diff --git a/packages/dart/lib/src/network/options.dart b/packages/dart/lib/src/network/options.dart
index 5b07d7303..4b6bb1c62 100644
--- a/packages/dart/lib/src/network/options.dart
+++ b/packages/dart/lib/src/network/options.dart
@@ -1,9 +1,14 @@
 part of '../../parse_server_sdk.dart';
 
 class ParseNetworkOptions {
-  ParseNetworkOptions({this.headers});
+  ParseNetworkOptions({this.headers, this.sendInstallationId});
 
   final Map<String, String>? headers;
+
+  /// When `false`, the client suppresses the `X-Parse-Installation-Id`
+  /// header for this request. `null` (the default) lets the client attach
+  /// the header — matching iOS PFURLSessionCommandRunner behaviour.
+  final bool? sendInstallationId;
   // final ParseNetworkResponseType responseType;
 }
 
diff --git a/packages/dart/lib/src/network/parse_client.dart b/packages/dart/lib/src/network/parse_client.dart
index 2104fc20a..a013cd5db 100644
--- a/packages/dart/lib/src/network/parse_client.dart
+++ b/packages/dart/lib/src/network/parse_client.dart
@@ -69,6 +69,33 @@ abstract class ParseClient {
 
   @Deprecated("Use ParseCoreData() instead.")
   ParseCoreData get data => ParseCoreData();
+
+  /// Returns `options.headers` with `X-Parse-Installation-Id` attached unless
+  /// the caller opted out via `ParseNetworkOptions.sendInstallationId = false`
+  /// or the header is already set. Installation lookup failures fall through
+  /// silently — a network call should not fail because the install ID could
+  /// not be read.
+  @protected
+  Future<Map<String, String>?> buildHeaders(
+    ParseNetworkOptions? options,
+  ) async {
+    if (options?.sendInstallationId == false) return options?.headers;
+    if (options?.headers?[keyHeaderInstallationId] != null) {
+      return options?.headers;
+    }
+    String? installationId;
+    try {
+      installationId =
+          (await ParseInstallation.currentInstallation()).installationId;
+    } catch (_) {
+      return options?.headers;
+    }
+    if (installationId == null) return options?.headers;
+    return <String, String>{
+      ...?options?.headers,
+      keyHeaderInstallationId: installationId,
+    };
+  }
 }
 
 /// Callback to listen the progress for sending/receiving data.
diff --git a/packages/dart/lib/src/network/parse_dio_client.dart b/packages/dart/lib/src/network/parse_dio_client.dart
index fb6072bee..417ba5a37 100644
--- a/packages/dart/lib/src/network/parse_dio_client.dart
+++ b/packages/dart/lib/src/network/parse_dio_client.dart
@@ -47,12 +47,13 @@ class ParseDioClient extends ParseClient {
     ParseNetworkOptions? options,
     ProgressCallback? onReceiveProgress,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       operation: () async {
         try {
           final dio.Response<String> dioResponse = await _client.get<String>(
             path,
-            options: _Options(headers: options?.headers),
+            options: _Options(headers: headers),
           );
 
           return ParseNetworkResponse(
@@ -76,6 +77,7 @@ class ParseDioClient extends ParseClient {
     ProgressCallback? onReceiveProgress,
     dynamic cancelToken,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       operation: () async {
         try {
@@ -85,7 +87,7 @@ class ParseDioClient extends ParseClient {
                 cancelToken: cancelToken,
                 onReceiveProgress: onReceiveProgress,
                 options: _Options(
-                  headers: options?.headers,
+                  headers: headers,
                   responseType: dio.ResponseType.bytes,
                 ),
               );
@@ -116,6 +118,7 @@ class ParseDioClient extends ParseClient {
     String? data,
     ParseNetworkOptions? options,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       isWriteOperation: true,
       operation: () async {
@@ -123,7 +126,7 @@ class ParseDioClient extends ParseClient {
           final dio.Response<String> dioResponse = await _client.put<String>(
             path,
             data: data,
-            options: _Options(headers: options?.headers),
+            options: _Options(headers: headers),
           );
 
