fix(web): persist generated session titles against the post-RPC title (BUG-557)

The first-round title guard compared the pre-RPC snapshot, so append_consultation_question had already rewritten the title and the model name never landed.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/session-title-guard.ts

@@ -0,0 +1,40 @@
+type GuardedTitleUpdate = {
+  eq: (column: string, value: string) => GuardedTitleUpdate;
+  select: (columns: "id") => PromiseLike<{ data: Array<{ id?: string }> | null; error: unknown }>;
+};
+
+export type GuardedTitleClient = {
+  from: (table: "chat_sessions") => {
+    update: (values: { title: string }) => GuardedTitleUpdate;
+  };
+};
+
+export async function persistGuardedSessionTitle(input: {
+  client: GuardedTitleClient;
+  sessionId: string;
+  userId: string;
+  expectedTitle: string;
+  title: string;
+  warn?: (message: string, extra?: unknown) => void;
+}): Promise<"updated" | "missed" | "failed"> {
+  const warn = input.warn ?? ((message: string, extra?: unknown) => console.warn(message, extra));
+  try {
+    const { data, error } = await input.client.from("chat_sessions").update({ title: input.title })
+      .eq("id", input.sessionId)
+      .eq("user_id", input.userId)
+      .eq("title", input.expectedTitle)
+      .select("id");
+    if (error) {
+      warn("session title persist failed", error);
+      return "failed";
+    }
+    if (!data?.length) {
+      warn("session title guard missed");
+      return "missed";
+    }
+    return "updated";
+  } catch (error) {
+    warn("session title persist failed", error);
+    return "failed";
+  }
+}