From a5dcbc632eb4e6922fb23b93fcb38ba85c3712ec Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 20:34:18 +0800
Subject: [PATCH 1/8] =?UTF-8?q?feat(macOS):=20=E6=B7=BB=E5=8A=A0=E6=97=A5?=
 =?UTF-8?q?=E5=BF=97=E7=9B=AE=E5=BD=95=E8=AE=BE=E7=BD=AE?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Lithe/Models/Settings/AppSettings.swift   | 19 +++++++
 Sources/Lithe/Views/App/SettingsView.swift    | 41 ++++++++++++-
 Tests/LitheTests/AppSettingsTests.swift       | 21 +++++++
 ...-17-cross-platform-logging-requirements.md | 57 +++++++++++++++++++
 4 files changed, 136 insertions(+), 2 deletions(-)
 create mode 100644 docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md

diff --git a/Sources/Lithe/Models/Settings/AppSettings.swift b/Sources/Lithe/Models/Settings/AppSettings.swift
index 5469979c0..83359215f 100644
--- a/Sources/Lithe/Models/Settings/AppSettings.swift
+++ b/Sources/Lithe/Models/Settings/AppSettings.swift
@@ -22,6 +22,7 @@ final class AppSettings: ObservableObject {
         static let javaLanguageServerJDKPath = "settings.javaLanguageServerJDKPath"
         static let commitMessageAI = "settings.commitMessageAI"
         static let keyboardShortcutOverrides = "settings.keyboardShortcutOverrides"
+        static let customLogDirectory = "settings.customLogDirectory"
     }
 
     private struct KeyboardShortcutOverridesPayload: Codable {
@@ -77,6 +78,7 @@ final class AppSettings: ObservableObject {
         didSet { saveCommitMessageAI() }
     }
     @Published private(set) var keyboardShortcutOverrides: [String: [KeyboardShortcutBinding]]
+    @Published private(set) var customLogDirectory: URL?
 
     private var fileVisibilityRulesObservers: [UUID: () -> Void] = [:]
 
@@ -110,6 +112,10 @@ final class AppSettings: ObservableObject {
         ) ?? .ask
         javaLanguageServerJDKPath = defaults.string(forKey: Key.javaLanguageServerJDKPath) ?? ""
         keyboardShortcutOverrides = Self.loadKeyboardShortcutOverrides(from: defaults)
+        customLogDirectory = defaults.string(forKey: Key.customLogDirectory).flatMap { path in
+            guard !path.isEmpty else { return nil }
+            return URL(fileURLWithPath: path, isDirectory: true).standardizedFileURL
+        }
         if let data = defaults.data(forKey: Key.commitMessageAI),
            let saved = try? JSONDecoder().decode(CommitMessageAISettings.self, from: data) {
             commitMessageAI = saved
@@ -121,6 +127,18 @@ final class AppSettings: ObservableObject {
 
     var terminalShellPath: String? { terminalShell.path }
 
+    var defaultLogDirectory: URL {
+        FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask)[0]
+            .appendingPathComponent("Logs/Lithe", isDirectory: true)
+    }
+
+    var logDirectory: URL { customLogDirectory ?? defaultLogDirectory }
+
+    func setCustomLogDirectory(_ url: URL?) {
+        customLogDirectory = url?.standardizedFileURL
+        defaults.set(customLogDirectory?.path, forKey: Key.customLogDirectory)
+    }
+
     var fileVisibilityRules: FileVisibilityRules {
         FileVisibilityRules(
             hiddenDirectoryNames: hiddenDirectoryNames,
@@ -162,6 +180,7 @@ final class AppSettings: ObservableObject {
         projectOpenBehavior = .ask
         javaLanguageServerJDKPath = ""
         commitMessageAI = .default
+        setCustomLogDirectory(nil)
         setKeyboardShortcutOverrides([:])
     }
 
diff --git a/Sources/Lithe/Views/App/SettingsView.swift b/Sources/Lithe/Views/App/SettingsView.swift
index b3e572c76..74811870c 100644
--- a/Sources/Lithe/Views/App/SettingsView.swift
+++ b/Sources/Lithe/Views/App/SettingsView.swift
@@ -1,4 +1,3 @@
-import AppKit
 import SwiftUI
 import LitheCoreContracts
 import LitheGitModule
@@ -168,7 +167,7 @@ struct SettingsView: View {
     private func searchTerms(for category: SettingsCategory) -> [String] {
         switch category {
         case .general:
-            ["General", "Appearance", "Color theme", "Appearance mode", "Language", "Projects", "Files", "Version control"]
+            ["General", "Appearance", "Color theme", "Appearance mode", "Language", "Projects", "Files", "Version control", "Logs", "Log directory"]
         case .editor:
             ["Editor", "Display", "Editor tabs", "Font size", "Indentation", "Tab width"]
         case .keymap:
@@ -368,6 +367,32 @@ struct SettingsView: View {
                         .buttonStyle(LithePrimaryButtonStyle())
                 }
             }
+
+            group("Logs") {
+                logDirectoryRow("Default directory", url: settings.defaultLogDirectory)
+                logDirectoryRow("Selected directory", url: settings.logDirectory)
+
+                HStack(spacing: 8) {
+                    Button {
+                        guard let directory = model.platformUI.chooseDirectory(
+                            title: "Choose Log Directory",
+                            prompt: "Choose"
+                        ) else { return }
+                        settings.setCustomLogDirectory(directory)
+                    } label: {
+                        Label("Choose Directory", systemImage: "folder.badge.plus")
+                    }
+                    .buttonStyle(LitheSecondaryButtonStyle())
+
+                    Button {
+                        settings.setCustomLogDirectory(nil)
+                    } label: {
+                        Label("Restore Default", systemImage: "arrow.counterclockwise")
+                    }
+                    .buttonStyle(LitheSecondaryButtonStyle())
+                    .disabled(settings.customLogDirectory == nil)
+                }
+            }
         }
     }
 
@@ -1063,6 +1088,18 @@ struct SettingsView: View {
         .frame(minHeight: 28)
     }
 
