docs: clarify default data flow

docs/target-architecture.md

@@ -154,6 +154,8 @@ source of truth for historical queries.
 
 ## Data Flow
 
+Default production flow:
+
 ```mermaid
 flowchart LR
   vehicle["Vehicles / Platforms"] --> ingest["Protocol apps"]
@@ -161,12 +163,14 @@ flowchart LR
   ingest --> kafka["Kafka<br/>event + raw envelopes"]
   kafka --> history["vehicle-history-app"]
   kafka --> analytics["vehicle-analytics-app"]
-  kafka --> state["vehicle-state-service"]
   history --> tdengine["TDengine<br/>raw_frames + locations"]
   analytics --> mysql["MySQL<br/>vehicle_stat_metric"]
-  state --> redisState["Redis<br/>latest state"]
 ```
 
+Optional latest-state flow, enabled only with `-Poptional-latest-state`, consumes
+the same Kafka envelopes and rebuilds Redis snapshots outside the default
+production deployment.
+
 ## Failure Handling
 
 - Protocol apps continue accepting traffic when history, analytics, or Redis

modules/apps/vehicle-history-app/src/test/java/com/lingniu/ingest/historyapp/MavenModuleProfileTest.java

@@ -494,6 +494,7 @@ class MavenModuleProfileTest {
     @Test
     void productionDocsMatchCompactHistoryAndJt808OnlyAnalyticsSurface() throws Exception {
         String moduleDataFlow = Files.readString(repositoryRoot().resolve("docs/module-data-flow.html"));
+        String targetArchitecture = Files.readString(repositoryRoot().resolve("docs/target-architecture.md"));
         String tdengineVerification = Files.readString(repositoryRoot()
                 .resolve("docs/operations/vehicle-ingest-tdengine-verification.md"));
         String runbook = Files.readString(repositoryRoot()
@@ -511,6 +512,10 @@ class MavenModuleProfileTest {
                 .contains("| `vehicle.event.gb32960.v1` | `gb32960-ingest-app` | `vehicle-history-app` |")
                 .contains("| `vehicle.event.jt808.v1` | `jt808-ingest-app` | `vehicle-history-app`, `vehicle-analytics-app` |")
                 .doesNotContain("| `vehicle.event.gb32960.v1` | `gb32960-ingest-app` | `vehicle-history-app`, `vehicle-analytics-app` |");
+        assertThat(targetArchitecture)
+                .contains("vehicle-state-service is absent from the default Maven reactor")
+                .doesNotContain("kafka --> state[\"vehicle-state-service\"]")
+                .doesNotContain("state --> redisState[\"Redis<br/>latest state\"]");
     }
 
     @Test