T-128: delete IsolateClient / Backend / backend_entry.dart

Fifth slice of T-99. After T-127 the socket-loopback DaemonClient
is the only IPC path; the isolate-backed third implementation
(IsolateClient + Backend + backend_entry.dart) was never wired
through and has no remaining references. Removed wholesale; the
single service-registration site lives in main.dart's
buildDispatcher.

flutter analyze + the kernel and ipc suites stay green.

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

.pql/changelog/ticket_history/2026-05.sql

@@ -1860,3 +1860,5 @@ INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by,
 INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-126', 'status', 'in_progress', 'done', NULL, '2026-05-18 16:04:29', '2026-05-18 16:04:29', '2026-05-18 16:04:29', NULL, 'b6c783f599585e55ecc36f69ccbcefb1', 1) ON CONFLICT(hash) DO NOTHING;
 INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-127', 'status', 'backlog', 'in_progress', NULL, '2026-05-19 09:57:18', '2026-05-19 09:57:18', '2026-05-19 09:57:18', NULL, '64a14cb5d8b9274fd9d72d1e7474040c', 1) ON CONFLICT(hash) DO NOTHING;
 INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-127', 'status', 'in_progress', 'done', NULL, '2026-05-19 10:03:26', '2026-05-19 10:03:26', '2026-05-19 10:03:26', NULL, 'b8bf877d2057f7baa5acf6af7a13d529', 1) ON CONFLICT(hash) DO NOTHING;
+INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-128', 'status', 'backlog', 'in_progress', NULL, '2026-05-19 10:05:09', '2026-05-19 10:05:09', '2026-05-19 10:05:09', NULL, '763a80ec25b5fe712e5ad44b75dbb22f', 1) ON CONFLICT(hash) DO NOTHING;
+INSERT INTO ticket_history (ticket_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-128', 'status', 'in_progress', 'done', NULL, '2026-05-19 10:06:46', '2026-05-19 10:06:46', '2026-05-19 10:06:46', NULL, 'cc53b46764f28515d735aa77c8eeef2c', 1) ON CONFLICT(hash) DO NOTHING;

.pql/changelog/tickets/2026-05.sql

@@ -2144,3 +2144,15 @@ Acceptance:
 5. Falls back to in-process direct dispatch if the perf delta is unacceptable; surface the finding in a Q-record before doing so.
 
 Source: T-99 sketch. Depends on T-124 (server must exist). Blocks T-128 (legacy IPC cleanup).', 'done', 'high', NULL, NULL, NULL, '2026-05-18 11:59:02', '2026-05-19 10:03:26', NULL, 'af4a706880181411b2aecf51d90ea748', 1) ON CONFLICT(id) DO UPDATE SET type=excluded.type, parent_id=excluded.parent_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);
+INSERT INTO tickets (id, type, parent_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('T-128', 'task', 'T-99', 'delete IsolateClient + Backend + backend_entry.dart; collapse service registration', 'Fifth slice of T-99(a). Pure cleanup once T-127 lands.
+
+Remove the third unused IPC path entirely. Today three implementations coexist: DaemonClient (socket — gets a real server in T-124), InProcessClient (deleted in T-127), and IsolateClient + Backend + backend_entry.dart (a backend isolate path that was never wired through). After T-127, none of those should still be referenced.
+
+Also: consolidate the two duplicate service-wiring sites into one (currently main.dart''s buildDispatcher and the kernel facade both register subsystem handlers; one should own it).
+
+Acceptance:
+1. lib/kernel/src/ipc/isolate_client.dart, lib/src/daemon/backend.dart, lib/src/daemon/backend_entry.dart removed.
+2. Single service-registration site; no duplicate registerPaneCommands / registerFilesCommands / etc. across files.
+3. flutter analyze + full test suite green.
+
+Source: T-99 sketch. Depends on T-127.', 'done', 'medium', NULL, NULL, NULL, '2026-05-18 11:59:06', '2026-05-19 10:06:46', NULL, '481c51b17b027b5a04279a0ef6a3a029', 1) ON CONFLICT(id) DO UPDATE SET type=excluded.type, parent_id=excluded.parent_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);

CHANGELOG.md

@@ -56,6 +56,10 @@ heading, and (b) bumping `pubspec.yaml` `version:` in the same commit.
 
 - `lib/kernel/src/ipc/in_process.dart` (`InProcessClient`) — replaced
   by the socket-loopback `DaemonClient` (T-127).
+- `lib/kernel/src/backend.dart`, `lib/kernel/src/backend_entry.dart`,
+  `lib/kernel/src/ipc/isolate_client.dart` — the third unused IPC
+  path (a backend-isolate model that was never wired through). Only
+  the socket model survives now (T-128).
 
