refactor(server): implement lazy agent initialization with state machine pattern

packages/server/agents.json

@@ -2,7 +2,7 @@
   {
     "id": "b203dc68-03e0-4971-a3d7-a4822c940b50",
     "title": "Agent b203dc68",
-    "sessionId": "019a16ed-36da-7407-aa21-b56f860f2db7",
+    "sessionId": "07f421be-98c1-4f23-9604-8f00274956c7",
     "options": {
       "type": "claude",
       "sessionId": "07f421be-98c1-4f23-9604-8f00274956c7"
@@ -13,7 +13,7 @@
   {
     "id": "d0633729-2f74-426a-a3a8-05e8c7206703",
     "title": "Assist with Voice Development",
-    "sessionId": "019a16f0-18d3-7656-85a8-dae38035049d",
+    "sessionId": "79c9a8e0-8a24-4851-baad-62747b815442",
     "options": {
       "type": "claude",
       "sessionId": "79c9a8e0-8a24-4851-baad-62747b815442"

packages/server/src/server/acp/agent-persistence.ts

@@ -22,7 +22,7 @@ export type AgentOptions = z.infer<typeof AgentOptionsSchema>;
 export const PersistedAgentSchema = z.object({
   id: z.string(),
   title: z.string(),
-  sessionId: z.string(), // ACP protocol session ID (for backward compatibility)
+  sessionId: z.string().nullable(), // ACP protocol session ID (null for uninitialized agents)
   options: AgentOptionsSchema, // Required field with discriminated union
   createdAt: z.string(),
   cwd: z.string(),

packages/server/src/server/acp/mcp-server.ts

@@ -364,7 +364,7 @@ export async function createAgentMcpServer(
       },
     },
     async ({ agentId, format = "curated", limit }) => {
-      const updates = agentManager.getAgentUpdates(agentId);
+      const updates = await agentManager.getAgentUpdates(agentId);
       const currentModeId = agentManager.getCurrentMode(agentId);
 
       if (format === "curated") {

packages/server/src/server/acp/types.ts

@@ -1,4 +1,5 @@
-import type { SessionNotification, RequestPermissionRequest } from "@agentclientprotocol/sdk";
+import type { SessionNotification, RequestPermissionRequest, ClientSideConnection } from "@agentclientprotocol/sdk";
+import type { ChildProcess } from "child_process";
 
 /**
  * Extended update types with messageId for proper deduplication
@@ -31,6 +32,7 @@ export type AgentNotification =
  * Status of an agent
  */
 export type AgentStatus =
+  | "uninitialized"
   | "initializing"
   | "ready"
   | "processing"
@@ -38,6 +40,38 @@ export type AgentStatus =
   | "failed"
   | "killed";
 
+/**
+ * Session mode definition from ACP
+ */
+export interface SessionMode {
+  id: string;
+  name: string;
+  description?: string | null;
+}
+
+/**
+ * Runtime state for an initialized agent
+ */
+export interface AgentRuntime {
+  process: ChildProcess;
+  connection: ClientSideConnection;
+  sessionId: string;
+  currentModeId: string | null;
+  availableModes: SessionMode[] | null;
+}
+
+/**
+ * Discriminated union for agent state
+ */
+export type ManagedAgentState =
+  | { type: "uninitialized"; persistedSessionId: string | null; lastError?: string }
+  | { type: "initializing"; persistedSessionId: string | null; initPromise: Promise<void>; initStartedAt: Date }
+  | { type: "ready"; runtime: AgentRuntime }
+  | { type: "processing"; runtime: AgentRuntime }
+  | { type: "completed"; runtime: AgentRuntime; stopReason?: string }
+  | { type: "failed"; lastError: string; runtime?: AgentRuntime }
+  | { type: "killed" };
+
 /**
  * Information about an agent
  */
@@ -64,15 +98,6 @@ export interface AgentUpdate {
   notification: AgentNotification;
 }
 
-/**
- * Session mode definition from ACP
- */
-export interface SessionMode {
-  id: string;
-  name: string;
-  description?: string | null;
-}
-
 /**
  * Options for creating an agent
  */