+    private func logDirectoryRow(_ title: String, url: URL) -> some View {
+        VStack(alignment: .leading, spacing: 5) {
+            Text(LocalizedStringKey(title))
+                .foregroundStyle(LitheTheme.secondaryText)
+            Text(url.path)
+                .font(.system(size: 11, design: .monospaced))
+                .textSelection(.enabled)
+                .lineLimit(2)
+                .fixedSize(horizontal: false, vertical: true)
+        }
+    }
+
     private func syncAIProviderDraft() {
         aiAPIKeyDraft = model.activeCommitMessageAPIKey
     }
diff --git a/Tests/LitheTests/AppSettingsTests.swift b/Tests/LitheTests/AppSettingsTests.swift
index 0977a1892..a28b5b384 100644
--- a/Tests/LitheTests/AppSettingsTests.swift
+++ b/Tests/LitheTests/AppSettingsTests.swift
@@ -28,6 +28,27 @@ struct AppSettingsTests {
         #expect(settings.autoSave)
         #expect(AppSettings(store: store).autoSave)
     }
+
+    @Test
+    func customLogDirectoryPersistsAndCanBeRestoredToDefault() {
+        let store = AppSettingsTestStore()
+        let settings = AppSettings(store: store)
+        let customDirectory = URL(fileURLWithPath: "/tmp/lithe-test-logs", isDirectory: true)
+
+        #expect(settings.customLogDirectory == nil)
+        #expect(settings.logDirectory == settings.defaultLogDirectory)
+
+        settings.setCustomLogDirectory(customDirectory)
+
+        let restored = AppSettings(store: store)
+        #expect(restored.customLogDirectory == customDirectory.standardizedFileURL)
+        #expect(restored.logDirectory == customDirectory.standardizedFileURL)
+
+        restored.restoreDefaults()
+
+        #expect(restored.customLogDirectory == nil)
+        #expect(AppSettings(store: store).logDirectory == restored.defaultLogDirectory)
+    }
 }
 
 private final class AppSettingsTestStore: KeyValueStore, @unchecked Sendable {
diff --git a/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md b/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
new file mode 100644
index 000000000..611638676
--- /dev/null
+++ b/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
@@ -0,0 +1,57 @@
+# Lithe macOS 日志目录设置需求
+
+## 背景
+
+macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修改日志保存目录。
+
+本需求只完善 macOS 日志目录的查看和配置，不重建日志系统，也不涉及 Windows 端。
+
+## 目标
+
+在设置中增加日志目录设置，让用户能够：
+
+- 查看系统默认日志目录；
+- 查看当前选定的日志目录；
+- 选择新的日志目录；
+- 恢复默认日志目录；
+- 复制完整目录路径。
+
+## 目录行为
+
+### 默认目录
+
+默认目录是 macOS 用户日志目录下的 `Lithe` 目录。设置页面展示系统解析后的真实绝对路径，不能硬编码开发机路径。
+
+### 自定义目录
+
+用户通过系统目录选择器选择目录。选择成功后保存配置，应用重启后继续显示该选择。该设置不影响其他配置。
+
+“恢复默认目录”只清除自定义日志目录。“恢复全部默认设置”也应清除该配置。
+
+## 界面要求
+
+日志设置页面显示默认目录和当前选定目录，并提供“选择目录”“恢复默认”操作。
+
+长路径可以换行或缩略显示，但必须支持复制完整路径。
+
+## 不在范围内
+
+本次不做：
+
+- 新建结构化日志协议；
+- 重写日志 writer、文件 sink 或导出逻辑；
+- 新增文件轮换和 ownership manifest；
+- 新增 Run、Build、Test、Debug、LSP、Terminal 生命周期日志；
+- 新增应用、窗口、工作区或文件事件日志；
+- 新增帧率采样或性能日志；
+- 修改日志格式、日志级别或日志内容；
+- 自动上传、云端查看或崩溃转储。
+
+## 验收标准
+
+1. 设置页显示真实默认目录和当前选定目录。
+2. 用户可以选择自定义目录，重启后配置仍然存在。
+3. 用户可以恢复默认目录。
+4. “恢复全部默认设置”会清除自定义日志目录。
+5. 用户可以复制完整路径。
+6. 没有引入新的日志协议、业务埋点、帧率监控或日志写入管线。

From 49827b714786d02441289d203fbe4cbb4c032d0b Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 20:58:15 +0800
Subject: [PATCH 2/8] =?UTF-8?q?fix(macOS):=20=E8=A1=A5=E5=85=85=E6=97=A5?=
 =?UTF-8?q?=E5=BF=97=E7=9B=AE=E5=BD=95=E8=AE=BE=E7=BD=AE=E4=B8=AD=E6=96=87?=
 =?UTF-8?q?=E7=BF=BB=E8=AF=91?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Resources/zh-Hans.lproj/Localizable.strings |  7 +++++++
 Tests/LitheTests/AppLocalizationTests.swift | 13 +++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/Resources/zh-Hans.lproj/Localizable.strings b/Resources/zh-Hans.lproj/Localizable.strings
index c1fb47ecd..e49be9c7f 100644
--- a/Resources/zh-Hans.lproj/Localizable.strings
+++ b/Resources/zh-Hans.lproj/Localizable.strings
@@ -178,6 +178,13 @@
 "The interface language changes immediately. English is the default." = "界面语言会立即生效。默认语言为英文。";
 "Files" = "文件";
 "Save changed files automatically" = "自动保存已修改的文件";
+"Logs" = "日志";
+"Log directory" = "日志目录";
+"Default directory" = "默认目录";
+"Selected directory" = "当前选择的目录";
+"Choose Directory" = "选择目录";
+"Choose Log Directory" = "选择日志目录";
+"Restore Default" = "恢复默认";
 "Save after" = "保存延迟";
 "Hidden paths" = "隐藏路径";
 "One entry per line. Directory names hide matching folders; file entries support * and ?." = "每行输入一项。目录名用于隐藏匹配的文件夹；文件条目支持 * 和 ?。";
diff --git a/Tests/LitheTests/AppLocalizationTests.swift b/Tests/LitheTests/AppLocalizationTests.swift
index 6bb5d4b2f..3ef5099e5 100644
--- a/Tests/LitheTests/AppLocalizationTests.swift
+++ b/Tests/LitheTests/AppLocalizationTests.swift
@@ -37,6 +37,19 @@ struct AppLocalizationTests {
         )
     }
 
+    @Test
+    func simplifiedChineseResourcesCoverLogDirectorySettings() throws {
+        let translations = try simplifiedChineseTranslations()
+
+        #expect(translations["Logs"] == "日志")
+        #expect(translations["Log directory"] == "日志目录")
+        #expect(translations["Default directory"] == "默认目录")
+        #expect(translations["Selected directory"] == "当前选择的目录")
+        #expect(translations["Choose Directory"] == "选择目录")
+        #expect(translations["Choose Log Directory"] == "选择日志目录")
+        #expect(translations["Restore Default"] == "恢复默认")
+    }
+
     @Test
     func simplifiedChineseResourcesCoverGitHubPullRequests() throws {
         let translations = try simplifiedChineseTranslations()

