feat(gateway): expose context usage and warning events

src/gateway/server.ts

@@ -33,7 +33,7 @@ import {
   createNodeHandlers,
 } from './handlers/index.js';
 import { discoverServices } from './handlers/services.js';
-import type { TokenUsageEntry } from './handlers/system.js';
+import type { TokenUsageEntry, ContextUsageEntry } from './handlers/system.js';
 import type { NodeConnectionState } from './handlers/node.js';
 import type { SessionManager } from '../session/manager.js';
 import type { Config } from '../config/index.js';
@@ -82,6 +82,8 @@ export interface GatewayServerConfig {
   gmailHandler?: GmailWatcher;
   /** Optional callback to retrieve per-session token usage data for the dashboard. */
   getTokenUsage?: () => TokenUsageEntry[];
+  /** Optional callback to retrieve per-session context usage data for the dashboard. */
+  getContextUsage?: () => ContextUsageEntry[];
   /** Maximum allowed request body size for inbound HTTP POST bodies. */
   maxRequestBodyBytes?: number;
   /** Per-connection WebSocket ingress rate limiting. */
@@ -294,6 +296,7 @@ export class GatewayServer {
         activeConnections: this.sessionBridge.connectionCount,
       }),
       getTokenUsage: this.config.getTokenUsage,
+      getContextUsage: this.config.getContextUsage,
       getMetrics: () => this.metrics.getSnapshot(),
       getEvents: (opts) => this.metrics.getEvents(opts),
       getActiveRequests: () => this.metrics.getActiveRequests(),