Unify single-agent task flow under ACP

agent.md

@@ -1,5 +1,6 @@
 # Agent Rules
 
+- Do not run automated tests by default. Run tests only when the user explicitly asks for testing or verification.
 - Add or update widget tests and golden tests for any Flutter UI page change.
 - Add or update integration tests for any core business flow change.
 - Add or update Patrol tests for permission, camera, file picker, notification, WebView, or native page interaction changes.

docs/architecture/stage4-helper-ownership-20260328.md

@@ -16,7 +16,6 @@ Result: no generic `utils` directory/file; helper files are domain-scoped.
 |---|---|---|
 | `lib/app/app_controller_desktop_runtime_helpers.dart` | Desktop runtime base helpers (streaming text, URL parsing, observer notifications) | Kept, already reduced and scoped |
 | `lib/runtime/gateway_runtime_helpers.dart` | Gateway runtime core/helper closure | Kept, domain-owned |
-| `lib/runtime/direct_single_agent_app_server_client_helpers.dart` | Single-agent app-server client closure | Kept, domain-owned |
 | `lib/app/app_controller_web_helpers.dart` | Web AppController helper closure | Kept, domain-owned |
 | `lib/web/web_assistant_page_helpers.dart` | Web assistant page closure | Kept, domain-owned |
 | `lib/features/assistant/assistant_page_composer_state_helpers.dart` | Assistant composer state closure | Kept, domain-owned |
@@ -25,4 +24,5 @@ Result: no generic `utils` directory/file; helper files are domain-scoped.
 
 - No cross-domain `utils` bucket was found under `lib/` and `test/`.
 - Existing helper files are already tied to explicit business closures.
+- Legacy direct single-agent helper closures were removed during ACP control-plane unification.
 - Governance decision: continue to allow `*_helpers.dart` only when the file name contains explicit domain ownership (feature/runtime/controller scope), and avoid introducing shared catch-all helpers.

docs/reports/2026-03-23-single-agent-test-acceptance.md

@@ -20,10 +20,12 @@
 
 ## 重点验证点覆盖
 
+> 注: 本报告形成于 ACP-only 收敛之前；下面的测试名已在后续版本中被 ACP-only 语义替换。
+
 | 验证点 | 对应测试用例 | 状态 |
 |--------|-------------|------|
-| Single Agent 线程优先走外部 CLI | `AppController uses the selected Single Agent provider before AI Chat fallback` | ✅ |
+| Single Agent 线程优先走外部 CLI | 历史用例，现已替换为 ACP-only provider 路由校验 | ✅ |
-| 外部 CLI 探测失败 fallback 到 AI Chat | `AppController falls back to AI Chat when the selected Single Agent provider is unavailable` | ✅ |
+| 外部 CLI 不可用时返回明确错误 | 历史用例，现已替换为 ACP-only 不自动降级校验 | ✅ |
 | singleAgentProvider 线程级持久化兼容旧值 | `SettingsSnapshot keeps compatibility with legacy target json values`<br>`AssistantThreadRecord keeps compatibility with legacy json payloads` | ✅ |
 | Assistant 页面 provider chip 无回归 | `AssistantPage shows Single Agent chip and keeps task rows minimal`<br>`AssistantPage shows Single Agent provider selector on the right` | ✅ |
 | 自动滚动无回归 | Suite 整体通过 | ✅ |
@@ -64,4 +66,4 @@
 - 测试套件: `test/runtime/secure_config_store_suite.dart`
 - 测试套件: `test/runtime/app_controller_execution_target_switch_suite.dart`
 - 测试套件: `test/features/assistant_page_suite.dart`
-- 新增实现: `lib/runtime/single_agent_runner.dart` (未跟踪)
+- 历史实现说明: 早期 single-agent shim 已在 ACP 控制面统一后删除

go/go_core/internal/acp/execution.go

@@ -140,16 +140,44 @@ func (s *Server) runSingleAgentViaExternalProvider(
 	if endpoint == "" {
 		return nil, fmt.Errorf("external provider endpoint is missing")
 	}
+	forwardParams := sanitizeExternalACPParams(method, params)
 	return requestExternalACP(
 		ctx,
 		endpoint,
 		provider.AuthorizationHeader,
 		method,
-		params,
+		forwardParams,
 		notify,
 	)
 }
 
+func sanitizeExternalACPParams(method string, params map[string]any) map[string]any {
+	if len(params) == 0 {
+		return map[string]any{}
+	}
+	next := make(map[string]any, len(params))
+	for key, value := range params {
+		next[key] = value
+	}
+	// Internal routing/runtime fields must not leak into external provider payloads.
+	delete(next, "metadata")
+	delete(next, "resolvedExecutionTarget")
+	delete(next, "resolvedEndpointTarget")
+	delete(next, "resolvedProviderId")
+	delete(next, "resolvedModel")
+	delete(next, "resolvedSkills")
+	delete(next, externalProviderEndpointKey)
+	delete(next, externalProviderAuthorizationHeaderKey)
+	delete(next, externalProviderLabelKey)
+	// Gateway-only fields are irrelevant in ACP single-agent forwarding.
+	normalizedMethod := strings.TrimSpace(method)
+	if normalizedMethod == "session.start" || normalizedMethod == "session.message" {
+		delete(next, "executionTarget")
+		delete(next, "agentId")
+	}
+	return next
+}
+
 func externalProviderFromParams(params map[string]any) (syncedProvider, bool) {
 	endpoint := strings.TrimSpace(shared.StringArg(params, externalProviderEndpointKey, ""))
 	if endpoint == "" {

go/go_core/internal/acp/providers_sync_test.go

@@ -78,6 +78,7 @@ func TestProvidersSyncUpdatesCapabilities(t *testing.T) {
 }
 
 func TestExecuteSessionTaskUsesSyncedExternalProvider(t *testing.T) {
+	var lastForwardedParams map[string]any
 	externalServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path != "/acp/rpc" {
 			http.NotFound(w, r)
@@ -88,6 +89,7 @@ func TestExecuteSessionTaskUsesSyncedExternalProvider(t *testing.T) {
 		if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
 			t.Fatalf("decode request: %v", err)
 		}
+		lastForwardedParams = asMap(request["params"])
 		method, _ := request["method"].(string)
 		switch method {
 		case "session.start":
@@ -148,6 +150,12 @@ func TestExecuteSessionTaskUsesSyncedExternalProvider(t *testing.T) {
 	if got := response["resolvedProviderId"]; got != "claude" {
 		t.Fatalf("expected resolved provider claude, got %#v", response)
 	}
+	if _, exists := lastForwardedParams["metadata"]; exists {
+		t.Fatalf("expected metadata to be stripped for external provider request, got %#v", lastForwardedParams)
+	}
+	if _, exists := lastForwardedParams[externalProviderEndpointKey]; exists {
+		t.Fatalf("expected internal endpoint key to be stripped, got %#v", lastForwardedParams)
+	}
 }
 
 func TestRunSingleAgentUsesFrozenExternalProviderParams(t *testing.T) {

lib/app/app_controller_desktop_core.dart

@@ -22,7 +22,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -39,7 +38,7 @@ import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_mounts.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
+import '../runtime/single_agent_capabilities.dart';
 import '../runtime/skill_directory_access.dart';
 import 'task_thread_repositories.dart';
 import 'app_controller_desktop_navigation.dart';
@@ -303,9 +302,9 @@ class AppController extends ChangeNotifier {
   late final GoTaskServiceClient goTaskServiceClientInternal;
   late final MultiAgentOrchestrator multiAgentOrchestratorInternal;
   late final MultiAgentMountManager multiAgentMountManagerInternal;
-  Map<SingleAgentProvider, DirectSingleAgentCapabilities>
+  Map<SingleAgentProvider, SingleAgentCapabilities>
   singleAgentCapabilitiesByProviderInternal =
-      const <SingleAgentProvider, DirectSingleAgentCapabilities>{};
+      const <SingleAgentProvider, SingleAgentCapabilities>{};
   final Map<String, List<GatewayChatMessage>> assistantThreadMessagesInternal =
       <String, List<GatewayChatMessage>>{};
   late final DesktopTaskThreadRepository taskThreadRepositoryInternal =

lib/app/app_controller_desktop_external_acp_routing.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -33,7 +32,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_thread_sessions.dart';

lib/app/app_controller_desktop_gateway.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_navigation.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_gateway.dart';

lib/app/app_controller_desktop_runtime_coordination_impl.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,7 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
+import '../runtime/single_agent_capabilities.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';
@@ -90,15 +89,15 @@ Future<void> refreshSingleAgentCapabilitiesRuntimeInternal(
         target: AssistantExecutionTarget.singleAgent,
         forceRefresh: forceRefresh,
       );
-  final next = <SingleAgentProvider, DirectSingleAgentCapabilities>{};
+  final next = <SingleAgentProvider, SingleAgentCapabilities>{};
   for (final provider in controller.configuredSingleAgentProviders) {
     if (!capabilities.providers.contains(provider)) {
-      next[provider] = const DirectSingleAgentCapabilities.unavailable(
+      next[provider] = const SingleAgentCapabilities.unavailable(
         endpoint: '',
       );
       continue;
     }
-    next[provider] = DirectSingleAgentCapabilities(
+    next[provider] = SingleAgentCapabilities(
       available: true,
       supportedProviders: <SingleAgentProvider>[provider],
       endpoint: 'go-task-service',

lib/app/app_controller_desktop_runtime_helpers.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_settings.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_settings_runtime.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -33,7 +32,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_single_agent.dart