 ### Fixed
 

lib/kernel/src/backend.dart

@@ -1,138 +0,0 @@
-/// Manages the backend isolate lifecycle.
-///
-/// Two-phase boot:
-///   1. [Backend.spawn] — starts the isolate, resolves toolchain (binary checks only).
-///   2. [Backend.openProject] — initializes services for a specific project root.
-library;
-
-import 'dart:async';
-import 'dart:isolate';
-
-import 'package:clide/kernel/src/backend_entry.dart';
-import 'package:clide/kernel/src/ipc/isolate_client.dart';
-import 'package:clide/kernel/src/toolchain.dart';
-
-class Backend {
-  Backend._({
-    required this.client,
-    required this.toolchain,
-    required SendPort backendRequestPort,
-    required Isolate isolate,
-    required ReceivePort receivePort,
-  })  : _backendRequestPort = backendRequestPort,
-        _isolate = isolate,
-        _receivePort = receivePort;
-
-  final IsolateClient client;
-  final Toolchain toolchain;
-  final SendPort _backendRequestPort;
-  final Isolate _isolate;
-  final ReceivePort _receivePort;
-
-  Completer<void>? _projectCompleter;
-  final Map<String, Completer<String?>> _validateCompleters = {};
-  int _validateId = 0;
-
-  /// Spawn the backend isolate. Returns when the toolchain is resolved.
-  /// No services are active yet — call [openProject] to activate.
-  static Future<Backend> spawn({
-    required IsolateClient Function(SendPort backendPort) clientFactory,
-    String? hintRoot,
-  }) async {
-    final receivePort = ReceivePort();
-    final completer = Completer<Backend>();
-
-    late final IsolateClient client;
-    late final Isolate isolate;
-    late final SendPort backendRequestPort;
-    late final Backend backend;
-
-    receivePort.listen((message) {
-      if (message is Map<String, Object?>) {
-        final type = message['type'] as String?;
-        if (type == 'ready') {
-          backendRequestPort = message['requestPort'] as SendPort;
-          client = clientFactory(backendRequestPort);
-
-          final tcData = message['toolchain'] as Map<String, Object?>;
-          final toolchain = Toolchain();
-          toolchain.applyResolved(ResolvedPaths(
-            git: tcData['git'] as String?,
-            pql: tcData['pql'] as String?,
-            tmux: tcData['tmux'] as String?,
-            shell: tcData['shell'] as String?,
-            gitEnv: (tcData['gitEnv'] as Map?)?.cast<String, String>(),
-          ));
-
-          backend = Backend._(
-            client: client,
-            toolchain: toolchain,
-            backendRequestPort: backendRequestPort,
-            isolate: isolate,
-            receivePort: receivePort,
-          );
-
-          if (!completer.isCompleted) completer.complete(backend);
-        } else if (type == 'project.validated') {
-          final id = message['id'] as String;
-          final root = message['root'] as String?;
-          final c = backend._validateCompleters.remove(id);
-          if (c != null && !c.isCompleted) c.complete(root);
-        } else if (type == 'project.ready') {
-          // Update toolchain with project-specific paths.
-          final tcData = message['toolchain'] as Map<String, Object?>;
-          backend.toolchain.applyResolved(ResolvedPaths(
-            git: tcData['git'] as String?,
-            pql: tcData['pql'] as String?,
-            tmux: tcData['tmux'] as String?,
-            shell: tcData['shell'] as String?,
-            gitEnv: (tcData['gitEnv'] as Map?)?.cast<String, String>(),
-          ));
-          backend._projectCompleter?.complete();
-          backend._projectCompleter = null;
-        } else {
-          // Response or event — forward to the client.
-          client.handleMessage(message);
-        }
-      }
-    });
-
-    isolate = await Isolate.spawn(
-      backendEntry,
-      BackendBootMessage(frontendPort: receivePort.sendPort, hintRoot: hintRoot),
-    );
-
-    return completer.future;
-  }
-
-  /// Validate a path as a git repo. Returns the repo root or null.
-  /// Runs git rev-parse in the backend isolate (no main-thread I/O).
-  Future<String?> validateProject(String path) {
-    final id = '${_validateId++}';
-    final c = Completer<String?>();
-    _validateCompleters[id] = c;
-    _backendRequestPort.send({
-      'type': 'project.validate',
-      'path': path,
-      'id': id,
-    });
-    return c.future;
-  }
-
-  /// Activate a project. The backend (re)initializes all services
-  /// for the given root directory. Returns when services are ready.
-  Future<void> openProject(String path) {
-    _projectCompleter = Completer<void>();
-    _backendRequestPort.send({
-      'type': 'project.open',
-      'path': path,
-    });
-    return _projectCompleter!.future;
-  }
-
-  /// Shut down the backend isolate.
-  void dispose() {
-    _isolate.kill(priority: Isolate.beforeNextEvent);
-    _receivePort.close();
-  }
-}

