Preserve positionless aircraft identities for classification

src/layers/aircraft/classification.js

@@ -129,10 +129,17 @@ export function createMilitaryRegistry({ source, now = Date.now } = {}) {
     const signal = AbortSignal.any([owner.signal, AbortSignal.timeout(10000)]);
     _polling = true;
     try {
-      const snapshot = await requestSource.getSnapshot({}, { signal });
+      const ids =
+        typeof requestSource.getIdentities === 'function'
+          ? await requestSource.getIdentities({}, { signal })
+          : (await requestSource.getSnapshot({}, { signal })).records.map(
+              (record) => record.id,
+            );
       signal.throwIfAborted();
       if (lifetime !== owner) return;
-      registerMilitaryIcaos(snapshot.records.map((record) => record.id));
+      if (!Array.isArray(ids))
+        throw new TypeError('Expected aircraft identities');
+      registerMilitaryIcaos(ids);
     } catch {
       // Keep the existing classification through source outages.
     } finally {

src/layers/aircraft/classification.test.mjs

@@ -121,3 +121,21 @@ test('disposing a registry fed directly by its layer also clears classification'
   registry.dispose();
   assert.equal(registry.isMilitaryIcao('abc123'), false);
 });
+
+test('classification prefers an explicit identity capability over positioned observations', async () => {
+  const registry = createMilitaryRegistry({
+    source: {
+      getSnapshot() {
+        assert.fail(
+          'position snapshots must not replace an available identity capability',
+        );
+      },
+      async getIdentities() {
+        return ['abc123'];
+      },
+    },
+  });
+  await registry.refreshMilitaryRegistryIfStale();
+  assert.equal(registry.isMilitaryIcao('abc123'), true);
+  registry.dispose();
+});