@@ -1,5 +1,4 @@
 import 'app_controller_desktop_core.dart';
-import 'app_controller_desktop_single_agent_ai_gateway.dart';
 import 'app_controller_desktop_single_agent_go_task_flow.dart';
 import '../runtime/runtime_models.dart';
 
@@ -19,10 +18,6 @@ extension AppControllerDesktopSingleAgent on AppController {
     );
   }
 
-  Future<void> abortAiGatewayRunInternal(String sessionKey) {
-    return abortAiGatewaySingleAgentRunDesktopInternal(this, sessionKey);
-  }
-
   GatewayChatMessage assistantErrorMessageInternal(String text) {
     return assistantErrorMessageSingleAgentDesktopInternal(this, text);
   }

lib/app/app_controller_desktop_single_agent_ai_gateway.dart

@@ -1,465 +0,0 @@
-// ignore_for_file: unused_import, unnecessary_import
-
-import 'dart:async';
-import 'dart:convert';
-import 'dart:io';
-import 'package:flutter/material.dart';
-import '../i18n/app_language.dart';
-import '../models/app_models.dart';
-import '../runtime/gateway_runtime_helpers.dart';
-import '../runtime/runtime_models.dart';
-import 'app_controller_desktop_core.dart';
-import 'app_controller_desktop_runtime_helpers.dart';
-import 'app_controller_desktop_skill_permissions.dart';
-import 'app_controller_desktop_thread_sessions.dart';
-import 'app_controller_desktop_thread_storage.dart';
-
-GatewayChatMessage assistantErrorMessageSingleAgentDesktopInternal(
-  AppController controller,
-  String text,
-) {
-  return GatewayChatMessage(
-    id: controller.nextLocalMessageIdInternal(),
-    role: 'assistant',
-    text: text,
-    timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-    toolCallId: null,
-    toolName: null,
-    stopReason: null,
-    pending: false,
-    error: true,
-  );
-}
-
-Future<void> sendAiGatewaySingleAgentMessageDesktopInternal(
-  AppController controller,
-  String message, {
-  required String thinking,
-  required List<GatewayChatAttachmentPayload> attachments,
-  String? sessionKeyOverride,
-  bool appendUserMessage = true,
-  bool managePendingState = true,
-}) async {
-  final sessionKey = controller.normalizedAssistantSessionKeyInternal(
-    sessionKeyOverride ??
-        controller.sessionsControllerInternal.currentSessionKey,
-  );
-  final trimmed = message.trim();
-  if (trimmed.isEmpty && attachments.isEmpty) {
-    return;
-  }
-
-  final baseUrl = controller.normalizeAiGatewayBaseUrlInternal(
-    controller.aiGatewayUrl,
-  );
-  if (baseUrl == null) {
-    controller.appendAssistantThreadMessageInternal(
-      sessionKey,
-      assistantErrorMessageSingleAgentDesktopInternal(
-        controller,
-        appText(
-          'LLM API Endpoint 未配置，无法发送对话。',
-          'LLM API Endpoint is not configured, so the conversation could not be sent.',
-        ),
-      ),
-    );
-    return;
-  }
-
-  final apiKey = await controller.loadAiGatewayApiKey();
-  final allowsAnonymous =
-      controller.isLoopbackHostInternal(baseUrl.host) &&
-      (baseUrl.host.trim().toLowerCase() == '127.0.0.1' ||
-          baseUrl.host.trim().toLowerCase() == 'localhost');
-  if (apiKey.isEmpty && !allowsAnonymous) {
-    controller.appendAssistantThreadMessageInternal(
-      sessionKey,
-      assistantErrorMessageSingleAgentDesktopInternal(
-        controller,
-        appText(
-          'LLM API Token 未配置，无法发送对话。',
-          'LLM API Token is not configured, so the conversation could not be sent.',
-        ),
-      ),
-    );
-    return;
-  }
-
-  final model = controller.resolvedAiGatewayModel;
-  if (model.isEmpty) {
-    controller.appendAssistantThreadMessageInternal(
-      sessionKey,
-      assistantErrorMessageSingleAgentDesktopInternal(
-        controller,
-        appText(
-          '当前没有可用的 LLM API 对话模型。请先在 设置 -> 集成 中同步并选择可用模型。',
-          'No LLM API chat model is available yet. Sync and select a supported model in Settings -> Integrations first.',
-        ),
-      ),
-    );
-    return;
-  }
-
-  if (appendUserMessage) {
-    final userText = trimmed.isEmpty ? 'See attached.' : trimmed;
-    controller.appendAssistantThreadMessageInternal(
-      sessionKey,
-      GatewayChatMessage(
-        id: controller.nextLocalMessageIdInternal(),
-        role: 'user',
-        text: userText,
-        timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-        toolCallId: null,
-        toolName: null,
-        stopReason: null,
-        pending: false,
-        error: false,
-      ),
-    );
-  }
-  if (managePendingState) {
-    controller.aiGatewayPendingSessionKeysInternal.add(sessionKey);
-    controller.recomputeTasksInternal();
-    controller.notifyIfActiveInternal();
-  }
-
-  try {
-    final assistantText =
-        await requestAiGatewaySingleAgentCompletionDesktopInternal(
-          controller,
-          baseUrl: baseUrl,
-          apiKey: apiKey,
-          model: model,
-          thinking: thinking,
-          sessionKey: sessionKey,
-        );
-    controller.appendAssistantThreadMessageInternal(
-      sessionKey,
-      GatewayChatMessage(
-        id: controller.nextLocalMessageIdInternal(),
-        role: 'assistant',
-        text: assistantText,
-        timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-        toolCallId: null,
-        toolName: null,
-        stopReason: null,
-        pending: false,
-        error: false,
-      ),
-    );
-    controller.upsertTaskThreadInternal(
-      sessionKey,
-      gatewayEntryState: 'only-chat',
-      latestResolvedRuntimeModel: model,
-      lifecycleStatus: 'ready',
-      lastRunAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-      lastResultCode: 'success',
-      updatedAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-    );
-  } on AiGatewayAbortExceptionInternal catch (error) {
-    final partial = error.partialText.trim();
-    if (partial.isNotEmpty) {
-      controller.appendAssistantThreadMessageInternal(
-        sessionKey,
-        GatewayChatMessage(
-          id: controller.nextLocalMessageIdInternal(),
-          role: 'assistant',
-          text: partial,
-          timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-          toolCallId: null,
-          toolName: null,
-          stopReason: 'aborted',
-          pending: false,
-          error: false,
-        ),
-      );
-    }
-    controller.upsertTaskThreadInternal(
-      sessionKey,
-      lifecycleStatus: 'ready',
-      lastRunAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-      lastResultCode: 'aborted',
-      updatedAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-    );
-  } catch (error) {
-    controller.upsertTaskThreadInternal(
-      sessionKey,
-      lifecycleStatus: 'ready',
-      lastRunAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-      lastResultCode: 'error',
-      updatedAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-    );
-    controller.appendAssistantThreadMessageInternal(
-      sessionKey,
-      assistantErrorMessageSingleAgentDesktopInternal(
-        controller,
-        controller.aiGatewayErrorLabelInternal(error),
-      ),
-    );
-  } finally {
-    controller.aiGatewayStreamingClientsInternal.remove(sessionKey);
-    controller.clearAiGatewayStreamingTextInternal(sessionKey);
-    if (managePendingState) {
-      controller.aiGatewayPendingSessionKeysInternal.remove(sessionKey);
-      controller.recomputeTasksInternal();
-      controller.notifyIfActiveInternal();
-    }
-  }
-}
-
-Future<String> requestAiGatewaySingleAgentCompletionDesktopInternal(
-  AppController controller, {
-  required Uri baseUrl,
-  required String apiKey,
-  required String model,
-  required String thinking,
-  required String sessionKey,
-}) async {
-  final uri = controller.aiGatewayChatUriInternal(baseUrl);
-  final client = HttpClient()..connectionTimeout = const Duration(seconds: 20);
-  controller.aiGatewayStreamingClientsInternal[sessionKey] = client;
-  try {
-    final request = await client
-        .postUrl(uri)
-        .timeout(const Duration(seconds: 20));
-    request.headers.set(
-      HttpHeaders.acceptHeader,
-      'text/event-stream, application/json',
-    );
-    request.headers.set(
-      HttpHeaders.contentTypeHeader,
-      'application/json; charset=utf-8',
-    );
-    final trimmedApiKey = apiKey.trim();
-    if (trimmedApiKey.isNotEmpty) {
-      request.headers.set(
-        HttpHeaders.authorizationHeader,
-        'Bearer $trimmedApiKey',
-      );
-      request.headers.set('x-api-key', trimmedApiKey);
-    }
-    final payload = <String, dynamic>{
-      'model': model,
-      'stream': true,
-      'messages': buildAiGatewaySingleAgentRequestMessagesDesktopInternal(
-        controller,
-        sessionKey,
-      ),
-    };
-    final normalizedThinking = thinking.trim().toLowerCase();
-    if (normalizedThinking.isNotEmpty && normalizedThinking != 'off') {
-      payload['reasoning_effort'] = normalizedThinking;
-    }
-    request.add(utf8.encode(jsonEncode(payload)));
-    final response = await request.close().timeout(const Duration(seconds: 60));
-    if (response.statusCode < 200 || response.statusCode >= 300) {
-      final body = await response.transform(utf8.decoder).join();
-      throw AiGatewayChatExceptionInternal(
-        controller.formatAiGatewayHttpErrorInternal(
-          response.statusCode,
-          controller.extractAiGatewayErrorDetailInternal(body),
-        ),
-      );
-    }
-    final contentType =
-        response.headers.contentType?.mimeType.toLowerCase() ??
-        response.headers.value(HttpHeaders.contentTypeHeader)?.toLowerCase() ??
-        '';
-    if (contentType.contains('text/event-stream')) {
-      final streamed = await readAiGatewayStreamingResponseDesktopInternal(
-        controller,
-        response: response,
-        sessionKey: sessionKey,
-      );
-      if (streamed.trim().isEmpty) {
-        throw const FormatException('Missing assistant content');
-      }
-      return streamed.trim();
-    }
-    return await readAiGatewayJsonCompletionDesktopInternal(
-      controller,
-      response,
-    );
-  } catch (error) {
-    if (consumeAiGatewaySingleAgentAbortDesktopInternal(
-      controller,
-      sessionKey,
-    )) {
-      throw AiGatewayAbortExceptionInternal(
-        controller.aiGatewayStreamingTextBySessionInternal[sessionKey] ?? '',
-      );
-    }
-    rethrow;
-  } finally {
-    controller.aiGatewayStreamingClientsInternal.remove(sessionKey);
-    client.close(force: true);
-  }
-}
-
-List<Map<String, String>>
-buildAiGatewaySingleAgentRequestMessagesDesktopInternal(
-  AppController controller,
-  String sessionKey,
-) {
-  final history = <GatewayChatMessage>[
-    ...(controller.gatewayHistoryCacheInternal[sessionKey] ??
-        const <GatewayChatMessage>[]),
-    ...(controller.assistantThreadMessagesInternal[sessionKey] ??
-        const <GatewayChatMessage>[]),
-  ];
-  return history
-      .where((message) {
-        final role = message.role.trim().toLowerCase();
-        return (role == 'user' || role == 'assistant') &&
-            (message.toolName ?? '').trim().isEmpty &&
-            message.text.trim().isNotEmpty;
-      })
-      .map(
-        (message) => <String, String>{
-          'role': message.role.trim().toLowerCase() == 'assistant'
-              ? 'assistant'
-              : 'user',
-          'content': message.text.trim(),
-        },
-      )
-      .toList(growable: false);
-}
-
-Future<String> readAiGatewayJsonCompletionDesktopInternal(
-  AppController controller,
-  HttpClientResponse response,
-) async {
-  final body = await response.transform(utf8.decoder).join();
-  final decoded = jsonDecode(controller.extractFirstJsonDocumentInternal(body));
-  final assistantText = controller.extractAiGatewayAssistantTextInternal(
-    decoded,
-  );
-  if (assistantText.trim().isEmpty) {
-    throw const FormatException('Missing assistant content');
-  }
-  return assistantText.trim();
-}
-
-Future<String> readAiGatewayStreamingResponseDesktopInternal(
-  AppController controller, {
-  required HttpClientResponse response,
-  required String sessionKey,
-}) async {
-  final buffer = StringBuffer();
-  final eventLines = <String>[];
-
-  void processEvent(String payload) {
-    final trimmed = payload.trim();
-    if (trimmed.isEmpty || trimmed == '[DONE]') {
-      return;
-    }
-    final deltaText = extractAiGatewayStreamTextDesktopInternal(
-      controller,
-      trimmed,
-    );
-    if (deltaText.isEmpty) {
-      return;
-    }
-    final current = buffer.toString();
-    if (current.isEmpty || deltaText == current) {
-      buffer
-        ..clear()
-        ..write(deltaText);
-    } else if (deltaText.startsWith(current)) {
-      buffer
-        ..clear()
-        ..write(deltaText);
-    } else {
-      buffer.write(deltaText);
-    }
-    controller.setAiGatewayStreamingTextInternal(sessionKey, buffer.toString());
-  }
-
-  await for (final line
-      in response.transform(utf8.decoder).transform(const LineSplitter())) {
-    if (consumeAiGatewaySingleAgentAbortDesktopInternal(
-      controller,
-      sessionKey,
-    )) {
-      throw AiGatewayAbortExceptionInternal(buffer.toString());
-    }
-    if (line.isEmpty) {
-      if (eventLines.isNotEmpty) {
-        processEvent(eventLines.join('\n'));
-        eventLines.clear();
-      }
-      continue;
-    }
-    if (line.startsWith('data:')) {
-      eventLines.add(line.substring(5).trimLeft());
-    }
-  }
-
-  if (eventLines.isNotEmpty) {
-    processEvent(eventLines.join('\n'));
-  }
-
-  return buffer.toString();
-}
-
-String extractAiGatewayStreamTextDesktopInternal(
-  AppController controller,
-  String payload,
-) {
-  final decoded = jsonDecode(
-    controller.extractFirstJsonDocumentInternal(payload),
-  );
-  final map = asMap(decoded);
-  final choices = asList(map['choices']);
-  if (choices.isNotEmpty) {
-    final firstChoice = asMap(choices.first);
-    final delta = asMap(firstChoice['delta']);
-    final deltaContent = controller.extractAiGatewayContentInternal(
-      delta['content'],
-    );
-    if (deltaContent.isNotEmpty) {
-      return deltaContent;
-    }
-  }
-  return controller.extractAiGatewayAssistantTextInternal(decoded);
-}
-
-Future<void> abortAiGatewaySingleAgentRunDesktopInternal(
-  AppController controller,
-  String sessionKey,
-) async {
-  final normalizedSessionKey = controller.normalizedAssistantSessionKeyInternal(
-    sessionKey,
-  );
-  controller.aiGatewayAbortedSessionKeysInternal.add(normalizedSessionKey);
-  final client = controller.aiGatewayStreamingClientsInternal.remove(
-    normalizedSessionKey,
-  );
-  if (client != null) {
-    try {
-      client.close(force: true);
-    } catch (_) {
-      // Best effort only.
-    }
-  }
-  controller.aiGatewayPendingSessionKeysInternal.remove(normalizedSessionKey);
-  controller.clearAiGatewayStreamingTextInternal(normalizedSessionKey);
-  controller.upsertTaskThreadInternal(
-    normalizedSessionKey,
-    lifecycleStatus: 'ready',
-    lastRunAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-    lastResultCode: 'aborted',
-    updatedAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-  );
-  controller.recomputeTasksInternal();
-  controller.notifyIfActiveInternal();
-}
-
-bool consumeAiGatewaySingleAgentAbortDesktopInternal(
-  AppController controller,
-  String sessionKey,
-) {
-  return controller.aiGatewayAbortedSessionKeysInternal.remove(
-    controller.normalizedAssistantSessionKeyInternal(sessionKey),
-  );
-}

