rename stale forkpty test tag to pty

forkpty was replaced by posix_openpt + posix_spawn in T-96, but the
test tag, ci/test.sh segregation, and dart_test.yaml comment kept the
forkpty name. The segregation is still required — verified the PTY
tests fail under the flutter-test runner (the master fd doesn't
reliably deliver output there) but pass under dart test — only the
name was wrong. Rename to `pty` and correct the rationale comment.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ci/test.sh

@@ -11,8 +11,8 @@ flutter analyze
 echo "==> dart format (whole tree)"
 dart format --set-exit-if-changed .
 
-echo "==> dart test (forkpty — incompatible with flutter test runner)"
-dart test --tags forkpty test/pty/session_test.dart test/panes/registry_test.dart
+echo "==> dart test (pty — unreliable under the flutter test runner)"
+dart test --tags pty test/pty/session_test.dart test/panes/registry_test.dart
 
 echo "==> flutter test --coverage (unit + widget + golden)"
-flutter test --coverage --exclude-tags forkpty
+flutter test --coverage --exclude-tags pty

dart_test.yaml

@@ -3,8 +3,10 @@
 # both honor them. Undeclared tags are ignored by the runners, which
 # silently breaks selective excludes.
 tags:
-  # Tests that call `forkpty()` via Dart FFI. Must run under `dart test`,
-  # not `flutter test` — the latter's runner hosts a multi-threaded
-  # Flutter engine in which forkpty produces a master fd that never
-  # delivers output. See `test/pty/session_test.dart`.
-  forkpty:
+  # Native-PTY tests (posix_openpt + posix_spawn via Dart FFI). Must run
+  # under `dart test`, not `flutter test`: the flutter-test runner hosts a
+  # multi-threaded engine in which the PTY master fd doesn't reliably
+  # deliver output, so these flake there (verified). They are reliable
+  # under `dart test`. (Tag was historically named `forkpty`, before
+  # T-96 replaced forkpty with posix_spawn.) See `test/pty/session_test.dart`.
+  pty:

test/panes/registry_test.dart

@@ -1,7 +1,7 @@
 /// Unit tests for [PaneRegistry].
 ///
 /// Exercises spawn / list / write / resize / close against the real
-/// NativePty (forkpty via FFI). Events are captured via
+/// NativePty (posix_spawn via FFI). Events are captured via
 /// [RecordingEventSink].
 library;
 
@@ -41,7 +41,7 @@ void main() {
       expect(evt.data['id'], pane.id);
     });
 
-    test('output events base64-encode the child bytes', tags: ['forkpty'], retry: 2, () async {
+    test('output events base64-encode the child bytes', tags: ['pty'], retry: 2, () async {
       // Subscribe to the sink stream BEFORE spawn so we don't miss
       // any pane.output events that arrive between spawn and listen.
       final buf = StringBuffer();

test/pty/env_test.dart

@@ -11,8 +11,8 @@ import 'package:test/test.dart';
 void main() {
   group('PtyException', () {
     test('toString includes the op + message', () {
-      const e = PtyException('forkpty', 'kaboom');
-      expect(e.toString(), contains('forkpty'));
+      const e = PtyException('posix_spawn', 'kaboom');
+      expect(e.toString(), contains('posix_spawn'));
       expect(e.toString(), contains('kaboom'));
       expect(e.toString(), isNot(contains('errno=')));
     });

test/pty/session_test.dart

@@ -3,7 +3,7 @@
 /// Exercises posix_spawn() end-to-end: spawn → child output through the
 /// reader isolate. Linux + macOS only; skipped elsewhere.
 ///
-/// Per-test `tags: ['forkpty']` marks the tests that depend on the
+/// Per-test `tags: ['pty']` marks the tests that depend on the
 /// reader isolate delivering output from the master fd — reads from a
 /// pty master under the flutter test runner are unstable when other
 /// suites run in parallel (intermittently empty). Only the
@@ -24,7 +24,7 @@ void main() {
   if (!Platform.isLinux && !Platform.isMacOS) return;
 
   group('NativePty', () {
-    test('spawns shell -c echo and reads output', tags: ['forkpty'], retry: 2, () async {
+    test('spawns shell -c echo and reads output', tags: ['pty'], retry: 2, () async {
       final s = NativePty.start(
         executable: '/bin/sh',
         arguments: ['-c', 'echo hello-pty'],
@@ -42,7 +42,7 @@ void main() {
       expect(got, contains('hello-pty'));
     });
 
-    test('write sends keystrokes to child', tags: ['forkpty'], retry: 2, () async {
+    test('write sends keystrokes to child', tags: ['pty'], retry: 2, () async {
       final s = NativePty.start(
         executable: '/bin/sh',
         arguments: [],
@@ -77,7 +77,7 @@ void main() {
       expect(result, contains('write-test-ok'));
     });
 
-    test('close kills child and closes output', tags: ['forkpty'], retry: 2, () async {
+    test('close kills child and closes output', tags: ['pty'], retry: 2, () async {
       final s = NativePty.start(
         executable: '/bin/sh',
         arguments: [],
@@ -101,7 +101,7 @@ void main() {
       expect(s.isClosed, isTrue);
     });
 
-    test('bare command name resolves via the PATH env var', tags: ['forkpty'], retry: 2, () async {
+    test('bare command name resolves via the PATH env var', tags: ['pty'], retry: 2, () async {
       // 'sh' is a bare command; without resolution, execve would fail.
       final s = NativePty.start(
         executable: 'sh',
@@ -163,7 +163,7 @@ void main() {
     test('start with a bare command name resolves it via PATH (no read)', () async {
       // Resolves "cat" to /bin/cat (or wherever it lives on PATH).
       // Doesn't read the master fd — that path is exercised by the
-      // forkpty-tagged version of this test under `dart test`.
+      // pty-tagged version of this test under `dart test`.
       final s = NativePty.start(
         executable: 'cat',
         arguments: const [],