fix: discover ThinLTO cache path from GN instead of hardcoding

Addresses review feedback from @deepak1556: the hardcoded
`out\Default\thinlto-cache` path goes out of sync if upstream
changes `cache_dir` in Chromium's build/config/compiler/BUILD.gn.

Read the `/lldltocache:` flag from `gn desc` on a linked target
(`//electron:electron_app`) and pre-create whatever path GN
actually configured. Skips the pre-create entirely when ThinLTO
is disabled (non-official builds), which is the correct no-op.

.github/actions/build-electron/action.yml

@@ -101,6 +101,21 @@ runs:
         git pack-refs
         cd ..
 
+        # Pre-create the ThinLTO cache directory so lld-link does not need to
+        # call CreateDirectoryW through the bindflt filter driver, which can
+        # return ERROR_INVALID_PARAMETER under concurrent I/O on ARC runners.
+        # Discover the path from GN instead of hardcoding it so we stay in
+        # sync with `cache_dir` in build/config/compiler/BUILD.gn; skip the
+        # pre-create when ThinLTO is disabled (non-official builds).
+        $env:ELECTRON_DEPOT_TOOLS_DISABLE_LOG = "1"
+        $ltoFlag = e d gn desc out/Default //electron:electron_app ldflags 2>$null |
+          Select-String -Pattern '^/lldltocache:(.+)$' |
+          Select-Object -First 1
+        if ($ltoFlag) {
+          $cachePath = Join-Path 'out\Default' $ltoFlag.Matches[0].Groups[1].Value
+          New-Item -ItemType Directory -Force -Path $cachePath | Out-Null
+        }
+
         $env:NINJA_SUMMARIZE_BUILD = 1
         if ("${{ inputs.is-release }}" -eq "true") {          
           e build --target electron:release_build

.github/siso-patches/0002-siso-retry-transient-ERROR_INVALID_PARAMETER-when-op.patch