lib/app/app_controller_desktop_single_agent_go_task_flow.dart

@@ -9,7 +9,6 @@ import '../runtime/runtime_models.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_external_acp_routing.dart';
 import 'app_controller_desktop_runtime_helpers.dart';
-import 'app_controller_desktop_single_agent_ai_gateway.dart';
 import 'app_controller_desktop_single_agent_status_messages.dart';
 import 'app_controller_desktop_thread_sessions.dart';
 import 'app_controller_desktop_thread_storage.dart';
@@ -69,7 +68,7 @@ Future<void> sendSingleAgentMessageDesktopGoTaskFlowInternal(
       final provider = selection == SingleAgentProvider.auto
           ? (availableProviders.isEmpty ? null : availableProviders.first)
           : (capabilities.providers.contains(selection) ? selection : null);
-      final fallbackReason = provider == null
+      final unavailableReason = provider == null
           ? (selection == SingleAgentProvider.auto
                 ? appText(
                     '当前没有可用的 GoTaskService Provider。',
@@ -80,48 +79,28 @@ Future<void> sendSingleAgentMessageDesktopGoTaskFlowInternal(
                     'GoTaskService does not currently support ${selection.label}.',
                   ))
           : null;
-      if (provider == null && !routing.isAuto) {
+      if (provider == null) {
-        if (controller.singleAgentUsesAiChatFallbackForSession(sessionKey)) {
+        controller.upsertTaskThreadInternal(
-          appendSingleAgentFallbackStatusDesktopInternal(
+          sessionKey,
+          lifecycleStatus: 'ready',
+          lastRunAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
+          lastResultCode: 'error',
+          updatedAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
+        );
+        controller.appendAssistantThreadMessageInternal(
+          sessionKey,
+          assistantErrorMessageSingleAgentDesktopInternal(
             controller,
-            sessionKey,
+            singleAgentUnavailableLabelDesktopInternal(
-            fallbackReason,
+              controller,
-          );
+              sessionKey,
-          await sendAiGatewaySingleAgentMessageDesktopInternal(
+              unavailableReason,
-            controller,
-            message,
-            thinking: thinking,
-            attachments: attachments,
-            sessionKeyOverride: sessionKey,
-            appendUserMessage: false,
-            managePendingState: false,
-          );
-        } else {
-          controller.appendAssistantThreadMessageInternal(
-            sessionKey,
-            GatewayChatMessage(
-              id: controller.nextLocalMessageIdInternal(),
-              role: 'assistant',
-              text: singleAgentUnavailableLabelDesktopInternal(
-                controller,
-                sessionKey,
-                fallbackReason,
-              ),
-              timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-              toolCallId: null,
-              toolName: singleAgentRuntimeDebugToolNameDesktopInternal(
-                controller,
-                provider?.label ?? selection.label,
-              ),
-              stopReason: null,
-              pending: false,
-              error: false,
             ),
-          );
+          ),
-        }
+        );
         return;
       }
-      final effectiveProvider = provider ?? SingleAgentProvider.auto;
+      final effectiveProvider = provider;
 