           return ParseNetworkResponse(
@@ -146,6 +149,7 @@ class ParseDioClient extends ParseClient {
     String? data,
     ParseNetworkOptions? options,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       isWriteOperation: true,
       operation: () async {
@@ -153,7 +157,7 @@ class ParseDioClient extends ParseClient {
           final dio.Response<String> dioResponse = await _client.post<String>(
             path,
             data: data,
-            options: _Options(headers: options?.headers),
+            options: _Options(headers: headers),
           );
 
           return ParseNetworkResponse(
@@ -178,6 +182,7 @@ class ParseDioClient extends ParseClient {
     ProgressCallback? onSendProgress,
     dynamic cancelToken,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       isWriteOperation: true,
       operation: () async {
@@ -186,7 +191,7 @@ class ParseDioClient extends ParseClient {
             path,
             data: data,
             cancelToken: cancelToken,
-            options: _Options(headers: options?.headers),
+            options: _Options(headers: headers),
             onSendProgress: onSendProgress,
           );
 
@@ -235,12 +240,13 @@ class ParseDioClient extends ParseClient {
     String path, {
     ParseNetworkOptions? options,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       operation: () async {
         try {
           final dio.Response<String> dioResponse = await _client.delete<String>(
             path,
-            options: _Options(headers: options?.headers),
+            options: _Options(headers: headers),
           );
 
           return ParseNetworkResponse(
diff --git a/packages/dart/lib/src/network/parse_http_client.dart b/packages/dart/lib/src/network/parse_http_client.dart
index d729733af..c88a78a07 100644
--- a/packages/dart/lib/src/network/parse_http_client.dart
+++ b/packages/dart/lib/src/network/parse_http_client.dart
@@ -47,12 +47,13 @@ class ParseHTTPClient extends ParseClient {
     ParseNetworkOptions? options,
     ProgressCallback? onReceiveProgress,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       operation: () async {
         try {
           final http.Response response = await _client.get(
             Uri.parse(path),
-            headers: options?.headers,
+            headers: headers,
           );
           return ParseNetworkResponse(
             data: response.body,
@@ -75,12 +76,13 @@ class ParseHTTPClient extends ParseClient {
     ProgressCallback? onReceiveProgress,
     dynamic cancelToken,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       operation: () async {
         try {
           final http.Response response = await _client.get(
             Uri.parse(path),
-            headers: options?.headers,
+            headers: headers,
           );
           return ParseNetworkByteResponse(
             bytes: response.bodyBytes,
@@ -102,6 +104,7 @@ class ParseHTTPClient extends ParseClient {
     String? data,
     ParseNetworkOptions? options,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       isWriteOperation: true,
       operation: () async {
@@ -109,7 +112,7 @@ class ParseHTTPClient extends ParseClient {
           final http.Response response = await _client.put(
             Uri.parse(path),
             body: data,
-            headers: options?.headers,
+            headers: headers,
           );
           return ParseNetworkResponse(
             data: response.body,
@@ -131,6 +134,7 @@ class ParseHTTPClient extends ParseClient {
     String? data,
     ParseNetworkOptions? options,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       isWriteOperation: true,
       operation: () async {
@@ -138,7 +142,7 @@ class ParseHTTPClient extends ParseClient {
           final http.Response response = await _client.post(
             Uri.parse(path),
             body: data,
-            headers: options?.headers,
+            headers: headers,
           );
           return ParseNetworkResponse(
             data: response.body,
@@ -162,6 +166,7 @@ class ParseHTTPClient extends ParseClient {
     ProgressCallback? onSendProgress,
     dynamic cancelToken,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       isWriteOperation: true,
       operation: () async {
@@ -174,7 +179,7 @@ class ParseHTTPClient extends ParseClient {
               (List<int> previous, List<int> element) =>
                   previous..addAll(element),
             ),
-            headers: options?.headers,
+            headers: headers,
           );
           return ParseNetworkResponse(
             data: response.body,
@@ -195,12 +200,13 @@ class ParseHTTPClient extends ParseClient {
     String path, {
     ParseNetworkOptions? options,
   }) async {
+    final Map<String, String>? headers = await buildHeaders(options);
     return executeWithRetry(
       operation: () async {
         try {
           final http.Response response = await _client.delete(
             Uri.parse(path),
-            headers: options?.headers,
+            headers: headers,
           );
           return ParseNetworkResponse(
             data: response.body,
diff --git a/packages/dart/lib/src/objects/parse_user.dart b/packages/dart/lib/src/objects/parse_user.dart
index c89a5e87d..f2858a9bd 100644
--- a/packages/dart/lib/src/objects/parse_user.dart
+++ b/packages/dart/lib/src/objects/parse_user.dart
@@ -216,15 +216,11 @@ class ParseUser extends ParseObject implements ParseCloneable {
       final Uri url = getSanitisedUri(_client, path);
       final String body = json.encode(toJson(forApiRQ: true));
       _saveChanges();
-      final String? installationId = await _getInstallationId();
       final ParseNetworkResponse response = await _client.post(
         url.toString(),
         options: ParseNetworkOptions(
-          headers: <String, String>{
-            keyHeaderRevocableSession: '1',
-            if (installationId != null && !doNotSendInstallationID)
-              keyHeaderInstallationId: installationId,
-          },
+          headers: <String, String>{keyHeaderRevocableSession: '1'},
+          sendInstallationId: !doNotSendInstallationID,
         ),
         data: body,
       );
@@ -255,18 +251,14 @@ class ParseUser extends ParseObject implements ParseCloneable {
         keyVarUsername: username!,
         keyVarPassword: password!,
       };
-      final String? installationId = await _getInstallationId();
       final Uri url = getSanitisedUri(_client, keyEndPointLogin);
       _saveChanges();
       final ParseNetworkResponse response = await _client.post(
         url.toString(),
         data: jsonEncode(queryParams),
         options: ParseNetworkOptions(
-          headers: <String, String>{
-            keyHeaderRevocableSession: '1',
-            if (installationId != null && !doNotSendInstallationID)
-              keyHeaderInstallationId: installationId,
-          },
+          headers: <String, String>{keyHeaderRevocableSession: '1'},
+          sendInstallationId: !doNotSendInstallationID,
         ),
       );
 