@@ -0,0 +1,132 @@
+From a8afee1089ec2ae9ab5837b438d07338aefb3bc4 Mon Sep 17 00:00:00 2001
+From: Samuel Attard <sam@electronjs.org>
+Date: Wed, 22 Apr 2026 16:27:51 -0700
+Subject: [PATCH] siso: retry transient ERROR_INVALID_PARAMETER when opening
+ ninja files on Windows
+
+ManifestParser.Load fans out across all subninja files (~90k in a
+Chromium build) at NumCPU parallelism. On Windows builders where out/
+is served through a filesystem filter driver (e.g. bindflt/wcifs for
+container bind mounts), CreateFileW can intermittently return
+ERROR_INVALID_PARAMETER under this concurrent open burst. The previous
+patch removes the redundant per-chunk re-open, but the single remaining
+open per file can still hit the race; without a retry a single transient
+failure aborts the entire manifest load.
+
+Wrap the remaining os.Open call in readFile in a small Windows-only
+retry for ERROR_INVALID_PARAMETER (5 attempts, 5-80ms backoff). Each
+retry is logged via clog.Warningf and also written to stderr so it is
+visible in CI step output where glog warnings are file-only by default.
+Other platforms keep the direct os.Open path.
+---
+ siso/toolsupport/ninjautil/file_parser.go     |  3 +-
+ siso/toolsupport/ninjautil/openfile_other.go  | 18 +++++++
+ .../toolsupport/ninjautil/openfile_windows.go | 50 +++++++++++++++++++
+ 3 files changed, 69 insertions(+), 2 deletions(-)
+ create mode 100644 siso/toolsupport/ninjautil/openfile_other.go
+ create mode 100644 siso/toolsupport/ninjautil/openfile_windows.go
+
+diff --git a/siso/toolsupport/ninjautil/file_parser.go b/siso/toolsupport/ninjautil/file_parser.go
+index 6311666..324528d 100644
+--- a/siso/toolsupport/ninjautil/file_parser.go
++++ b/siso/toolsupport/ninjautil/file_parser.go
+@@ -7,7 +7,6 @@ package ninjautil
+ import (
+ 	"context"
+ 	"fmt"
+-	"os"
+ 	"runtime/trace"
+ 	"sync"
+ 	"time"
+@@ -91,7 +90,7 @@ func (p *fileParser) parseFile(ctx context.Context, fname string) error {
+ // readFile reads a file of fname in parallel.
+ func (p *fileParser) readFile(ctx context.Context, fname string) ([]byte, error) {
+ 	defer trace.StartRegion(ctx, "ninja.read").End()
+-	f, err := os.Open(fname)
++	f, err := openFile(ctx, fname)
+ 	if err != nil {
+ 		return nil, err
+ 	}
+diff --git a/siso/toolsupport/ninjautil/openfile_other.go b/siso/toolsupport/ninjautil/openfile_other.go
+new file mode 100644
+index 0000000..9fca690
+--- /dev/null
++++ b/siso/toolsupport/ninjautil/openfile_other.go
+@@ -0,0 +1,18 @@
++// Copyright 2026 The Chromium Authors
++// Use of this source code is governed by a BSD-style license that can be
++// found in the LICENSE file.
++
++//go:build !windows
++
++package ninjautil
++
++import (
++	"context"
++	"os"
++)
++
++// openFile opens fname for reading.
++// See openfile_windows.go for the Windows variant with transient-error retry.
++func openFile(ctx context.Context, fname string) (*os.File, error) {
++	return os.Open(fname)
++}
+diff --git a/siso/toolsupport/ninjautil/openfile_windows.go b/siso/toolsupport/ninjautil/openfile_windows.go
+new file mode 100644
+index 0000000..f9d8e9d
+--- /dev/null
++++ b/siso/toolsupport/ninjautil/openfile_windows.go
+@@ -0,0 +1,50 @@
++// Copyright 2026 The Chromium Authors
++// Use of this source code is governed by a BSD-style license that can be
++// found in the LICENSE file.
++
++//go:build windows
++
++package ninjautil
++
++import (
++	"context"
++	"errors"
++	"fmt"
++	"os"
++	"time"
++
++	"golang.org/x/sys/windows"
++
++	"go.chromium.org/build/siso/o11y/clog"
++)
++
++// openFile opens fname for reading, retrying transient
++// ERROR_INVALID_PARAMETER failures.
++//
++// On Windows, CreateFileW can intermittently return
++// ERROR_INVALID_PARAMETER when the target lives behind a filesystem
++// filter driver (e.g. bindflt/wcifs for container bind mounts) under
++// highly concurrent opens. loadFile fans out across ~90k subninja
++// files at NumCPU parallelism, so a single transient failure would
++// otherwise abort the whole manifest load.
++func openFile(ctx context.Context, fname string) (*os.File, error) {
++	const maxAttempts = 5
++	delay := 5 * time.Millisecond
++	for i := 0; ; i++ {
++		f, err := os.Open(fname)
++		if err == nil {
++			return f, nil
++		}
++		if i+1 >= maxAttempts || !errors.Is(err, windows.ERROR_INVALID_PARAMETER) {
++			return nil, err
++		}
++		clog.Warningf(ctx, "open %s: %v; retrying (%d/%d) after %s", fname, err, i+1, maxAttempts, delay)
++		fmt.Fprintf(os.Stderr, "siso: open %s: %v; retrying (%d/%d) after %s\n", fname, err, i+1, maxAttempts, delay)
++		select {
++		case <-time.After(delay):
++		case <-ctx.Done():
++			return nil, context.Cause(ctx)
++		}
++		delay *= 2
++	}
++}
+-- 
+2.53.0
+

.github/workflows/build.yml

@@ -398,7 +398,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     if: ${{ needs.setup.outputs.src == 'true' && !inputs.skip-windows }}
     with:
-      build-runs-on: electron-arc-centralus-windows-amd64-16core
+      build-runs-on: electron-arc-centralus-windows-amd64-32core
       clang-tidy-runs-on: electron-arc-centralus-linux-amd64-8core
       test-runs-on: windows-latest
       clang-tidy-container: '{"image":"ghcr.io/electron/build:${{ needs.checkout-windows.outputs.build-image-sha }}","options":"--user root --device /dev/fuse --cap-add SYS_ADMIN","volumes":["/mnt/win-cache:/mnt/win-cache"]}'
@@ -419,7 +419,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     if: ${{ needs.setup.outputs.src == 'true' && !inputs.skip-windows }}
     with:
-      build-runs-on: electron-arc-centralus-windows-amd64-16core
+      build-runs-on: electron-arc-centralus-windows-amd64-32core
       test-runs-on: windows-latest
       target-platform: win
       target-arch: x86
@@ -438,7 +438,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     if: ${{ needs.setup.outputs.src == 'true' && !inputs.skip-windows }}
     with:
-      build-runs-on: electron-arc-centralus-windows-amd64-16core
+      build-runs-on: electron-arc-centralus-windows-amd64-32core
       test-runs-on: windows-11-arm
       target-platform: win
       target-arch: arm64

