@@ -315,6 +315,8 @@ class FirebaseFirestore extends FirebasePluginPlatform {
 persistenceEnabled: settings.persistenceEnabled,
 host: settings.host,
 cacheSizeBytes: settings.cacheSizeBytes,
+webExperimentalForceLongPolling: settings.webExperimentalForceLongPolling,
+webExperimentalAutoDetectLongPolling: settings.webExperimentalAutoDetectLongPolling,
 );
 }
 

@@ -16,6 +16,9 @@ class Settings {
 this.host,
 this.sslEnabled,
 this.cacheSizeBytes,
+this.webExperimentalForceLongPolling = true,
+this.webExperimentalAutoDetectLongPolling = true,
+this.timeoutSeconds = 30,
 this.ignoreUndefinedProperties = false,
 });
 
@@ -51,13 +54,41 @@ class Settings {
 /// Web only.
 final bool ignoreUndefinedProperties;
 
+/// Forces the SDK’s underlying network transport (WebChannel) to use long-polling.
+///
+/// Each response from the backend will be closed immediately after the backend sends data
+/// (by default responses are kept open in case the backend has more data to send).
+/// This avoids incompatibility issues with certain proxies, antivirus software, etc.
+/// that incorrectly buffer traffic indefinitely.
+/// Use of this option will cause some performance degradation though.
+final bool webExperimentalForceLongPolling;
+
+///	Configures the SDK's underlying transport (WebChannel) to automatically detect if long-polling should be used.
+///
+///This is very similar to [webExperimentalForceLongPolling], but only uses long-polling if required.
+final bool webExperimentalAutoDetectLongPolling;
+
+/// The desired maximum timeout interval, in seconds, to complete a long-polling GET response
+///
+/// Valid values are between 5 and 30, inclusive.
+/// By default, when long-polling is used the "hanging GET" request sent by the client times out after 30 seconds.
+/// To request a different timeout from the server, set this setting with the desired timeout.
+/// Changing the default timeout may be useful, for example,
+/// if the buffering proxy that necessitated enabling long-polling in the first place has a shorter timeout for hanging GET requests,
+/// in which case setting the long-polling timeout to a shorter value,
+/// such as 25 seconds, may fix prematurely-closed hanging GET requests.
+final int timeoutSeconds;
+
 /// Returns the settings as a [Map]
 Map<String, dynamic> get asMap {
 return {
 'persistenceEnabled': persistenceEnabled,
 'host': host,
 'sslEnabled': sslEnabled,
 'cacheSizeBytes': cacheSizeBytes,
+'webExperimentalForceLongPolling': webExperimentalForceLongPolling,
+'webExperimentalAutoDetectLongPolling': webExperimentalAutoDetectLongPolling,
+'timeoutSeconds': timeoutSeconds,
 if (kIsWeb) 'ignoreUndefinedProperties': ignoreUndefinedProperties,
 };
 }
@@ -67,7 +98,10 @@ class Settings {
 String? host,
 bool? sslEnabled,
 int? cacheSizeBytes,
+bool? webExperimentalForceLongPolling,
+bool? webExperimentalAutoDetectLongPolling,
 bool? ignoreUndefinedProperties,
+int? timeoutSeconds,
 }) {
 assert(
 cacheSizeBytes == null ||
@@ -81,6 +115,9 @@ class Settings {
 host: host ?? this.host,
 sslEnabled: sslEnabled ?? this.sslEnabled,
 cacheSizeBytes: cacheSizeBytes ?? this.cacheSizeBytes,
+webExperimentalForceLongPolling: webExperimentalForceLongPolling ?? this.webExperimentalForceLongPolling,
+webExperimentalAutoDetectLongPolling: webExperimentalAutoDetectLongPolling ?? this.webExperimentalAutoDetectLongPolling,
+timeoutSeconds: timeoutSeconds ?? this.timeoutSeconds,
 ignoreUndefinedProperties:
 ignoreUndefinedProperties ?? this.ignoreUndefinedProperties,
 );
@@ -94,6 +131,9 @@ class Settings {
 other.host == host &&
 other.sslEnabled == sslEnabled &&
 other.cacheSizeBytes == cacheSizeBytes &&
+other.webExperimentalForceLongPolling == webExperimentalForceLongPolling &&
+other.webExperimentalAutoDetectLongPolling == webExperimentalAutoDetectLongPolling &&
+other.timeoutSeconds == timeoutSeconds &&
 other.ignoreUndefinedProperties == ignoreUndefinedProperties;
 