From 7321d53de66ca8c4a1c81e47fb310982c0ccf6d9 Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 21:00:37 +0800
Subject: [PATCH 3/8] =?UTF-8?q?style(macOS):=20=E8=B0=83=E6=95=B4=E6=97=A5?=
 =?UTF-8?q?=E5=BF=97=E7=9B=AE=E5=BD=95=E9=80=89=E6=8B=A9=E6=8E=A7=E4=BB=B6?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/Lithe/Views/App/SettingsView.swift | 74 +++++++++++++++-------
 1 file changed, 51 insertions(+), 23 deletions(-)

diff --git a/Sources/Lithe/Views/App/SettingsView.swift b/Sources/Lithe/Views/App/SettingsView.swift
index 74811870c..111f2ee4e 100644
--- a/Sources/Lithe/Views/App/SettingsView.swift
+++ b/Sources/Lithe/Views/App/SettingsView.swift
@@ -369,10 +369,19 @@ struct SettingsView: View {
             }
 
             group("Logs") {
-                logDirectoryRow("Default directory", url: settings.defaultLogDirectory)
-                logDirectoryRow("Selected directory", url: settings.logDirectory)
+                Text("Log directory")
+                    .font(.system(size: 11.5, weight: .medium))
+
+                HStack(spacing: 10) {
+                    Text(settings.logDirectory.path)
+                        .font(.system(size: 13, weight: .medium))
+                        .lineLimit(1)
+                        .truncationMode(.middle)
+                        .textSelection(.enabled)
+                        .help(settings.logDirectory.path)
+
+                    Spacer(minLength: 8)
 
-                HStack(spacing: 8) {
                     Button {
                         guard let directory = model.platformUI.chooseDirectory(
                             title: "Choose Log Directory",
@@ -380,18 +389,49 @@ struct SettingsView: View {
                         ) else { return }
                         settings.setCustomLogDirectory(directory)
                     } label: {
-                        Label("Choose Directory", systemImage: "folder.badge.plus")
+                        Image(systemName: "folder")
+                            .font(.system(size: 16, weight: .regular))
+                            .frame(width: 26, height: 26)
                     }
-                    .buttonStyle(LitheSecondaryButtonStyle())
+                    .buttonStyle(.plain)
+                    .foregroundStyle(LitheTheme.secondaryText)
+                    .contentShape(Rectangle())
+                    .lithePointer()
+                    .help("Choose Directory")
+                }
+                .padding(.horizontal, 12)
+                .frame(maxWidth: .infinity, minHeight: 46, maxHeight: 46)
+                .background(LitheTheme.inputBackground)
+                .clipShape(RoundedRectangle(cornerRadius: 6))
+                .overlay {
+                    RoundedRectangle(cornerRadius: 6)
+                        .stroke(LitheTheme.inputBorder, lineWidth: 1)
+                }
 
-                    Button {
-                        settings.setCustomLogDirectory(nil)
-                    } label: {
-                        Label("Restore Default", systemImage: "arrow.counterclockwise")
+                HStack(spacing: 6) {
+                    Text("Default directory")
+                        .foregroundStyle(LitheTheme.secondaryText)
+                    Text(settings.defaultLogDirectory.path)
+                        .foregroundStyle(LitheTheme.tertiaryText)
+                        .lineLimit(1)
+                        .truncationMode(.middle)
+                        .textSelection(.enabled)
+                        .help(settings.defaultLogDirectory.path)
+
+                    Spacer(minLength: 8)
+
+                    if settings.customLogDirectory != nil {
+                        Button {
+                            settings.setCustomLogDirectory(nil)
+                        } label: {
+                            Text("Restore Default")
+                        }
+                        .buttonStyle(.plain)
+                        .foregroundStyle(LitheTheme.accent)
+                        .lithePointer()
                     }
-                    .buttonStyle(LitheSecondaryButtonStyle())
-                    .disabled(settings.customLogDirectory == nil)
                 }
+                .font(LitheTheme.smallFont)
             }
         }
     }
@@ -1088,18 +1128,6 @@ struct SettingsView: View {
         .frame(minHeight: 28)
     }
 
-    private func logDirectoryRow(_ title: String, url: URL) -> some View {
-        VStack(alignment: .leading, spacing: 5) {
-            Text(LocalizedStringKey(title))
-                .foregroundStyle(LitheTheme.secondaryText)
-            Text(url.path)
-                .font(.system(size: 11, design: .monospaced))
-                .textSelection(.enabled)
-                .lineLimit(2)
-                .fixedSize(horizontal: false, vertical: true)
-        }
-    }
-
     private func syncAIProviderDraft() {
         aiAPIKeyDraft = model.activeCommitMessageAPIKey
     }

From 721736eb9b6f8af2f71b72dc2559d94e3711b5ff Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 21:49:47 +0800
Subject: [PATCH 4/8] =?UTF-8?q?fix(macOS):=20=E6=8E=A5=E5=85=A5=E5=8F=AF?=
 =?UTF-8?q?=E9=85=8D=E7=BD=AE=E6=97=A5=E5=BF=97=E8=BE=93=E5=87=BA=E7=9B=AE?=
 =?UTF-8?q?=E5=BD=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Core/Ports/LogDirectoryProviding.swift    |  5 ++
 Sources/Lithe/LitheApp.swift                  | 36 ++++++++++++-
 .../Lithe/Models/Settings/AppSettings.swift   | 21 ++++++--
 .../Logging/MacApplicationLogWriter.swift     | 32 ++++++++++++
 .../Logging/MacLogDirectoryProvider.swift     |  8 +++
 .../Platform/MacOS/MacServiceContainer.swift  |  8 +++
 Tests/LitheTests/AppSettingsTests.swift       | 16 ++++++
 .../MacApplicationLogWriterTests.swift        | 51 +++++++++++++++++++
 .../LitheTests/TestLogDirectoryProvider.swift | 12 +++++
 ...-17-cross-platform-logging-requirements.md | 11 ++--
 10 files changed, 191 insertions(+), 9 deletions(-)
 create mode 100644 Sources/Lithe/Core/Ports/LogDirectoryProviding.swift
 create mode 100644 Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
 create mode 100644 Sources/Lithe/Platform/MacOS/Logging/MacLogDirectoryProvider.swift
 create mode 100644 Tests/LitheTests/MacApplicationLogWriterTests.swift
 create mode 100644 Tests/LitheTests/TestLogDirectoryProvider.swift

