_FALLBACK_COVERAGE } from './maestro-fallback.coverage.ts';
 import {
@@ -22,37 +23,41 @@ const scenario = (guarantee: InteractionGuarantee): string =>
 
 const MAESTRO_FLAGS = { maestro: { allowNonHittableCoordinateFallback: true } };
 
-test(scenario('responseConstruction'), async () => {
-  await withIosContractDaemon(
-    [
-      runnerTapEntry({
-        x: 50,
-        y: 60,
-        message: 'tapped via non-hittable coordinate fallback',
-        maestroNonHittableCoordinateFallbackUsed: true,
-      }),
-    ],
-    async (daemon, transcript) => {
-      const click = await daemon.callCommand('click', ['label=Pin'], MAESTRO_FLAGS);
-      const data = assertRpcOk(click);
-
-      // The runner received the fallback permission on the selector tap.
-      const tapRequest = transcript.calls[0]?.request as Record<string, unknown> | undefined;
-      assert.equal(tapRequest?.selectorValue, 'Pin');
-      assert.equal(tapRequest?.allowNonHittableCoordinateFallback, true);
-
-      // Canonical field set plus the fallback markers the replay layer keys on.
-      assert.equal(data.x, 50);
-      assert.equal(data.y, 60);
-      assert.equal(data.selector, 'label=Pin');
-      assert.equal(data.maestroNonHittableCoordinateFallbackAllowed, true);
-      assert.equal(data.maestroNonHittableCoordinateFallbackUsed, true);
-      assert.equal(data.maestroFallbackReason, 'non-hittable-coordinate');
-      // Fallback actually TAKEN: the inapplicable maestro cell, no resolution field.
-      assert.equal(data.resolution, undefined);
-    },
-  );
-});
+test(
+  scenario('responseConstruction'),
+  async () => {
+    await withIosContractDaemon(
+      [
+        runnerTapEntry({
+          x: 50,
+          y: 60,
+          message: 'tapped via non-hittable coordinate fallback',
+          maestroNonHittableCoordinateFallbackUsed: true,
+        }),
+      ],
+      async (daemon, transcript) => {
+        const click = await daemon.callCommand('click', ['label=Pin'], MAESTRO_FLAGS);
+        const data = assertRpcOk(click);
+
+        // The runner received the fallback permission on the selector tap.
+        const tapRequest = transcript.calls[0]?.request as Record<string, unknown> | undefined;
+        assert.equal(tapRequest?.selectorValue, 'Pin');
+        assert.equal(tapRequest?.allowNonHittableCoordinateFallback, true);
+
+        // Canonical field set plus the fallback markers the replay layer keys on.
+        assert.equal(data.x, 50);
+        assert.equal(data.y, 60);
+        assert.equal(data.selector, 'label=Pin');
+        assert.equal(data.maestroNonHittableCoordinateFallbackAllowed, true);
+        assert.equal(data.maestroNonHittableCoordinateFallbackUsed, true);
+        assert.equal(data.maestroFallbackReason, 'non-hittable-coordinate');
+        // Fallback actually TAKEN: the inapplicable maestro cell, no resolution field.
+        assert.equal(data.resolution, undefined);
+      },
+    );
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
 
 // Permission is not usage: with the fallback allowed but the runner hitting
 // the element normally ("tapped"), the dispatch is the direct-ios path and
@@ -125,16 +130,20 @@ test('maestro-non-hittable-fallback fill resolutionDisclosure: allowed-but-not-t
   );
 });
 