.github/workflows/windows-publish.yml

@@ -82,7 +82,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     with:
       environment: production-release
-      build-runs-on: electron-arc-centralus-windows-amd64-16core
+      build-runs-on: electron-arc-centralus-windows-amd64-32core
       target-platform: win
       target-arch: x64
       is-release: true
@@ -101,7 +101,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     with:
       environment: production-release
-      build-runs-on: electron-arc-centralus-windows-amd64-16core
+      build-runs-on: electron-arc-centralus-windows-amd64-32core
       target-platform: win
       target-arch: arm64
       is-release: true
@@ -120,7 +120,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     with:
       environment: production-release
-      build-runs-on: electron-arc-centralus-windows-amd64-16core
+      build-runs-on: electron-arc-centralus-windows-amd64-32core
       target-platform: win
       target-arch: x86
       is-release: true

lib/common/deprecate.ts

@@ -56,7 +56,7 @@ export function removeFunction<T extends Function>(fn: T, removedName: string):
   const warn = warnOnce(`${fn.name} function`);
   return function (this: any) {
     warn();
-    fn.apply(this, arguments);
+    return fn.apply(this, arguments);
   } as unknown as typeof fn;
 }
 

package.json

@@ -78,7 +78,7 @@
     "gn-typescript-definitions": "npm run create-typescript-definitions && node script/cp.mjs electron.d.ts",
     "pre-flight": "pre-flight",
     "gn-check": "node ./script/gn-check.js",
-    "gn-format": "python3 script/run-gn-format.py",
+    "gn-format": "node ./script/lint.js --gn --fix",
     "precommit": "lint-staged",
     "preinstall": "node -e 'process.exit(0)'",
     "pretest": "npm run create-typescript-definitions",
@@ -117,7 +117,7 @@
     ],
     "*.{gn,gni}": [
       "npm run gn-check",
-      "npm run gn-format"
+      "node ./script/lint.js --gn --fix --only --"
     ],
     "*.py": [
       "node script/lint.js --py --fix --only --"

script/run-gn-format.py

@@ -1,25 +0,0 @@
-import os
-import subprocess
-import sys
-
-from lib.util import get_depot_tools_env
-
-SOURCE_ROOT = os.path.dirname(os.path.dirname(__file__))
-
-# Helper to run gn format on multiple files
-# (gn only formats a single file at a time)
-def main():
-  new_env = get_depot_tools_env()
-  new_env['DEPOT_TOOLS_WIN_TOOLCHAIN'] = '0'
-  new_env['CHROMIUM_BUILDTOOLS_PATH'] = os.path.realpath(
-    os.path.join(SOURCE_ROOT, '..', 'buildtools')
-  )
-
-  for gn_file in sys.argv[1:]:
-    subprocess.check_call(
-      ['gn', 'format', gn_file],
-      env=new_env
-    )
-
-if __name__ == '__main__':
-  sys.exit(main())

shell/browser/api/electron_api_auto_updater.cc

@@ -12,20 +12,28 @@
 #include "shell/common/gin_converters/time_converter.h"
 #include "shell/common/gin_helper/dictionary.h"
 #include "shell/common/gin_helper/event_emitter_caller.h"
-#include "shell/common/gin_helper/handle.h"
 #include "shell/common/gin_helper/object_template_builder.h"
+#include "shell/common/gin_helper/wrappable_pointer_tags.h"
 #include "shell/common/node_includes.h"
+#include "v8/include/cppgc/allocation.h"
+#include "v8/include/v8-cppgc.h"
 
 namespace electron::api {
 
-gin::DeprecatedWrapperInfo AutoUpdater::kWrapperInfo = {
-    gin::kEmbedderNativeGin};
+const gin::WrapperInfo AutoUpdater::kWrapperInfo =
+    electron::MakeWrapperInfo(electron::kElectronAutoUpdater);
 
