fix: revert grandchild fix for now

src/main.ts

@@ -17,8 +17,6 @@ export {NonZeroExitError, normalizeSpawnCommand};
 
 const LINE_SEPARATOR_REGEX = /\r?\n/;
 
-const pipedStreams = new WeakSet<Readable>();
-
 export interface Output {
   stderr: string;
   stdout: string;
@@ -336,7 +334,6 @@ export class ExecProcess implements Result {
 
     this._process = handle;
     handle.once('error', this._onError);
-    handle.once('exit', this._onExit);
     handle.once('close', this._onClose);
 
     if (handle.stdin) {
@@ -345,11 +342,7 @@ export class ExecProcess implements Result {
       if (typeof stdin === 'string') {
         handle.stdin.end(stdin);
       } else {
-        const src = stdin?.process?.stdout;
-        if (src) {
-          src.pipe(handle.stdin);
-          pipedStreams.add(src);
-        }
+        stdin?.process?.stdout?.pipe(handle.stdin);
       }
     }
   }
@@ -373,28 +366,6 @@ export class ExecProcess implements Result {
     this._thrownError = err;
   };
 
-  protected _onExit = (): void => {
-    // Node emits 'exit' before stdio streams have drained. Use setImmediate
-    // to let buffered data flow through before destroying the streams.
-    // If grandchild processes hold the pipe fds open, they would never fire
-    // 'close', so we destroy here to unblock readStream and combineStreams.
-    const out =
-      this._streamOut && !pipedStreams.has(this._streamOut)
-        ? this._streamOut
-        : undefined;
-    const err =
-      this._streamErr && !pipedStreams.has(this._streamErr)
-        ? this._streamErr
-        : undefined;
-    if (!out && !err) {
-      return;
-    }
-    setImmediate(() => {
-      out?.destroy();
-      err?.destroy();
-    });
-  };
-
   protected _onClose = (): void => {
     if (this._resolveClose) {
       this._resolveClose();

src/test/main_test.ts

@@ -367,15 +367,13 @@ if (!isWindows) {
       }
     });
 
-    test('resolves when grandchild holds piped stdout open', async () => {
+    test.skip('resolves when grandchild holds piped stdout open', async () => {
       const dir = fs.mkdtempSync(
         path.join(os.tmpdir(), 'tinyexec-grandchild-')
       );
       const runnerScript = path.join(dir, 'runner.mjs');
       const distPath = JSON.stringify(path.join(distDir, 'main.mjs'));
-      const fixturePath = JSON.stringify(
-        path.join(fixturesDir, 'grandchild.mjs')
-      );
+      const fixturePath = JSON.stringify(path.join(fixturesDir, 'child.mjs'));
 
       fs.writeFileSync(
         runnerScript,
@@ -399,19 +397,19 @@ if (!isWindows) {
         expect(parsed.exitCode).toBe(0);
         expect(parsed.stdout).toBe('output\n');
       } finally {
-        spawnSync('pkill', ['-f', 'tinyexec-test-grandchild']);
+        spawnSync('pkill', ['-f', 'grandchild.mjs']);
         fs.rmSync(dir, {recursive: true, force: true});
       }
     });
 
-    test('iterator completes when grandchild holds piped stdout open', async () => {
+    test.skip('iterator completes when grandchild holds piped stdout open', async () => {
       const dir = fs.mkdtempSync(
         path.join(os.tmpdir(), 'tinyexec-grandchild-')
       );
       const runnerScript = path.join(dir, 'runner.mjs');
       const distPath = JSON.stringify(path.join(distDir, 'main.mjs'));
       const fixturePath = JSON.stringify(
-        path.join(fixturesDir, 'grandchild_multiline.mjs')
+        path.join(fixturesDir, 'child_multiline.mjs')
       );
 
       fs.writeFileSync(
@@ -438,7 +436,7 @@ if (!isWindows) {
         const parsed = JSON.parse(proc.stdout.trim());
         expect(parsed).toEqual(['line1', 'line2']);
       } finally {
-        spawnSync('pkill', ['-f', 'tinyexec-test-grandchild']);
+        spawnSync('pkill', ['-f', 'grandchild.mjs']);
         fs.rmSync(dir, {recursive: true, force: true});
       }
     });

test/fixtures/child.mjs

@@ -0,0 +1,11 @@
+import {spawn} from 'node:child_process';
+import path from 'node:path';
+
+// Spawn a grandchild that inherits our piped stdout fd (fd 1), simulating
+// tsserver inheriting eslint's piped streams. The grandchild outlives us and
+// holds the pipe open.
+const grandchild = path.join(import.meta.dirname, 'grandchild.mjs');
+spawn(process.argv[0], [grandchild], {stdio: ['ignore', 1, 'ignore']});
+
+console.log('output');
+process.exit(0);

test/fixtures/child_multiline.mjs

@@ -0,0 +1,9 @@
+import {spawn} from 'node:child_process';
+import path from 'node:path';
+
+const grandchild = path.join(import.meta.dirname, 'grandchild.mjs');
+spawn(process.argv[0], [grandchild], {stdio: ['ignore', 1, 'ignore']});
+
+console.log('line1');
+console.log('line2');
+process.exit(0);

test/fixtures/grandchild.mjs

@@ -1,13 +1,2 @@
-import {spawn} from 'node:child_process';
-
-// Spawn a grandchild that inherits the piped stdout fd, simulating
-// tsserver inheriting eslint's piped streams. Short timeout to avoid
-// blocking test teardown.
-spawn(
-  process.argv[0],
-  ['-e', 'setTimeout(() => void 0, 3000)'],
-  {stdio: ['ignore', 1, 'ignore']}
-);
-
-console.log('output');
-process.exit(0);
+// Run for longer than the test timeout
+setTimeout(() => {}, 30000);