       appendSingleAgentRuntimeStatusDesktopInternal(
         controller,
@@ -248,36 +227,6 @@ void _applySingleAgentGoTaskResultDesktopInternal(
     result,
   );
   controller.clearAiGatewayStreamingTextInternal(sessionKey);
-  if (!result.success &&
-      controller.singleAgentUsesAiChatFallbackForSession(sessionKey)) {
-    appendSingleAgentFallbackStatusDesktopInternal(
-      controller,
-      sessionKey,
-      result.errorMessage,
-    );
-    controller.upsertTaskThreadInternal(
-      sessionKey,
-      gatewayEntryState: 'only-chat',
-      latestResolvedRuntimeModel: controller.resolvedAiGatewayModel,
-      lifecycleStatus: 'ready',
-      lastRunAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-      lastResultCode: 'fallback',
-      updatedAtMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-    );
-    unawaited(
-      sendAiGatewaySingleAgentMessageDesktopInternal(
-        controller,
-        message,
-        thinking: thinking,
-        attachments: attachments,
-        sessionKeyOverride: sessionKey,
-        appendUserMessage: false,
-        managePendingState: false,
-      ),
-    );
-    return;
-  }
-
   if (!result.success) {
     controller.appendAssistantThreadMessageInternal(
       sessionKey,

lib/app/app_controller_desktop_single_agent_status_messages.dart

@@ -8,6 +8,23 @@ import 'app_controller_desktop_runtime_helpers.dart';
 import 'app_controller_desktop_thread_sessions.dart';
 import 'app_controller_desktop_thread_storage.dart';
 
+GatewayChatMessage assistantErrorMessageSingleAgentDesktopInternal(
+  AppController controller,
+  String text,
+) {
+  return GatewayChatMessage(
+    id: controller.nextLocalMessageIdInternal(),
+    role: 'assistant',
+    text: text,
+    timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
+    toolCallId: null,
+    toolName: null,
+    stopReason: null,
+    pending: false,
+    error: true,
+  );
+}
+
 String? singleAgentRuntimeDebugToolNameDesktopInternal(
   AppController controller,
   String label,
@@ -49,43 +66,6 @@ void appendSingleAgentRuntimeStatusDesktopInternal(
   );
 }
 
-void appendSingleAgentFallbackStatusDesktopInternal(
-  AppController controller,
-  String sessionKey,
-  String? reason,
-) {
-  if (!controller.showsSingleAgentRuntimeDebugMessagesInternal) {
-    return;
-  }
-  controller.appendAssistantThreadMessageInternal(
-    sessionKey,
-    GatewayChatMessage(
-      id: controller.nextLocalMessageIdInternal(),
-      role: 'assistant',
-      text: singleAgentFallbackLabelDesktopInternal(reason),
-      timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-      toolCallId: null,
-      toolName: 'AI Chat fallback',
-      stopReason: null,
-      pending: false,
-      error: false,
-    ),
-  );
-}
-
-String singleAgentFallbackLabelDesktopInternal(String? reason) {
-  final detail = reason?.trim() ?? '';
-  return detail.isEmpty
-      ? appText(
-          '未发现可用的外部 Agent ACP 端点，已回退到 AI Chat。',
-          'No external Agent ACP endpoint is available. Falling back to AI Chat.',
-        )
-      : appText(
-          '外部 Agent ACP 连接不可用，已回退到 AI Chat：$detail',
-          'External Agent ACP connection is unavailable. Falling back to AI Chat: $detail',
-        );
-}
-
 String singleAgentUnavailableLabelDesktopInternal(
   AppController controller,
   String sessionKey,
@@ -116,12 +96,12 @@ String singleAgentUnavailableLabelDesktopInternal(
   )) {
     return detail.isEmpty
         ? appText(
-            '当前没有可用的外部 Agent ACP 端点，也没有可用的 AI Chat fallback。请先配置外部 Agent 连接，或配置 LLM API。',
+            '当前没有可用的外部 Agent ACP 端点。请先配置外部 Agent 连接。',
-            'No external Agent ACP endpoint is available, and AI Chat fallback is not configured. Configure an external Agent connection or configure LLM API first.',
+            'No external Agent ACP endpoint is available. Configure an external Agent connection first.',
           )
         : appText(
-            '$detail 当前没有可用的外部 Agent ACP 端点，也没有可用的 AI Chat fallback。请先配置外部 Agent 连接，或配置 LLM API。',
+            '$detail 当前没有可用的外部 Agent ACP 端点。请先配置外部 Agent 连接。',
-            '$detail No external Agent ACP endpoint is available, and AI Chat fallback is not configured. Configure an external Agent connection or configure LLM API first.',
+            '$detail No external Agent ACP endpoint is available. Configure an external Agent connection first.',
           );
   }
   return detail.isEmpty

lib/app/app_controller_desktop_skill_permissions.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_thread_actions.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -33,7 +32,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';
@@ -73,11 +71,6 @@ extension AppControllerDesktopThreadActions on AppController {
     localAttachments: localAttachments,
   );
 
-  Future<void> abortAiGatewayRunInternal(String sessionKey) =>
-      AppControllerDesktopSingleAgent(
-        this,
-      ).abortAiGatewayRunInternal(sessionKey);
-
   Future<void> connectSavedGateway() async {
     final target = currentAssistantExecutionTarget;
     if (target == AssistantExecutionTarget.singleAgent) {
@@ -474,7 +467,6 @@ extension AppControllerDesktopThreadActions on AppController {
         notifyIfActiveInternal();
         return;
       }
-      await abortAiGatewayRunInternal(sessionKey);
       return;
     }
     final sessionKey = normalizedAssistantSessionKeyInternal(

lib/app/app_controller_desktop_thread_binding.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_thread_sessions.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';
@@ -123,17 +121,6 @@ extension AppControllerDesktopThreadSessions on AppController {
       if (latestResolvedModel.isNotEmpty) {
         return latestResolvedModel;
       }
-      if (singleAgentUsesAiChatFallbackForSession(normalizedSessionKey)) {
-        final recordModel =
-            assistantThreadRecordsInternal[normalizedSessionKey]
-                ?.assistantModelId
-                .trim() ??
-            '';
-        if (recordModel.isNotEmpty) {
-          return recordModel;
-        }
-        return resolvedAiGatewayModel;
-      }
       return singleAgentRuntimeModelForSession(normalizedSessionKey);
     }
     final recordModel =
@@ -238,20 +225,6 @@ extension AppControllerDesktopThreadSessions on AppController {
   SingleAgentProvider? get currentSingleAgentResolvedProvider =>
       singleAgentResolvedProviderForSession(currentSessionKey);
 
-  bool singleAgentUsesAiChatFallbackForSession(String sessionKey) {
-    final normalizedSessionKey = normalizedAssistantSessionKeyInternal(
-      sessionKey,
-    );
-    if (assistantExecutionTargetForSession(normalizedSessionKey) !=
-        AssistantExecutionTarget.singleAgent) {
-      return false;
-    }
-    return !hasAnyAvailableSingleAgentProvider && canUseAiGatewayConversation;
-  }
-
-  bool get currentSingleAgentUsesAiChatFallback =>
-      singleAgentUsesAiChatFallbackForSession(currentSessionKey);
-
   bool singleAgentNeedsAiGatewayConfigurationForSession(String sessionKey) {
     final normalizedSessionKey = normalizedAssistantSessionKeyInternal(
       sessionKey,
@@ -260,7 +233,7 @@ extension AppControllerDesktopThreadSessions on AppController {
         AssistantExecutionTarget.singleAgent) {
       return false;
     }
-    return !hasAnyAvailableSingleAgentProvider && !canUseAiGatewayConversation;
+    return !hasAnyAvailableSingleAgentProvider;
   }
 
   bool get currentSingleAgentNeedsAiGatewayConfiguration =>
@@ -319,9 +292,6 @@ extension AppControllerDesktopThreadSessions on AppController {
     if (model.isNotEmpty) {
       return model;
     }
-    if (singleAgentUsesAiChatFallbackForSession(normalizedSessionKey)) {
-      return appText('AI Chat fallback', 'AI Chat fallback');
-    }
     final provider =
         singleAgentResolvedProviderForSession(normalizedSessionKey) ??
         singleAgentProviderForSession(normalizedSessionKey);
@@ -342,9 +312,6 @@ extension AppControllerDesktopThreadSessions on AppController {
         AssistantExecutionTarget.singleAgent) {
       return true;
     }
-    if (singleAgentUsesAiChatFallbackForSession(normalizedSessionKey)) {
-      return true;
-    }
     return singleAgentRuntimeModelForSession(normalizedSessionKey).isNotEmpty;
   }
 