@@ -292,16 +284,12 @@ class ParseUser extends ParseObject implements ParseCloneable {
     try {
       final Uri url = getSanitisedUri(_client, keyEndPointUsers);
       const Uuid uuid = Uuid();
-      final String? installationId = await _getInstallationId();
 
       final ParseNetworkResponse response = await _client.post(
         url.toString(),
         options: ParseNetworkOptions(
-          headers: <String, String>{
-            keyHeaderRevocableSession: '1',
-            if (installationId != null && !doNotSendInstallationID)
-              keyHeaderInstallationId: installationId,
-          },
+          headers: <String, String>{keyHeaderRevocableSession: '1'},
+          sendInstallationId: !doNotSendInstallationID,
         ),
         data: jsonEncode(<String, dynamic>{
           'authData': <String, dynamic>{
@@ -356,17 +344,13 @@ class ParseUser extends ParseObject implements ParseCloneable {
   }) async {
     try {
       final Uri url = getSanitisedUri(_client, keyEndPointUsers);
-      final String? installationId = await _getInstallationId();
       final Map<String, dynamic> body = toJson(forApiRQ: true);
       body['authData'] = <String, dynamic>{provider: authData};
       final ParseNetworkResponse response = await _client.post(
         url.toString(),
         options: ParseNetworkOptions(
-          headers: <String, String>{
-            keyHeaderRevocableSession: '1',
-            if (installationId != null && !doNotSendInstallationID)
-              keyHeaderInstallationId: installationId,
-          },
+          headers: <String, String>{keyHeaderRevocableSession: '1'},
+          sendInstallationId: !doNotSendInstallationID,
         ),
         data: jsonEncode(body),
       );
@@ -630,10 +614,4 @@ class ParseUser extends ParseObject implements ParseCloneable {
 
