replace ptyc with forkpty() via Dart FFI

NativePty calls forkpty() directly — no helper binary, no socketpair,
no SCM_RIGHTS. The master fd stays in-process. Reader isolate uses
poll() for clean shutdown.

Based on the pty-spike proof-of-concept. Platform-aware: macOS uses
libSystem (DynamicLibrary.process), Linux needs libutil.so.1.
TIOCSWINSZ platform-detected.

PaneRegistry updated to use NativePty. registerPaneCommands no longer
needs a Toolchain parameter. All ptyc references removed from the
daemon layer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/daemon/pane_commands_test.dart

@@ -28,7 +28,7 @@ void main() {
       final sink = RecordingEventSink();
       registry = PaneRegistry(events: sink);
       dispatcher = DaemonDispatcher();
-      registerPaneCommands(dispatcher, registry, toolchain: toolchain);
+      registerPaneCommands(dispatcher, registry);
     });
 
     tearDown(() => registry.shutdown());

test/panes/registry_test.dart

@@ -35,7 +35,6 @@ void main() {
       final pane = await registry.spawn(
         kind: PaneKind.terminal,
         argv: const ['/bin/echo', 'hi'],
-        ptycPath: ptycPath,
       );
 
       expect(pane.id, startsWith('p_'));
@@ -50,7 +49,6 @@ void main() {
       await registry.spawn(
         kind: PaneKind.terminal,
         argv: const ['/bin/echo', 'hello-panes'],
-        ptycPath: ptycPath,
       );
 
       // /bin/echo closes its pty quickly. Wait briefly for output +
@@ -73,7 +71,6 @@ void main() {
       final pane = await registry.spawn(
         kind: PaneKind.terminal,
         argv: const ['/bin/cat'],
-        ptycPath: ptycPath,
       );
 
       final writeCount = registry.write(pane.id, utf8.encode('abc'));
@@ -90,7 +87,6 @@ void main() {
       final pane = await registry.spawn(
         kind: PaneKind.terminal,
         argv: const ['/bin/cat'],
-        ptycPath: ptycPath,
       );
 
       await registry.close(pane.id);
@@ -109,7 +105,6 @@ void main() {
       final pane = await registry.spawn(
         kind: PaneKind.claude,
         argv: const ['/bin/sh', '-c', 'exit 0'],
-        ptycPath: ptycPath,
       );
       expect(pane.kind, PaneKind.claude);
       expect(pane.toJson()['kind'], 'claude');

test/pty/session_test.dart

@@ -1,114 +1,94 @@
-/// `PtySession` smoke tests.
+/// NativePty smoke tests.
 ///
-/// Exercises the real `ptyc` binary end-to-end: socketpair → spawn →
-/// SCM_RIGHTS fd receive → child output through the reader isolate.
-/// Linux + macOS only; skipped elsewhere.
+/// Exercises forkpty() end-to-end: spawn → child output through the
+/// reader isolate. Linux + macOS only; skipped elsewhere.
 library;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:clide/src/pty/pty.dart';
+import 'package:clide/src/pty/native_pty.dart';
 import 'package:test/test.dart';
 
 void main() {
-  if (!Platform.isLinux && !Platform.isMacOS) {
-    return; // POSIX-only wrapper for now.
-  }
+  if (!Platform.isLinux && !Platform.isMacOS) return;
 
-  final ptycPath = _resolvePtyc();
+  final shell = Platform.environment['SHELL'] ?? '/bin/zsh';
 
-  group('PtySession', () {
-    test('spawns /bin/echo and reads its output', () async {
-      final s = await PtySession.spawn(
-        argv: const ['/bin/echo', 'hello-pty'],
-        ptycPath: ptycPath,
+  group('NativePty', () {
+    test('spawns shell -c echo and reads output', () async {
+      final s = NativePty.start(
+        executable: shell,
+        arguments: ['-l', '-c', 'echo hello-pty'],
+        columns: 80,
+        rows: 24,
+        workingDirectory: Platform.environment['HOME'] ?? '/',
+        environment: {
+          ...Platform.environment,
+          'TERM': 'xterm-256color',
+        },
       );
       addTearDown(s.close);
 
       final buf = StringBuffer();
-      final sub = s.output.listen((bytes) => buf.write(utf8.decode(bytes)));
-      try {
-        // echo exits quickly; give the reader up to 2s to see its
-        // output before we assert.
-        await Future<void>.delayed(const Duration(milliseconds: 500));
-        for (var i = 0; i < 20 && !buf.toString().contains('hello-pty'); i++) {
-          await Future<void>.delayed(const Duration(milliseconds: 100));
-        }
-      } finally {
-        await sub.cancel();
-      }
+      s.output.listen((bytes) => buf.write(utf8.decode(bytes, allowMalformed: true)));
 
