fix(chat): make the server the only writer of session messages

List GET no longer ships transcripts; consult appends questions after reserve and ignores client history so dual-tab last-write-wins cannot erase messages.

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

frontend/src/app/api/consult/route.ts

@@ -71,6 +71,7 @@ import {
   loadGeneralDailyPanchangaContext,
   type GeneralDailyPanchangaContext,
 } from "@/lib/general-daily-panchanga";
+import { consultationHistoryFromStoredMessages } from "@/lib/consultation-session-history";
 import { z } from "zod";
 
 export const runtime = "nodejs";
@@ -94,6 +95,7 @@ const chatRequestMetadataSchema = z.object({
       }),
     )
     .max(20)
+    .optional()
     .default([]),
 });
 
@@ -143,6 +145,11 @@ const consultationCompletionSchema = z.object({
   error_code: z.string().nullable().optional(),
 });
 
+const consultationQuestionAppendSchema = z.object({
+  success: z.boolean(),
+  error_code: z.string().nullable().optional(),
+});
+
 function first<T>(value: T | T[]): T {
   return Array.isArray(value) ? value[0] : value;
 }
@@ -273,7 +280,7 @@ export async function POST(request: Request) {
 
   const { data: chatSession, error: chatSessionError } = await supabase
     .from("chat_sessions")
-    .select("id,model_id,model_config_version,session_type")
+    .select("id,model_id,model_config_version,session_type,messages")
     .eq("id", parsed.data.sessionId)
     .eq("user_id", user.id)
     .maybeSingle();
@@ -329,11 +336,11 @@ export async function POST(request: Request) {
   const consultationTheme = parsed.data.theme;
   const visibleQuestion = parsed.data.question;
 
+  // Client `history` stays in the request schema for old bundles and is not read.
+  const storedHistory = consultationHistoryFromStoredMessages(chatSession.messages);
   const userControlledPrompt = [
     parsed.data.question,
-    ...parsed.data.history
-      .filter((message) => message.role === "user")
-      .map((message) => message.text),
+    ...storedHistory.filter((message) => message.role === "user").map((message) => message.text),
   ].join("\n");
   if (blocksPromptExtraction(userControlledPrompt)) {
     return NextResponse.json(
@@ -504,6 +511,46 @@ export async function POST(request: Request) {
     }
   }
 
+  let appendedQuestion: { success: boolean; error_code?: string | null };
+  try {
+    appendedQuestion = await retryDetachedSettlement(async () => {
+      const { data, error } = await accounting.rpc("append_consultation_question", {
+        p_user_id: userId,
+        p_request_id: requestId,
+        p_session_id: sessionId,
+        p_question_message: { role: "user", text: visibleQuestion },
+      });
+      const parsedAppend = consultationQuestionAppendSchema.safeParse(first(data ?? []));
+      if (error || !parsedAppend.success) {
+        throw new CreditRpcError(error?.message || "invalid_question_append_response");
+      }
+      return parsedAppend.data;
+    });
+  } catch {
+    await cancel();
+    return NextResponse.json(
+      { error: "暂时无法保存问题", message: "请稍后重试。" },
+      { status: 503 },
+    );
+  }
+  if (!appendedQuestion.success) {
+    await cancel();
+    if (appendedQuestion.error_code === "session_full") {
+      return NextResponse.json(
+        {
+          error: "这段对话已写满",
+          message: "这段对话已写满，开个新对话继续吧",
+          code: "session_full",
+        },
+        { status: 409 },
+      );
+    }
+    return NextResponse.json(
+      { error: "暂时无法保存问题", message: "请稍后重试。" },
+      { status: 503 },
+    );
+  }
+
   const usageStartedAt = Date.now();
   async function usagePayload(usage: Promise<{ inputTokens?: number; outputTokens?: number }>) {
     const resolved = await usage;
@@ -1044,7 +1091,7 @@ export async function POST(request: Request) {
   }
 
   try {
-    const { history } = parsed.data;
+    const history = storedHistory;
     const name = prepared.serverChart?.name ?? prepared.declaredWindow?.name ?? parsed.data.name;
     const consultationMode: ConsultationBirthTimeMode = prepared.consultationMode;
     const generalDailyContext = shouldLoadGeneralDailyPanchanga({