-AutoUpdater::AutoUpdater() {
+AutoUpdater::AutoUpdater(v8::Isolate* isolate) {
   auto_updater::AutoUpdater::SetDelegate(this);
+  gin::PerIsolateData* data = gin::PerIsolateData::From(isolate);
+  data->AddDisposeObserver(this);
 }
 
-AutoUpdater::~AutoUpdater() {
+AutoUpdater::~AutoUpdater() = default;
+
+void AutoUpdater::OnBeforeMicrotasksRunnerDispose(v8::Isolate* isolate) {
+  gin::PerIsolateData* data = gin::PerIsolateData::From(isolate);
+  data->RemoveDisposeObserver(this);
   auto_updater::AutoUpdater::SetDelegate(nullptr);
 }
 
@@ -120,8 +128,9 @@ void AutoUpdater::QuitAndInstall() {
 }
 
 // static
-gin_helper::Handle<AutoUpdater> AutoUpdater::Create(v8::Isolate* isolate) {
-  return gin_helper::CreateHandle(isolate, new AutoUpdater());
+AutoUpdater* AutoUpdater::Create(v8::Isolate* isolate) {
+  return cppgc::MakeGarbageCollected<AutoUpdater>(
+      isolate->GetCppHeap()->GetAllocationHandle(), isolate);
 }
 
 gin::ObjectTemplateBuilder AutoUpdater::GetObjectTemplateBuilder(
@@ -138,8 +147,12 @@ gin::ObjectTemplateBuilder AutoUpdater::GetObjectTemplateBuilder(
       .SetMethod("quitAndInstall", &AutoUpdater::QuitAndInstall);
 }
 
-const char* AutoUpdater::GetTypeName() {
-  return "AutoUpdater";
+const gin::WrapperInfo* AutoUpdater::wrapper_info() const {
+  return &kWrapperInfo;
+}
+
+const char* AutoUpdater::GetHumanReadableName() const {
+  return "Electron / AutoUpdater";
 }
 
 }  // namespace electron::api

shell/browser/api/electron_api_auto_updater.h

@@ -7,39 +7,44 @@
 
 #include <string>
 
+#include "gin/per_isolate_data.h"
+#include "gin/wrappable.h"
 #include "shell/browser/auto_updater.h"
 #include "shell/browser/event_emitter_mixin.h"
 #include "shell/browser/window_list_observer.h"
-#include "shell/common/gin_helper/wrappable.h"
-
-namespace gin_helper {
-template <typename T>
-class Handle;
-}  // namespace gin_helper
 
 namespace electron::api {
 
-class AutoUpdater final : public gin_helper::DeprecatedWrappable<AutoUpdater>,
+class AutoUpdater final : public gin::Wrappable<AutoUpdater>,
                           public gin_helper::EventEmitterMixin<AutoUpdater>,
                           public auto_updater::Delegate,
+                          public gin::PerIsolateData::DisposeObserver,
                           private WindowListObserver {
  public:
-  static gin_helper::Handle<AutoUpdater> Create(v8::Isolate* isolate);
+  static AutoUpdater* Create(v8::Isolate* isolate);
 
-  // gin_helper::Wrappable
-  static gin::DeprecatedWrapperInfo kWrapperInfo;
+  // gin::Wrappable
+  static const gin::WrapperInfo kWrapperInfo;
+  const gin::WrapperInfo* wrapper_info() const override;
+  const char* GetHumanReadableName() const override;
   gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
       v8::Isolate* isolate) override;
-  const char* GetTypeName() override;
+  const char* GetClassName() const { return "AutoUpdater"; }
+
+  // gin::PerIsolateData::DisposeObserver
+  void OnBeforeDispose(v8::Isolate* isolate) override {}
+  void OnBeforeMicrotasksRunnerDispose(v8::Isolate* isolate) override;
+  void OnDisposed() override {}
+
+  // Make public for cppgc::MakeGarbageCollected.
+  explicit AutoUpdater(v8::Isolate* isolate);
+  ~AutoUpdater() override;
 
