fix: scope observation to current turn

Require assistant natural language after the latest user message so a completed prompt cannot reuse historical replies when queuing the observation snapshot.

src/lib/agent-session-sync.ts

@@ -363,8 +363,22 @@ export function queueAgentSessionSync(
 
 /** Queue the final product Conversation snapshot after a completed prompt turn. */
 export function queueCodingConversationSessionSync(snapshot: ConversationSnapshot): void {
-  const messages: RawMessage[] = snapshot.nodes.flatMap((node) => {
-    if (node.kind !== 'message') return [];
+  const messageNodes = snapshot.nodes.filter((node) => node.kind === 'message');
+  let lastUserIndex = -1;
+  for (let index = messageNodes.length - 1; index >= 0; index -= 1) {
+    if (messageNodes[index].role === 'user') {
+      lastUserIndex = index;
+      break;
+    }
+  }
+  if (lastUserIndex < 0) return;
+  const currentTurnAssistantIds = new Set(messageNodes
+    .slice(lastUserIndex + 1)
+    .filter((node) => node.role === 'assistant')
+    .map((node) => node.id));
+  if (currentTurnAssistantIds.size === 0) return;
+
+  const messages: RawMessage[] = messageNodes.flatMap((node) => {
     return [{
       id: node.id,
       role: node.role,
@@ -384,7 +398,11 @@ export function queueCodingConversationSessionSync(snapshot: ConversationSnapsho
     messages,
     updatedAt,
   );
-  if (!data?.messages.some((message) => message.role === 'assistant')) return;
+  if (!data?.messages.some((message) => (
+    message.role === 'assistant'
+    && typeof message.id === 'string'
+    && currentTurnAssistantIds.has(message.id)
+  ))) return;
   queueAgentSessionData(data);
 }