fix(mobile): deduplicate people in asset details panel (#28972)

mobile/lib/infrastructure/repositories/people.repository.dart

@@ -16,20 +16,21 @@ class DriftPeopleRepository extends DriftDatabaseRepository {
   }
 
   Future<List<DriftPerson>> getAssetPeople(String assetId) async {
-    final query =
-        _db.select(_db.assetFaceEntity).join([
-          innerJoin(_db.personEntity, _db.personEntity.id.equalsExp(_db.assetFaceEntity.personId)),
-        ])..where(
-          _db.assetFaceEntity.assetId.equals(assetId) &
-              _db.assetFaceEntity.isVisible.equals(true) &
-              _db.assetFaceEntity.deletedAt.isNull() &
-              _db.personEntity.isHidden.equals(false),
-        );
+    // An asset can have multiple face records for the same person (e.g., metadata
+    // imports alongside ML detections). Use a subquery instead of a join so each
+    // person is returned once, regardless of how many of their faces are on the asset
+    final faceQuery = _db.assetFaceEntity.selectOnly()
+      ..addColumns([_db.assetFaceEntity.personId])
+      ..where(
+        _db.assetFaceEntity.assetId.equals(assetId) &
+            _db.assetFaceEntity.isVisible.equals(true) &
+            _db.assetFaceEntity.deletedAt.isNull(),
+      );
 
-    return query.map((row) {
-      final person = row.readTable(_db.personEntity);
-      return person.toDto();
-    }).get();
+    final query = _db.select(_db.personEntity)
+      ..where((row) => row.id.isInQuery(faceQuery) & row.isHidden.equals(false));
+
+    return query.map((row) => row.toDto()).get();
   }
 
   Future<List<DriftPerson>> getAllPeople({int minFaces = 3}) async {

mobile/test/medium/repositories/people_repository_test.dart

@@ -0,0 +1,77 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_mobile/infrastructure/repositories/people.repository.dart';
+
+import '../repository_context.dart';
+
+void main() {
+  late MediumRepositoryContext ctx;
+  late DriftPeopleRepository sut;
+
+  setUp(() {
+    ctx = MediumRepositoryContext();
+    sut = DriftPeopleRepository(ctx.db);
+  });
+
+  tearDown(() async {
+    await ctx.dispose();
+  });
+
+  group('getAssetPeople', () {
+    test('does not duplicate a person with multiple face records on the same asset', () async {
+      // Regression check for #20585: a join on asset_face_entity returned one row
+      // per face, so a person appeared twice in the asset details panel when the
+      // same face was on the asset more than once (e.g., metadata import + ML)
+      final user = await ctx.newUser();
+      final asset = await ctx.newRemoteAsset(ownerId: user.id);
+
+      final person = await ctx.newPerson(ownerId: user.id);
+      await ctx.newFace(assetId: asset.id, personId: person.id);
+      await ctx.newFace(assetId: asset.id, personId: person.id);
+
+      final people = await sut.getAssetPeople(asset.id);
+
+      expect(people, hasLength(1));
+      expect(people.single.id, person.id);
+    });
+
+    test('returns all distinct people of an asset', () async {
+      final user = await ctx.newUser();
+      final asset = await ctx.newRemoteAsset(ownerId: user.id);
+
+      final person1 = await ctx.newPerson(ownerId: user.id);
+      final person2 = await ctx.newPerson(ownerId: user.id);
+      await ctx.newFace(assetId: asset.id, personId: person1.id);
+      await ctx.newFace(assetId: asset.id, personId: person2.id);
+
+      final people = await sut.getAssetPeople(asset.id);
+
+      expect(people, hasLength(2));
+      expect(people.map((person) => person.id), containsAll([person1.id, person2.id]));
+    });
+
+    test('does not return hidden people', () async {
+      final user = await ctx.newUser();
+      final asset = await ctx.newRemoteAsset(ownerId: user.id);
+
+      final hidden = await ctx.newPerson(ownerId: user.id, isHidden: true);
+      await ctx.newFace(assetId: asset.id, personId: hidden.id);
+
+      final people = await sut.getAssetPeople(asset.id);
+
+      expect(people, isEmpty);
+    });
+
+    test('does not return people from other assets', () async {
+      final user = await ctx.newUser();
+      final asset = await ctx.newRemoteAsset(ownerId: user.id);
+      final otherAsset = await ctx.newRemoteAsset(ownerId: user.id);
+
+      final person = await ctx.newPerson(ownerId: user.id);
+      await ctx.newFace(assetId: otherAsset.id, personId: person.id);
+
+      final people = await sut.getAssetPeople(asset.id);
+
+      expect(people, isEmpty);
+    });
+  });
+}