diff --git a/Sources/Lithe/Core/Ports/LogDirectoryProviding.swift b/Sources/Lithe/Core/Ports/LogDirectoryProviding.swift
new file mode 100644
index 000000000..836f960fd
--- /dev/null
+++ b/Sources/Lithe/Core/Ports/LogDirectoryProviding.swift
@@ -0,0 +1,5 @@
+import Foundation
+
+protocol LogDirectoryProviding {
+    var defaultLogDirectory: URL { get }
+}
diff --git a/Sources/Lithe/LitheApp.swift b/Sources/Lithe/LitheApp.swift
index 6be8d2660..8de14e9ea 100644
--- a/Sources/Lithe/LitheApp.swift
+++ b/Sources/Lithe/LitheApp.swift
@@ -133,11 +133,27 @@ struct LitheApp: App {
     @StateObject private var memoryUsageMonitor: MemoryUsageMonitor
     @StateObject private var frameRateMonitor = FrameRateMonitor()
     @StateObject private var updateChecker = UpdateChecker()
+    private let applicationLogWriter: MacApplicationLogWriter
 
     init() {
-        MacBundledFontRegistry.registerFonts()
         let store = MacUserDefaultsStore()
-        let settings = AppSettings(store: store)
+        let settings = AppSettings(
+            store: store,
+            logDirectoryProvider: MacServiceContainer.makeLogDirectoryProvider()
+        )
+        let applicationLogWriter = MacServiceContainer.makeApplicationLogWriter()
+        if !Self.redirectApplicationLogs(applicationLogWriter, to: settings.logDirectory),
+           settings.customLogDirectory != nil {
+            settings.setCustomLogDirectory(nil)
+            _ = Self.redirectApplicationLogs(applicationLogWriter, to: settings.defaultLogDirectory)
+        }
+        settings.addLogDirectoryObserver { [weak settings] directory in
+            guard !Self.redirectApplicationLogs(applicationLogWriter, to: directory),
+                  settings?.customLogDirectory != nil else { return }
+            settings?.setCustomLogDirectory(nil)
+        }
+        self.applicationLogWriter = applicationLogWriter
+        MacBundledFontRegistry.registerFonts()
         let processRegistry = ManagedProcessRegistry()
         let moduleStore = MacModuleConfigurationStore(store: store)
         let pluginRuntimeRecovery = MacPluginRuntimeRecoveryCoordinator()
@@ -185,6 +201,22 @@ struct LitheApp: App {
         }
     }
 
+    private static func redirectApplicationLogs(
+        _ writer: MacApplicationLogWriter,
+        to directory: URL
+    ) -> Bool {
+        do {
+            try writer.redirect(to: directory)
+            return true
+        } catch {
+            let message = "Could not redirect Lithe logs to \(directory.path): \(error.localizedDescription)\n"
+            if let data = message.data(using: .utf8) {
+                FileHandle.standardError.write(data)
+            }
+            return false
+        }
+    }
+
     private var model: AppModel { projectSessions.activeModel }
 
     var body: some Scene {
diff --git a/Sources/Lithe/Models/Settings/AppSettings.swift b/Sources/Lithe/Models/Settings/AppSettings.swift
index 83359215f..be7be26a0 100644
--- a/Sources/Lithe/Models/Settings/AppSettings.swift
+++ b/Sources/Lithe/Models/Settings/AppSettings.swift
@@ -33,6 +33,7 @@ final class AppSettings: ObservableObject {
     }
 
     private let defaults: any KeyValueStore
+    private let logDirectoryProvider: any LogDirectoryProviding
 
     @Published var colorTheme: AppColorTheme {
         didSet {
@@ -81,9 +82,14 @@ final class AppSettings: ObservableObject {
     @Published private(set) var customLogDirectory: URL?
 
     private var fileVisibilityRulesObservers: [UUID: () -> Void] = [:]
+    private var logDirectoryObservers: [UUID: (URL) -> Void] = [:]
 
-    init(store: any KeyValueStore) {
+    init(
+        store: any KeyValueStore,
+        logDirectoryProvider: any LogDirectoryProviding
+    ) {
         self.defaults = store
+        self.logDirectoryProvider = logDirectoryProvider
         colorTheme = AppColorTheme(
             rawValue: defaults.string(forKey: Key.colorTheme) ?? ""
         ) ?? .lithe
@@ -128,8 +134,7 @@ final class AppSettings: ObservableObject {
     var terminalShellPath: String? { terminalShell.path }
 
     var defaultLogDirectory: URL {
-        FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask)[0]
-            .appendingPathComponent("Logs/Lithe", isDirectory: true)
+        logDirectoryProvider.defaultLogDirectory
     }
 
     var logDirectory: URL { customLogDirectory ?? defaultLogDirectory }
@@ -137,6 +142,16 @@ final class AppSettings: ObservableObject {
     func setCustomLogDirectory(_ url: URL?) {
         customLogDirectory = url?.standardizedFileURL
         defaults.set(customLogDirectory?.path, forKey: Key.customLogDirectory)
+        for observer in logDirectoryObservers.values {
+            observer(logDirectory)
+        }
+    }
+
+    @discardableResult
+    func addLogDirectoryObserver(_ observer: @escaping (URL) -> Void) -> UUID {
+        let id = UUID()
+        logDirectoryObservers[id] = observer
+        return id
     }
 
