fix(android): record the instrumentation result when the snapshot helper exits without output

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

@@ -483,3 +483,20 @@ test('commandHostEnvironment names the enclosing host and refuses outside one',
     assert.equal(commandHostEnvironment(), host);
   });
 });
+
+// Windows reports no signal for a terminated process.
+test.skipIf(process.platform === 'win32')(
+  'every foreground executor reports the signal that ended the process',
+  async () => {
+    const kill = ['-e', "process.kill(process.pid, 'SIGKILL')"];
+    const options = { allowFailure: true };
+
+    assert.equal((await runCmd(process.execPath, kill, options)).signal, 'SIGKILL');
+    assert.equal((await runCmdStreaming(process.execPath, kill, options)).signal, 'SIGKILL');
+    assert.equal(runCmdSync(process.execPath, kill, options).signal, 'SIGKILL');
+
+    const exited = await runCmd(process.execPath, ['-e', 'process.exit(3)'], options);
+    assert.equal(exited.exitCode, 3);
+    assert.equal('signal' in exited, false);
+  },
+);

packages/host-kit/src/internal/exec.ts

@@ -14,6 +14,8 @@ export type ExecResult = {
   stderr: string;
   exitCode: number;
   stdoutBuffer?: Buffer;
+  /** The signal that ended the process, when one did. */
+  signal?: string;
 };
 
 export type ExecOptions = {
@@ -46,7 +48,8 @@ export type ExecStreamOptions = ExecOptions & {
 
 export type ExecBackgroundResult = {
   child: ReturnType<typeof spawn>;
-  wait: Promise<ExecResult>;
+  /** A background run reports no `signal`: its caller owns the child and reads its exit directly. */
+  wait: Promise<Omit<ExecResult, 'signal'>>;
 };
 
 type ExecDetachedOptions = ExecOptions & {
@@ -268,12 +271,14 @@ function runSpawnedCommand(
         reject(failure);
         return;
       }
-      resolve({
-        stdout,
-        stderr,
-        exitCode: finalExitCode,
-        stdoutBuffer: stdoutChunks ? Buffer.concat(stdoutChunks) : undefined,
-      });
+      resolve(
+        execResult(child, {
+          stdout,
+          stderr,
+          exitCode: finalExitCode,
+          stdoutBuffer: stdoutChunks ? Buffer.concat(stdoutChunks) : undefined,
+        }),
+      );
     }
     // A deadline that fires after the child exited on its own still has to settle: the
     // group kill that would have ended the pipe holder can no longer run through a child
@@ -336,6 +341,11 @@ function runSpawnedCommand(
   });
 }
 
+/** Returns the result with `signal` added when a signal terminated the process. */
+function execResult(ended: { signalCode: string | null }, result: ExecResult): ExecResult {
+  return ended.signalCode ? { ...result, signal: ended.signalCode } : result;
+}
+
 export async function whichCmd(cmd: string, env: EnvMap): Promise<boolean> {
   const candidate = normalizeExecutableLookup(cmd);
   if (!candidate) return false;
@@ -449,7 +459,7 @@ export function runCmdSync(
     throw createExitError(executable, cmd, args, exitCode, stdout, stderr);
   }
 
-  return { stdout, stderr, exitCode, stdoutBuffer };
+  return execResult({ signalCode: result.signal }, { stdout, stderr, exitCode, stdoutBuffer });
 }
 
 export function runCmdDetached(
@@ -524,7 +534,7 @@ export function runCmdBackground(
     });
   }
 
-  const wait = new Promise<ExecResult>((resolve, reject) => {
+  const wait = new Promise<Omit<ExecResult, 'signal'>>((resolve, reject) => {
     let settled = false;
     function finish(event: 'error' | 'exit'): boolean {
       if (settled) return false;