feat: 已接受契约持久化 — 保存/加载/自动展示

- PATCH /api/blindbox/plan: 接受契约时更新状态为 accepted
- GET /api/blindbox/plan: 查询房间内最近一次已接受的计划
- 进入房间时自动加载已接受计划并展示行程视图
- 修复整个周末想法不足时重复活动的问题（不足则只生成一天）

src/app/api/blindbox/plan/route.ts

@@ -190,16 +190,18 @@ export const POST = apiHandler(async (req) => {
         ]
       : [at];
 
-  // Select ideas per day, avoiding duplicates across days when possible
+  // Select ideas per day — skip extra days when ideas run out
   const dayIdeas: TaggedIdea[][] = [];
   const usedIds = new Set<string>();
   for (const dayConfig of dayConfigs) {
     const remaining = taggedIdeas.filter((i) => !usedIds.has(i.id));
-    const pool = remaining.length >= 2 ? remaining : taggedIdeas;
-    const selected = selectIdeasForSlots(pool, dayConfig.endHour - dayConfig.startHour);
+    if (remaining.length < 2) break;
+    const selected = selectIdeasForSlots(remaining, dayConfig.endHour - dayConfig.startHour);
     for (const idea of selected) usedIds.add(idea.id);
     dayIdeas.push(selected);
   }
+  // Trim to actual days generated (may be fewer than requested for "整个周末")
+  const actualDayConfigs = dayConfigs.slice(0, dayIdeas.length);
 
   const allSelected = dayIdeas.flat();
   if (allSelected.length === 0) {
@@ -260,7 +262,7 @@ export const POST = apiHandler(async (req) => {
 
   // Generate schedule for each day (parallel AI calls)
   const schedules = await Promise.all(
-    dayConfigs.map((dayConfig, idx) => {
+    actualDayConfigs.map((dayConfig, idx) => {
       const ideas = dayIdeas[idx];
       const ctx: ScheduleContext = {
         ideas: ideas.map((i) => ({
@@ -282,7 +284,7 @@ export const POST = apiHandler(async (req) => {
   const days = schedules
     .map((schedule, idx) =>
       schedule
-        ? { date: dayConfigs[idx].date, items: schedule.items, summary: schedule.summary }
+        ? { date: actualDayConfigs[idx].date, items: schedule.items, summary: schedule.summary }
         : null,
     )
     .filter((d) => d !== null);
@@ -308,3 +310,47 @@ export const POST = apiHandler(async (req) => {
     createdAt: plan.createdAt,
   });
 });
+
+export const PATCH = apiHandler(async (req) => {
+  const { planId, userId } = await req.json();
+  requireUserId(userId);
+  if (!planId) throw new ApiError("planId 不能为空");
+
+  const plan = await prisma.weekendPlan.findUnique({ where: { id: planId } });
+  if (!plan) throw new ApiError("计划不存在", 404);
+  if (plan.userId !== userId) throw new ApiError("只能接受自己的计划", 403);
+
+  await prisma.weekendPlan.update({
+    where: { id: planId },
+    data: { status: "accepted" },
+  });
+
+  return NextResponse.json({ ok: true });
+});
+
+export const GET = apiHandler(async (req) => {
+  const { searchParams } = new URL(req.url);
+  const roomId = searchParams.get("roomId");
+  const userId = searchParams.get("userId");
+
+  requireUserId(userId);
+  if (!roomId) throw new ApiError("roomId 不能为空");
+
+  const plan = await prisma.weekendPlan.findFirst({
+    where: { roomId, userId: userId!, status: "accepted" },
+    orderBy: { createdAt: "desc" },
+    select: { id: true, planData: true, createdAt: true },
+  });
+
+  if (!plan) return NextResponse.json({ plan: null });
+
+  const parsed = JSON.parse(plan.planData);
+
+  return NextResponse.json({
+    plan: {
+      id: plan.id,
+      days: parsed.days,
+      createdAt: plan.createdAt,
+    },
+  });
+});