     var fileVisibilityRules: FileVisibilityRules {
diff --git a/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift b/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
new file mode 100644
index 000000000..c69a49f5b
--- /dev/null
+++ b/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
@@ -0,0 +1,32 @@
+import Darwin
+import Foundation
+
+final class MacApplicationLogWriter {
+    static let fileName = "lithe.log"
+
+    private let targetFileDescriptor: Int32
+
+    init(targetFileDescriptor: Int32 = STDERR_FILENO) {
+        self.targetFileDescriptor = targetFileDescriptor
+    }
+
+    func redirect(to directory: URL) throws {
+        try FileManager.default.createDirectory(
+            at: directory,
+            withIntermediateDirectories: true
+        )
+        let logURL = directory.appendingPathComponent(Self.fileName, isDirectory: false)
+        let descriptor = logURL.withUnsafeFileSystemRepresentation { path in
+            guard let path else { return -1 }
+            return open(path, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)
+        }
+        guard descriptor >= 0 else {
+            throw POSIXError(POSIXErrorCode(rawValue: errno) ?? .EIO)
+        }
+        defer { close(descriptor) }
+
+        guard dup2(descriptor, targetFileDescriptor) >= 0 else {
+            throw POSIXError(POSIXErrorCode(rawValue: errno) ?? .EIO)
+        }
+    }
+}
diff --git a/Sources/Lithe/Platform/MacOS/Logging/MacLogDirectoryProvider.swift b/Sources/Lithe/Platform/MacOS/Logging/MacLogDirectoryProvider.swift
new file mode 100644
index 000000000..98161e48c
--- /dev/null
+++ b/Sources/Lithe/Platform/MacOS/Logging/MacLogDirectoryProvider.swift
@@ -0,0 +1,8 @@
+import Foundation
+
+struct MacLogDirectoryProvider: LogDirectoryProviding {
+    var defaultLogDirectory: URL {
+        FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask)[0]
+            .appendingPathComponent("Logs/Lithe", isDirectory: true)
+    }
+}
diff --git a/Sources/Lithe/Platform/MacOS/MacServiceContainer.swift b/Sources/Lithe/Platform/MacOS/MacServiceContainer.swift
index 0d88d68f1..f4682835c 100644
--- a/Sources/Lithe/Platform/MacOS/MacServiceContainer.swift
+++ b/Sources/Lithe/Platform/MacOS/MacServiceContainer.swift
@@ -38,6 +38,14 @@ final class MacServiceContainer {
     let runConfigurationStore: MacRunConfigurationStore
     let moduleLifecycleCoordinator: ModuleLifecycleCoordinator
 
+    static func makeLogDirectoryProvider() -> any LogDirectoryProviding {
+        MacLogDirectoryProvider()
+    }
+
+    static func makeApplicationLogWriter() -> MacApplicationLogWriter {
+        MacApplicationLogWriter()
+    }
+
     init(
         store: any KeyValueStore,
         settings: AppSettings,
diff --git a/Tests/LitheTests/AppSettingsTests.swift b/Tests/LitheTests/AppSettingsTests.swift
index a28b5b384..f7ae14f34 100644
--- a/Tests/LitheTests/AppSettingsTests.swift
+++ b/Tests/LitheTests/AppSettingsTests.swift
@@ -49,6 +49,22 @@ struct AppSettingsTests {
         #expect(restored.customLogDirectory == nil)
         #expect(AppSettings(store: store).logDirectory == restored.defaultLogDirectory)
     }
+
+    @Test
+    func logDirectoryObserversReceiveCustomAndRestoredDirectories() {
+        let settings = AppSettings(store: AppSettingsTestStore())
+        let customDirectory = URL(fileURLWithPath: "/tmp/lithe-observed-logs", isDirectory: true)
+        var observedDirectories: [URL] = []
+        settings.addLogDirectoryObserver { observedDirectories.append($0) }
+
+        settings.setCustomLogDirectory(customDirectory)
+        settings.setCustomLogDirectory(nil)
+
+        #expect(observedDirectories == [
+            customDirectory.standardizedFileURL,
+            settings.defaultLogDirectory
+        ])
+    }
 }
 
 private final class AppSettingsTestStore: KeyValueStore, @unchecked Sendable {
diff --git a/Tests/LitheTests/MacApplicationLogWriterTests.swift b/Tests/LitheTests/MacApplicationLogWriterTests.swift
new file mode 100644
index 000000000..36098e46d
--- /dev/null
+++ b/Tests/LitheTests/MacApplicationLogWriterTests.swift
@@ -0,0 +1,51 @@
+import Darwin
+import Foundation
+import Testing
+@testable import Lithe
+
+@Suite("macOS application log writer")
+struct MacApplicationLogWriterTests {
+    @Test
+    func changingDirectoryMovesSubsequentStandardErrorOutputToTheSelection() throws {
+        let root = FileManager.default.temporaryDirectory
+            .appendingPathComponent(UUID().uuidString, isDirectory: true)
+        let originalTarget = root.appendingPathComponent("original-target")
+        try FileManager.default.createDirectory(at: root, withIntermediateDirectories: true)
+        #expect(FileManager.default.createFile(atPath: originalTarget.path, contents: nil))
+        let targetHandle = try FileHandle(forWritingTo: originalTarget)
+        defer {
+            try? targetHandle.close()
+            try? FileManager.default.removeItem(at: root)
+        }
+
+        let writer = MacApplicationLogWriter(targetFileDescriptor: targetHandle.fileDescriptor)
+        let defaultDirectory = root.appendingPathComponent("default", isDirectory: true)
+        let selectedDirectory = root.appendingPathComponent("selected", isDirectory: true)
+
+        try writer.redirect(to: defaultDirectory)
+        try targetHandle.write(contentsOf: Data("default log line\n".utf8))
+        try targetHandle.synchronize()
+
+        try writer.redirect(to: selectedDirectory)
+        try targetHandle.write(contentsOf: Data("selected log line\n".utf8))
+        try targetHandle.synchronize()
+
+        let defaultContents = try String(
+            contentsOf: defaultDirectory.appendingPathComponent("lithe.log"),
+            encoding: .utf8
+        )
+        let selectedContents = try String(
+            contentsOf: selectedDirectory.appendingPathComponent("lithe.log"),
+            encoding: .utf8
+        )
+        #expect(defaultContents == "default log line\n")
+        #expect(selectedContents == "selected log line\n")
+    }
+
+    @Test
+    func defaultDirectoryProviderUsesTheMacUserLogsDirectory() {
+        let directory = MacLogDirectoryProvider().defaultLogDirectory
+
+        #expect(directory.path.hasSuffix("/Library/Logs/Lithe"))
+    }
+}
diff --git a/Tests/LitheTests/TestLogDirectoryProvider.swift b/Tests/LitheTests/TestLogDirectoryProvider.swift
new file mode 100644
index 000000000..05bf59205
--- /dev/null
+++ b/Tests/LitheTests/TestLogDirectoryProvider.swift
@@ -0,0 +1,12 @@
+import Foundation
+@testable import Lithe
+
+struct TestLogDirectoryProvider: LogDirectoryProviding {
+    let defaultLogDirectory = URL(fileURLWithPath: "/test/default-logs", isDirectory: true)
+}
+
+extension AppSettings {
+    convenience init(store: any KeyValueStore) {
+        self.init(store: store, logDirectoryProvider: TestLogDirectoryProvider())
+    }
+}
diff --git a/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md b/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
index 611638676..be21878cb 100644
--- a/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
+++ b/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
@@ -4,7 +4,7 @@
 
 macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修改日志保存目录。
 
-本需求只完善 macOS 日志目录的查看和配置，不重建日志系统，也不涉及 Windows 端。
+本需求只完善 macOS 日志目录的查看和配置，并将应用现有的标准错误输出写入该目录，不涉及 Windows 端或业务日志扩展。
 