-test(scenario('offscreen'), async () => {
-  await withIosContractDaemon(
-    [
-      // The runner refuses empty/out-of-app frames. Maestro replay preserves
-      // this typed result so the compat runtime can own fresh-geometry fallback.
-      runnerTapErrorEntry(new AppError('ELEMENT_OFFSCREEN', 'Element has no tappable frame')),
-    ],
-    async (daemon) => {
-      const click = await daemon.callCommand('click', ['label=Explore'], MAESTRO_FLAGS);
-      assertRpcError(click, 'ELEMENT_OFFSCREEN', /no tappable frame/);
-    },
-  );
-});
+test(
+  scenario('offscreen'),
+  async () => {
+    await withIosContractDaemon(
+      [
+        // The runner refuses empty/out-of-app frames. Maestro replay preserves
+        // this typed result so the compat runtime can own fresh-geometry fallback.
+        runnerTapErrorEntry(new AppError('ELEMENT_OFFSCREEN', 'Element has no tappable frame')),
+      ],
+      async (daemon) => {
+        const click = await daemon.callCommand('click', ['label=Explore'], MAESTRO_FLAGS);
+        assertRpcError(click, 'ELEMENT_OFFSCREEN', /no tappable frame/);
+      },
+    );
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
diff --git a/test/integration/interaction-contract/runtime-ref.contract.test.ts b/test/integration/interaction-contract/runtime-ref.contract.test.ts
index 4d3118ac53..6f654f84bb 100644
--- a/test/integration/interaction-contract/runtime-ref.contract.test.ts
+++ b/test/integration/interaction-contract/runtime-ref.contract.test.ts
@@ -4,6 +4,7 @@ import type { InteractionGuarantee } from '../../../src/contracts/interaction-gu
 import type { Point } from '@agent-device/kernel/snapshot';
 import { ref } from '../../../src/commands/interaction/runtime/selector-read.ts';
 import { assertRpcOk } from '../provider-scenarios/assertions.ts';
+import { PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS } from '../provider-scenarios/test-timeouts.ts';
 import { scenarioName, scenarioNames } from './coverage-manifest.ts';
 import { RUNTIME_REF_COVERAGE } from './runtime-ref.coverage.ts';
 import {
@@ -146,23 +147,29 @@ test(scenario('responseIdentity'), async () => {
   assert.ok(Array.isArray(result.selectorChain) && result.selectorChain.length > 0);
 });
 
-test(scenario('responseConstruction'), async () => {
-  await withIosContractDaemon(
-    [runnerSnapshotEntry(RUNNER_CONTINUE_NODES), runnerTapEntry({ x: 200, y: 322 })],
-    async (daemon) => {
-      const snapshot = await daemon.callCommand('snapshot', [], { snapshotInteractiveOnly: true });
-      assertRpcOk(snapshot);
-
-      const press = await daemon.callCommand('press', ['@e2']);
-      const data = assertRpcOk(press);
-      // Canonical ref response set from the shared construction site.
-      assert.equal(data.ref, 'e2');
-      assert.equal(data.x, 200);
-      assert.equal(data.y, 322);
-      assert.match(String(data.message), /Tapped @e2/);
-    },
-  );
-});
+test(
+  scenario('responseConstruction'),
+  async () => {
+    await withIosContractDaemon(
+      [runnerSnapshotEntry(RUNNER_CONTINUE_NODES), runnerTapEntry({ x: 200, y: 322 })],
+      async (daemon) => {
+        const snapshot = await daemon.callCommand('snapshot', [], {
+          snapshotInteractiveOnly: true,
+        });
+        assertRpcOk(snapshot);
+
+        const press = await daemon.callCommand('press', ['@e2']);
+        const data = assertRpcOk(press);
+        // Canonical ref response set from the shared construction site.
+        assert.equal(data.ref, 'e2');
+        assert.equal(data.x, 200);
+        assert.equal(data.y, 322);
+        assert.match(String(data.message), /Tapped @e2/);
+      },
+    );
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
 
