tear down the previous workspace's services on project switch (T-367)

buildDispatcher composed a fresh PaneRegistry, FilesService,
SearchService, and EditorRegistry per workspace, but their shutdown()
methods had zero callers — every project switch left the old set's
file watcher emitting into the new workspace's bus and its PTYs
alive. The dispatcher now pairs with a teardown closure that the
serialized swap invokes after the old server stops; the same-path
reuse fast-path drops the unused new set without teardown since its
services are inert until a command starts them. SearchService gains
the shutdown() it was missing (cancels in-flight searches).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/daemon/files_commands_test.dart

@@ -11,6 +11,7 @@ void main() {
   late Directory sandbox;
   late DaemonDispatcher dispatcher;
   late FilesService files;
+  late RecordingEventSink sink;
 
   setUp(() async {
     sandbox = await Directory.systemTemp.createTemp('clide-files-test-');
@@ -22,7 +23,7 @@ void main() {
     Directory('${sandbox.path}/.dart_tool').createSync();
     File('${sandbox.path}/.dart_tool/hidden').writeAsStringSync('x');
 
-    final sink = RecordingEventSink();
+    sink = RecordingEventSink();
     files = FilesService(
       root: sandbox,
       events: sink,
@@ -229,6 +230,27 @@ void main() {
     // assertion is covered in test/files/watcher_test.dart.
   });
 
+  test('shutdown stops the watcher delivering into the bus (T-367)', () async {
+    // Project switch tears the old workspace's services down; a leaked
+    // watcher would keep emitting the OLD workspace's events into the
+    // new one's bus.
+    final ack = await call('files.watch', const {});
+    expect(ack.ok, isTrue);
+    await Future<void>.delayed(const Duration(milliseconds: 50));
+    await files.shutdown();
+    final before = sink.ofKind('files.changed').length;
+    await File('${sandbox.path}/after-shutdown.txt').writeAsString('x');
+    await Future<void>.delayed(const Duration(milliseconds: 200));
+    expect(sink.ofKind('files.changed').length, before, reason: 'no events after shutdown');
+  });
+
+  test('shutdown is idempotent and re-watch works after it', () async {
+    await files.shutdown();
+    await files.shutdown();
+    final r = await call('files.watch', const {});
+    expect(r.ok, isTrue);
+  });
+
   test('FilesService.atCwd walks parent dirs looking for .git, falls back to CWD if none', () async {
     final deepNoGit = await Directory.systemTemp.createTemp('clide-no-git-');
     addTearDown(() => deepNoGit.deleteSync(recursive: true));

test/daemon/search_commands_test.dart

@@ -11,13 +11,14 @@ void main() {
   late Directory dir;
   late RecordingEventSink sink;
   late DaemonDispatcher d;
+  late SearchService service;
 
   setUp(() async {
     dir = await Directory.systemTemp.createTemp('clide-search-cmd-');
     File('${dir.path}/a.dart').writeAsStringSync('final answer = 42;\n');
     File('${dir.path}/b.dart').writeAsStringSync('// no hits here\n');
     sink = RecordingEventSink();
-    final service = SearchService(root: dir, ignore: IgnoreSet([]), events: sink, useIsolates: false);
+    service = SearchService(root: dir, ignore: IgnoreSet([]), events: sink, useIsolates: false);
     d = DaemonDispatcher();
     registerSearchCommands(d, service);
   });
@@ -78,6 +79,19 @@ void main() {
     expect(r.data['cancelled'], 'search-0');
   });
 
+  test('shutdown cancels in-flight searches and is idempotent (T-367)', () async {
+    // Subscribe before dispatching — the done event is broadcast.
+    final doneFuture = sink.stream.firstWhere((e) => e.kind == 'search.done');
+    final r = await call('search.grep', const {'pattern': 'answer'});
+    expect(r.ok, isTrue);
+    await service.shutdown();
+    await service.shutdown();
+    // The search still terminates (cancelled or already complete,
+    // depending on timing) — shutdown must not wedge the stream.
+    final done = await doneFuture;
+    expect(done.data['searchId'], r.data['searchId']);
+  });
+
   test('search.replace preview reports edits without touching disk', () async {
     final r = await call('search.replace', const {'pattern': 'answer', 'replacement': 'result'});
     expect(r.ok, isTrue);