 ## 目标
 
@@ -24,7 +24,9 @@ macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修
 
 ### 自定义目录
 
-用户通过系统目录选择器选择目录。选择成功后保存配置，应用重启后继续显示该选择。该设置不影响其他配置。
+用户通过系统目录选择器选择目录。选择成功后保存配置，应用标准错误输出立即切换到该目录中的 `lithe.log`，应用重启后继续使用该选择。该设置不影响其他配置。
+
+如果自定义目录无法创建或打开，应用清除该选择并恢复默认目录，界面不得继续把失败目录显示为当前日志目录。
 
 “恢复默认目录”只清除自定义日志目录。“恢复全部默认设置”也应清除该配置。
 
@@ -39,7 +41,7 @@ macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修
 本次不做：
 
 - 新建结构化日志协议；
-- 重写日志 writer、文件 sink 或导出逻辑；
+- 新建结构化日志 writer、业务 sink 或导出逻辑；
 - 新增文件轮换和 ownership manifest；
 - 新增 Run、Build、Test、Debug、LSP、Terminal 生命周期日志；
 - 新增应用、窗口、工作区或文件事件日志；
@@ -54,4 +56,5 @@ macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修
 3. 用户可以恢复默认目录。
 4. “恢复全部默认设置”会清除自定义日志目录。
 5. 用户可以复制完整路径。
-6. 没有引入新的日志协议、业务埋点、帧率监控或日志写入管线。
+6. 标准错误输出写入当前目录的 `lithe.log`，切换目录后新输出写入新目录。
+7. 没有引入新的结构化日志协议、业务埋点或帧率监控。

From 03d87a191182606ab427b2e5a3d08ebb31ae451c Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 22:00:18 +0800
Subject: [PATCH 5/8] =?UTF-8?q?fix(macOS):=20=E4=BF=AE=E6=AD=A3=E6=97=A5?=
 =?UTF-8?q?=E5=BF=97=E6=96=87=E4=BB=B6=E6=8F=8F=E8=BF=B0=E7=AC=A6=E7=B1=BB?=
 =?UTF-8?q?=E5=9E=8B?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Platform/MacOS/Logging/MacApplicationLogWriter.swift      | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift b/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
index c69a49f5b..0c428655d 100644
--- a/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
+++ b/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
@@ -16,8 +16,8 @@ final class MacApplicationLogWriter {
             withIntermediateDirectories: true
         )
         let logURL = directory.appendingPathComponent(Self.fileName, isDirectory: false)
-        let descriptor = logURL.withUnsafeFileSystemRepresentation { path in
-            guard let path else { return -1 }
+        let descriptor: Int32 = logURL.withUnsafeFileSystemRepresentation { path in
+            guard let path else { return Int32(-1) }
             return open(path, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)
         }
         guard descriptor >= 0 else {

From 182b1f7bdabc5442c8576023f4c376cbf12104d3 Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 22:33:22 +0800
Subject: [PATCH 6/8] =?UTF-8?q?fix(macOS):=20=E9=81=BF=E5=85=8D=E6=97=A5?=
 =?UTF-8?q?=E5=BF=97=E9=87=8D=E5=AE=9A=E5=90=91=E6=B5=8B=E8=AF=95=E9=98=BB?=
 =?UTF-8?q?=E5=A1=9E?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../MacApplicationLogWriterTests.swift        | 27 +++++++++++++------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/Tests/LitheTests/MacApplicationLogWriterTests.swift b/Tests/LitheTests/MacApplicationLogWriterTests.swift
index 36098e46d..b400737e3 100644
--- a/Tests/LitheTests/MacApplicationLogWriterTests.swift
+++ b/Tests/LitheTests/MacApplicationLogWriterTests.swift
@@ -11,24 +11,25 @@ struct MacApplicationLogWriterTests {
             .appendingPathComponent(UUID().uuidString, isDirectory: true)
         let originalTarget = root.appendingPathComponent("original-target")
         try FileManager.default.createDirectory(at: root, withIntermediateDirectories: true)
-        #expect(FileManager.default.createFile(atPath: originalTarget.path, contents: nil))
-        let targetHandle = try FileHandle(forWritingTo: originalTarget)
+        let targetDescriptor: Int32 = originalTarget.withUnsafeFileSystemRepresentation { path in
+            guard let path else { return Int32(-1) }
+            return open(path, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR)
+        }
+        #expect(targetDescriptor >= 0)
         defer {
-            try? targetHandle.close()
+            close(targetDescriptor)
             try? FileManager.default.removeItem(at: root)
         }
 
-        let writer = MacApplicationLogWriter(targetFileDescriptor: targetHandle.fileDescriptor)
+        let writer = MacApplicationLogWriter(targetFileDescriptor: targetDescriptor)
         let defaultDirectory = root.appendingPathComponent("default", isDirectory: true)
         let selectedDirectory = root.appendingPathComponent("selected", isDirectory: true)
 
         try writer.redirect(to: defaultDirectory)
-        try targetHandle.write(contentsOf: Data("default log line\n".utf8))
-        try targetHandle.synchronize()
+        try write("default log line\n", to: targetDescriptor)
 
         try writer.redirect(to: selectedDirectory)
-        try targetHandle.write(contentsOf: Data("selected log line\n".utf8))
-        try targetHandle.synchronize()
+        try write("selected log line\n", to: targetDescriptor)
 
         let defaultContents = try String(
             contentsOf: defaultDirectory.appendingPathComponent("lithe.log"),
@@ -48,4 +49,14 @@ struct MacApplicationLogWriterTests {
 
         #expect(directory.path.hasSuffix("/Library/Logs/Lithe"))
     }
+
+    private func write(_ value: String, to descriptor: Int32) throws {
+        let data = Data(value.utf8)
+        let written = data.withUnsafeBytes { bytes in
+            Darwin.write(descriptor, bytes.baseAddress, bytes.count)
+        }
+        guard written == data.count, fsync(descriptor) == 0 else {
+            throw POSIXError(POSIXErrorCode(rawValue: errno) ?? .EIO)
+        }
+    }
 }

