docs: align jt808 mileage storage

docs/operations/jt808-daily-mileage-runbook.md

@@ -2,11 +2,11 @@
 
 ## Scope
 
-The analytics app can calculate daily mileage from JT808 telemetry only. It consumes `vehicle.event.jt808.v1`, keeps the rolling per-vehicle daily state in Redis, and saves the current daily result into the common `vehicle-stat` metric repository.
+The analytics app can calculate daily mileage from JT808 telemetry only. It consumes `vehicle.event.jt808.v1` and saves the current daily result into the common `vehicle-stat` metric repository.
 
 ## Storage
 
-There is no separate JT808 daily-mileage table. Runtime state is stored under the configured JT808 state store so the stream can continue after restart. The derived metric is written through `VehicleStatRepository.saveDailyStat(...)` into the common JDBC/MySQL metric table `vehicle_stat_metric`.
+There is no separate JT808 daily-mileage table and no Redis mileage state. The current day start total, latest total, and derived daily mileage are all stored in the common JDBC/MySQL metric table `vehicle_stat_metric`.
 
 The JT808 daily-mileage value is calculated from the GPS total mileage reported in location additional information:
 
@@ -15,7 +15,7 @@ daily_mileage_km = last_total_mileage_km - first_total_mileage_km
 calculation_method = JT808_TOTAL_MILEAGE_DIFF
 ```
 
-The metric is saved only after at least two ordered JT808 location points with valid `total_mileage_km` have been received for the same vehicle and local day. If the difference is negative, no metric row is saved for that state update.
+The first valid JT808 location point for a vehicle and local day stores the day start total and writes `daily_mileage_km=0.0`. Later ordered points update the latest total and the derived `daily_mileage_km`. If a later total mileage is lower than the stored start or latest total, the update is ignored and the previous metric remains.
 
 ## Runtime Settings
 
@@ -27,10 +27,6 @@ VEHICLE_STAT_JT808_MILEAGE_ENABLED=true
 MYSQL_JDBC_URL=<jdbc-url>
 MYSQL_USERNAME=<user>
 MYSQL_PASSWORD=<password>
-REDIS_HOST=<host>
-REDIS_PORT=6379
-REDIS_DATABASE=50
-REDIS_PASSWORD=<password>
 ```
 
-Algorithm defaults use the Asia/Shanghai daily boundary. The rolling state stores only the fields needed by the GPS total-mileage difference calculation.
+Algorithm defaults use the Asia/Shanghai daily boundary. Restart recovery reads the same `vehicle_stat_metric` rows, so no separate mileage state store is required.

docs/target-architecture.md

@@ -126,10 +126,11 @@ calculation_method = JT808_TOTAL_MILEAGE_DIFF
 
 - Store the metric in `vehicle_stat_metric` with
   `metric_key = daily_mileage_km`.
-- Keep rolling daily calculation state in Redis.
 
 There is no JT808-specific daily mileage table and no in-memory production
-state-store mode.
+state-store mode. Daily start total, latest total, and derived mileage are all
+stored in `vehicle_stat_metric`, so restart recovery does not require a separate
+Redis mileage state.
 
 ### Latest State
 
@@ -156,7 +157,6 @@ flowchart LR
   kafka --> state["vehicle-state-service"]
   history --> tdengine["TDengine<br/>raw_frames + locations"]
   analytics --> mysql["MySQL<br/>vehicle_stat_metric"]
-  analytics --> redisCalc["Redis<br/>mileage state"]
   state --> redisState["Redis<br/>latest state"]
 ```
 
@@ -167,7 +167,8 @@ flowchart LR
 - Kafka producer failures are handled by sink retry/circuit-breaker behavior and
   DLQ topics where configured.
 - History consumers should commit offsets only after TDengine writes succeed.
-- Analytics state can recover from Redis state or Kafka replay.
+- Analytics daily mileage state can recover from `vehicle_stat_metric` or Kafka
+  replay.
 - Raw archive failures must be observable, but event publication and history
   indexing remain separate concerns.
 
@@ -182,6 +183,6 @@ flowchart LR
 - Location queries page over compact rows and reference raw records instead of
   duplicating full raw JSON.
 - JT808 daily mileage is stored only in `vehicle_stat_metric`.
-- Runtime state needed for 808 mileage uses Redis, with no production memory
+- Runtime state needed for 808 mileage is also in `vehicle_stat_metric`, with no
-  mode.
+  Redis or production memory state-store mode.
 - Build validation covers the active modules and their composition tests.