feat(hub): persist agent list to disk for restart recovery

Store agent records in ~/.super-multica/agents/agents.json.
Hub restores agents on startup and updates the file on create/delete.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/hub/agent-store.ts

@@ -0,0 +1,47 @@
+import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { DATA_DIR } from "../shared/index.js";
+
+export interface AgentRecord {
+  id: string;
+  createdAt: number;
+}
+
+const AGENTS_DIR = join(DATA_DIR, "agents");
+const AGENTS_FILE = join(AGENTS_DIR, "agents.json");
+
+function ensureDir(): void {
+  if (!existsSync(AGENTS_DIR)) {
+    mkdirSync(AGENTS_DIR, { recursive: true });
+  }
+}
+
+export function loadAgentRecords(): AgentRecord[] {
+  if (!existsSync(AGENTS_FILE)) return [];
+  try {
+    const content = readFileSync(AGENTS_FILE, "utf-8");
+    return JSON.parse(content) as AgentRecord[];
+  } catch {
+    return [];
+  }
+}
+
+export function saveAgentRecords(records: AgentRecord[]): void {
+  ensureDir();
+  writeFileSync(AGENTS_FILE, JSON.stringify(records, null, 2), "utf-8");
+}
+
+export function addAgentRecord(record: AgentRecord): void {
+  const records = loadAgentRecords();
+  if (records.some((r) => r.id === record.id)) return;
+  records.push(record);
+  saveAgentRecords(records);
+}
+
+export function removeAgentRecord(id: string): void {
+  const records = loadAgentRecords();
+  const filtered = records.filter((r) => r.id !== id);
+  if (filtered.length !== records.length) {
+    saveAgentRecords(filtered);
+  }
+}

src/hub/hub.ts

@@ -3,6 +3,7 @@ import type { ConnectionState } from "../shared/gateway-sdk/types.js";
 import { AsyncAgent } from "../agent/async-agent.js";
 import { getDeviceId } from "./device.js";
 import { GatewayClient } from "../shared/gateway-sdk/client.js";
+import { loadAgentRecords, addAgentRecord, removeAgentRecord } from "./agent-store.js";
 
 export class Hub {
   private readonly agents = new Map<string, AsyncAgent>();
@@ -23,6 +24,18 @@ export class Hub {
     this.deviceId = getDeviceId();
     this.client = this.createClient(this.url);
     this.client.connect();
+    this.restoreAgents();
+  }
+
+  /** Restore agents from persistent storage */
+  private restoreAgents(): void {
+    const records = loadAgentRecords();
+    for (const record of records) {
+      this.createAgent(record.id, { persist: false });
+    }
+    if (records.length > 0) {
+      console.log(`[Hub] Restored ${records.length} agent(s)`);
+    }
   }
 
   private createClient(url: string): GatewayClient {
@@ -82,7 +95,7 @@ export class Hub {
   }
 
   /** Create new Agent, or rebuild with existing ID */
-  createAgent(id?: string): AsyncAgent {
+  createAgent(id?: string, options?: { persist?: boolean }): AsyncAgent {
     if (id) {
       const existing = this.agents.get(id);
       if (existing && !existing.closed) {
@@ -93,6 +106,11 @@ export class Hub {
     const agent = new AsyncAgent({ sessionId: id });
     this.agents.set(agent.sessionId, agent);
 
+    // Persist to agent store (skip during restore to avoid duplicates)
+    if (options?.persist !== false) {
+      addAgentRecord({ id: agent.sessionId, createdAt: Date.now() });
+    }
+
     // Internally consume messages produced by agent
     void this.consumeAgent(agent);
 
@@ -130,6 +148,7 @@ export class Hub {
     agent.close();
     this.agents.delete(id);
     this.agentSenders.delete(id);
+    removeAgentRecord(id);
     return true;
   }