fix(workbench): gc stale empty sessions

internal/cloud/server.ts

@@ -68,6 +68,7 @@ import {
   handleCodeAgentTraceHttp
 } from "./server-code-agent-http.ts";
 import { handleWorkbenchReadModelHttp, handleWorkbenchRealtimeHttp } from "./server-workbench-http.ts";
+import { startWorkbenchEmptySessionGc } from "./workbench-empty-session-gc.ts";
 import { handleM3IoControlHttp } from "./server-m3-http.ts";
 import { handleSkillsHttp } from "./server-skills-http.ts";
 import { handleProviderProfileCatalogHttp, handleProviderProfilesHttp } from "./provider-profile-management.ts";
@@ -115,7 +116,8 @@ export function createCloudApiServer(options = {}) {
   if (typeof accessController.configureCodeAgentWorkspaceContext === "function") {
     accessController.configureCodeAgentWorkspaceContext({ env, fetchImpl: options.fetchImpl, traceStore, codeAgentChatResults });
   }
-  return createServer(async (request, response) => {
+  const workbenchEmptySessionGc = startWorkbenchEmptySessionGc({ env, accessController, logger: console });
+  const server = createServer(async (request, response) => {
     const backendPerformance = backendPerformanceStore.beginHttpRequest(request, response);
     await withBackendPerformanceContext(backendPerformance, async () => {
       try {
@@ -133,6 +135,8 @@ export function createCloudApiServer(options = {}) {
       }
     });
   });
+  server.on("close", () => workbenchEmptySessionGc.stop());
+  return server;
 }
 
 export function ensureCodeAgentRuntimeBase(env = process.env) {