fix(host-kit): a killed command settles on its exit, and background exec cannot take a timeout

packages/contracts/src/app-log-runtime.ts

@@ -110,13 +110,18 @@ export type AppLogBackgroundProcess = AsyncDisposable &
 export type AppLogProcessCommand =
   | Readonly<{
       kind: 'host';
-      request: HostCommandRequest;
+      /**
+       * A streamed log tail is stopped by its owner, so a host command here has no deadline to
+       * honour: the background exec drops `timeoutMs`. It stays out of the type so a producer
+       * cannot pass a budget that silently never fires.
+       */
+      request: Omit<HostCommandRequest, 'timeoutMs'>;
     }>
   | Readonly<{
       kind: 'android-adb';
       serial: string;
       args: readonly string[];
-      options?: Pick<HostCommandRequest, 'allowFailure' | 'cwd' | 'env' | 'timeoutMs'>;
+      options?: Pick<HostCommandRequest, 'allowFailure' | 'cwd' | 'env'>;
     }>;
 
 export type AppLogBackgroundProcessRequest = Readonly<{

packages/host-kit/src/internal/exec-boundary-faults.test.ts

@@ -3,6 +3,10 @@ import { test } from 'vitest';
 import { AppError } from '@agent-device/kernel/errors';
 import {
   runCmd,
+  runCmdBackground,
+  runCmdDetached,
+  runCmdStreaming,
+  runCmdSync,
   withCommandExecutorOverride,
   type CommandExecutorOverride,
 } from '@agent-device/host-kit/command';
@@ -28,3 +32,27 @@ test('fail-Nth executor drives one deterministic command failure without hiding
 
   assert.deepEqual(calls, [['first'], ['second'], ['third']]);
 });
+
+test('the override seam covers the foreground commands and no other spawn path', async () => {
+  const consulted: string[] = [];
+
+  await withCommandExecutorOverride(
+    (command) => {
+      consulted.push(command);
+      return undefined;
+    },
+    async () => {
+      runCmdSync(process.execPath, ['-e', 'process.stdout.write("sync")']);
+      const background = runCmdBackground(process.execPath, [
+        '-e',
+        'process.stdout.write("background")',
+      ]);
+      await background.wait;
+      runCmdDetached(process.execPath, ['-e', 'process.exit(0)']);
+      await runCmdStreaming(process.execPath, ['-e', 'process.stdout.write("streaming")']);
+      await runCmd(process.execPath, ['-e', 'process.stdout.write("foreground")']);
+    },
+  );
+
+  assert.deepEqual(consulted, [process.execPath, process.execPath]);
+});