fix(process): preserve command completion and input ownership

src/process/ExecFileOutput.test.ts

@@ -53,6 +53,21 @@ it.each([undefined, "SIGTERM"] as const)(
   },
 );
 
+it.each([undefined, "SIGTERM"] as const)(
+  "closes unused command input with stop signal %s",
+  async (stopSignal) => {
+    const result = await execFileOutput(
+      process.execPath,
+      [
+        "-e",
+        'process.stdin.resume(); process.stdin.on("end", () => process.stdout.write("input closed"));',
+      ],
+      { timeout: 2_000, ...(stopSignal === undefined ? {} : { stopSignal }) },
+    );
+    expect(result.stdout).toBe("input closed");
+  },
+);
+
 describe("execFileOutput", () => {
   it("ignores non-Error and incomplete failure metadata", () => {
     expect(execFileOutputFailure("failure")).toBeUndefined();

src/process/ExecFileOutput.ts

@@ -142,7 +142,7 @@ export const execFileFailureCapturedOutput = (
   truncated: failure.outputTruncated,
 });
 
-/** Run a shell-free command while capturing its complete output bytes. */
+/** Run a shell-free command with no input while capturing its complete output bytes. */
 export const execFileBytes = (
   command: string,
   arguments_: readonly string[],
@@ -175,7 +175,7 @@ export const execFileBytes = (
       resolve({ stdout, stderr });
     };
     if (stopSignal === undefined) {
-      execFile(
+      const child = execFile(
         command,
         [...arguments_],
         {
@@ -194,6 +194,8 @@ export const execFileBytes = (
             stderr,
           ),
       );
+      // This promise API exposes no input writer; EOF belongs to the owner.
+      child.stdin?.end();
       return;
     }
     startStoppableCommand(
@@ -229,7 +231,7 @@ const startStoppableCommand = (
   // pipe lifetime of descendants still using caller-owned temporary files.
   const child = spawn(command, [...arguments_], {
     ...execOptions,
-    stdio: "pipe",
+    stdio: ["ignore", "pipe", "pipe"],
     killSignal: stopSignal,
   });
   // The first stop request names the failure; a later one is not resent.