新鲜度只管「今天该用哪份」：显式指定日期是复盘取历史那份，不受今天的界约束

plan.py

@@ -946,9 +946,10 @@ def from_snapshot(date: str | None = None, top: int = 20, obs_top: int = 10,
     full_main, full_obs = snap.get("main"), snap.get("observe")
     if not isinstance(full_main, list) or not isinstance(full_obs, list):
         raise RuntimeError(f"快照缺全量主榜或观察档: {path}")
-    ok, why = snapshot_fresh_enough(snap)
-    if not ok:
-        raise StaleSnapshot(why)
+    if not date:                 # 只有「要今天该用的那份」才谈新鲜度
+        ok, why = snapshot_fresh_enough(snap)
+        if not ok:
+            raise StaleSnapshot(why)
 
     data = {k: v for k, v in snap.items()
             # 前三个是落盘那次的裁剪结果与参数，与本次请求无关；

test_plan_snapshot.py

@@ -148,6 +148,17 @@ def test_freshness_guard():
 
     t("守卫用的是专门的异常类型，调用方接得住", issubclass(plan.StaleSnapshot, RuntimeError))
 
+    # 新鲜度只管「今天该用哪份」。复盘要看 09-08 那天的计划，拿的就该是那天那份旧快照
+    import glob as _g, os as _o
+    fs = sorted(_g.glob(_o.path.join(config.PLAN_SNAPSHOT_DIR, "plan_*.json")))
+    if fs:
+        ds = _o.path.basename(fs[-1])[len("plan_"):-len(".json")]
+        try:
+            plan.from_snapshot(ds, 5, 3, 2)
+            t("显式指定日期不受今天的新鲜度约束（复盘要拿历史那份）", True)
+        except plan.StaleSnapshot as e:
+            t("显式指定日期不受今天的新鲜度约束（复盘要拿历史那份）", False, e)
+
 
 def test_api_falls_back():
     print("[接口回落：读不到快照不能让接口挂掉]")