+      // Shell exits quickly; give reader up to 3s.
+      for (var i = 0; i < 30 && !buf.toString().contains('hello-pty'); i++) {
+        await Future<void>.delayed(const Duration(milliseconds: 100));
+      }
       expect(buf.toString(), contains('hello-pty'));
-      expect(s.pid, greaterThan(0));
     });
 
-    test('write round-trips through /bin/cat', () async {
-      final s = await PtySession.spawn(
-        argv: const ['/bin/cat'],
-        ptycPath: ptycPath,
-      );
-      addTearDown(s.close);
-
-      final got = Completer<String>();
-      final buf = StringBuffer();
-      s.output.listen((bytes) {
-        buf.write(utf8.decode(bytes));
-        if (buf.toString().contains('echo-me')) {
-          if (!got.isCompleted) got.complete(buf.toString());
-        }
-      });
-
-      // Give the PTY a moment to be ready.
-      await Future<void>.delayed(const Duration(milliseconds: 100));
-      s.write(utf8.encode('echo-me\n'));
-
-      final out = await got.future.timeout(const Duration(seconds: 3));
-      expect(out, contains('echo-me'));
-    });
-
-    test('COLORTERM truecolor propagates to the child', () async {
-      // `/usr/bin/env` prints the child's environment. We should see
-      // COLORTERM=truecolor because clidePtyEnvDefaults sets it.
-      final s = await PtySession.spawn(
-        argv: const ['/usr/bin/env'],
-        ptycPath: ptycPath,
+    test('write sends keystrokes to child', () async {
+      final s = NativePty.start(
+        executable: shell,
+        arguments: ['-l'],
+        columns: 80,
+        rows: 24,
+        workingDirectory: Platform.environment['HOME'] ?? '/',
+        environment: {
+          ...Platform.environment,
+          'TERM': 'xterm-256color',
+        },
       );
       addTearDown(s.close);
 
       final buf = StringBuffer();
-      final sub = s.output.listen((bytes) => buf.write(utf8.decode(bytes)));
-      try {
-        for (var i = 0; i < 20; i++) {
-          if (buf.toString().contains('COLORTERM=truecolor')) break;
-          await Future<void>.delayed(const Duration(milliseconds: 100));
-        }
-      } finally {
-        await sub.cancel();
+      s.output.listen((bytes) => buf.write(utf8.decode(bytes, allowMalformed: true)));
+
+      // Wait for prompt.
+      await Future<void>.delayed(const Duration(seconds: 1));
+
+      // Type a command.
+      s.write(utf8.encode('echo write-test-ok\n'));
+
+      for (var i = 0; i < 30 && !buf.toString().contains('write-test-ok'); i++) {
+        await Future<void>.delayed(const Duration(milliseconds: 100));
       }
-
-      expect(buf.toString(), contains('COLORTERM=truecolor'));
-      expect(buf.toString(), contains('TERM=xterm-256color'));
+      expect(buf.toString(), contains('write-test-ok'));
     });
 
-    test('close is idempotent and stops the stream', () async {
-      final s = await PtySession.spawn(
-        argv: const ['/bin/cat'],
-        ptycPath: ptycPath,
+    test('close kills child and closes output', () async {
+      final s = NativePty.start(
+        executable: shell,
+        arguments: ['-l'],
+        columns: 80,
+        rows: 24,
+        workingDirectory: Platform.environment['HOME'] ?? '/',
+        environment: {
+          ...Platform.environment,
+          'TERM': 'xterm-256color',
+        },
       );
-      expect(s.isClosed, isFalse);
+
+      final done = Completer<void>();
+      s.output.listen((_) {}, onDone: () => done.complete());
+
       await s.close();
+      await done.future.timeout(const Duration(seconds: 3));
       expect(s.isClosed, isTrue);
-      await s.close(); // second call should not throw
     });
   });
 }
-
-/// Locate the `ptyc` binary relative to the repo root, falling back to
-/// PATH. Lets tests run in fresh clones before anyone's touched PATH.
-String _resolvePtyc() {
-  final devPath = File('ptyc/bin/ptyc');
-  if (devPath.existsSync()) return devPath.absolute.path;
-  return 'ptyc';
-}