   static ParseUser _getEmptyUser() =>
       ParseCoreData.instance.createParseUser(null, null, null);
-
-  static Future<String?> _getInstallationId() async {
-    final ParseInstallation parseInstallation =
-        await ParseInstallation.currentInstallation();
-    return parseInstallation.installationId;
-  }
 }
diff --git a/packages/dart/test/src/network/parse_client_retry_integration_test.mocks.dart b/packages/dart/test/src/network/parse_client_retry_integration_test.mocks.dart
index 9bc333c4e..ff801802b 100644
--- a/packages/dart/test/src/network/parse_client_retry_integration_test.mocks.dart
+++ b/packages/dart/test/src/network/parse_client_retry_integration_test.mocks.dart
@@ -209,4 +209,14 @@ class MockParseClient extends _i1.Mock implements _i2.ParseClient {
             ),
           )
           as _i3.Future<_i2.ParseNetworkByteResponse>);
+
+  @override
+  _i3.Future<Map<String, String>?> buildHeaders(
+    _i2.ParseNetworkOptions? options,
+  ) =>
+      (super.noSuchMethod(
+            Invocation.method(#buildHeaders, [options]),
+            returnValue: _i3.Future<Map<String, String>?>.value(),
+          )
+          as _i3.Future<Map<String, String>?>);
 }
diff --git a/packages/dart/test/src/network/parse_client_test.dart b/packages/dart/test/src/network/parse_client_test.dart
new file mode 100644
index 000000000..5ed1e11d8
--- /dev/null
+++ b/packages/dart/test/src/network/parse_client_test.dart
@@ -0,0 +1,128 @@
+import 'package:parse_server_sdk/parse_server_sdk.dart';
+import 'package:test/test.dart';
+
+import '../../test_utils.dart';
+
+/// Minimal concrete subclass for exercising methods on the abstract
+/// [ParseClient]. All HTTP methods throw — the test suite only targets the
+/// inherited helpers (`buildHeaders`) and never dispatches a real request.
+class _StubParseClient extends ParseClient {
+  @override
+  Future<ParseNetworkResponse> get(
+    String path, {
+    ParseNetworkOptions? options,
+    ProgressCallback? onReceiveProgress,
+  }) => throw UnimplementedError();
+
+  @override
+  Future<ParseNetworkResponse> put(
+    String path, {
+    String? data,
+    ParseNetworkOptions? options,
+  }) => throw UnimplementedError();
+
+  @override
+  Future<ParseNetworkResponse> post(
+    String path, {
+    String? data,
+    ParseNetworkOptions? options,
+  }) => throw UnimplementedError();
+
+  @override
+  Future<ParseNetworkResponse> postBytes(
+    String path, {
+    Stream<List<int>>? data,
+    ParseNetworkOptions? options,
+    ProgressCallback? onSendProgress,
+    dynamic cancelToken,
+  }) => throw UnimplementedError();
+
+  @override
+  Future<ParseNetworkResponse> delete(
+    String path, {
+    ParseNetworkOptions? options,
+  }) => throw UnimplementedError();
+
+  @override
+  Future<ParseNetworkByteResponse> getBytes(
+    String path, {
+    ParseNetworkOptions? options,
+    ProgressCallback? onReceiveProgress,
+    dynamic cancelToken,
+  }) => throw UnimplementedError();
+
+  // Exposes the protected helper so tests can call it without subclass tricks.
+  Future<Map<String, String>?> exposedBuildHeaders(
+    ParseNetworkOptions? options,
+  ) => buildHeaders(options);
+}
+
+void main() {
+  setUpAll(() async {
+    await initializeParse();
+  });
+
+  group('ParseClient.buildHeaders — X-Parse-Installation-Id handling', () {
+    late _StubParseClient client;
+
+    setUp(() {
+      client = _StubParseClient();
+    });
+
+    test('attaches X-Parse-Installation-Id by default. Matches iOS '
+        'PFURLSessionCommandRunner behaviour — every request carries the '
+        'install ID so parse-server can bind created _Session rows to the '
+        'right installation and so destroyDuplicatedSessions can clean up '
+        'prior sessions on the same install during login', () async {
+      final Map<String, String>? headers = await client.exposedBuildHeaders(
+        null,
+      );
+
+      expect(headers, isNotNull);
+      expect(headers![keyHeaderInstallationId], isNotEmpty);
+    });
+
+    test('omits X-Parse-Installation-Id when caller passes '
+        'sendInstallationId: false. The opt-out is forwarded by methods such '
+        'as ParseUser.signUp(doNotSendInstallationID: true) for callers that '
+        'cannot allow-list the header on their parse-server', () async {
+      final Map<String, String>? headers = await client.exposedBuildHeaders(
+        ParseNetworkOptions(sendInstallationId: false),
+      );
+
+      expect(
+        headers?[keyHeaderInstallationId],
+        isNull,
+        reason:
+            'sendInstallationId=false must suppress the header even when '
+            'an install ID is available',
+      );
+    });
+
+    test(
+      'preserves a caller-supplied X-Parse-Installation-Id rather than '
+      'overwriting it. Lets advanced callers (tests, multi-tenant proxies) '
+      'inject a specific install ID without the client clobbering it',
+      () async {
+        final Map<String, String>? headers = await client.exposedBuildHeaders(
+          ParseNetworkOptions(
+            headers: <String, String>{keyHeaderInstallationId: 'caller-id'},
+          ),
+        );
+
+        expect(headers![keyHeaderInstallationId], equals('caller-id'));
+      },
+    );
+
+    test('merges caller-supplied headers with the install ID. Custom headers '
+        'and the auto-attached install ID must coexist — neither side '
+        'overrides the other', () async {
+      final Map<String, String>? headers = await client.exposedBuildHeaders(
+        ParseNetworkOptions(headers: <String, String>{'X-Custom': 'value'}),
+      );
+
+      expect(headers!['X-Custom'], equals('value'));
+      expect(headers[keyHeaderInstallationId], isNotEmpty);
+    });
+  });
+}
diff --git a/packages/dart/test/src/network/parse_dio_client_test.dart b/packages/dart/test/src/network/parse_dio_client_test.dart
index a0723808c..4ff75130e 100644
--- a/packages/dart/test/src/network/parse_dio_client_test.dart
+++ b/packages/dart/test/src/network/parse_dio_client_test.dart
@@ -4,6 +4,31 @@ import 'package:test/test.dart';
 
