robobun · Nov 5, 2026 · Nov 5, 2026 · Nov 5, 2026 · Nov 5, 2026 · Nov 5, 2026
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
@@ -163,29 +163,32 @@ AllowedSPI*.toml @emw-apple
 # ================================================================================
 # WebKit
 
-*ContentExtension* @b-weinstein @xeenon
-*InspectorExtension* @b-weinstein @xeenon
-*WebExtension* @b-weinstein @xeenon
+*ContentExtension* @b-weinstein @xeenon @elijahsawyers @kiaraarose
+*InspectorExtension* @b-weinstein @xeenon @elijahsawyers @kiaraarose
+*WebExtension* @b-weinstein @xeenon @elijahsawyers @kiaraarose
 /Source/WebKit/_WebKit_SwiftUI @rr-codes
 /Source/WebKit/GPUProcess/mac/com.apple.WebKit.GPUProcess.sb.in @brentfulgham @pvollan
 /Source/WebKit/NetworkProcess @cdumez
 /Source/WebKit/NetworkProcess/mac/com.apple.WebKit.NetworkProcess.sb.in @brentfulgham @pvollan
 /Source/WebKit/Platform @cdumez
 /Source/WebKit/Resources/SandboxProfiles @brentfulgham @pvollan
+/Source/WebKit/Shared/Extensions @b-weinstein @xeenon @elijahsawyers @kiaraarose
 /Source/WebKit/Shared/Sandbox @brentfulgham @pvollan
 /Source/WebKit/UIProcess @cdumez
-/Source/WebKit/UIProcess/Extensions @b-weinstein @xeenon
+/Source/WebKit/UIProcess/Extensions @b-weinstein @xeenon @elijahsawyers @kiaraarose
 /Source/WebKit/UIProcess/Inspector @patrickangle @burg
 /Source/WebKit/WebKitSwift @rr-codes
 /Source/WebKit/UIProcess/DigitalCredentials @marcoscaceres
 /Source/WebKit/UIProcess/WebsiteData/Cocoa/ScreenTimeWebsiteDataSupport.* @jesxilin
 /Source/WebKit/WebProcess @cdumez
 /Source/WebKit/WebProcess/DigitalCredentials @marcoscaceres
 /Source/WebKit/WebKitSwift/IdentityDocumentServices @marcoscaceres
-/Source/WebKit/WebProcess/Extensions @b-weinstein @xeenon
+/Source/WebKit/WebProcess/Extensions @b-weinstein @xeenon @elijahsawyers @kiaraarose
 /Source/WebKit/WebProcess/Inspector @patrickangle @burg
 /Source/WebKit/WebProcess/com.apple.WebProcess.sb.in  @brentfulgham @pvollan
 /Source/WebKit/Scripts/webkit/opaque_ipc_types.* @sheeparegreat
+/Tools/Scripts/webkitpy/webextensions @b-weinstein @xeenon @elijahsawyers @kiaraarose
+/Tools/TestWebKitAPI/Resources/cocoa/web-extension* @b-weinstein @xeenon @elijahsawyers @kiaraarose
 
 # ================================================================================
 # WebDriver

diff --git a/.gitignore b/.gitignore
@@ -90,7 +90,7 @@ bun-webkit
 BenchmarkTemp
 
 # Ignore Claude Code init file and autogenerated files
-CLAUDE.md
+/CLAUDE.md
 .claude/commands
 .claude/settings.local.json
 .claude/skills

diff --git a/.wkdev-sdk-version b/.wkdev-sdk-version
@@ -1 +1 @@
-2.55-v3-a507ffd
+2.55-v4-8898cc2
diff --git a/CLAUDE.md b/CLAUDE.md
@@ -160,7 +160,7 @@ Custom event loop implementation for Bun's runtime requirements
 ```
 
 ### When a test fails, and after an upstream sync
-`JSTests/`, `LayoutTests/js` and the PerformanceTests collections are upstream's tests, and this fork has changed 129 of them. `JSTests/BUN-TEST-DIFFERENCES.md` lists every one by reason: the behaviors the fork has on purpose (with the fork code behind each and the files whose expectations follow it), the tests narrowed to the modes or builds they can pass in, and the ones skipped with `TODO(bun)` for a known gap. Read it before changing a test's expectation or skipping one: a failure that matches an entry there means the test is what to change; one that matches none is a regression in the engine. Its last section is the procedure for sorting a new failure. When a test is changed, add it to that file, and put a `// Bun:` or `// TODO(bun):` comment on the changed line saying what upstream expects. `JSTests/CLAUDE.md` and `JSTests/README.md` are upstream's files: leave them as they are.
