fix: complete session persistence overhaul (Codex 5.2)

1. Implemented auto-selection of tasks in MultiXV2 to prevent empty initial state.
2. Added force-loading logic for task session messages with debouncing.
3. Updated session-actions to return full assistant text and immediately persist native messages.
4. Fixed caching logic in instance-shell2 to retain active task sessions in memory.

packages/server/src/storage/session-store.ts

@@ -27,6 +27,12 @@ export interface SessionMessage {
     status?: "pending" | "streaming" | "completed" | "error"
 }
 
+type IncomingSessionMessage = Omit<SessionMessage, "id" | "sessionId" | "createdAt" | "updatedAt"> & {
+    id?: string
+    createdAt?: number
+    updatedAt?: number
+}
+
 export interface MessagePart {
     type: "text" | "tool_call" | "tool_result" | "thinking" | "code"
     content?: string
@@ -260,23 +266,29 @@ export class NativeSessionManager {
             .filter((msg): msg is SessionMessage => msg !== undefined)
     }
 
-    async addMessage(workspaceId: string, sessionId: string, message: Omit<SessionMessage, "id" | "sessionId" | "createdAt" | "updatedAt">): Promise<SessionMessage> {
+    async addMessage(workspaceId: string, sessionId: string, message: IncomingSessionMessage): Promise<SessionMessage> {
         const store = await this.loadStore(workspaceId)
         const session = store.sessions[sessionId]
         if (!session) throw new Error(`Session not found: ${sessionId}`)
 
         const now = Date.now()
+        const messageId = message.id ?? ulid()
+        const createdAt = typeof message.createdAt === "number" ? message.createdAt : now
+        const updatedAt = typeof message.updatedAt === "number" ? message.updatedAt : createdAt
+
         const newMessage: SessionMessage = {
             ...message,
-            id: ulid(),
+            id: messageId,
             sessionId,
-            createdAt: now,
-            updatedAt: now,
+            createdAt,
+            updatedAt,
         }
 
         store.messages[newMessage.id] = newMessage
-        session.messageIds.push(newMessage.id)
-        session.updatedAt = now
+        if (!session.messageIds.includes(newMessage.id)) {
+            session.messageIds.push(newMessage.id)
+        }
+        session.updatedAt = updatedAt
 
         await this.saveStore(workspaceId)
         return newMessage