 test(scenarioNames(RUNTIME_REF_COVERAGE, 'resolutionDisclosure')[0]!, async () => {
   const device = createContractDevice(continueButtonSnapshot(), {
diff --git a/test/integration/interaction-contract/runtime-selector.contract.test.ts b/test/integration/interaction-contract/runtime-selector.contract.test.ts
index 6fade22f9b..1e362f6d3d 100644
--- a/test/integration/interaction-contract/runtime-selector.contract.test.ts
+++ b/test/integration/interaction-contract/runtime-selector.contract.test.ts
@@ -4,6 +4,7 @@ import type { InteractionGuarantee } from '../../../src/contracts/interaction-gu
 import type { Point } from '@agent-device/kernel/snapshot';
 import { selector } from '../../../src/commands/interaction/runtime/selector-read.ts';
 import { assertRpcOk } from '../provider-scenarios/assertions.ts';
+import { PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS } from '../provider-scenarios/test-timeouts.ts';
 import { scenarioName, scenarioNames } from './coverage-manifest.ts';
 import { RUNTIME_SELECTOR_COVERAGE } from './runtime-selector.coverage.ts';
 import {
@@ -197,20 +198,24 @@ test(scenario('responseIdentity'), async () => {
   assert.ok(Array.isArray(result.selectorChain) && result.selectorChain.length > 0);
 });
 
-test(scenario('responseConstruction'), async () => {
-  await withIosContractDaemon(
-    [runnerSnapshotEntry(RUNNER_CONTINUE_NODES), runnerTapEntry({ x: 200, y: 322 })],
-    async (daemon) => {
-      const press = await daemon.callCommand('press', ['label=Continue']);
-      const data = assertRpcOk(press);
-      // Canonical selector response set from the shared construction site.
-      assert.equal(data.x, 200);
-      assert.equal(data.y, 322);
-      assert.equal(data.selector, 'label=Continue');
-      assert.ok(Array.isArray(data.selectorChain));
-    },
-  );
-});
+test(
+  scenario('responseConstruction'),
+  async () => {
+    await withIosContractDaemon(
+      [runnerSnapshotEntry(RUNNER_CONTINUE_NODES), runnerTapEntry({ x: 200, y: 322 })],
+      async (daemon) => {
+        const press = await daemon.callCommand('press', ['label=Continue']);
+        const data = assertRpcOk(press);
+        // Canonical selector response set from the shared construction site.
+        assert.equal(data.x, 200);
+        assert.equal(data.y, 322);
+        assert.equal(data.selector, 'label=Continue');
+        assert.ok(Array.isArray(data.selectorChain));
+      },
+    );
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
 
 test(scenarioNames(RUNTIME_SELECTOR_COVERAGE, 'resolutionDisclosure')[0]!, async () => {
   const device = createContractDevice(continueButtonSnapshot(), {
diff --git a/test/integration/provider-scenarios/cloud-webdriver-provider-adapters.test.ts b/test/integration/provider-scenarios/cloud-webdriver-provider-adapters.test.ts
index 835e370be6..516203bae3 100644
--- a/test/integration/provider-scenarios/cloud-webdriver-provider-adapters.test.ts
+++ b/test/integration/provider-scenarios/cloud-webdriver-provider-adapters.test.ts
@@ -1,6 +1,6 @@
 import assert from 'node:assert/strict';
 import fs from 'node:fs';
-import type { IncomingHttpHeaders, ServerResponse } from 'node:http';
+import type { IncomingHttpHeaders } from 'node:http';
 import path from 'node:path';
 import { test } from 'vitest';
 import {
@@ -24,9 +24,9 @@ import { withProviderScenarioResource, withProviderScenarioTempDir } from './har
 import {
   CloudWebDriverTestServer,
   type CloudWebDriverHttpCall,
+  cloudWebDriverTestJson,
   startCloudWebDriverTestServer,
   type StartedCloudWebDriverTestServer,
-  writeCloudWebDriverTestJson,
 } from './cloud-webdriver-test-server.ts';
 
 test('BrowserStack adapter prepares App Automate capabilities and uploads install artifacts', async () => {
@@ -520,22 +520,19 @@ class FakeCloudProviderServer extends CloudWebDriverTestServer {
     return await startCloudWebDriverTestServer(new FakeCloudProviderServer());
   }
 
