gateway: add local backend daemon controls to dashboard

src/gateway/handlers/system.ts

@@ -4,6 +4,7 @@ import type { MetricsSnapshot, EventEntry, ActiveRequestInfo } from '../metrics.
 import type { ServiceInfo } from './services.js';
 import type { NodeLocation, NodeStatus, NodePushToken } from './node.js';
 import type { SessionAnalyticsSnapshot } from '../../session/index.js';
+import type { LocalBackendAction, LocalBackendControlResult, LocalBackendStatus } from './localBackends.js';
 
 /** Per-session token usage report returned by system.tokenUsage. */
 export interface TokenUsageEntry {
@@ -103,6 +104,20 @@ export interface SystemHandlerDeps {
     error?: string;
     fetchedAt: number;
   }>>;
+  /** Optional callback to retrieve local backend daemon statuses. */
+  getLocalBackends?: () => Promise<LocalBackendStatus[]> | LocalBackendStatus[];
+  /** Optional callback to control local backend daemons. */
+  controlLocalBackend?: (backend: string, action: string) => Promise<LocalBackendControlResult>;
+}
+
+function normalizeErrorMessage(error: unknown): string {
+  if (error instanceof Error && error.message.trim().length > 0) {
+    return error.message;
+  }
+  if (typeof error === 'string' && error.trim().length > 0) {
+    return error;
+  }
+  return 'Unknown error';
 }
 
 export function createSystemHandlers(deps: SystemHandlerDeps) {
@@ -285,5 +300,40 @@ export function createSystemHandlers(deps: SystemHandlerDeps) {
       });
       return makeResponse(request.id, { providers });
     },
+
+    'system.localBackends': async (request: GatewayRequest): Promise<OutboundMessage> => {
+      if (!deps.getLocalBackends) {
+        return makeResponse(request.id, { backends: [] });
+      }
+      try {
+        const backends = await deps.getLocalBackends();
+        return makeResponse(request.id, { backends });
+      } catch (error) {
+        return makeError(request.id, ErrorCode.InternalError, `Failed to load local backends: ${normalizeErrorMessage(error)}`);
+      }
+    },
+
+    'system.localBackendControl': async (request: GatewayRequest): Promise<OutboundMessage> => {
+      if (!deps.controlLocalBackend) {
+        return makeError(request.id, ErrorCode.InternalError, 'Local backend control is not available in this environment');
+      }
+      const params = request.params as { backend?: string; action?: LocalBackendAction } | undefined;
+      if (!params?.backend || typeof params.backend !== 'string') {
+        return makeError(request.id, ErrorCode.InvalidRequest, 'backend is required');
+      }
+      if (!params?.action || typeof params.action !== 'string') {
+        return makeError(request.id, ErrorCode.InvalidRequest, 'action is required');
+      }
+      if (!['start', 'restart', 'stop'].includes(params.action)) {
+        return makeError(request.id, ErrorCode.InvalidRequest, 'action must be one of: start, restart, stop');
+      }
+
+      try {
+        const result = await deps.controlLocalBackend(params.backend, params.action);
+        return makeResponse(request.id, result);
+      } catch (error) {
+        return makeError(request.id, ErrorCode.InternalError, `Local backend control failed: ${normalizeErrorMessage(error)}`);
+      }
+    },
   };
 }