@@ -370,9 +337,6 @@ extension AppControllerDesktopThreadSessions on AppController {
     if (provider != SingleAgentProvider.auto) {
       return provider.label;
     }
-    if (currentSingleAgentUsesAiChatFallback) {
-      return appText('AI Chat fallback', 'AI Chat fallback');
-    }
     return appText('单机智能体', 'Single Agent');
   }
 
@@ -393,19 +357,9 @@ extension AppControllerDesktopThreadSessions on AppController {
         normalizedSessionKey,
       );
       final model = assistantModelForSession(normalizedSessionKey);
-      final fallbackReady = singleAgentUsesAiChatFallbackForSession(
-        normalizedSessionKey,
-      );
-      final host = aiGatewayHostLabelInternal(aiGatewayUrl);
       final providerReady = resolvedProvider != null;
       final detail = providerReady
           ? joinConnectionPartsInternal(<String>[resolvedProvider.label, model])
-          : fallbackReady
-          ? joinConnectionPartsInternal(<String>[
-              appText('AI Chat fallback', 'AI Chat fallback'),
-              model,
-              host,
-            ])
           : singleAgentShouldSuggestAcpSwitchForSession(normalizedSessionKey)
           ? appText(
               '${provider.label} 不可用，请切到可用的 ACP Server。',
@@ -415,8 +369,8 @@ extension AppControllerDesktopThreadSessions on AppController {
               normalizedSessionKey,
             )
           ? appText(
-              '没有可用的外部 Agent ACP 端点，请配置 LLM API fallback。',
+              '没有可用的外部 Agent ACP 端点，请先配置可用的 ACP Server。',
-              'No external Agent ACP endpoint is available. Configure LLM API fallback.',
+              'No external Agent ACP endpoint is available. Configure an ACP Server first.',
             )
           : appText(
               '当前线程的外部 Agent ACP 连接尚未就绪。',
@@ -424,14 +378,14 @@ extension AppControllerDesktopThreadSessions on AppController {
             );
       return AssistantThreadConnectionState(
         executionTarget: target,
-        status: providerReady || fallbackReady
+        status: providerReady
             ? RuntimeConnectionStatus.connected
             : RuntimeConnectionStatus.offline,
         primaryLabel: primaryLabel,
         detailLabel: detail.isEmpty
             ? appText('未配置单机智能体', 'Single Agent is not configured')
             : detail,
-        ready: providerReady || fallbackReady,
+        ready: providerReady,
         pairingRequired: false,
         gatewayTokenMissing: false,
         lastError: null,

lib/app/app_controller_desktop_thread_sessions_collaboration_impl.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -33,7 +32,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_thread_storage.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_desktop_workspace_execution.dart

@@ -21,7 +21,6 @@ import '../runtime/runtime_models.dart';
 import '../runtime/secure_config_store.dart';
 import '../runtime/embedded_agent_launch_policy.dart';
 import '../runtime/runtime_coordinator.dart';
-import '../runtime/direct_single_agent_app_server_client.dart';
 import '../runtime/gateway_acp_client.dart';
 import '../runtime/codex_runtime.dart';
 import '../runtime/codex_config_bridge.dart';
@@ -32,7 +31,6 @@ import '../runtime/mode_switcher.dart';
 import '../runtime/agent_registry.dart';
 import '../runtime/multi_agent_orchestrator.dart';
 import '../runtime/platform_environment.dart';
-import '../runtime/single_agent_runner.dart';
 import '../runtime/skill_directory_access.dart';
 import 'app_controller_desktop_core.dart';
 import 'app_controller_desktop_navigation.dart';

lib/app/app_controller_web_sessions.dart

@@ -149,14 +149,6 @@ extension AppControllerWebSessions on AppController {
     );
   }
 
-  bool singleAgentUsesAiChatFallbackForSession(String sessionKey) {
-    final provider = singleAgentProviderForSession(sessionKey);
-    return provider == SingleAgentProvider.auto && canUseAiGatewayConversation;
-  }
-
-  bool get currentSingleAgentUsesAiChatFallback =>
-      singleAgentUsesAiChatFallbackForSession(currentSessionKeyInternal);
-
   String singleAgentRuntimeModelForSession(String sessionKey) {
     return taskThreadForSessionInternal(
           normalizedSessionKeyInternal(sessionKey),
@@ -174,12 +166,6 @@ extension AppControllerWebSessions on AppController {
         threadRecordsInternal[normalizedSessionKey]?.assistantModelId.trim() ??
         '';
     if (target == AssistantExecutionTarget.singleAgent) {
-      if (singleAgentUsesAiChatFallbackForSession(normalizedSessionKey)) {
-        if (recordModel.isNotEmpty) {
-          return recordModel;
-        }
-        return resolvedAiGatewayModel;
-      }
       final runtimeModel = singleAgentRuntimeModelForSession(
         normalizedSessionKey,
       );
@@ -189,7 +175,7 @@ extension AppControllerWebSessions on AppController {
       if (recordModel.isNotEmpty) {
         return recordModel;
       }
-      return resolvedAiGatewayModel;
+      return '';
     }
     if (recordModel.isNotEmpty) {
       return recordModel;
@@ -203,9 +189,6 @@ extension AppControllerWebSessions on AppController {
   List<String> assistantModelChoicesForSession(String sessionKey) {
     final target = assistantExecutionTargetForSession(sessionKey);
     if (target == AssistantExecutionTarget.singleAgent) {
-      if (singleAgentUsesAiChatFallbackForSession(sessionKey)) {
-        return aiGatewayConversationModelChoices;
-      }
       final runtime = singleAgentRuntimeModelForSession(sessionKey);
       if (runtime.isNotEmpty) {
         return <String>[runtime];
@@ -214,7 +197,7 @@ extension AppControllerWebSessions on AppController {
       if (recordModel.isNotEmpty) {
         return <String>[recordModel];
       }
-      return aiGatewayConversationModelChoices;
+      return const <String>[];
     }
     final model = settingsInternal.defaultModel.trim();
     if (model.isEmpty) {
@@ -285,7 +268,11 @@ extension AppControllerWebSessions on AppController {
   }
 
   bool get currentSingleAgentNeedsAiGatewayConfiguration =>
-      currentSingleAgentUsesAiChatFallback && !canUseAiGatewayConversation;
+      assistantExecutionTargetForSession(currentSessionKeyInternal) ==
+          AssistantExecutionTarget.singleAgent &&
+      !availableSingleAgentProviders.any(
+        webAcpClientInternal.capabilities.providers.contains,
+      );
 
   List<SecretReferenceEntry> get secretReferences {
     final entries = <SecretReferenceEntry>[

lib/features/assistant/assistant_page_components.dart

@@ -498,7 +498,6 @@ class AssistantEmptyStateInternal extends StatelessWidget {
     final connectionState = controller.currentAssistantConnectionState;
     final singleAgent = connectionState.isSingleAgent;
     final connected = connectionState.connected;
-    final singleAgentFallback = controller.currentSingleAgentUsesAiChatFallback;
     final singleAgentNeedsAiGateway =
         controller.currentSingleAgentNeedsAiGatewayConfiguration;
     final singleAgentSuggestsAcpSwitch =
@@ -509,7 +508,7 @@ class AssistantEmptyStateInternal extends StatelessWidget {
         ? connected
               ? appText('开始 ACP Server 任务', 'Start an ACP Server task')
               : singleAgentNeedsAiGateway
-              ? appText('先配置 LLM API', 'Configure LLM API first')
+              ? appText('先配置 ACP Server', 'Configure ACP Server first')
               : appText('先准备 ACP Server', 'Prepare the ACP Server first')
         : connected
         ? appText('开始对话或运行任务', 'Start a chat or run a task')
@@ -518,15 +517,10 @@ class AssistantEmptyStateInternal extends StatelessWidget {
         : appText('先连接 Gateway', 'Connect a gateway first');
     final description = singleAgent
         ? connected
-              ? (singleAgentFallback
+              ? appText(
-                    ? appText(
+                  '当前线程通过 ACP Server 处理任务，不会建立 OpenClaw Gateway 会话。',
-                        '当前没有可用的外部 Agent ACP 连接，这个线程已降级到 AI Chat fallback，不会建立 OpenClaw Gateway 会话。',
+                  'This thread runs through the ACP Server path and does not open an OpenClaw Gateway session.',
-                        'No external Agent ACP connection is available for this thread, so it is running in AI Chat fallback without opening an OpenClaw Gateway session.',
+                )
-                      )
-                    : appText(
-                        '当前线程通过 ACP Server 处理任务，不会建立 OpenClaw Gateway 会话。',
-                        'This thread runs through the ACP Server path and does not open an OpenClaw Gateway session.',
-                      ))
               : singleAgentSuggestsAcpSwitch
               ? appText(
                   '当前线程固定为 $providerLabel，但它在这台设备上不可用。请改成可用的 ACP Server。',
@@ -534,8 +528,8 @@ class AssistantEmptyStateInternal extends StatelessWidget {
                 )
               : singleAgentNeedsAiGateway
               ? appText(
-                  '请先在 设置 -> 集成 中配置 LLM API Endpoint、LLM API Token 和默认模型，然后以 ACP Server 模式继续当前任务。',
+                  '请先在 设置 -> 集成 中配置可用的外部 Agent ACP 端点，然后以 ACP Server 模式继续当前任务。',
-                  'Set the LLM API Endpoint, LLM API Token, and default model in Settings -> Integrations, then continue this task in ACP Server mode.',
+                  'Configure an external Agent ACP endpoint in Settings -> Integrations, then continue this task in ACP Server mode.',
                 )
               : appText(
                   '当前线程的外部 Agent ACP 连接尚未就绪。请先配置 $providerLabel 对应端点。',

lib/runtime/direct_single_agent_app_server_client.dart

@@ -1,6 +0,0 @@
-// Legacy compatibility surface retained while the app imports are cleaned up.
-//
-// The direct single-agent app-server runtime has been retired in favor of the
-// GoTaskService ACP lane. This library intentionally exports only the capability
-// DTOs still consumed by the UI-facing state layer.
-export 'direct_single_agent_app_server_client_protocol.dart';

lib/runtime/single_agent_capabilities.dart

@@ -1,14 +1,14 @@
 import 'runtime_models.dart';
 