 import '../../test_utils.dart';
 
+/// Records the headers of every request made through it without performing
+/// the actual HTTP call. Returns an empty 200 OK so callers can `await`.
+class _HeaderCapturingAdapter implements HttpClientAdapter {
+  final List<Map<String, dynamic>> requests = [];
+
+  @override
+  Future<ResponseBody> fetch(
+    RequestOptions options,
+    Stream<List<int>>? requestStream,
+    Future<void>? cancelFuture,
+  ) async {
+    requests.add(Map<String, dynamic>.from(options.headers));
+    return ResponseBody.fromString(
+      '{}',
+      200,
+      headers: <String, List<String>>{
+        Headers.contentTypeHeader: <String>[Headers.jsonContentType],
+      },
+    );
+  }
+
+  @override
+  void close({bool force = false}) {}
+}
+
 void main() {
   setUpAll(() async {
     await initializeParse();
@@ -57,4 +82,88 @@ void main() {
       expect(parseDioClient.additionalHeaders, isNull);
     });
   });
+
+  group('ParseDioClient request pipeline integration', () {
+    late ParseDioClient parseDioClient;
+    late _HeaderCapturingAdapter adapter;
+
+    setUp(() async {
+      parseDioClient = ParseDioClient();
+      adapter = _HeaderCapturingAdapter();
+      parseDioClient.client.httpClientAdapter = adapter;
+    });
+
+    test('headers returned by buildHeaders reach the outgoing request. This is '
+        'the wiring check between the inherited helper (covered in detail by '
+        'parse_client_test.dart) and dio\'s request pipeline — without it, a '
+        'refactor that bypassed buildHeaders would silently drop install IDs '
+        'on every request', () async {
+      await parseDioClient.put('$serverUrl/classes/_User/abc', data: '{}');
+
+      expect(adapter.requests, hasLength(1));
+      expect(
+        adapter.requests.first[keyHeaderInstallationId],
+        isNotEmpty,
+        reason: 'install ID added by buildHeaders must reach the wire',
+      );
+    });
+
+    test('get() attaches X-Parse-Installation-Id', () async {
+      await parseDioClient.get('$serverUrl/classes/Item/abc');
+
+      expect(adapter.requests, hasLength(1));
+      expect(adapter.requests.first[keyHeaderInstallationId], isNotEmpty);
+    });
+
+    test('getBytes() attaches X-Parse-Installation-Id', () async {
+      await parseDioClient.getBytes('$serverUrl/files/abc.bin');
+
+      expect(adapter.requests, hasLength(1));
+      expect(adapter.requests.first[keyHeaderInstallationId], isNotEmpty);
+    });
+
+    test('post() attaches X-Parse-Installation-Id', () async {
+      await parseDioClient.post('$serverUrl/classes/Item', data: '{"k":"v"}');
+
+      expect(adapter.requests, hasLength(1));
+      expect(adapter.requests.first[keyHeaderInstallationId], isNotEmpty);
+    });
+
+    test('postBytes() attaches X-Parse-Installation-Id', () async {
+      await parseDioClient.postBytes(
+        '$serverUrl/files/abc.bin',
+        data: Stream<List<int>>.fromIterable(<List<int>>[
+          <int>[1, 2, 3],
+        ]),
+      );
+
+      expect(adapter.requests, hasLength(1));
+      expect(adapter.requests.first[keyHeaderInstallationId], isNotEmpty);
+    });
+
+    test('delete() attaches X-Parse-Installation-Id', () async {
+      await parseDioClient.delete('$serverUrl/classes/Item/abc');
+
+      expect(adapter.requests, hasLength(1));
+      expect(adapter.requests.first[keyHeaderInstallationId], isNotEmpty);
+    });
+
+    test('caller can suppress X-Parse-Installation-Id per request. '
+        'sendInstallationId: false matches ParseUser.signUp(doNotSendInstallationID: true) '
+        'and must propagate through every verb', () async {
+      await parseDioClient.post(
+        '$serverUrl/classes/Item',
+        data: '{"k":"v"}',
+        options: ParseNetworkOptions(sendInstallationId: false),
+      );
+
+      expect(adapter.requests, hasLength(1));
+      expect(
+        adapter.requests.first[keyHeaderInstallationId],
+        isNull,
+        reason:
+            'sendInstallationId: false must suppress the header on the wire',
+      );
+    });
+  });
 }
diff --git a/packages/dart/test/src/network/parse_http_client_test.dart b/packages/dart/test/src/network/parse_http_client_test.dart
index 9f0a79751..3a7672767 100644
--- a/packages/dart/test/src/network/parse_http_client_test.dart
+++ b/packages/dart/test/src/network/parse_http_client_test.dart
@@ -1,3 +1,6 @@
+import 'dart:async';
+import 'dart:io';
+
 import 'package:http/http.dart' as http;
 import 'package:parse_server_sdk/parse_server_sdk.dart';
 import 'package:test/test.dart';
@@ -9,20 +12,119 @@ void main() {
     await initializeParse();
   });
 