lib/kernel/src/backend_entry.dart

@@ -1,154 +0,0 @@
-/// Backend isolate entry point.
-///
-/// Two-phase boot:
-///   1. Resolve toolchain (find binaries) → report ready.
-///   2. On `project.open` message → initialize services for the project.
-///
-/// The dispatcher only registers command handlers after a project is
-/// activated. IPC requests arriving before that get an error response.
-library;
-
-import 'dart:io';
-import 'dart:isolate';
-
-import 'package:clide/kernel/src/toolchain.dart';
-import 'package:clide/src/daemon/dispatcher.dart';
-import 'package:clide/src/daemon/editor_commands.dart';
-import 'package:clide/src/daemon/files_commands.dart';
-import 'package:clide/src/daemon/git_commands.dart';
-import 'package:clide/src/daemon/pane_commands.dart';
-import 'package:clide/src/daemon/pql_commands.dart';
-import 'package:clide/src/editor/registry.dart' show EditorRegistry;
-import 'package:clide/src/git/client.dart';
-import 'package:clide/src/ipc/envelope.dart';
-import 'package:clide/src/ipc/schema_v1.dart';
-import 'package:clide/src/panes/event_sink.dart';
-import 'package:clide/src/panes/registry.dart';
-import 'package:clide/src/pql/client.dart';
-
-/// Message sent from main isolate to bootstrap the backend.
-class BackendBootMessage {
-  const BackendBootMessage({required this.frontendPort, this.hintRoot});
-  final SendPort frontendPort;
-
-  /// Optional path hint for initial toolchain resolution (e.g. CLIDE_PROJECT).
-  /// Used to find project-local binaries like dugite before a project opens.
-  final String? hintRoot;
-}
-
-/// Top-level entry point for the backend isolate.
-void backendEntry(BackendBootMessage boot) {
-  final frontendPort = boot.frontendPort;
-  final requestPort = ReceivePort();
-  final eventSink = _IsolateEventSink(frontendPort);
-  final dispatcher = DaemonDispatcher();
-  late Toolchain toolchain;
-
-  // Phase 1: resolve toolchain — just find binaries, don't init services.
-  // Dugite is resolved against the install dir; per T-98 the project
-  // root is never inspected during toolchain resolution.
-  toolchain = Toolchain();
-  toolchain.applyResolved(resolveToolchainPaths());
-
-  // Listen for messages from the frontend.
-  requestPort.listen((message) async {
-    if (message is! Map<String, Object?>) return;
-    final type = message['type'] as String?;
-
-    if (type == 'project.validate') {
-      // Validate a path as a git repo. Runs git rev-parse in the backend
-      // isolate (safe from the merged thread). Returns the repo root or null.
-      final path = message['path'] as String;
-      final id = message['id'] as String;
-      try {
-        final r = await Process.run(toolchain.git, ['rev-parse', '--show-toplevel'], workingDirectory: path, environment: toolchain.gitEnv);
-        if (r.exitCode == 0) {
-          final root = (r.stdout as String).trim();
-          frontendPort.send({'type': 'project.validated', 'id': id, 'root': root});
-        } else {
-          frontendPort.send({'type': 'project.validated', 'id': id, 'root': null});
-        }
-      } catch (_) {
-        frontendPort.send({'type': 'project.validated', 'id': id, 'root': null});
-      }
-    } else if (type == 'project.open') {
-      // Phase 2: (re)initialize services for the given project.
-      final projectPath = message['path'] as String;
-      final workDir = Directory(projectPath);
-
-      // Re-resolve toolchain. Project path is not inspected (T-98);
-      // dugite still comes from the install dir + env override.
-      toolchain = Toolchain();
-      toolchain.applyResolved(resolveToolchainPaths());
-
-      // Clear existing handlers and re-register with new project.
-      dispatcher.clear();
-
-      final filesService = FilesService(root: workDir, events: eventSink);
-      registerFilesCommands(dispatcher, filesService);
-
-      final editorRegistry = EditorRegistry(events: eventSink, workspaceRoot: workDir);
-      registerEditorCommands(dispatcher, editorRegistry);
-
-      final gitClient = GitClient(toolchain: toolchain, workDir: workDir);
-      registerGitCommands(dispatcher, gitClient, eventSink);
-
-      final pql = PqlClient(workDir: workDir, toolchain: toolchain);
-      registerPqlCommands(dispatcher, pql);
-
-      final paneRegistry = PaneRegistry(events: eventSink);
-      registerPaneCommands(dispatcher, paneRegistry);
-
-      // Tell the frontend the project is active.
-      frontendPort.send({
-        'type': 'project.ready',
-        'path': projectPath,
-        'toolchain': _serializeToolchain(toolchain),
-      });
-    } else {
-      // IPC request — dispatch if we have handlers.
-      final req = IpcRequest.fromJson(message);
-      if (dispatcher.isEmpty) {
-        frontendPort.send(IpcResponse.err(
-          id: req.id,
-          error: IpcError(
-            code: IpcExitCode.toolError,
-            kind: IpcErrorKind.toolError,
-            message: 'No project active',
-            hint: 'Open a project first',
-          ),
-        ).toJson());
-      } else {
-        final resp = await dispatcher.dispatch(req);
-        frontendPort.send(resp.toJson());
-      }
-    }
-  });
-
-  // Send ready with toolchain state and request port.
-  frontendPort.send({
-    'type': 'ready',
-    'requestPort': requestPort.sendPort,
-    'toolchain': _serializeToolchain(toolchain),
-  });
-}
-
-Map<String, Object?> _serializeToolchain(Toolchain tc) => {
-      'git': tc.git,
-      'pql': tc.pql,
-      'tmux': tc.tmux,
-      'shell': tc.shell,
-      'gitEnv': tc.gitEnv,
-      'missing': tc.missing,
-    };
-
-/// Sends IPC events to the frontend via SendPort.
-class _IsolateEventSink implements DaemonEventSink {
-  _IsolateEventSink(this._port);
-  final SendPort _port;
-
-  @override
-  void emit(IpcEvent event) {
-    _port.send(event.toJson());
-  }
-}