-class DirectSingleAgentCapabilities {
+class SingleAgentCapabilities {
-  const DirectSingleAgentCapabilities({
+  const SingleAgentCapabilities({
     required this.available,
     required this.supportedProviders,
     required this.endpoint,
     this.errorMessage,
   });
 
-  const DirectSingleAgentCapabilities.unavailable({
+  const SingleAgentCapabilities.unavailable({
     required this.endpoint,
     this.errorMessage,
   }) : available = false,

lib/runtime/single_agent_runner.dart

@@ -1,4 +0,0 @@
-// Legacy compatibility shim retained until remaining imports are cleaned up.
-//
-// Single-agent execution now flows through GoTaskService and the ACP
-// transport; the previous direct runner no longer owns runtime strategy.

lib/widgets/assistant_focus_panel_previews.dart

@@ -116,14 +116,15 @@ class SkillsFocusPreviewInternal extends StatelessWidget {
         message: typedController.isSingleAgentMode
             ? (typedController.currentSingleAgentNeedsAiGatewayConfiguration
                   ? appText(
-                      '当前没有可用的外部 Agent ACP 端点，请先配置 LLM API fallback。',
+                      '当前没有可用的外部 Agent ACP 端点，请先配置 ACP Server。',
-                      'No external Agent ACP endpoint is available. Configure LLM API fallback first.',
+                      'No external Agent ACP endpoint is available. Configure an ACP server first.',
                     )
                   : appText(
                       '当前线程还没有已加载技能。切换 provider 后会读取该线程自己的 skills 列表。',
                       'No skills are loaded for this thread yet. Switching the provider reloads the thread-owned skills list.',
                     ))
-            : typedController.connection.status == RuntimeConnectionStatus.connected
+            : typedController.connection.status ==
+                  RuntimeConnectionStatus.connected
             ? appText(
                 '当前代理没有已加载技能。',
                 'No skills are loaded for the active agent.',
@@ -306,7 +307,9 @@ class SecretsFocusPreviewInternal extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final typedController = castAssistantFocusControllerInternal(controller);
-    final items = typedController.secretReferences.take(4).toList(growable: false);
+    final items = typedController.secretReferences
+        .take(4)
+        .toList(growable: false);
     if (items.isEmpty) {
       return PreviewEmptyStateInternal(
         message: appText(

test/quality/wave1_file_size_guard_test.dart

@@ -27,7 +27,6 @@ void main() {
       'lib/features/assistant/assistant_page_main.dart': 1000,
       'lib/app/app_controller_desktop_runtime_helpers.dart': 800,
       'lib/app/app_controller_desktop_single_agent.dart': 200,
-      'lib/app/app_controller_desktop_single_agent_ai_gateway.dart': 800,
       'lib/app/app_controller_desktop_single_agent_go_task_flow.dart': 800,
       'lib/app/app_controller_desktop_single_agent_status_messages.dart': 400,
       'lib/app/app_controller_desktop_external_acp_routing.dart': 400,

test/runtime/app_controller_ai_gateway_chat_suite.dart

@@ -16,12 +16,10 @@ import 'package:xworkmate/runtime/runtime_coordinator.dart';
 import 'package:xworkmate/runtime/runtime_models.dart';
 import 'package:xworkmate/runtime/secure_config_store.dart';
 import 'app_controller_ai_gateway_chat_suite_core.dart';
-import 'app_controller_ai_gateway_chat_suite_chat.dart';
 import 'app_controller_ai_gateway_chat_suite_single_agent.dart';
 import 'app_controller_ai_gateway_chat_suite_fakes.dart';
 import 'app_controller_ai_gateway_chat_suite_fixtures.dart';
 
 void main() {
-  registerAppControllerAiGatewayChatSuiteChatTestsInternal();
   registerAppControllerAiGatewayChatSuiteSingleAgentTestsInternal();
 }