From 7a7280d1051cdd1b9ac802d9eb710b8e68f9685c Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 22:46:03 +0800
Subject: [PATCH 7/8] =?UTF-8?q?fix(macOS):=20=E9=9A=94=E7=A6=BB=E6=97=A5?=
 =?UTF-8?q?=E5=BF=97=E5=86=99=E5=85=A5=E4=B8=8E=E6=B5=8B=E8=AF=95=E8=BF=9B?=
 =?UTF-8?q?=E7=A8=8B?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/Lithe/LitheApp.swift                  | 21 +++++++++--
 .../Logging/MacApplicationLogWriter.swift     | 35 +++++++++++++++----
 .../MacOS/UI/MacBundledFontRegistry.swift     | 13 +++++--
 .../MacApplicationLogWriterTests.swift        | 25 +++----------
 ...-17-cross-platform-logging-requirements.md |  6 ++--
 5 files changed, 64 insertions(+), 36 deletions(-)

diff --git a/Sources/Lithe/LitheApp.swift b/Sources/Lithe/LitheApp.swift
index 8de14e9ea..852eaf0d8 100644
--- a/Sources/Lithe/LitheApp.swift
+++ b/Sources/Lithe/LitheApp.swift
@@ -153,7 +153,9 @@ struct LitheApp: App {
             settings?.setCustomLogDirectory(nil)
         }
         self.applicationLogWriter = applicationLogWriter
-        MacBundledFontRegistry.registerFonts()
+        MacBundledFontRegistry.registerFonts { message in
+            Self.appendApplicationLog(applicationLogWriter, message: message)
+        }
         let processRegistry = ManagedProcessRegistry()
         let moduleStore = MacModuleConfigurationStore(store: store)
         let pluginRuntimeRecovery = MacPluginRuntimeRecoveryCoordinator()
@@ -187,8 +189,7 @@ struct LitheApp: App {
         _memoryUsageMonitor = StateObject(wrappedValue: MemoryUsageMonitor(
             startedAt: litheProcessLaunchDate,
             baselineReporter: { marker in
-                guard let data = (marker + "\n").data(using: .utf8) else { return }
-                FileHandle.standardError.write(data)
+                Self.appendApplicationLog(applicationLogWriter, message: marker + "\n")
             },
             logsPerformanceBaseline: ProcessInfo.processInfo.environment["LITHE_PERFORMANCE_BASELINE"] == "1",
             processRegistry: processRegistry,
@@ -217,6 +218,20 @@ struct LitheApp: App {
         }
     }
 
+    private static func appendApplicationLog(
+        _ writer: MacApplicationLogWriter,
+        message: String
+    ) {
+        do {
+            try writer.append(message)
+        } catch {
+            let fallback = "Could not write Lithe log: \(error.localizedDescription)\n"
+            if let data = fallback.data(using: .utf8) {
+                FileHandle.standardError.write(data)
+            }
+        }
+    }
+
     private var model: AppModel { projectSessions.activeModel }
 
     var body: some Scene {
diff --git a/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift b/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
index 0c428655d..c40670940 100644
--- a/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
+++ b/Sources/Lithe/Platform/MacOS/Logging/MacApplicationLogWriter.swift
@@ -4,17 +4,36 @@ import Foundation
 final class MacApplicationLogWriter {
     static let fileName = "lithe.log"
 
-    private let targetFileDescriptor: Int32
-
-    init(targetFileDescriptor: Int32 = STDERR_FILENO) {
-        self.targetFileDescriptor = targetFileDescriptor
-    }
+    private let lock = NSLock()
+    private var directory: URL?
 
     func redirect(to directory: URL) throws {
         try FileManager.default.createDirectory(
             at: directory,
             withIntermediateDirectories: true
         )
+        let logURL = directory.appendingPathComponent(Self.fileName, isDirectory: false)
+        let descriptor: Int32 = logURL.withUnsafeFileSystemRepresentation { path in
+            guard let path else { return Int32(-1) }
+            return open(path, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)
+        }
+        guard descriptor >= 0 else {
+            throw POSIXError(POSIXErrorCode(rawValue: errno) ?? .EIO)
+        }
+        close(descriptor)
+
+        lock.lock()
+        self.directory = directory
+        lock.unlock()
+    }
+
+    func append(_ message: String) throws {
+        lock.lock()
+        defer { lock.unlock() }
+        guard let directory else {
+            throw CocoaError(.fileNoSuchFile)
+        }
+
         let logURL = directory.appendingPathComponent(Self.fileName, isDirectory: false)
         let descriptor: Int32 = logURL.withUnsafeFileSystemRepresentation { path in
             guard let path else { return Int32(-1) }
@@ -25,7 +44,11 @@ final class MacApplicationLogWriter {
         }
         defer { close(descriptor) }
 
-        guard dup2(descriptor, targetFileDescriptor) >= 0 else {
+        let data = Data(message.utf8)
+        let written = data.withUnsafeBytes { bytes in
+            Darwin.write(descriptor, bytes.baseAddress, bytes.count)
+        }
+        guard written == data.count else {
             throw POSIXError(POSIXErrorCode(rawValue: errno) ?? .EIO)
         }
     }
diff --git a/Sources/Lithe/Platform/MacOS/UI/MacBundledFontRegistry.swift b/Sources/Lithe/Platform/MacOS/UI/MacBundledFontRegistry.swift
index 749114018..0f734e1fb 100644
--- a/Sources/Lithe/Platform/MacOS/UI/MacBundledFontRegistry.swift
+++ b/Sources/Lithe/Platform/MacOS/UI/MacBundledFontRegistry.swift
@@ -11,6 +11,13 @@ enum MacBundledFontRegistry {
     ]
 
     static func registerFonts(bundle: Bundle = .main) {
+        registerFonts(bundle: bundle, reporter: report)
+    }
+
+    static func registerFonts(
+        bundle: Bundle = .main,
+        reporter: (String) -> Void
+    ) {
         guard bundle.url(forResource: "JetBrainsMono-Regular", withExtension: "ttf", subdirectory: "Fonts") != nil else {
             return
         }
@@ -21,7 +28,7 @@ enum MacBundledFontRegistry {
                 withExtension: "ttf",
                 subdirectory: "Fonts"
             ) else {
-                report("Missing bundled font: \(font.resource).ttf")
+                reporter("Lithe font registration: Missing bundled font: \(font.resource).ttf\n")
                 continue
             }
 