   // disable copy
   AutoUpdater(const AutoUpdater&) = delete;
   AutoUpdater& operator=(const AutoUpdater&) = delete;
 
- protected:
-  AutoUpdater();
-  ~AutoUpdater() override;
-
+ private:
   // auto_updater::Delegate:
   void OnError(const std::string& message) override;
   void OnError(const std::string& message,
@@ -56,7 +61,6 @@ class AutoUpdater final : public gin_helper::DeprecatedWrappable<AutoUpdater>,
   // WindowListObserver:
   void OnWindowAllClosed() override;
 
- private:
   std::string GetFeedURL();
   void QuitAndInstall();
 };

shell/common/gin_helper/wrappable_pointer_tags.h

@@ -13,6 +13,7 @@ namespace electron {
 // Electron-specific WrappablePointerTag values that extend gin's tag range.
 enum ElectronWrappablePointerTag : uint16_t {
   kElectronApp = gin::kLastPointerTag + 1,  // electron::api::App
+  kElectronAutoUpdater,                     // electron::api::AutoUpdater
   kElectronCookies,                         // electron::api::Cookies
   kElectronDataPipeHolder,                  // electron::api::DataPipeHolder
   kElectronDebugger,                        // electron::api::Debugger

spec/api-app-spec.ts

@@ -9,16 +9,32 @@ import * as fs from 'node:fs';
 import * as http from 'node:http';
 import * as https from 'node:https';
 import * as net from 'node:net';
+import * as os from 'node:os';
 import * as path from 'node:path';
 import * as readline from 'node:readline';
 import { setTimeout } from 'node:timers/promises';
 import { promisify } from 'node:util';
 
 import { collectStreamBody, getResponse } from './lib/net-helpers';
-import { ifdescribe, ifit, isWayland, listen, waitUntil } from './lib/spec-helpers';
+import { defer, ifdescribe, ifit, isWayland, listen, waitUntil } from './lib/spec-helpers';
 import { closeWindow, closeAllWindows } from './lib/window-helpers';
 
 const fixturesPath = path.resolve(__dirname, 'fixtures');
+const xdgMockFixturePath = path.join(fixturesPath, 'api', 'xdg-mock');
+
+function makeXdgMockDirectories(prefix: string) {
+  const xdgDir = fs.mkdtempSync(path.join(os.tmpdir(), prefix));
+  fs.cpSync(xdgMockFixturePath, xdgDir, { recursive: true });
+
+  const xdgDataHome = path.join(xdgDir, 'data');
+  const xdgConfigHome = path.join(xdgDir, 'config');
+  const xdgBinDir = path.join(xdgDir, 'bin');
+
+  fs.chmodSync(path.join(xdgBinDir, 'xdg-mime'), 0o755);
+  fs.chmodSync(path.join(xdgBinDir, 'xdg-settings'), 0o755);
+
+  return { xdgDir, xdgDataHome, xdgConfigHome, xdgBinDir };
+}
 
 const isMacOSx64 = process.platform === 'darwin' && process.arch === 'x64';
 
@@ -1515,7 +1531,6 @@ describe('app module', () => {
       const fixtureApp = path.join(fixturesPath, 'api', 'protocol-name');
       const desktopFileId = 'mock-browser.desktop';
       const mockScheme = 'mockproto';
-      const mockMimeType = `x-scheme-handler/${mockScheme}`;
 