-  group('ParseDioClient Tests', () {
+  group('ParseHTTPClient Tests', () {
     late ParseHTTPClient parseHTTPClient;
 
     setUp(() async {
       parseHTTPClient = ParseHTTPClient();
     });
 
-    test('should return an instance of Dio from dioClient', () {
+    test('should return an instance of http.BaseClient from client getter', () {
       // arrange
-      final dioClient = parseHTTPClient.client;
+      final httpClient = parseHTTPClient.client;
 
       // assert
-      expect(dioClient, isNotNull);
-      expect(dioClient, isA<http.BaseClient>());
+      expect(httpClient, isNotNull);
+      expect(httpClient, isA<http.BaseClient>());
+    });
+  });
+
+  /// Verifies headers returned by `buildHeaders` reach the wire through each
+  /// HTTP verb. ParseHTTPClient has no in-process injection seam for its
+  /// underlying http.Client, so the test spins up a localhost HttpServer that
+  /// captures the request headers and replies with a minimal 200 response.
+  group('ParseHTTPClient request pipeline integration', () {
+    late ParseHTTPClient parseHTTPClient;
+    late HttpServer server;
+    late List<HttpRequest> captured;
+    late String baseUrl;
+
+    setUp(() async {
+      parseHTTPClient = ParseHTTPClient();
+      server = await HttpServer.bind(InternetAddress.loopbackIPv4, 0);
+      baseUrl = 'http://${server.address.host}:${server.port}';
+      captured = <HttpRequest>[];
+      server.listen((HttpRequest request) async {
+        captured.add(request);
+        // Drain any body so the client receives a complete response.
+        await request.drain<void>();
+        request.response.statusCode = HttpStatus.ok;
+        request.response.headers.contentType = ContentType.json;
+        request.response.write('{}');
+        await request.response.close();
+      });
+    });
+
+    tearDown(() async {
+      await server.close(force: true);
+    });
+
+    String headerOf(HttpRequest request, String name) =>
+        request.headers.value(name) ?? '';
+
+    test('get() attaches X-Parse-Installation-Id', () async {
+      await parseHTTPClient.get('$baseUrl/classes/Item/abc');
+
+      expect(captured, hasLength(1));
+      expect(headerOf(captured.first, keyHeaderInstallationId), isNotEmpty);
+    });
+
+    test('getBytes() attaches X-Parse-Installation-Id', () async {
+      await parseHTTPClient.getBytes('$baseUrl/files/abc.bin');
+
+      expect(captured, hasLength(1));
+      expect(headerOf(captured.first, keyHeaderInstallationId), isNotEmpty);
+    });
+
+    test('put() attaches X-Parse-Installation-Id', () async {
+      await parseHTTPClient.put('$baseUrl/classes/Item/abc', data: '{}');
+
+      expect(captured, hasLength(1));
+      expect(headerOf(captured.first, keyHeaderInstallationId), isNotEmpty);
+    });
+
+    test('post() attaches X-Parse-Installation-Id', () async {
+      await parseHTTPClient.post('$baseUrl/classes/Item', data: '{"k":"v"}');
+
+      expect(captured, hasLength(1));