 @override
@@ -103,6 +143,8 @@ class Settings {
 host,
 sslEnabled,
 cacheSizeBytes,
+webExperimentalForceLongPolling,
+webExperimentalAutoDetectLongPolling,
 ignoreUndefinedProperties,
 );
 

@@ -11,17 +11,22 @@ void main() {
 test('equality', () {
 expect(
 const Settings(
-persistenceEnabled: true,
-host: 'foo bar',
-sslEnabled: true,
-cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
-),
+persistenceEnabled: true,
+host: 'foo bar',
+sslEnabled: true,
+webExperimentalForceLongPolling: false,
+webExperimentalAutoDetectLongPolling: false,
+cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
+timeoutSeconds: 25),
 equals(
 const Settings(
 persistenceEnabled: true,
 host: 'foo bar',
 sslEnabled: true,
+webExperimentalForceLongPolling: false,
+webExperimentalAutoDetectLongPolling: false,
 cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
+timeoutSeconds: 25,
 ),
 ),
 );
@@ -49,6 +54,9 @@ void main() {
 persistenceEnabled: true,
 host: 'foo bar',
 sslEnabled: true,
+webExperimentalAutoDetectLongPolling: false,
+webExperimentalForceLongPolling: false,
+timeoutSeconds: 25,
 cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
 );
 
@@ -60,7 +68,9 @@ void main() {
 'persistenceEnabled': null,
 'host': null,
 'sslEnabled': null,
-'cacheSizeBytes': null
+'cacheSizeBytes': null,
+'webExperimentalForceLongPolling': true,
+'webExperimentalAutoDetectLongPolling': true
 });
 
 expect(
@@ -75,6 +85,8 @@ void main() {
 'host': 'foo bar',
 'sslEnabled': true,
 'cacheSizeBytes': Settings.CACHE_SIZE_UNLIMITED,
+'webExperimentalForceLongPolling': true,
+'webExperimentalAutoDetectLongPolling': true,
 });
 });
 

@@ -719,6 +719,9 @@ abstract class FirestoreSettings {
 JSString? host,
 JSBoolean? ssl,
 JSBoolean? ignoreUndefinedProperties,
+JSBoolean? experimentalForceLongPolling,
+JSBoolean? experimentalAutoDetectLongPolling,
+JSObject? experimentalLongPollingOptions,
 JSObject localCache,
 });
 }
@@ -748,6 +751,34 @@ extension FirestoreSettingsExtension on FirestoreSettings {
 external set localCache(JSObject u);
 }
 
+/// Options that configure the SDK’s underlying network transport (WebChannel) when long-polling is used
+/// These options are only used if experimentalForceLongPolling is true
+/// or if experimentalAutoDetectLongPolling is true and the auto-detection determined that long-polling was needed.
+/// Otherwise, these options have no effect.
+@anonymous
+@JS()
+@staticInterop
+abstract class ExperimentalLongPollingOptions {
+external factory ExperimentalLongPollingOptions ({
+JSNumber? timeoutSeconds,
+});
+}
+
+extension ExperimentalLongPollingOptionsExtension on ExperimentalLongPollingOptions {
+/// The desired maximum timeout interval, in seconds, to complete a long-polling GET response
+/// Valid values are between 5 and 30, inclusive.
+/// Floating point values are allowed and will be rounded to the nearest millisecond
+/// By default, when long-polling is used the "hanging GET" request sent by the client times out after 30 seconds.
+/// To request a different timeout from the server, set this setting with the desired timeout.
+/// Changing the default timeout may be useful, for example,
+/// if the buffering proxy that necessitated enabling long-polling in the first place has a shorter timeout for hanging GET requests,
+/// in which case setting the long-polling timeout to a shorter value,
+/// such as 25 seconds, may fix prematurely-closed hanging GET requests.
+external JSNumber? get timeoutSeconds;
+
+external set timeoutSeconds(JSNumber? v);
+}
+
 /// Union type from all supported SDK cache layer.
 ///
 /// [MemoryLocalCache] and [MemoryCacheSettings] are the two only cache types supported by the SDK. Custom implementation is not supported.