       function spawnWithXdgMock(
         url: string,
@@ -1564,62 +1579,7 @@ describe('app module', () => {
       let xdgConfigHome: string;
       let xdgBinDir: string;
       before(() => {
-        xdgDir = fs.mkdtempSync(path.join(require('node:os').tmpdir(), 'electron-xdg-'));
-        xdgDataHome = path.join(xdgDir, 'data');
-        xdgConfigHome = path.join(xdgDir, 'config');
-        xdgBinDir = path.join(xdgDir, 'bin');
-        const appsDir = path.join(xdgDataHome, 'applications');
-        fs.mkdirSync(appsDir, { recursive: true });
-        fs.mkdirSync(xdgConfigHome, { recursive: true });
-        fs.mkdirSync(xdgBinDir, { recursive: true });
-
-        fs.writeFileSync(
-          path.join(appsDir, desktopFileId),
-          [
-            '[Desktop Entry]',
-            'Name=Mock Browser',
-            'Exec=/usr/bin/true %u',
-            'Type=Application',
-            `MimeType=${mockMimeType};`
-          ].join('\n')
-        );
-
-        const mimeAppsContents = [
-          '[Default Applications]',
-          `${mockMimeType}=${desktopFileId}`,
-          '',
-          '[Added Associations]',
-          `${mockMimeType}=${desktopFileId};`
-        ].join('\n');
-
-        fs.writeFileSync(path.join(xdgConfigHome, 'mimeapps.list'), mimeAppsContents);
-        fs.writeFileSync(path.join(appsDir, 'mimeapps.list'), mimeAppsContents);
-        fs.writeFileSync(path.join(appsDir, 'defaults.list'), mimeAppsContents);
-
-        // Different xdg-utils versions resolve custom XDG dirs differently, so
-        // prepend a deterministic xdg-mime shim for this test.
-        const xdgMimePath = path.join(xdgBinDir, 'xdg-mime');
-        fs.writeFileSync(
-          xdgMimePath,
-          [
-            '#!/bin/sh',
-            'if [ "$1" != "query" ] || [ "$2" != "default" ]; then',
-            '  exit 1',
-            'fi',
-            'mime="$3"',
-            'for list in "$XDG_CONFIG_HOME/mimeapps.list" "$XDG_DATA_HOME/applications/mimeapps.list" "$XDG_DATA_HOME/applications/defaults.list"; do',
-            '  if [ -f "$list" ]; then',
-            '    result=$(grep "^$mime=" "$list" | head -n 1 | cut -d= -f2 | cut -d";" -f1)',
-            '    if [ -n "$result" ]; then',
-            '      printf "%s\\n" "$result"',
-            '      exit 0',
-            '    fi',
-            '  fi',
-            'done',
-            'exit 0'
-          ].join('\n')
-        );
-        fs.chmodSync(xdgMimePath, 0o755);
+        ({ xdgDir, xdgDataHome, xdgConfigHome, xdgBinDir } = makeXdgMockDirectories('electron-xdg-'));
       });
 
       after(() => {
@@ -1659,6 +1619,95 @@ describe('app module', () => {
     });
   });
 