+      expect(headerOf(captured.first, keyHeaderInstallationId), isNotEmpty);
+    });
+
+    test('postBytes() attaches X-Parse-Installation-Id', () async {
+      await parseHTTPClient.postBytes(
+        '$baseUrl/files/abc.bin',
+        data: Stream<List<int>>.fromIterable(<List<int>>[
+          <int>[1, 2, 3],
+        ]),
+      );
+
+      expect(captured, hasLength(1));
+      expect(headerOf(captured.first, keyHeaderInstallationId), isNotEmpty);
+    });
+
+    test('delete() attaches X-Parse-Installation-Id', () async {
+      await parseHTTPClient.delete('$baseUrl/classes/Item/abc');
+
+      expect(captured, hasLength(1));
+      expect(headerOf(captured.first, keyHeaderInstallationId), isNotEmpty);
+    });
+
+    test('caller can suppress X-Parse-Installation-Id per request. '
+        'sendInstallationId: false matches ParseUser.signUp(doNotSendInstallationID: true) '
+        'and must propagate through every verb', () async {
+      await parseHTTPClient.post(
+        '$baseUrl/classes/Item',
+        data: '{"k":"v"}',
+        options: ParseNetworkOptions(sendInstallationId: false),
+      );
+
+      expect(captured, hasLength(1));
+      expect(
+        captured.first.headers.value(keyHeaderInstallationId),
+        isNull,
+        reason:
+            'sendInstallationId: false must suppress the header on the wire',
+      );
     });
   });
 }
diff --git a/packages/dart/test/src/network/parse_query_test.mocks.dart b/packages/dart/test/src/network/parse_query_test.mocks.dart
index 4cdbf3808..862284629 100644
--- a/packages/dart/test/src/network/parse_query_test.mocks.dart
+++ b/packages/dart/test/src/network/parse_query_test.mocks.dart
@@ -209,4 +209,14 @@ class MockParseClient extends _i1.Mock implements _i2.ParseClient {
             ),
           )
           as _i3.Future<_i2.ParseNetworkByteResponse>);
+
+  @override
+  _i3.Future<Map<String, String>?> buildHeaders(
+    _i2.ParseNetworkOptions? options,
+  ) =>
+      (super.noSuchMethod(
+            Invocation.method(#buildHeaders, [options]),
+            returnValue: _i3.Future<Map<String, String>?>.value(),
+          )
+          as _i3.Future<Map<String, String>?>);
 }
diff --git a/packages/dart/test/src/objects/parse_object/parse_object_test.mocks.dart b/packages/dart/test/src/objects/parse_object/parse_object_test.mocks.dart
index 39a066aef..21904274f 100644
--- a/packages/dart/test/src/objects/parse_object/parse_object_test.mocks.dart
+++ b/packages/dart/test/src/objects/parse_object/parse_object_test.mocks.dart
@@ -209,4 +209,14 @@ class MockParseClient extends _i1.Mock implements _i2.ParseClient {
             ),
           )
           as _i3.Future<_i2.ParseNetworkByteResponse>);
+
+  @override
+  _i3.Future<Map<String, String>?> buildHeaders(
+    _i2.ParseNetworkOptions? options,
+  ) =>
+      (super.noSuchMethod(
+            Invocation.method(#buildHeaders, [options]),
+            returnValue: _i3.Future<Map<String, String>?>.value(),
+          )
+          as _i3.Future<Map<String, String>?>);
 }