+`JSTests/`, `LayoutTests/js` and the PerformanceTests collections are upstream's tests, and this fork has changed 130 of them. `JSTests/BUN-TEST-DIFFERENCES.md` lists every one by reason: the behaviors the fork has on purpose (with the fork code behind each and the files whose expectations follow it), the tests narrowed to the modes or builds they can pass in, and the ones skipped with `TODO(bun)` for a known gap. Read it before changing a test's expectation or skipping one: a failure that matches an entry there means the test is what to change; one that matches none is a regression in the engine. Its last section is the procedure for sorting a new failure. When a test is changed, add it to that file, and put a `// Bun:` or `// TODO(bun):` comment on the changed line saying what upstream expects. `JSTests/CLAUDE.md` and `JSTests/README.md` are upstream's files: leave them as they are.
 
 ## Development Tips
 

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -32,6 +32,7 @@ include(WebKitCommon)
 if (SWIFT_REQUIRED)
     if (POLICY CMP0157)
         cmake_policy(SET CMP0157 NEW)
+        set(CMAKE_Swift_COMPILATION_MODE "$<IF:$<CONFIG:Debug>,incremental,wholemodule>")
     endif ()
 
     enable_language(Swift)

diff --git a/CMakePresets.json b/CMakePresets.json
@@ -68,13 +68,32 @@
             "inherits": ["cocoa"]
         },
         {
-            "name": "gtk",
+            "name": "glib",
             "hidden": true,
             "generator": "Ninja",
+            "cacheVariables": {
+                "CMAKE_C_COMPILER": {
+                    "type": "STRING",
+                    "value": "clang"
+                },
+                "CMAKE_CXX_COMPILER": {
+                    "type": "STRING",
+                    "value": "clang++"
+                }
+            }
+        },
+        {
+            "name": "gtk",
+            "hidden": true,
+            "inherits": ["glib"],
             "cacheVariables": {
                 "PORT": {
                     "type": "STRING",
                     "value": "GTK"
+                },
+                "CMAKE_MAKE_PROGRAM": {
+                    "type": "FILEPATH",
+                    "value": "${sourceDir}/Source/cmake/ninja-wrapper"
                 }
             }
         },
@@ -302,6 +321,39 @@
             "displayName": "macOS x86_64/Rosetta Development (Debug, ccache, compile_commands)",
             "inherits": ["mac-rosetta-debug", "dev"]
         },
+        {
+            "name": "maccatalyst",
+            "hidden": true,
+            "inherits": ["mac"],
+            "cacheVariables": {
+                "WEBKIT_SDK_VARIANT": {
+                    "type": "STRING",
+                    "value": "iosmac"
+                }
+            }
+        },
+        {
+            "name": "maccatalyst-release",
+            "displayName": "Mac Catalyst Release",
+            "inherits": ["maccatalyst", "release"],
+            "binaryDir": "WebKitBuild/cmake-maccatalyst/Release"
+        },
+        {
+            "name": "maccatalyst-debug",
+            "displayName": "Mac Catalyst Debug",
+            "inherits": ["maccatalyst", "debug"],
+            "binaryDir": "WebKitBuild/cmake-maccatalyst/Debug"
+        },
+        {
+            "name": "maccatalyst-dev-release",
+            "displayName": "Mac Catalyst Development (Release, ccache, compile_commands)",
+            "inherits": ["maccatalyst-release", "dev"]
+        },
+        {
+            "name": "maccatalyst-dev-debug",
+            "displayName": "Mac Catalyst Development (Debug, ccache, compile_commands)",
+            "inherits": ["maccatalyst-debug", "dev"]
+        },
         {
             "name": "ios",
             "hidden": true,
@@ -515,11 +567,15 @@
         {
             "name": "wpe",
             "hidden": true,
-            "generator": "Ninja",