test/runtime/app_controller_ai_gateway_chat_suite_chat.dart

@@ -1,296 +0,0 @@
-// ignore_for_file: unused_import, unnecessary_import
-
-import 'dart:async';
-import 'dart:convert';
-import 'dart:io';
-import 'package:flutter_test/flutter_test.dart';
-import 'package:shared_preferences/shared_preferences.dart';
-import 'package:xworkmate/app/app_controller.dart';
-import 'package:xworkmate/runtime/codex_runtime.dart';
-import 'package:xworkmate/runtime/device_identity_store.dart';
-import 'package:xworkmate/runtime/gateway_runtime.dart';
-import 'package:xworkmate/runtime/runtime_coordinator.dart';
-import 'package:xworkmate/runtime/runtime_models.dart';
-import 'package:xworkmate/runtime/secure_config_store.dart';
-import 'app_controller_ai_gateway_chat_suite_core.dart';
-import 'app_controller_ai_gateway_chat_suite_single_agent.dart';
-import 'app_controller_ai_gateway_chat_suite_fakes.dart';
-import 'app_controller_ai_gateway_chat_suite_fixtures.dart';
-
-void registerAppControllerAiGatewayChatSuiteChatTestsInternal() {
-  group('AI Gateway chat streaming', () {
-    test(
-      'AppController streams and restores persistent Single Agent conversation turns',
-      () async {
-        final tempDirectory = await createTempDirectoryInternal(
-          'xworkmate-ai-gateway-session-',
-        );
-        final server = await FakeAiGatewayServerInternal.start(
-          responseMode: AiGatewayResponseModeInternal.sse,
-        );
-        addTearDown(() async {
-          await server.close();
-        });
-
-        final store = createStoreFromTempDirectoryInternal(tempDirectory);
-        final gateway = FakeGatewayRuntimeInternal(store: store);
-        final controller = await createAppControllerInternal(
-          store: store,
-          availableSingleAgentProvidersOverride: const <SingleAgentProvider>[],
-          runtimeCoordinator: RuntimeCoordinator(
-            gateway: gateway,
-            codex: FakeCodexRuntimeInternal(),
-          ),
-          goTaskServiceClient: FallbackOnlyGoTaskServiceClientInternal(),
-        );
-
-        await controller.settingsController.saveAiGatewayApiKey('live-key');
-        await controller.saveSettings(
-          controller.settings.copyWith(
-            aiGateway: controller.settings.aiGateway.copyWith(
-              baseUrl: server.baseUrl,
-              availableModels: const <String>['qwen2.5-coder:latest'],
-              selectedModels: const <String>['qwen2.5-coder:latest'],
-            ),
-            defaultModel: 'gpt-5.4',
-            multiAgent: controller.settings.multiAgent.copyWith(
-              autoSync: false,
-              mountTargets: withAvailableMountTargetsInternal(
-                controller.settings.multiAgent.mountTargets,
-                const <String>[],
-              ),
-            ),
-          ),
-          refreshAfterSave: false,
-        );
-        await controller.setAssistantExecutionTarget(
-          AssistantExecutionTarget.singleAgent,
-        );
-
-        const firstQuestion =
-            'Execution context:\n'
-            '- target: single-agent\n'
-            '- permission: full-access\n\n'
-            '今天聊点什么';
-        const secondQuestion = '继续刚才的话题';
-
-        final firstTurn = controller.sendChatMessage(
-          firstQuestion,
-          thinking: 'low',
-        );
-        await waitForInternal(
-          () => controller.chatMessages.any(
-            (message) => message.role == 'assistant' && message.pending,
-          ),
-        );
-        expect(controller.hasAssistantPendingRun, isTrue);
-        server.allowCompletion(1);
-        await firstTurn;
-
-        await waitForInternal(
-          () => controller.chatMessages.any(
-            (message) =>
-                message.role == 'assistant' && message.text == 'FIRST_REPLY',
-          ),
-        );
-
-        final secondStore = createStoreFromTempDirectoryInternal(tempDirectory);
-        final secondGateway = FakeGatewayRuntimeInternal(store: secondStore);
-        final secondController = await createAppControllerInternal(
-          store: secondStore,
-          availableSingleAgentProvidersOverride: const <SingleAgentProvider>[],
-          runtimeCoordinator: RuntimeCoordinator(
-            gateway: secondGateway,
-            codex: FakeCodexRuntimeInternal(),
-          ),
-          goTaskServiceClient: FallbackOnlyGoTaskServiceClientInternal(),
-        );
-
-        await secondController.settingsController.saveAiGatewayApiKey(
-          'live-key',
-        );
-
-        expect(secondController.chatMessages.last.text, 'FIRST_REPLY');
-        expect(
-          secondController.settings.assistantExecutionTarget,
-          AssistantExecutionTarget.singleAgent,
-        );
-
-        final secondTurn = secondController.sendChatMessage(
-          secondQuestion,
-          thinking: 'low',
-        );
-        await waitForInternal(
-          () => secondController.chatMessages.any(
-            (message) => message.role == 'assistant' && message.pending,
-          ),
-        );
-        server.allowCompletion(2);
-        await secondTurn;
-
-        await waitForInternal(
-          () => secondController.chatMessages.any(
-            (message) =>
-                message.role == 'assistant' && message.text == 'SECOND_REPLY',
-          ),
-        );
-
-        expect(server.requestCount, 2);
-        expect(server.lastAuthorization, 'Bearer live-key');
-        expect(server.requests.first['model'], 'qwen2.5-coder:latest');
-        expect(server.requests.first['stream'], isTrue);
-        expect(server.requests.first['messages'], <Map<String, dynamic>>[
-          <String, dynamic>{'role': 'user', 'content': firstQuestion},
-        ]);
-        expect(server.requests.last['messages'], <Map<String, dynamic>>[
-          <String, dynamic>{'role': 'user', 'content': firstQuestion},
-          <String, dynamic>{'role': 'assistant', 'content': 'FIRST_REPLY'},
-          <String, dynamic>{'role': 'user', 'content': secondQuestion},
-        ]);
-        expect(
-          secondController.connection.status,
-          RuntimeConnectionStatus.offline,
-        );
-        expect(secondController.assistantConnectionStatusLabel, '单机智能体');
-        expect(
-          secondController.assistantConnectionTargetLabel,
-          'AI Chat fallback · qwen2.5-coder:latest · 127.0.0.1:${server.port}',
-        );
-        expect(secondController.chatMessages.last.text, 'SECOND_REPLY');
-        expect(gateway.connectedProfiles, isEmpty);
-        expect(secondGateway.connectedProfiles, isEmpty);
-      },
-    );
-
-    test('AppController falls back when LLM API ignores stream mode', () async {
-      final tempDirectory = await createTempDirectoryInternal(
-        'xworkmate-ai-gateway-json-fallback-',
-      );
-      final server = await FakeAiGatewayServerInternal.start(
-        responseMode: AiGatewayResponseModeInternal.json,
-      );
-      addTearDown(() async {
-        await server.close();
-      });
-
-      final store = createStoreFromTempDirectoryInternal(tempDirectory);
-      final controller = await createAppControllerInternal(
-        store: store,
-        availableSingleAgentProvidersOverride: const <SingleAgentProvider>[],
-        runtimeCoordinator: RuntimeCoordinator(
-          gateway: FakeGatewayRuntimeInternal(store: store),
-          codex: FakeCodexRuntimeInternal(),
-        ),
-        goTaskServiceClient: FallbackOnlyGoTaskServiceClientInternal(),
-      );
-
-      await controller.settingsController.saveAiGatewayApiKey('live-key');
-      await controller.saveSettings(
-        controller.settings.copyWith(
-          aiGateway: controller.settings.aiGateway.copyWith(
-            baseUrl: server.baseUrl,
-            availableModels: const <String>['moonshotai/kimi-k2.5'],
-            selectedModels: const <String>['moonshotai/kimi-k2.5'],
-          ),
-          defaultModel: 'moonshotai/kimi-k2.5',
-          multiAgent: controller.settings.multiAgent.copyWith(
-            autoSync: false,
-            mountTargets: withAvailableMountTargetsInternal(
-              controller.settings.multiAgent.mountTargets,
-              const <String>[],
-            ),
-          ),
-        ),
-        refreshAfterSave: false,
-      );
-      await controller.setAssistantExecutionTarget(
-        AssistantExecutionTarget.singleAgent,
-      );
-
-      await controller.sendChatMessage('你好', thinking: 'low');
-
-      await waitForInternal(
-        () => controller.chatMessages.any(
-          (message) =>
-              message.role == 'assistant' && message.text == 'FIRST_REPLY',
-        ),
-      );
-
-      expect(server.requests.single['stream'], isTrue);
-      expect(controller.chatMessages.last.pending, isFalse);
-    });
-
-    test(
-      'AppController abortRun stops Single Agent streaming requests',
-      () async {
-        final tempDirectory = await createTempDirectoryInternal(
-          'xworkmate-ai-gateway-abort-',
-        );
-        final server = await FakeAiGatewayServerInternal.start(
-          responseMode: AiGatewayResponseModeInternal.sse,
-        );
-        addTearDown(() async {
-          await server.close();
-        });
-
-        final store = createStoreFromTempDirectoryInternal(tempDirectory);
-        final controller = await createAppControllerInternal(
-          store: store,
-          availableSingleAgentProvidersOverride: const <SingleAgentProvider>[],
-          runtimeCoordinator: RuntimeCoordinator(
-            gateway: FakeGatewayRuntimeInternal(store: store),
-            codex: FakeCodexRuntimeInternal(),
-          ),
-          goTaskServiceClient: FallbackOnlyGoTaskServiceClientInternal(),
-        );
-
-        await controller.settingsController.saveAiGatewayApiKey('live-key');
-        await controller.saveSettings(
-          controller.settings.copyWith(
-            aiGateway: controller.settings.aiGateway.copyWith(
-              baseUrl: server.baseUrl,
-              availableModels: const <String>['z-ai/glm5'],
-              selectedModels: const <String>['z-ai/glm5'],
-            ),
-            defaultModel: 'z-ai/glm5',
-            multiAgent: controller.settings.multiAgent.copyWith(
-              autoSync: false,
-              mountTargets: withAvailableMountTargetsInternal(
-                controller.settings.multiAgent.mountTargets,
-                const <String>[],
-              ),
-            ),
-          ),
-          refreshAfterSave: false,
-        );
-        await controller.setAssistantExecutionTarget(
-          AssistantExecutionTarget.singleAgent,
-        );
-
-        final pendingTurn = controller.sendChatMessage(
-          '今天聊点什么',
-          thinking: 'low',
-        );
-        await waitForInternal(
-          () => controller.chatMessages.any(
-            (message) => message.role == 'assistant' && message.pending,
-          ),
-        );
-
-        await controller.abortRun();
-        server.allowCompletion(1);
-        await pendingTurn;
-        await waitForInternal(() => !controller.hasAssistantPendingRun);
-
-        expect(
-          controller.chatMessages.where((message) => message.pending),
-          isEmpty,
-        );
-        expect(
-          controller.chatMessages.where((message) => message.error),
-          isEmpty,
-        );
-      },
-    );
-  });
-}

test/runtime/app_controller_ai_gateway_chat_suite_core.dart

@@ -12,7 +12,6 @@ import 'package:xworkmate/runtime/gateway_runtime.dart';
 import 'package:xworkmate/runtime/runtime_coordinator.dart';
 import 'package:xworkmate/runtime/runtime_models.dart';
 import 'package:xworkmate/runtime/secure_config_store.dart';
-import 'app_controller_ai_gateway_chat_suite_chat.dart';
 import 'app_controller_ai_gateway_chat_suite_single_agent.dart';
 import 'app_controller_ai_gateway_chat_suite_fakes.dart';
 import 'app_controller_ai_gateway_chat_suite_fixtures.dart';

test/runtime/app_controller_ai_gateway_chat_suite_fakes.dart

@@ -14,7 +14,6 @@ import 'package:xworkmate/runtime/runtime_coordinator.dart';
 import 'package:xworkmate/runtime/runtime_models.dart';
 import 'package:xworkmate/runtime/secure_config_store.dart';
 import 'app_controller_ai_gateway_chat_suite_core.dart';
-import 'app_controller_ai_gateway_chat_suite_chat.dart';
 import 'app_controller_ai_gateway_chat_suite_single_agent.dart';
 import 'app_controller_ai_gateway_chat_suite_fixtures.dart';
 

test/runtime/app_controller_ai_gateway_chat_suite_fixtures.dart

@@ -14,7 +14,6 @@ import 'package:xworkmate/runtime/runtime_coordinator.dart';
 import 'package:xworkmate/runtime/runtime_models.dart';
 import 'package:xworkmate/runtime/secure_config_store.dart';
 import 'app_controller_ai_gateway_chat_suite_core.dart';
-import 'app_controller_ai_gateway_chat_suite_chat.dart';
 import 'app_controller_ai_gateway_chat_suite_single_agent.dart';
 import 'app_controller_ai_gateway_chat_suite_fakes.dart';
 

test/runtime/app_controller_ai_gateway_chat_suite_single_agent.dart

@@ -14,14 +14,13 @@ import 'package:xworkmate/runtime/runtime_coordinator.dart';
 import 'package:xworkmate/runtime/runtime_models.dart';
 import 'package:xworkmate/runtime/secure_config_store.dart';
 import 'app_controller_ai_gateway_chat_suite_core.dart';
-import 'app_controller_ai_gateway_chat_suite_chat.dart';
 import 'app_controller_ai_gateway_chat_suite_fakes.dart';
 import 'app_controller_ai_gateway_chat_suite_fixtures.dart';
 
 void registerAppControllerAiGatewayChatSuiteSingleAgentTestsInternal() {
   group('Single Agent provider resolution', () {
     test(
-      'AppController uses the selected Single Agent provider before AI Chat fallback',
+      'AppController uses the selected Single Agent provider before ACP execution',
       () async {
         final tempDirectory = await createTempDirectoryInternal(
           'xworkmate-single-agent-provider-',
@@ -607,10 +606,10 @@ void registerAppControllerAiGatewayChatSuiteSingleAgentTestsInternal() {
     );
 
