feat: add gb32960 session diagnostics

modules/protocols/protocol-gb32960/src/test/java/com/lingniu/ingest/protocol/gb32960/inbound/Gb32960ChannelHandlerAckBoundaryTest.java

@@ -139,7 +139,8 @@ class Gb32960ChannelHandlerAckBoundaryTest {
                 dispatcher,
                 accessService(),
                 new Gb32960AckService(),
-                new Gb32960FrameDiagnostics(16));
+                new Gb32960FrameDiagnostics(16),
+                new Gb32960ConnectionDiagnostics());
     }
 
     private static Gb32960MessageDecoder decoder() {

modules/protocols/protocol-gb32960/src/test/java/com/lingniu/ingest/protocol/gb32960/inbound/Gb32960ConnectionDiagnosticsTest.java

@@ -0,0 +1,78 @@
+package com.lingniu.ingest.protocol.gb32960.inbound;
+
+import com.lingniu.ingest.protocol.gb32960.model.CommandType;
+import org.junit.jupiter.api.Test;
+
+import java.time.Clock;
+import java.time.Instant;
+import java.time.ZoneOffset;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class Gb32960ConnectionDiagnosticsTest {
+
+    private static final Instant NOW = Instant.parse("2026-06-29T10:00:00Z");
+
+    @Test
+    void tracksActiveSessionCommandPlatformAccountAndReadIdleCount() {
+        MutableClock clock = new MutableClock(NOW);
+        Gb32960ConnectionDiagnostics diagnostics = new Gb32960ConnectionDiagnostics(clock);
+
+        diagnostics.opened("session-1", "127.0.0.1:65469");
+        clock.advanceSeconds(5);
+        diagnostics.received("session-1", CommandType.PLATFORM_LOGIN, "");
+        diagnostics.platformLoginAccepted("session-1", "Hyundai");
+        clock.advanceSeconds(30);
+        diagnostics.readIdle("session-1");
+
+        assertThat(diagnostics.activeSessions()).singleElement().satisfies(session -> {
+            assertThat(session.sessionId()).isEqualTo("session-1");
+            assertThat(session.peer()).isEqualTo("127.0.0.1:65469");
+            assertThat(session.connectedAt()).isEqualTo(NOW);
+            assertThat(session.lastInboundAt()).isEqualTo(NOW.plusSeconds(5));
+            assertThat(session.idleSeconds()).isEqualTo(30);
+            assertThat(session.lastCommandCode()).isEqualTo(0x05);
+            assertThat(session.lastCommand()).isEqualTo("PLATFORM_LOGIN");
+            assertThat(session.vin()).isEmpty();
+            assertThat(session.platformAccount()).isEqualTo("Hyundai");
+            assertThat(session.readIdleCount()).isEqualTo(1);
+        });
+    }
+
+    @Test
+    void removesSessionWhenChannelCloses() {
+        Gb32960ConnectionDiagnostics diagnostics = new Gb32960ConnectionDiagnostics(Clock.fixed(NOW, ZoneOffset.UTC));
+
+        diagnostics.opened("session-1", "127.0.0.1:65469");
+        diagnostics.closed("session-1");
+
+        assertThat(diagnostics.activeSessions()).isEmpty();
+    }
+
+    private static final class MutableClock extends Clock {
+        private Instant instant;
+
+        private MutableClock(Instant instant) {
+            this.instant = instant;
+        }
+
+        void advanceSeconds(long seconds) {
+            instant = instant.plusSeconds(seconds);
+        }
+
+        @Override
+        public ZoneOffset getZone() {
+            return ZoneOffset.UTC;
+        }
+
+        @Override
+        public Clock withZone(java.time.ZoneId zone) {
+            return this;
+        }
+
+        @Override
+        public Instant instant() {
+            return instant;
+        }
+    }
+}