@@ -1,8 +1,20 @@
 import type { SessionAction } from '@agent-device/contracts/session';
-import { isSessionRuntimePlatform, type SessionRuntimeHints } from '@agent-device/kernel/contracts';
+import type { SessionRuntimeHints } from '@agent-device/kernel/contracts';
 import { appendScreenshotScriptFlags } from '@agent-device/contracts/capture';
 import { splitRefGenerationSuffix } from '@agent-device/kernel/snapshot';
 
+const SCRIPT_RUNTIME_PLATFORMS = {
+  ios: true,
+  android: true,
+  harmonyos: true,
+} satisfies Record<NonNullable<SessionRuntimeHints['platform']>, true>;
+
+function isScriptRuntimePlatform(
+  value: unknown,
+): value is NonNullable<SessionRuntimeHints['platform']> {
+  return typeof value === 'string' && Object.hasOwn(SCRIPT_RUNTIME_PLATFORMS, value);
+}
+
 /**
  * #1076 versioned refs: a recorded ref positional may carry a `~s<generation>`
  * pin from the client that issued it (`@e12~s3`). Generations are meaningless
@@ -168,7 +180,7 @@ export function appendRuntimeHintFlags(
   flags: Pick<SessionAction, 'flags'>['flags'] | SessionRuntimeHints | undefined,
 ): void {
   if (!flags) return;
-  if (isSessionRuntimePlatform(flags.platform)) {
+  if (isScriptRuntimePlatform(flags.platform)) {
     parts.push('--platform', flags.platform);
   }
   if (typeof flags.metroHost === 'string' && flags.metroHost.length > 0) {
@@ -325,7 +337,7 @@ export function parseReplayRuntimeFlags(args: string[]): {
     const nextArg = args[index + 1];
     if (token === '--platform' && nextArg !== undefined) {
       const platform = nextArg;
-      if (isSessionRuntimePlatform(platform)) {
+      if (isScriptRuntimePlatform(platform)) {
         flags.platform = platform;
       }
       index += 1;
 
@@ -3,13 +3,29 @@ import fs from 'node:fs';
 import {
   connectionWorkspace,
   createTestClient,
+  forceConnectFlags,
   seedConnectionState,
 } from './remote-connection.fixtures.ts';
-import { materializeRemoteConnectionForCommand } from '../cli/commands/connection-runtime.ts';
+import {
+  materializeRemoteConnectionForCommand,
+  resolveRequestedLeaseBackend,
+} from '../cli/commands/connection-runtime.ts';
 import { disconnectCommand } from '../cli/commands/connection.ts';
 import { readRemoteConnectionState } from '../remote/remote-connection-state.ts';
 import { LeaseRegistry } from '../daemon/lease-registry.ts';
 
+test('HarmonyOS platform resolves to its proxy lease backend', () => {
+  expect(
+    resolveRequestedLeaseBackend(
+      forceConnectFlags({
+        stateDir: '/tmp/agent-device',
+        remoteConfig: '/tmp/remote.json',
+        platform: 'harmonyos',
+      }),
+    ),
+  ).toBe('harmonyos-instance');
+});
+
 test.each(['apple', 'harmonyos', 'ios', 'android'] as const)(
   'stored Harmony runtime compatibility respects %s selection',
   async (platform) => {
 
@@ -34,9 +34,7 @@ import {
   materializeRemoteConnectionForCommand,
   CLOUD_WEBDRIVER_REMOTE_LEASE_TTL_MS,
   PROXY_REMOTE_LEASE_TTL_MS,
-  resolveRequestedLeaseBackend,
 } from '../cli/commands/connection-runtime.ts';
-
 import { stopMetroCompanion } from '../metro/client-metro-companion.ts';
 import { AppError } from '@agent-device/kernel/errors';
 import {
@@ -47,19 +45,6 @@ import {
 } from '../remote/remote-connection-state.ts';
 import type { AgentDeviceClient } from '../agent-device-client.ts';
 
-test('HarmonyOS platform resolves to its proxy lease backend', () => {
-  assert.equal(
-    resolveRequestedLeaseBackend(
-      forceConnectFlags({
-        stateDir: '/tmp/agent-device',
-        remoteConfig: '/tmp/remote.json',
-        platform: 'harmonyos',
-      }),
-    ),
-    'harmonyos-instance',
-  );
-});
-
 afterEach(() => {
   vi.clearAllMocks();
   vi.restoreAllMocks();