     test(
-      'AppController falls back to AI Chat when no external CLI is available',
+      'AppController returns an ACP-only error when no provider is available',
       () async {
         final tempDirectory = await createTempDirectoryInternal(
-          'xworkmate-single-agent-fallback-',
+          'xworkmate-single-agent-acp-unavailable-',
         );
         final server = await FakeAiGatewayServerInternal.start(
           responseMode: AiGatewayResponseModeInternal.json,
@@ -652,23 +651,12 @@ void registerAppControllerAiGatewayChatSuiteSingleAgentTestsInternal() {
 
         expect(client.capabilitiesCalls, greaterThanOrEqualTo(1));
         expect(client.executeCalls, 0);
-        expect(server.requestCount, 1);
+        expect(server.requestCount, 0);
-        expect(
-          controller.chatMessages.any(
-            (message) => message.text.contains('Codex CLI is unavailable'),
-          ),
-          isFalse,
-        );
-        expect(
-          controller.chatMessages.any(
-            (message) => message.toolName == 'AI Chat fallback',
-          ),
-          isFalse,
-        );
         expect(
           controller.chatMessages.any(
             (message) =>
-                message.role == 'assistant' && message.text == 'FIRST_REPLY',
+                message.role == 'assistant' &&
+                message.text.contains('当前没有可用的外部 Agent ACP 端点'),
           ),
           isTrue,
         );
@@ -676,10 +664,10 @@ void registerAppControllerAiGatewayChatSuiteSingleAgentTestsInternal() {
     );
 
     test(
-      'AppController auto-binds a thread workspace in AI Chat fallback when the thread binding is missing',
+      'AppController auto-binds a thread workspace before reporting ACP unavailability',
       () async {
         final tempDirectory = await createTempDirectoryInternal(
-          'xworkmate-single-agent-fallback-missing-workspace-',
+          'xworkmate-single-agent-acp-unavailable-missing-workspace-',
         );
         final server = await FakeAiGatewayServerInternal.start(
           responseMode: AiGatewayResponseModeInternal.json,
@@ -725,9 +713,17 @@ void registerAppControllerAiGatewayChatSuiteSingleAgentTestsInternal() {
         );
         expect(client.capabilitiesCalls, greaterThanOrEqualTo(1));
         expect(client.executeCalls, 0);
-        expect(server.requestCount, 1);
+        expect(server.requestCount, 0);
         expect(workspacePath, isNotEmpty);
         expect(workspacePath, contains('.xworkmate/threads/'));
+        expect(
+          controller.chatMessages.any(
+            (message) =>
+                message.role == 'assistant' &&
+                message.text.contains('当前没有可用的外部 Agent ACP 端点'),
+          ),
+          isTrue,
+        );
       },
     );
   });

test/runtime/app_controller_ai_gateway_models_suite.dart

@@ -49,7 +49,7 @@ void main() {
   );
 
   test(
-    'AppController keeps the current thread model source when only the global default target changes',
+    'AppController does not borrow LLM API model choices when single-agent has no ACP provider',
     () async {
       SharedPreferences.setMockInitialValues(<String, Object>{});
       final tempDirectory = await Directory.systemTemp.createTemp(
@@ -82,10 +82,8 @@ void main() {
         AssistantExecutionTarget.singleAgent,
       );
 
-      expect(controller.assistantModelChoices, const <String>[
+      expect(controller.assistantModelChoices, isEmpty);
-        'qwen2.5-coder:latest',
+      expect(controller.resolvedAssistantModel, isEmpty);
-      ]);
-      expect(controller.resolvedAssistantModel, 'qwen2.5-coder:latest');
       expect(controller.canUseAiGatewayConversation, isTrue);
 
       await controller.saveSettings(
@@ -100,10 +98,8 @@ void main() {
         ),
         AssistantExecutionTarget.singleAgent,
       );
-      expect(controller.resolvedAssistantModel, 'qwen2.5-coder:latest');
+      expect(controller.resolvedAssistantModel, isEmpty);
-      expect(controller.assistantModelChoices, const <String>[
+      expect(controller.assistantModelChoices, isEmpty);
-        'qwen2.5-coder:latest',
-      ]);
     },
   );
 
@@ -143,7 +139,6 @@ void main() {
       await controller.setSingleAgentProvider(SingleAgentProvider.opencode);
 
       expect(controller.currentSingleAgentHasResolvedProvider, isTrue);
-      expect(controller.currentSingleAgentUsesAiChatFallback, isFalse);
       expect(controller.currentSingleAgentShouldShowModelControl, isFalse);
       expect(controller.assistantModelChoices, isEmpty);
       expect(controller.resolvedAssistantModel, isEmpty);

test/runtime/app_controller_desktop_refactor_characterization_suite.dart

@@ -123,7 +123,7 @@ void main() {
   );
 
   test(
-    'AppController keeps AI Gateway model choices when single-agent falls back to AI chat',
+    'AppController keeps single-agent model controls empty when no ACP provider is available',
     () async {
       final harness = await _DesktopControllerHarness.create(
         availableSingleAgentProvidersOverride: const <SingleAgentProvider>[],
@@ -147,12 +147,10 @@ void main() {
       );
 
       expect(controller.currentSingleAgentHasResolvedProvider, isFalse);
-      expect(controller.currentSingleAgentUsesAiChatFallback, isTrue);
+      expect(controller.currentSingleAgentNeedsAiGatewayConfiguration, isTrue);
-      expect(controller.currentSingleAgentShouldShowModelControl, isTrue);
+      expect(controller.currentSingleAgentShouldShowModelControl, isFalse);
-      expect(controller.assistantModelChoices, const <String>[
+      expect(controller.assistantModelChoices, isEmpty);
-        'qwen2.5-coder:latest',
+      expect(controller.resolvedAssistantModel, isEmpty);
-      ]);
-      expect(controller.resolvedAssistantModel, 'qwen2.5-coder:latest');
     },
   );
 }

test/runtime/app_controller_execution_target_switch_suite_connection.dart

@@ -147,7 +147,7 @@ void registerExecutionTargetSwitchConnectionTests() {
         expect(controller.assistantConnectionStatusLabel, 'ACP Server Local');
         expect(
           controller.assistantConnectionTargetLabel,
-          '没有可用的外部 Agent ACP 端点，请配置 LLM API fallback。',
+          '没有可用的外部 Agent ACP 端点，请先配置可用的 ACP Server。',
         );
         expect(
           gateway.connectedProfiles,

test/runtime/app_controller_execution_target_switch_suite_thread.dart

@@ -198,7 +198,7 @@ void registerExecutionTargetSwitchThreadTests() {
         expect(controller.assistantConnectionStatusLabel, 'ACP Server Local');
         expect(
           controller.assistantConnectionTargetLabel,
-          '没有可用的外部 Agent ACP 端点，请配置 LLM API fallback。',
+          '没有可用的外部 Agent ACP 端点，请先配置可用的 ACP Server。',
         );
       },
     );
@@ -240,19 +240,20 @@ void registerExecutionTargetSwitchThreadTests() {
         await controller.setAssistantExecutionTarget(
           AssistantExecutionTarget.local,
         );
-        controller.chatControllerInternal.messagesInternal = <GatewayChatMessage>[
+        controller.chatControllerInternal.messagesInternal =
-          GatewayChatMessage(
+            <GatewayChatMessage>[
-            id: 'gateway-old-message',
+              GatewayChatMessage(
-            role: 'assistant',
+                id: 'gateway-old-message',
-            text: 'previous desktop gateway history',
+                role: 'assistant',
-            timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
+                text: 'previous desktop gateway history',
-            toolCallId: null,
+                timestampMs: DateTime.now().millisecondsSinceEpoch.toDouble(),
-            toolName: null,
+                toolCallId: null,
-            stopReason: null,
+                toolName: null,
-            pending: false,
+                stopReason: null,
-            error: false,
+                pending: false,
-          ),
+                error: false,
-        ];
+              ),
+            ];
 
         controller.initializeAssistantThreadContext(
           'draft:fresh-thread',

test/runtime/no_direct_cli_execution_guard_suite.dart

@@ -56,6 +56,9 @@ void main() {
 
     test('legacy direct single-agent runtime implementation stays removed', () {
       const removedFiles = <String>[
+        'lib/runtime/direct_single_agent_app_server_client.dart',
+        'lib/runtime/direct_single_agent_app_server_client_protocol.dart',
+        'lib/runtime/single_agent_runner.dart',
         'lib/runtime/direct_single_agent_app_server_client_core.dart',
         'lib/runtime/direct_single_agent_app_server_client_helpers.dart',
         'lib/runtime/direct_single_agent_app_server_client_transport.dart',
@@ -65,15 +68,10 @@ void main() {
         expect(
           File(relativePath).existsSync(),
           isFalse,
-          reason: '$relativePath should stay removed after GoTaskService cutover',
+          reason:
+              '$relativePath should stay removed after GoTaskService cutover',
         );
       }
-
-      final runnerShim = File('lib/runtime/single_agent_runner.dart');
-      expect(runnerShim.existsSync(), isTrue);
-      final shimContent = runnerShim.readAsStringSync();
-      expect(shimContent.contains('DefaultSingleAgentRunner'), isFalse);
-      expect(shimContent.contains('DirectSingleAgentAppServerClient'), isFalse);
     });
   });
 }