+            "inherits": ["glib"],
             "cacheVariables": {
                 "PORT": {
                     "type": "STRING",
                     "value": "WPE"
+                },
+                "CMAKE_MAKE_PROGRAM": {
+                    "type": "FILEPATH",
+                    "value": "${sourceDir}/Source/cmake/ninja-wrapper"
                 }
             }
         },
@@ -612,6 +668,26 @@
             "displayName": "macOS x86_64/Rosetta Development Debug",
             "configurePreset": "mac-rosetta-dev-debug"
         },
+        {
+            "name": "maccatalyst-release",
+            "displayName": "Mac Catalyst Release",
+            "configurePreset": "maccatalyst-release"
+        },
+        {
+            "name": "maccatalyst-debug",
+            "displayName": "Mac Catalyst Debug",
+            "configurePreset": "maccatalyst-debug"
+        },
+        {
+            "name": "maccatalyst-dev-release",
+            "displayName": "Mac Catalyst Development Release",
+            "configurePreset": "maccatalyst-dev-release"
+        },
+        {
+            "name": "maccatalyst-dev-debug",
+            "displayName": "Mac Catalyst Development Debug",
+            "configurePreset": "maccatalyst-dev-debug"
+        },
         {
             "name": "gtk-release",
             "displayName": "GTK Release",

diff --git a/Configurations/CommonBase.xcconfig b/Configurations/CommonBase.xcconfig
@@ -119,7 +119,7 @@ WK_OTHER_AUDIT_SPI_FLAGS_164901718[sdk=iphoneos26.*.internal] = -DSDKDB_HAS_1649
 GCC_WARN_NON_VIRTUAL_DESTRUCTOR = YES;
 GCC_THREADSAFE_STATICS = YES;
 
-WK_COMMON_WARNING_CFLAGS = -Wall -Wc99-designator -Wconditional-uninitialized -Wextra -Wdeprecated-enum-enum-conversion -Wdeprecated-enum-float-conversion -Wenum-float-conversion -Wfinal-dtor-non-final-class -Wformat=2 -Wmisleading-indentation -Wpointer-to-int-cast -Wreorder-init-list -Wundef -Wunused-but-set-variable -Wvla -Werror=unguarded-availability -Wthread-safety;
+WK_COMMON_WARNING_CFLAGS = -Wall -Wc99-designator -Wconditional-uninitialized -Wextra -Wdeprecated-enum-enum-conversion -Wdeprecated-enum-float-conversion -Wenum-float-conversion -Wfinal-dtor-non-final-class -Wformat=2 -Wmisleading-indentation -Wpointer-to-int-cast -Wreorder-init-list -Wundef -Wunused-but-set-variable -Wvla -Walloca -Werror=unguarded-availability -Wthread-safety;
 WARNING_CFLAGS = $(inherited) $(WK_COMMON_WARNING_CFLAGS) $(WK_SANITIZER_WARNING_CFLAGS);
 
 CLANG_CXX_STANDARD_LIBRARY_HARDENING = extensive;
@@ -129,11 +129,14 @@ SWIFT_VERSION = 6.0;
 SWIFT_OPTIMIZATION_LEVEL = -O;
 SWIFT_OPTIMIZATION_LEVEL[config=Debug] = -Onone;
 
+SWIFT_COMPILATION_MODE = wholemodule;
+SWIFT_COMPILATION_MODE[config=Debug] = singlefile;
+
 // Enable strict memory safety in Swift.
 WK_SWIFT_MEMORY_SAFETY_FLAGS = -strict-memory-safety -enable-experimental-feature Lifetimes -enable-experimental-feature LifetimeDependence -enable-experimental-feature ImportNonPublicCxxMembers;
 
 // Treat memory safety warnings as errors.
-WK_SWIFT_MEMORY_SAFETY_ERROR_FLAGS = -Werror StrictMemorySafety -Werror ForeignReferenceType -Werror RegionIsolation;
+WK_SWIFT_MEMORY_SAFETY_ERROR_FLAGS = -Werror StrictMemorySafety -Werror ForeignReferenceType -Werror RegionIsolation -Werror SendableClosureCaptures;
 // rdar://164903024: Work around false positives in some SDK versions.
 WK_SWIFT_MEMORY_SAFETY_ERROR_FLAGS[sdk=*26.3*] = ;
 
@@ -147,6 +150,11 @@ WK_SWIFT_VARIABLE_NEVER_MUTATED_ERROR_FLAGS[sdk=*26.*] = ;
 WK_SWIFT_UNUSED_IMPORT_ACCESS_ERROR_FLAGS = -Werror UnusedImportAccess;
 WK_SWIFT_UNUSED_IMPORT_ACCESS_ERROR_FLAGS[sdk=*26.*] = ;
 
+// Enable the experimental SuppressedAssociatedTypes feature only with SDKs that ship Swift 6.3. Later Swift
+// versions deprecate it in favor of SE-503, which SuppressedAssociatedTypesWithDefaults enables.
+WK_SWIFT_SUPPRESSED_ASSOCIATED_TYPES_FLAGS = ;
+WK_SWIFT_SUPPRESSED_ASSOCIATED_TYPES_FLAGS[sdk=*26.*] = -enable-experimental-feature SuppressedAssociatedTypes;
+
 // rdar://168992837 requires us to tell swiftc to tell clang how to set version macros
 // when interpreting C++ headers as clang modules, so that we get identical feature
 // enablement to C++ interpretation of those headers (otherwise we get mismatched data members etc.)
@@ -155,6 +163,6 @@ WK_SWIFT_CLANG_DEPLOYMENT_TARGET_macosx = -clang-target $(CURRENT_ARCH)-apple-ma
 
 // rdar://170129992: remove -track-system-dependencies when resolved
 // FIXME(rdar://189511928, rdar://189512247): remove -disable-round-trip-debug-types when both are resolved
-OTHER_SWIFT_FLAGS = $(inherited) $(WK_AVAILABILITY_OVERLAY_SWIFT_FLAGS) -Xcc -fvisibility=hidden -Werror ExistentialAny -Werror NoUseUnstructuredThrowingTask -Werror NoUsage $(WK_SWIFT_VARIABLE_NEVER_MUTATED_ERROR_FLAGS) $(WK_SWIFT_UNUSED_IMPORT_ACCESS_ERROR_FLAGS) -enable-upcoming-feature ExistentialAny $(WK_SWIFT_MEMORY_SAFETY_FLAGS) $(WK_SWIFT_MEMORY_SAFETY_ERROR_FLAGS) $(WK_SWIFT_CLANG_DEPLOYMENT_TARGET) $(WK_SANITIZER_OTHER_SWIFT_FLAGS) -enable-upcoming-feature InternalImportsByDefault -enable-upcoming-feature MemberImportVisibility -track-system-dependencies -enable-experimental-feature ImportCxxMembersLazily -enable-experimental-feature SuppressedAssociatedTypes -enable-experimental-feature SuppressedAssociatedTypesWithDefaults -enable-experimental-feature ForeignReferenceTypeInheritance -Xfrontend -disable-round-trip-debug-types -enable-experimental-feature SafeInteropWrappers;
+OTHER_SWIFT_FLAGS = $(inherited) $(WK_AVAILABILITY_OVERLAY_SWIFT_FLAGS) -Xcc -fvisibility=hidden -Werror ExistentialAny -Werror NoUseUnstructuredThrowingTask -Werror NoUsage -Werror UnnecessaryEffectMarker $(WK_SWIFT_VARIABLE_NEVER_MUTATED_ERROR_FLAGS) $(WK_SWIFT_UNUSED_IMPORT_ACCESS_ERROR_FLAGS) -enable-upcoming-feature ExistentialAny $(WK_SWIFT_MEMORY_SAFETY_FLAGS) $(WK_SWIFT_MEMORY_SAFETY_ERROR_FLAGS) $(WK_SWIFT_CLANG_DEPLOYMENT_TARGET) $(WK_SANITIZER_OTHER_SWIFT_FLAGS) -enable-upcoming-feature InternalImportsByDefault -enable-upcoming-feature MemberImportVisibility -enable-upcoming-feature NonisolatedNonsendingByDefault -track-system-dependencies -enable-experimental-feature ImportCxxMembersLazily $(WK_SWIFT_SUPPRESSED_ASSOCIATED_TYPES_FLAGS) -enable-experimental-feature SuppressedAssociatedTypesWithDefaults -enable-experimental-feature ForeignReferenceTypeInheritance -Xfrontend -disable-round-trip-debug-types -enable-experimental-feature SafeInteropWrappers;
 
 OTHER_LIBTOOLFLAGS = -no_warning_for_no_symbols;
diff --git a/Configurations/Version.xcconfig b/Configurations/Version.xcconfig
@@ -23,7 +23,7 @@
 
 MAJOR_VERSION = 627;
 MINOR_VERSION = 1;
-TINY_VERSION = 5;
+TINY_VERSION = 8;
 MICRO_VERSION = 0;
 NANO_VERSION = 0;
 FULL_VERSION = $(MAJOR_VERSION).$(MINOR_VERSION).$(TINY_VERSION);

diff --git a/Configurations/WebKitProjectPaths.xcconfig b/Configurations/WebKitProjectPaths.xcconfig
@@ -86,18 +86,6 @@ WK_WEBKITADDITIONS_POSTPROCESS_SCRIPTS_INPUT_YES_NO = $(WK_WEBKITADDITIONS_HEADE
 WK_WEBKITADDITIONS_BRANCH_CONFIG_INPUT = $(WK_WEBKITADDITIONS_BRANCH_CONFIG_INPUT_$(USE_INTERNAL_SDK)_$(WK_IS_INSTALLHDRS));
 WK_WEBKITADDITIONS_BRANCH_CONFIG_INPUT_YES_NO = $(WK_WEBKITADDITIONS_HEADERS_FOLDER_PATH)/Scripts/branch_config.json;
 
-WK_WEBKITADDITIONS_HEADER_REPLACEMENT_FEATURE_INPUT = $(WK_WEBKITADDITIONS_HEADER_REPLACEMENT_FEATURE_INPUT_$(USE_INTERNAL_SDK)_$(WK_IS_INSTALLHDRS));
-WK_WEBKITADDITIONS_HEADER_REPLACEMENT_FEATURE_INPUT_YES_NO = $(WK_WEBKITADDITIONS_HEADERS_FOLDER_PATH)/FeatureNeededForHeaderReplacement;
-
-WK_WEBKITADDITIONS_WKWEBVIEW_INPUT = $(WK_WEBKITADDITIONS_WKWEBVIEW_INPUT_$(USE_INTERNAL_SDK)_$(WK_IS_INSTALLHDRS));
-WK_WEBKITADDITIONS_WKWEBVIEW_INPUT_YES_NO = $(WK_WEBKITADDITIONS_HEADERS_FOLDER_PATH)/WKWebViewAdditions.h;
-
-WK_WEBKITADDITIONS_WKWEBVIEW_PRIVATE_INPUT = $(WK_WEBKITADDITIONS_WKWEBVIEW_PRIVATE_INPUT_$(USE_INTERNAL_SDK)_$(WK_IS_INSTALLHDRS));
-WK_WEBKITADDITIONS_WKWEBVIEW_PRIVATE_INPUT_YES_NO = $(WK_WEBKITADDITIONS_HEADERS_FOLDER_PATH)/WKWebViewPrivateAdditions.h;
-
-WK_WEBKITADDITIONS_WKPREFERENCES_PRIVATE_INPUT = $(WK_WEBKITADDITIONS_WKPREFERENCES_PRIVATE_INPUT_$(USE_INTERNAL_SDK)_$(WK_IS_INSTALLHDRS));
-WK_WEBKITADDITIONS_WKPREFERENCES_PRIVATE_INPUT_YES_NO = $(WK_WEBKITADDITIONS_HEADERS_FOLDER_PATH)/WKPreferencesPrivateAdditions.h;
-
 // The root directory of the workspace / WebKit repo is determined by how many directories up "Source" or "Tools" is from the SRCROOT.
 WK_WORKSPACE_DIR = $(WK_WORKSPACE_DIR_1_$(SRCROOT:dir:standardizepath:file):standardizepath:default=$(WK_WORKSPACE_DIR_2_$(SRCROOT:dir:standardizepath:dir:standardizepath:file):standardizepath:default=$(WK_WORKSPACE_DIR_3_$(SRCROOT:dir:standardizepath:dir:standardizepath:dir:standardizepath:file):standardizepath:default=$(WK_WORKSPACE_DIR_4_$(SRCROOT:dir:standardizepath:dir:standardizepath:dir:standardizepath:dir:standardizepath:file):standardizepath:default=$(WK_WORKSPACE_DIR_5_$(SRCROOT:dir:standardizepath:dir:standardizepath:dir:standardizepath:dir:standardizepath:dir:standardizepath:file):standardizepath:default=$(WK_WORKSPACE_DIR_6_$(SRCROOT:dir:standardizepath:dir:standardizepath:dir:standardizepath:dir:standardizepath:dir:standardizepath:dir:standardizepath:file):standardizepath))))));
 WK_WORKSPACE_DIR_1_Source = $(SRCROOT)/../..;