update

backend/README.md

@@ -32,9 +32,17 @@ uv run ruff check .
 ## Gold Cache and Notifications
 
 - Application startup checks both realtime and official gold caches, then checks
-  them every minute. Data older than 30 minutes refreshes without HTTP traffic.
+  them at wall-clock minute boundaries. Each half-hour batch starts 5 minutes
+  early: 01:25 collects the 01:30 batch, 01:55 collects the 02:00 batch, without
+  HTTP traffic. All regions in a refresh share the batch timestamp selected at
+  the start, even if the work crosses a half-hour boundary. Existing public
+  `updataTime` types remain number for realtime and string for official.
   Redis locks prevent duplicate work across workers. Realtime region pages stay
   8 seconds apart. Failures retain the last successful data for up to 24 hours.
+- Realtime uses the arithmetic mean of displayed unit prices from rows 4–10
+  (`i.item1`, slice `[3:10]`), in 元/万金币, rounded to 2 decimals. This replaces
+  the earlier 万金币/元 average and uses a new Redis namespace so old units are
+  never returned as new prices. No BeautifulSoup or browser dependency is added.
 - Official authentication uses `HELPER_TOKEN` and `HELPER_ID`. Authentication
   failures (`returnCode=-30003`, explicit token-expiry messages or HTTP 401) can
   notify via Bark. Network errors do not trigger token-expiry notifications.
@@ -46,8 +54,9 @@ uv run ruff check .
   included in notification text or logged push errors.
 - Official gold responses also contain `max` and `min`: the largest/smallest
   values of `10000 / price` across both rank arrays, in 万金币 per 100点券,
-  rounded to 4 decimals. Nonpositive/invalid prices are excluded; absent valid
-  quotes yield `null`. Existing rank arrays retain their 点券 per 100万金币 unit.
+  rounded to 2 decimals. Nonpositive/invalid prices are excluded; absent valid
+  quotes yield `null`. Rank arrays retain their 点券 per 100万金币 unit and are
+  also rounded to 2 decimals. JSON numbers do not force trailing zeroes.
 
 ## Compatibility Rules