+  ifdescribe(process.platform === 'linux')('default protocol client APIs with mocked XDG settings', () => {
+    const protocol = 'electron-test-linux';
+    const desktopFileId = 'electron-test.desktop';
+    const protocolMimeType = `x-scheme-handler/${protocol}`;
+
+    let xdgDir: string;
+    let xdgDataHome: string;
+    let xdgConfigHome: string;
+    let xdgBinDir: string;
+    let oldEnv: Record<string, string | undefined>;
+
+    const getRegisteredHandler = () => {
+      for (const list of [
+        path.join(xdgConfigHome, 'mimeapps.list'),
+        path.join(xdgDataHome, 'applications', 'mimeapps.list'),
+        path.join(xdgDataHome, 'applications', 'defaults.list')
+      ]) {
+        if (!fs.existsSync(list)) continue;
+
+        const match = fs
+          .readFileSync(list, 'utf8')
+          .split('\n')
+          .find((line) => line.startsWith(`${protocolMimeType}=`));
+
+        // foo=bar.desktop; --> bar.desktop
+        if (match) return match.split('=', 2)[1].split(';', 1)[0];
+      }
+
+      return '';
+    };
+
+    beforeEach(() => {
+      ({ xdgDir, xdgDataHome, xdgConfigHome, xdgBinDir } = makeXdgMockDirectories('electron-xdg-default-client-'));
+
+      oldEnv = {
+        PATH: process.env.PATH,
+        CHROME_DESKTOP: process.env.CHROME_DESKTOP,
+        XDG_DATA_HOME: process.env.XDG_DATA_HOME,
+        XDG_DATA_DIRS: process.env.XDG_DATA_DIRS,
+        XDG_CONFIG_HOME: process.env.XDG_CONFIG_HOME
+      };
+
+      defer(() => {
+        for (const [key, value] of Object.entries(oldEnv)) {
+          if (value === undefined) {
+            delete process.env[key];
+          } else {
+            process.env[key] = value;
+          }
+        }
+
+        fs.rmSync(xdgDir, { recursive: true, force: true });
+      });
+
+      process.env.PATH = [xdgBinDir, oldEnv.PATH].filter(Boolean).join(':');
+      process.env.XDG_DATA_HOME = xdgDataHome;
+      process.env.XDG_DATA_DIRS = [xdgDataHome, oldEnv.XDG_DATA_DIRS].filter(Boolean).join(':');
+      process.env.XDG_CONFIG_HOME = xdgConfigHome;
+      app.setDesktopName(desktopFileId);
+    });
+
+    it('writes the default handler to the XDG association files', async () => {
+      expect(getRegisteredHandler()).to.equal('');
+
+      expect(app.setAsDefaultProtocolClient(protocol)).to.equal(true);
+
+      await waitUntil(() => getRegisteredHandler() === desktopFileId);
+      expect(getRegisteredHandler()).to.equal(desktopFileId);
+    });
+
+    it('detects whether the app is the default protocol client', async () => {
+      expect(app.isDefaultProtocolClient(protocol)).to.equal(false);
+
+      fs.writeFileSync(
+        path.join(xdgConfigHome, 'mimeapps.list'),
+        ['[Default Applications]', `${protocolMimeType}=other.desktop`].join('\n')
+      );
+      expect(app.isDefaultProtocolClient(protocol)).to.equal(false);
+
+      fs.writeFileSync(
+        path.join(xdgConfigHome, 'mimeapps.list'),
+        ['[Default Applications]', `${protocolMimeType}=${desktopFileId}`].join('\n')
+      );
+
+      await waitUntil(() => app.isDefaultProtocolClient(protocol));
+      expect(app.isDefaultProtocolClient(protocol)).to.equal(true);
+    });
+  });
+
   describe('protocol scheme validation', () => {
     it('rejects empty protocol names', () => {
       expect(app.setAsDefaultProtocolClient('')).to.equal(false);

spec/cpp-heap-spec.ts

@@ -615,4 +615,53 @@ describe('cpp heap', () => {
       );
     });
   });
+
+  ifdescribe(process.platform === 'darwin')('autoUpdater module', () => {
+    it('is retained after garbage collection', async () => {
+      const rc = await startRemoteControlApp(['--js-flags=--expose-gc']);
+      const result = await rc.remotely(async () => {
+        const { autoUpdater } = require('electron');
+        const v8Util = (process as any)._linkedBinding('electron_common_v8_util');
+        const wr = new WeakRef(autoUpdater);
+        for (let i = 0; i < 10; i++) {
+          await new Promise((resolve) => setTimeout(resolve, 0));
+          v8Util.requestGarbageCollectionForTesting();
+        }
+        return {
+          retained: wr.deref() !== undefined,
+          functional: typeof autoUpdater.getFeedURL() === 'string'
+        };
+      });
+      expect(result.retained).to.equal(true, 'autoUpdater should survive GC');
+      expect(result.functional).to.equal(true, 'autoUpdater should still be functional after GC');
+    });
+
+    it('should record as node in heap snapshot', async () => {
+      const rc = await startRemoteControlApp(['--expose-internals', '--js-flags=--expose-gc']);
+      const result = await rc.remotely(
+        async (heap: string) => {
+          const { autoUpdater, app } = require('electron');
+          const { recordState } = require(heap);
+          const v8Util = (process as any)._linkedBinding('electron_common_v8_util');
+          console.log(autoUpdater.getFeedURL());
+          for (let i = 0; i < 10; i++) {
+            await new Promise((resolve) => setTimeout(resolve, 0));
+            v8Util.requestGarbageCollectionForTesting();
+          }
+          const state = recordState();
+          const nodes = state.snapshot.filter((node: any) => node.name === 'Electron / AutoUpdater');
+          const found = nodes.length > 0;
+          const noDuplicates = nodes.length === 1;
+          setTimeout(() => app.quit());
+          return { found, noDuplicates };
+        },
+        path.join(__dirname, '../../third_party/electron_node/test/common/heap')
+      );
+
+      const [code] = await once(rc.process, 'exit');
+      expect(code).to.equal(0);
+      expect(result.found).to.equal(true, 'AutoUpdater should be in snapshot (held by JS module)');
+      expect(result.noDuplicates).to.equal(true, 'should have exactly one AutoUpdater instance');
+    });
+  });
 });

spec/deprecate-spec.ts

@@ -130,6 +130,19 @@ describe('deprecate', () => {
     expect(msg).to.include('oldFn');
   });
 