@@ -29,14 +36,14 @@ enum MacBundledFontRegistry {
             guard CTFontManagerRegisterFontsForURL(url as CFURL, .process, &registrationError) else {
                 let detail = registrationError?.takeRetainedValue().localizedDescription
                     ?? "Unknown CoreText error"
-                report("Could not register \(font.resource).ttf: \(detail)")
+                reporter("Lithe font registration: Could not register \(font.resource).ttf: \(detail)\n")
                 continue
             }
         }
     }
 
     private static func report(_ message: String) {
-        guard let data = ("Lithe font registration: \(message)\n").data(using: .utf8) else { return }
+        guard let data = message.data(using: .utf8) else { return }
         FileHandle.standardError.write(data)
     }
 }
diff --git a/Tests/LitheTests/MacApplicationLogWriterTests.swift b/Tests/LitheTests/MacApplicationLogWriterTests.swift
index b400737e3..bf1eb68ba 100644
--- a/Tests/LitheTests/MacApplicationLogWriterTests.swift
+++ b/Tests/LitheTests/MacApplicationLogWriterTests.swift
@@ -1,4 +1,3 @@
-import Darwin
 import Foundation
 import Testing
 @testable import Lithe
@@ -6,30 +5,23 @@ import Testing
 @Suite("macOS application log writer")
 struct MacApplicationLogWriterTests {
     @Test
-    func changingDirectoryMovesSubsequentStandardErrorOutputToTheSelection() throws {
+    func changingDirectoryMovesSubsequentApplicationLogOutputToTheSelection() throws {
         let root = FileManager.default.temporaryDirectory
             .appendingPathComponent(UUID().uuidString, isDirectory: true)
-        let originalTarget = root.appendingPathComponent("original-target")
         try FileManager.default.createDirectory(at: root, withIntermediateDirectories: true)
-        let targetDescriptor: Int32 = originalTarget.withUnsafeFileSystemRepresentation { path in
-            guard let path else { return Int32(-1) }
-            return open(path, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR)
-        }
-        #expect(targetDescriptor >= 0)
         defer {
-            close(targetDescriptor)
             try? FileManager.default.removeItem(at: root)
         }
 
-        let writer = MacApplicationLogWriter(targetFileDescriptor: targetDescriptor)
+        let writer = MacApplicationLogWriter()
         let defaultDirectory = root.appendingPathComponent("default", isDirectory: true)
         let selectedDirectory = root.appendingPathComponent("selected", isDirectory: true)
 
         try writer.redirect(to: defaultDirectory)
-        try write("default log line\n", to: targetDescriptor)
+        try writer.append("default log line\n")
 
         try writer.redirect(to: selectedDirectory)
-        try write("selected log line\n", to: targetDescriptor)
+        try writer.append("selected log line\n")
 
         let defaultContents = try String(
             contentsOf: defaultDirectory.appendingPathComponent("lithe.log"),
@@ -50,13 +42,4 @@ struct MacApplicationLogWriterTests {
         #expect(directory.path.hasSuffix("/Library/Logs/Lithe"))
     }
 
-    private func write(_ value: String, to descriptor: Int32) throws {
-        let data = Data(value.utf8)
-        let written = data.withUnsafeBytes { bytes in
-            Darwin.write(descriptor, bytes.baseAddress, bytes.count)
-        }
-        guard written == data.count, fsync(descriptor) == 0 else {
-            throw POSIXError(POSIXErrorCode(rawValue: errno) ?? .EIO)
-        }
-    }
 }
diff --git a/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md b/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
index be21878cb..b688006ea 100644
--- a/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
+++ b/docs/superpowers/specs/2026-08-17-cross-platform-logging-requirements.md
@@ -4,7 +4,7 @@
 
 macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修改日志保存目录。
 
-本需求只完善 macOS 日志目录的查看和配置，并将应用现有的标准错误输出写入该目录，不涉及 Windows 端或业务日志扩展。
+本需求只完善 macOS 日志目录的查看和配置，并将应用现有的字体注册和性能基线诊断写入该目录，不涉及 Windows 端或业务日志扩展。
 
 ## 目标
 
@@ -24,7 +24,7 @@ macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修
 
 ### 自定义目录
 
-用户通过系统目录选择器选择目录。选择成功后保存配置，应用标准错误输出立即切换到该目录中的 `lithe.log`，应用重启后继续使用该选择。该设置不影响其他配置。
+用户通过系统目录选择器选择目录。选择成功后保存配置，应用诊断输出立即切换到该目录中的 `lithe.log`，应用重启后继续使用该选择。该设置不影响其他配置。
 
 如果自定义目录无法创建或打开，应用清除该选择并恢复默认目录，界面不得继续把失败目录显示为当前日志目录。
 
@@ -56,5 +56,5 @@ macOS 设置界面没有告诉用户日志默认保存在哪里，也不能修
 3. 用户可以恢复默认目录。
 4. “恢复全部默认设置”会清除自定义日志目录。
 5. 用户可以复制完整路径。
-6. 标准错误输出写入当前目录的 `lithe.log`，切换目录后新输出写入新目录。
+6. 现有字体注册和性能基线诊断写入当前目录的 `lithe.log`，切换目录后新输出写入新目录。
 7. 没有引入新的结构化日志协议、业务埋点或帧率监控。

From 215f463a0b99ff1720fcce0f6bfc12b477c24fd5 Mon Sep 17 00:00:00 2001
From: Sunwenzhi58 <2514832692@qq.com>
Date: Tue, 18 Aug 2026 23:07:25 +0800
Subject: [PATCH 8/8] =?UTF-8?q?ci(macOS):=20=E6=94=BE=E5=AE=BD=20Swift=20?=
 =?UTF-8?q?=E6=B5=8B=E8=AF=95=E8=B6=85=E6=97=B6=E6=97=B6=E9=97=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .github/workflows/ci-macos.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci-macos.yml b/.github/workflows/ci-macos.yml
index ffdffb8eb..4a9f185a7 100644
--- a/.github/workflows/ci-macos.yml
+++ b/.github/workflows/ci-macos.yml
@@ -81,7 +81,7 @@ jobs:
     needs: changes
     if: needs.changes.outputs.full == 'true'
     runs-on: macos-14
-    timeout-minutes: 20
+    timeout-minutes: 30
 
     steps:
       - name: Check out source
@@ -104,12 +104,12 @@ jobs:
       - name: Run Swift tests
         id: swift-tests-primary
         continue-on-error: true
-        timeout-minutes: 8
+        timeout-minutes: 12
         run: ./scripts/test-macos.sh
 
       - name: Retry Swift tests after a failed attempt
         if: steps.swift-tests-primary.outcome == 'failure'
-        timeout-minutes: 8
+        timeout-minutes: 12
         run: ./scripts/test-macos.sh --skip-build
 
   rust-tests: