fix: harden typed metrics review findings

crates/crank-metrics/tests/contract.rs

@@ -182,7 +182,7 @@ fn every_recording_api_matches_the_declared_schema() {
     let snapshotter = recorder.snapshotter();
 
     metrics::with_local_recorder(&recorder, || {
-        initialize_gauges();
+        initialize_gauges(crank_metrics::MetricService::McpServer);
         record_http_request(
             HttpRoute::from_matched_path("/api/auth/session"),
             HttpMethod::Get,
@@ -256,3 +256,22 @@ fn every_recording_api_matches_the_declared_schema() {
         );
     }
 }
+
+#[test]
+fn admin_gauge_initialization_never_emits_mcp_only_series() {
+    let recorder = DebuggingRecorder::new();
+    let snapshotter = recorder.snapshotter();
+    metrics::with_local_recorder(&recorder, || {
+        initialize_gauges(crank_metrics::MetricService::AdminApi);
+    });
+    let names = snapshotter
+        .snapshot()
+        .into_vec()
+        .into_iter()
+        .map(|(key, _, _, _)| key.key().name().to_owned())
+        .collect::<BTreeSet<_>>();
+    assert!(!names.iter().any(|name| name.starts_with("crank_mcp_")));
+    assert!(!names.iter().any(|name| name.starts_with("crank_catalog_")));
+    assert!(names.contains("crank_http_inflight"));
+    assert!(names.contains("crank_runtime_inflight"));
+}