+  it('preserves the return value and `this` of a deprecated function with no replacement', () => {
+    deprecate.setHandler(() => {});
+
+    function oldFn(this: any, a: number, b: number) {
+      return { self: this, sum: a + b };
+    }
+    const deprecatedFn = deprecate.removeFunction(oldFn, 'oldFn');
+    const context = { name: 'ctx' };
+    const result = deprecatedFn.call(context, 2, 3);
+
+    expect(result).to.deep.equal({ self: context, sum: 5 });
+  });
+
   it('warns exactly once when a function is deprecated with a replacement', () => {
     let msg;
     deprecate.setHandler((m) => {

spec/fixtures/api/xdg-mock/bin/xdg-mime

@@ -0,0 +1,15 @@
+#!/bin/sh
+if [ "$1" != "query" ] || [ "$2" != "default" ]; then
+  exit 1
+fi
+mime="$3"
+for list in "$XDG_CONFIG_HOME/mimeapps.list" "$XDG_DATA_HOME/applications/mimeapps.list" "$XDG_DATA_HOME/applications/defaults.list"; do
+  if [ -f "$list" ]; then
+    result=$(grep "^$mime=" "$list" | head -n 1 | cut -d= -f2 | cut -d";" -f1)
+    if [ -n "$result" ]; then
+      printf "%s\n" "$result"
+      exit 0
+    fi
+  fi
+done
+exit 0

spec/fixtures/api/xdg-mock/bin/xdg-settings

@@ -0,0 +1,31 @@
+#!/bin/sh
+set -eu
+get_handler() {
+  for list in "$XDG_CONFIG_HOME/mimeapps.list" "$XDG_DATA_HOME/applications/mimeapps.list" "$XDG_DATA_HOME/applications/defaults.list"; do
+    if [ -f "$list" ]; then
+      result=$(grep "^x-scheme-handler/$1=" "$list" | head -n 1 | cut -d= -f2 | cut -d";" -f1)
+      if [ -n "$result" ]; then
+        printf "%s\n" "$result"
+        return 0
+      fi
+    fi
+  done
+  return 1
+}
+if [ "$1" = "set" ] && [ "$2" = "default-url-scheme-handler" ]; then
+  mkdir -p "$XDG_CONFIG_HOME"
+  {
+    printf "[Default Applications]\n"
+    printf "x-scheme-handler/%s=%s\n" "$3" "$4"
+  } > "$XDG_CONFIG_HOME/mimeapps.list"
+  exit 0
+fi
+if [ "$1" = "check" ] && [ "$2" = "default-url-scheme-handler" ]; then
+  if [ "$(get_handler "$3" 2>/dev/null || true)" = "$4" ]; then
+    printf "yes\n"
+  else
+    printf "no\n"
+  fi
+  exit 0
+fi
+exit 1

spec/fixtures/api/xdg-mock/config/mimeapps.list

@@ -0,0 +1,5 @@
+[Default Applications]
+x-scheme-handler/mockproto=mock-browser.desktop
+
+[Added Associations]
+x-scheme-handler/mockproto=mock-browser.desktop;

spec/fixtures/api/xdg-mock/data/applications/electron-test.desktop

@@ -0,0 +1,5 @@
+[Desktop Entry]
+Name=Electron Test
+Exec=/usr/bin/true %u
+Type=Application
+MimeType=x-scheme-handler/electron-test-linux;

spec/fixtures/api/xdg-mock/data/applications/mock-browser.desktop

@@ -0,0 +1,5 @@
+[Desktop Entry]
+Name=Mock Browser
+Exec=/usr/bin/true %u
+Type=Application
+MimeType=x-scheme-handler/mockproto;