Prevent stale session overwrite on new tasks

backend/api/server.py

@@ -2382,6 +2382,19 @@ def create_app(state: AgentState) -> FastAPI:
         ) or uuid4().hex
         account_key = state._account_key(request.account_id)
         prompt = request.prompt.strip()
+        session_directory = state.account_paths(request.account_id)['sessions']
+        if (
+            request.resume_session_id is None
+            and run_record is None
+            and _agent_session_exists(session_directory, requested_session_id)
+        ):
+            raise HTTPException(
+                status_code=409,
+                detail=(
+                    'Session already exists; pass resume_session_id to continue '
+                    'or create a fresh session_id.'
+                ),
+            )
         if run_record is None:
             run_record = state.run_manager.start(
                 account_key,
@@ -2398,7 +2411,6 @@ def create_app(state: AgentState) -> FastAPI:
         run_lock = state.run_lock_for(request.account_id, requested_session_id)
         agent = state.agent_for(request.account_id, requested_session_id)
         config = state.config_for(request.account_id)
-        session_directory = state.account_paths(request.account_id)['sessions']
         jupyter_runtime = _jupyter_runtime_for_session(
             state,
             request.account_id,
@@ -2658,6 +2670,18 @@ def create_app(state: AgentState) -> FastAPI:
         ) or uuid4().hex
         account_key = state._account_key(request.account_id)
         prompt = request.prompt.strip()
+        session_directory = state.account_paths(request.account_id)['sessions']
+        if (
+            request.resume_session_id is None
+            and _agent_session_exists(session_directory, requested_session_id)
+        ):
+            raise HTTPException(
+                status_code=409,
+                detail=(
+                    'Session already exists; pass resume_session_id to continue '
+                    'or create a fresh session_id.'
+                ),
+            )
         run_record = state.run_manager.start(account_key, requested_session_id, prompt)
         state.run_state_store.start(
             run_id=run_record.run_id,
@@ -2672,7 +2696,7 @@ def create_app(state: AgentState) -> FastAPI:
         try:
             agent = state.agent_for(request.account_id, requested_session_id)
             _save_in_progress_session(
-                directory=state.account_paths(request.account_id)['sessions'],
+                directory=session_directory,
                 agent=agent,
                 session_id=requested_session_id,
                 prompt=prompt,
@@ -3347,6 +3371,14 @@ def _save_in_progress_session(
         return None
 
 
+def _agent_session_exists(directory: Path, session_id: str) -> bool:
+    try:
+        load_agent_session(session_id, directory=directory)
+    except (FileNotFoundError, OSError, json.JSONDecodeError):
+        return False
+    return True
+
+
 def _derive_initial_session_title(prompt: str) -> str | None:
     # 第一条消息刚发出时先给侧边栏一个可读标题，后续再由模型摘要精修。
     stripped = _strip_session_context(prompt)

frontend/app/app/api/chat/route.ts

@@ -102,7 +102,7 @@ export async function POST(req: Request) {
 	if (!account) return new Response("请先登录账号", { status: 401 });
 
 	const { id, messages, resumeSessionId }: ChatRequestBody = await req.json();
-	const resumeId = resumeSessionId ?? getLastSessionId(messages);
+	const resumeId = resumeSessionId;
 	const sessionId = safeSessionId(resumeId ?? id ?? crypto.randomUUID());
 	await ensureSessionDirectories(account.id, sessionId);
 	const userPrompt = await getLastUserText(messages, account.id, sessionId);
@@ -362,18 +362,6 @@ function renderSessionRuntimeContext(accountId: string, sessionId: string) {
 	].join("\n\n");
 }
 
-function getLastSessionId(messages: UIMessage[]) {
-	for (const message of [...messages].reverse()) {
-		if (message.role !== "assistant") continue;
-		const metadata = message.metadata;
-		if (metadata && typeof metadata === "object" && "sessionId" in metadata) {
-			const sessionId = (metadata as { sessionId?: unknown }).sessionId;
-			if (typeof sessionId === "string" && sessionId) return sessionId;
-		}
-	}
-	return undefined;
-}
-
 async function saveFilePart(
 	part: Extract<UIMessage["parts"][number], { type: "file" }>,
 	accountId: string,

frontend/app/app/assistant.tsx

@@ -30,6 +30,7 @@ import {
 import {
 	ACTIVE_SESSION_CHANGED_EVENT,
 	consumeFreshLocalId,
+	createLocalSessionId,
 	readActiveSessionId,
 	readPendingWorkspaceSessionId,
 	writeActiveSessionId,
@@ -60,11 +61,7 @@ export const Assistant = ({ initialSessionId }: AssistantProps = {}) => {
 					const body = options.body as Record<string, unknown>;
 					const messages = options.messages as UIMessage[];
 					const selectedSessionId =
-						readSessionIdFromUrl() ??
-						readActiveSessionId() ??
-						initialSessionId?.trim() ??
-						null;
-					const lastSessionId = getLastSessionId(messages);
+						readSessionIdFromUrl() ?? readActiveSessionId() ?? null;
 					const pendingWorkspaceSessionId =
 						!selectedSessionId && messages.length <= 1
 							? readPendingWorkspaceSessionId()
@@ -73,8 +70,7 @@ export const Assistant = ({ initialSessionId }: AssistantProps = {}) => {
 					const outgoingSessionId =
 						selectedResumeSessionId ??
 						pendingWorkspaceSessionId ??
-						lastSessionId ??
-						options.id;
+						createLocalSessionId();
 					const lastUserMessage = [...messages]
 						.reverse()
 						.find((message) => message.role === "user");
@@ -86,13 +82,12 @@ export const Assistant = ({ initialSessionId }: AssistantProps = {}) => {
 							...body,
 							id: outgoingSessionId,
 							messages: lastUserMessage ? [lastUserMessage] : [],
-							resumeSessionId:
-								selectedResumeSessionId ?? lastSessionId ?? undefined,
+							resumeSessionId: selectedResumeSessionId ?? undefined,
 						},
 					};
 				},
 			}),
-		[initialSessionId],
+		[],
 	);
 	const runtime = useChatRuntime({
 		transport,
@@ -410,15 +405,3 @@ function ActivityDrawerTrigger() {
 		</Button>
 	);
 }
-
-function getLastSessionId(messages: UIMessage[]) {
-	for (const message of [...messages].reverse()) {
-		if (message.role !== "assistant") continue;
-		const metadata = message.metadata;
-		if (metadata && typeof metadata === "object" && "sessionId" in metadata) {
-			const sessionId = (metadata as { sessionId?: unknown }).sessionId;
-			if (typeof sessionId === "string" && sessionId) return sessionId;
-		}
-	}
-	return undefined;
-}

frontend/app/lib/claw-active-session.ts

@@ -50,6 +50,13 @@ export function clearActiveSessionId() {
 	);
 }
 
+export function createLocalSessionId() {
+	if (typeof crypto !== "undefined" && "randomUUID" in crypto) {
+		return `__LOCALID_${crypto.randomUUID().replace(/-/g, "").slice(0, 8)}`;
+	}
+	return `__LOCALID_${Math.random().toString(36).slice(2, 10)}`;
+}
+
 export function writePendingWorkspaceSessionId(
 	sessionId: string | null | undefined,
 ) {