lib/kernel/src/ipc/isolate_client.dart

@@ -1,71 +0,0 @@
-/// IPC client that sends requests to a backend isolate via SendPort.
-///
-/// Replaces [InProcessClient] for production use. The backend isolate
-/// owns the [DaemonDispatcher] and all subprocess/file-I/O services.
-/// Requests and responses travel as serialized Maps over SendPort,
-/// reusing the existing IPC protocol (IpcRequest/IpcResponse/IpcEvent).
-library;
-
-import 'dart:async';
-import 'dart:isolate';
-
-import 'package:clide/clide.dart';
-import 'package:clide/kernel/src/events/bus.dart';
-import 'package:clide/kernel/src/events/types.dart';
-import 'package:clide/kernel/src/ipc/client.dart';
-
-class IsolateClient extends DaemonClient {
-  IsolateClient({
-    required super.log,
-    required super.events,
-    required SendPort backendPort,
-  })  : _backendPort = backendPort,
-        _events = events,
-        super(socketPath: '');
-
-  final SendPort _backendPort;
-  final DaemonBus _events;
-
-  /// The event bus that receives events from the backend.
-  DaemonBus get events => _events;
-  final Map<String, Completer<IpcResponse>> _pending = {};
-  int _nextId = 0;
-
-  /// Called by [Backend] to feed incoming messages from the backend isolate.
-  void handleMessage(Map<String, Object?> msg) {
-    final type = msg['type'] as String?;
-    switch (type) {
-      case 'response':
-        final resp = IpcResponse.fromJson(msg);
-        final c = _pending.remove(resp.id);
-        if (c != null && !c.isCompleted) c.complete(resp);
-      case 'event':
-        final evt = IpcEvent.fromJson(msg);
-        _events.emit(DaemonEvent(
-          subsystem: evt.subsystem,
-          kind: evt.kind,
-          data: evt.data,
-          ts: evt.timestamp,
-        ));
-    }
-  }
-
-  @override
-  bool get isConnected => true;
-
-  @override
-  Future<void> start() async {}
-
-  @override
-  Future<void> stop() async {}
-
-  @override
-  Future<IpcResponse> request(String cmd, {Map<String, Object?> args = const {}}) {
-    final id = '${_nextId++}';
-    final req = IpcRequest(id: id, cmd: cmd, args: args);
-    final c = Completer<IpcResponse>();
-    _pending[id] = c;
-    _backendPort.send(req.toJson());
-    return c.future;
-  }
-}