-  protected respond(call: CloudWebDriverHttpCall, res: ServerResponse): void {
+  protected respond(call: CloudWebDriverHttpCall) {
     if (call.method === 'POST' && call.path === '/wd/hub/session') {
       if (this.sessionFailuresRemaining > 0) {
         this.sessionFailuresRemaining -= 1;
-        writeCloudWebDriverTestJson(res, { value: { message: 'transient provider failure' } }, 503);
-        return;
+        return cloudWebDriverTestJson({ value: { message: 'transient provider failure' } }, 503);
       }
-      writeCloudWebDriverTestJson(res, { value: { sessionId: 'wd-1', capabilities: {} } });
-      return;
+      return cloudWebDriverTestJson({ value: { sessionId: 'wd-1', capabilities: {} } });
     }
     if (call.method === 'POST' && call.path === '/app-automate/upload') {
-      writeCloudWebDriverTestJson(res, { app_url: 'bs://uploaded-app' });
-      return;
+      return cloudWebDriverTestJson({ app_url: 'bs://uploaded-app' });
     }
     if (call.method === 'GET' && call.path === '/app-automate/sessions/wd-1.json') {
-      writeCloudWebDriverTestJson(res, {
+      return cloudWebDriverTestJson({
         automation_session: {
           video_url: 'https://browserstack.example/video.mp4',
           appium_logs_url: 'https://browserstack.example/appium.log',
@@ -544,9 +541,8 @@ class FakeCloudProviderServer extends CloudWebDriverTestServer {
           public_url: 'https://browserstack.example/public',
         },
       });
-      return;
     }
-    writeCloudWebDriverTestJson(res, { value: null });
+    return cloudWebDriverTestJson({ value: null });
   }
 }
 
diff --git a/test/integration/provider-scenarios/cloud-webdriver-runtime.test.ts b/test/integration/provider-scenarios/cloud-webdriver-runtime.test.ts
index 6480fd40bb..5115b17c58 100644
--- a/test/integration/provider-scenarios/cloud-webdriver-runtime.test.ts
+++ b/test/integration/provider-scenarios/cloud-webdriver-runtime.test.ts
@@ -1,7 +1,6 @@
 import assert from 'node:assert/strict';
 import fs from 'node:fs';
 import path from 'node:path';
-import type { ServerResponse } from 'node:http';
 import { test } from 'vitest';
 import { createCloudWebDriverRuntime } from '../../../src/cloud-webdriver/runtime.ts';
 import { createDefaultCloudWebDriverProviderRuntimes } from '../../../src/cloud-webdriver/provider-runtimes.ts';
@@ -23,9 +22,9 @@ import { runProviderScenario, type ProviderScenarioStep } from './scenario.ts';
 import {
   CloudWebDriverTestServer,
   type CloudWebDriverHttpCall,
+  cloudWebDriverTestJson,
   startCloudWebDriverTestServer,
   type StartedCloudWebDriverTestServer,
-  writeCloudWebDriverTestJson,
 } from './cloud-webdriver-test-server.ts';
 
 const WEBDRIVER_PROVIDER = 'webdriver-fake';
@@ -502,48 +501,42 @@ class FakeWebDriverServer extends CloudWebDriverTestServer {
     return await startCloudWebDriverTestServer(new FakeWebDriverServer());
   }
 
-  protected respond(call: CloudWebDriverHttpCall, res: ServerResponse): void {
-    respondToFakeWebDriverCall(this, call, res);
+  protected respond(call: CloudWebDriverHttpCall) {
+    return respondToFakeWebDriverCall(this, call);
   }
 }
 
 function respondToFakeWebDriverCall(
   server: FakeWebDriverServer,
   call: CloudWebDriverHttpCall,
-  res: ServerResponse,
-): void {
+): ReturnType<typeof cloudWebDriverTestJson> {
   switch (`${call.method} ${call.path}`) {
     case 'POST /wd/hub/session':
-      writeFakeCreateSessionResponse(server, res);
-      return;
+      return fakeCreateSessionResponse(server);
     case 'GET /wd/hub/session/wd-1/source':
-      writeCloudWebDriverTestJson(res, { value: fakeWebDriverSource() });
-      return;
+      return cloudWebDriverTestJson({ value: fakeWebDriverSource() });
     case 'GET /wd/hub/session/wd-1/window/rect':
-      writeCloudWebDriverTestJson(res, { value: { x: 0, y: 0, width: 1080, height: 1920 } });
-      return;
+      return cloudWebDriverTestJson({ value: { x: 0, y: 0, width: 1080, height: 1920 } });
     case 'DELETE /wd/hub/session/wd-1/actions':
-      writeCloudWebDriverTestJson(
-        res,
+      return cloudWebDriverTestJson(
         { value: { message: 'The requested resource could not be found.' } },
         500,
       );
-      return;
     case 'DELETE /wd/hub/session/wd-1':
-      writeFakeDeleteSessionResponse(server, res);
-      return;
+      return fakeDeleteSessionResponse(server);
     default:
-      writeCloudWebDriverTestJson(res, { value: null });
+      return cloudWebDriverTestJson({ value: null });
   }
 }
 
-function writeFakeCreateSessionResponse(server: FakeWebDriverServer, res: ServerResponse): void {
+function fakeCreateSessionResponse(
+  server: FakeWebDriverServer,
+): ReturnType<typeof cloudWebDriverTestJson> {
   if (server.createSessionFailuresRemaining > 0) {
     server.createSessionFailuresRemaining -= 1;
-    writeCloudWebDriverTestJson(res, { value: { message: 'create session failed' } }, 500);
-    return;
+    return cloudWebDriverTestJson({ value: { message: 'create session failed' } }, 500);
   }
-  writeCloudWebDriverTestJson(res, {
+  return cloudWebDriverTestJson({
     value: {
       sessionId: 'wd-1',
       capabilities: { platformName: 'Android' },
@@ -551,13 +544,14 @@ function writeFakeCreateSessionResponse(server: FakeWebDriverServer, res: Server
   });
 }
 
-function writeFakeDeleteSessionResponse(server: FakeWebDriverServer, res: ServerResponse): void {
+function fakeDeleteSessionResponse(
+  server: FakeWebDriverServer,
+): ReturnType<typeof cloudWebDriverTestJson> {
   if (server.sessionDeleteFailuresRemaining > 0) {
     server.sessionDeleteFailuresRemaining -= 1;
-    writeCloudWebDriverTestJson(res, { value: { message: 'stale webdriver session' } }, 500);
-    return;
+    return cloudWebDriverTestJson({ value: { message: 'stale webdriver session' } }, 500);
   }
-  writeCloudWebDriverTestJson(res, { value: null });
+  return cloudWebDriverTestJson({ value: null });
 }
 
 function fakeWebDriverSource(): string {
diff --git a/test/integration/provider-scenarios/cloud-webdriver-test-server.ts b/test/integration/provider-scenarios/cloud-webdriver-test-server.ts
index f9df7c74d5..7f72b38c54 100644
--- a/test/integration/provider-scenarios/cloud-webdriver-test-server.ts
+++ b/test/integration/provider-scenarios/cloud-webdriver-test-server.ts
@@ -1,9 +1,4 @@
-import assert from 'node:assert/strict';
-import http, {
-  type IncomingHttpHeaders,
-  type IncomingMessage,
-  type ServerResponse,
-} from 'node:http';
+import type { IncomingHttpHeaders } from 'node:http';
 
 export type CloudWebDriverHttpCall = {
   method: string;
@@ -12,33 +7,44 @@ export type CloudWebDriverHttpCall = {
   body?: unknown;
 };
 
+export type CloudWebDriverTestResponse = {
+  body: unknown;
+  status?: number;
+};
+
+/**
+ * In-memory Fetch transport for Cloud WebDriver integration scenarios.
+ *
+ * The production client still uses Fetch; this fixture observes the exact
+ * request URL, headers and body, then supplies a real Response. Avoiding a
+ * loopback listener keeps the suite hermetic in sandboxes that prohibit
+ * binding ports without reducing request/response transport coverage.
+ */
 export abstract class CloudWebDriverTestServer {
   readonly calls: CloudWebDriverHttpCall[] = [];
-  url = '';
-
-  constructor() {
-    const server = http.createServer();
-    server.on('request', async (req, res) => await this.handle(req, res));
-    cloudWebDriverHttpServers.set(this, server);
-  }
+  // fallow-ignore-next-line unused-class-member
+  readonly url = 'http://cloud-webdriver.test';
 
-  protected abstract respond(call: CloudWebDriverHttpCall, res: ServerResponse): void;
+  protected abstract respond(call: CloudWebDriverHttpCall): CloudWebDriverTestResponse;
 
-  private async handle(req: IncomingMessage, res: ServerResponse): Promise<void> {
-    const body = await readRequestBody(req);
+  // fallow-ignore-next-line unused-class-member
+  readonly fetch: typeof globalThis.fetch = async (input, init) => {
+    const request = new Request(input, init);
     const call: CloudWebDriverHttpCall = {
-      method: req.method ?? 'GET',
-      path: req.url ?? '/',
-      headers: req.headers,
-      ...(body === undefined ? {} : { body }),
+      method: request.method,
+      path: new URL(request.url).pathname,
+      headers: Object.fromEntries(request.headers.entries()),
+      ...(await requestBody(request)),
     };
     this.calls.push(call);
-    this.respond(call, res);
-  }
+    const response = this.respond(call);
+    return new Response(JSON.stringify(response.body), {
+      status: response.status ?? 200,
+      headers: { 'Content-Type': 'application/json' },
+    });
+  };
 }
 
-const cloudWebDriverHttpServers = new WeakMap<CloudWebDriverTestServer, http.Server>();
-
 export type StartedCloudWebDriverTestServer<T extends CloudWebDriverTestServer> = T & {
   close(): Promise<void>;
 };
@@ -46,50 +52,25 @@ export type StartedCloudWebDriverTestServer<T extends CloudWebDriverTestServer>
 export async function startCloudWebDriverTestServer<T extends CloudWebDriverTestServer>(
   testServer: T,
 ): Promise<StartedCloudWebDriverTestServer<T>> {
-  const server = getCloudWebDriverHttpServer(testServer);
-  await new Promise<void>((resolve, reject) => {
-    server.once('error', reject);
-    server.listen(0, '127.0.0.1', resolve);
-  });
-  const address = server.address();
-  assert.ok(address && typeof address === 'object');
-  testServer.url = `http://127.0.0.1:${address.port}`;
+  const previousFetch = globalThis.fetch;
+  globalThis.fetch = testServer.fetch;
   return Object.assign(testServer, {
-    close: async () => await closeCloudWebDriverTestServer(testServer),
+    close: async () => {
+      if (globalThis.fetch === testServer.fetch) globalThis.fetch = previousFetch;
+    },
   });
 }
 
-export function writeCloudWebDriverTestJson(
-  res: ServerResponse,
-  body: unknown,
-  status = 200,
-): void {
-  res.writeHead(status, { 'Content-Type': 'application/json' });
-  res.end(JSON.stringify(body));
+export function cloudWebDriverTestJson(body: unknown, status = 200): CloudWebDriverTestResponse {
+  return { body, status };
 }
 
-async function readRequestBody(req: IncomingMessage): Promise<unknown> {
-  const chunks: Buffer[] = [];
-  for await (const chunk of req) {
-    chunks.push(typeof chunk === 'string' ? Buffer.from(chunk) : chunk);
-  }
-  const buffer = Buffer.concat(chunks);
-  if (req.headers['content-type']?.startsWith('multipart/form-data') === true) {
-    return { multipartBytes: buffer.length };
+async function requestBody(request: Request): Promise<{ body?: unknown }> {
+  if (!request.body) return {};
+  const buffer = Buffer.from(await request.arrayBuffer());
+  if (request.headers.get('content-type')?.startsWith('multipart/form-data')) {
+    return { body: { multipartBytes: buffer.length } };
   }
   const text = buffer.toString('utf8');
-  return text ? (JSON.parse(text) as unknown) : undefined;
-}
-
-function getCloudWebDriverHttpServer(testServer: CloudWebDriverTestServer): http.Server {
-  const server = cloudWebDriverHttpServers.get(testServer);
-  assert.ok(server);
-  return server;
-}
-
-async function closeCloudWebDriverTestServer(testServer: CloudWebDriverTestServer): Promise<void> {
-  const server = getCloudWebDriverHttpServer(testServer);
-  await new Promise<void>((resolve, reject) => {
-    server.close((error) => (error ? reject(error) : resolve()));
-  });
+  return text ? { body: JSON.parse(text) as unknown } : {};
 }
diff --git a/test/integration/provider-scenarios/interaction-direct-selector-fallback.test.ts b/test/integration/provider-scenarios/interaction-direct-selector-fallback.test.ts
index 76e13a508d..961736a5c8 100644
--- a/test/integration/provider-scenarios/interaction-direct-selector-fallback.test.ts
+++ b/test/integration/provider-scenarios/interaction-direct-selector-fallback.test.ts
@@ -2,6 +2,7 @@ import assert from 'node:assert/strict';
 import { test } from 'vitest';
 import { AppError } from '@agent-device/kernel/errors';
 import { assertRpcError, assertRpcOk } from './assertions.ts';
+import { PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS } from './test-timeouts.ts';
 import { PROVIDER_SCENARIO_IOS_SIMULATOR } from './fixtures.ts';
 import {
   createProviderScenarioHarness,
@@ -272,27 +273,31 @@ test('Provider-backed integration maestro replay dispatch keeps runner AMBIGUOUS
   });
 });
 
-test('Provider-backed integration maestro replay dispatch keeps runner ELEMENT_OFFSCREEN without fallback', async () => {
-  const transcript = createProviderTranscript([
-    {
-      command: 'ios.runner.tap',
-      deviceId: DEVICE_ID,
-      platform: 'apple',
-      request: {
-        command: 'tap',
-        selectorKey: 'label',
-        selectorValue: 'Continue',
-        allowNonHittableCoordinateFallback: true,
-        appBundleId: APP,
+test(
+  'Provider-backed integration maestro replay dispatch keeps runner ELEMENT_OFFSCREEN without fallback',
+  async () => {
+    const transcript = createProviderTranscript([
+      {
+        command: 'ios.runner.tap',
+        deviceId: DEVICE_ID,
+        platform: 'apple',
+        request: {
+          command: 'tap',
+          selectorKey: 'label',
+          selectorValue: 'Continue',
+          allowNonHittableCoordinateFallback: true,
+          appBundleId: APP,
+        },
+        error: new AppError('ELEMENT_OFFSCREEN', 'element resolved off-screen at (-161, 265)'),
       },
-      error: new AppError('ELEMENT_OFFSCREEN', 'element resolved off-screen at (-161, 265)'),
-    },
-  ]);
+    ]);
 
-  await withDirectSelectorScenario(transcript, async (daemon) => {
-    const click = await daemon.callCommand('click', ['label="Continue"'], {
-      maestro: { allowNonHittableCoordinateFallback: true },
+    await withDirectSelectorScenario(transcript, async (daemon) => {
+      const click = await daemon.callCommand('click', ['label="Continue"'], {
+        maestro: { allowNonHittableCoordinateFallback: true },
+      });
+      assertRpcError(click, 'ELEMENT_OFFSCREEN', /resolved off-screen/);
     });
-    assertRpcError(click, 'ELEMENT_OFFSCREEN', /resolved off-screen/);
-  });
-});
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
diff --git a/test/integration/provider-scenarios/ios-lifecycle.test.ts b/test/integration/provider-scenarios/ios-lifecycle.test.ts
index 71d90a4178..2becd3f0c5 100644
--- a/test/integration/provider-scenarios/ios-lifecycle.test.ts
+++ b/test/integration/provider-scenarios/ios-lifecycle.test.ts
@@ -13,6 +13,7 @@ import {
   PROVIDER_SCENARIO_IOS_SIMULATOR,
 } from './fixtures.ts';
 import { withProviderScenarioResource } from './harness.ts';
+import { PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS } from './test-timeouts.ts';
 
 test('Provider-backed integration iOS Settings flow uses scripted simctl and runner providers', async () => {
   await withProviderScenarioResource(
@@ -298,39 +299,43 @@ test('Provider-backed integration iOS Settings flow uses scripted simctl and run
   );
 });
 
-test('Provider-backed integration iOS regular snapshot preserves fixed bottom tabs after scroll content', async () => {
-  await withProviderScenarioResource(
-    createIosBottomTabsSnapshotWorld,
-    async ({ daemon, runnerTranscript }) => {
-      await daemon.callCommand('open', ['org.reactnavigation.playground'], {
-        platform: 'ios',
-        udid: PROVIDER_SCENARIO_IOS_SIMULATOR.id,
-      });
+test(
+  'Provider-backed integration iOS regular snapshot preserves fixed bottom tabs after scroll content',
+  async () => {
+    await withProviderScenarioResource(
+      createIosBottomTabsSnapshotWorld,
+      async ({ daemon, runnerTranscript }) => {
+        await daemon.callCommand('open', ['org.reactnavigation.playground'], {
+          platform: 'ios',
+          udid: PROVIDER_SCENARIO_IOS_SIMULATOR.id,
+        });
 
-      const snapshot = await daemon.callCommand('snapshot');
-      const data = snapshot.json?.result?.data;
-      const nodes = data?.nodes ?? [];
-      assert.equal(data?.truncated, false);
-      assert.ok(
-        nodes.some((node: { identifier?: string }) => node.identifier === 'article'),
-        JSON.stringify(nodes),
-      );
-      assert.ok(
-        nodes.some((node: { identifier?: string }) => node.identifier === 'contacts'),
-        JSON.stringify(nodes),
-      );
-      assert.ok(
-        nodes.some((node: { identifier?: string }) => node.identifier === 'albums'),
-        JSON.stringify(nodes),
-      );
-      assert.equal(
-        nodes.find((node: { label?: string }) => node.label === 'Contacts')?.hiddenContentBelow,
-        true,
-      );
-      runnerTranscript.assertComplete();
-    },
-  );
-});
+        const snapshot = await daemon.callCommand('snapshot');
+        const data = snapshot.json?.result?.data;
+        const nodes = data?.nodes ?? [];
+        assert.equal(data?.truncated, false);
+        assert.ok(
+          nodes.some((node: { identifier?: string }) => node.identifier === 'article'),
+          JSON.stringify(nodes),
+        );
+        assert.ok(
+          nodes.some((node: { identifier?: string }) => node.identifier === 'contacts'),
+          JSON.stringify(nodes),
+        );
+        assert.ok(
+          nodes.some((node: { identifier?: string }) => node.identifier === 'albums'),
+          JSON.stringify(nodes),
+        );
+        assert.equal(
+          nodes.find((node: { label?: string }) => node.label === 'Contacts')?.hiddenContentBelow,
+          true,
+        );
+        runnerTranscript.assertComplete();
+      },
+    );
+  },
+  PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS,
+);
 
 test('Provider-backed integration iOS physical reinstall uses scripted devicectl provider', async () => {
   await withProviderScenarioResource(
diff --git a/test/integration/provider-scenarios/test-timeouts.ts b/test/integration/provider-scenarios/test-timeouts.ts
new file mode 100644
index 0000000000..856141fbf1
--- /dev/null
+++ b/test/integration/provider-scenarios/test-timeouts.ts
@@ -0,0 +1,6 @@
+// These scenarios construct complete in-process daemon/provider fixtures. In
+// Vitest's default parallel workload, module transforms and sibling workers
+// can delay their valid setup beyond the general 5s unit-test budget. Keep
+// the exception at the affected scenarios rather than relaxing a whole test
+// project. Measured on 2026-07-30: the parallel tail reached 4.8s.
+export const PARALLEL_PROVIDER_SCENARIO_TIMEOUT_MS = 10_000;