diff --git a/macos/Sources/Ghostty/Ghostty.Config.swift b/macos/Sources/Ghostty/Ghostty.Config.swift
--- a/macos/Sources/Ghostty/Ghostty.Config.swift
+++ b/macos/Sources/Ghostty/Ghostty.Config.swift
@@ -354,14 +354,14 @@
             return MacOSWindowButtons(rawValue: str) ?? defaultValue
         }
 
-        var macosTitlebarStyle: String {
-            let defaultValue = "transparent"
+        var macosTitlebarStyle: MacOSTitlebarStyle {
+            let defaultValue = MacOSTitlebarStyle.transparent
             guard let config = self.config else { return defaultValue }
             var v: UnsafePointer<Int8>?
             let key = "macos-titlebar-style"
             guard ghostty_config_get(config, &v, key, UInt(key.lengthOfBytes(using: .utf8))) else { return defaultValue }
             guard let ptr = v else { return defaultValue }
-            return String(cString: ptr)
+            return MacOSTitlebarStyle(rawValue: String(cString: ptr)) ?? defaultValue
         }
 
         var macosTitlebarProxyIcon: MacOSTitlebarProxyIcon {
@@ -905,5 +905,10 @@
 
         static let bell = NotifyOnCommandFinishAction(rawValue: 1 << 0)
         static let notify = NotifyOnCommandFinishAction(rawValue: 1 << 1)
+    }
+
+    enum MacOSTitlebarStyle: String {
+        static let `default` = MacOSTitlebarStyle.transparent
+        case native, transparent, tabs, hidden
     }
 }
diff --git a/macos/Tests/Terminal/IntrinsicSizeTimingTests.swift b/macos/Tests/Terminal/IntrinsicSizeTimingTests.swift
--- a/macos/Tests/Terminal/IntrinsicSizeTimingTests.swift
+++ b/macos/Tests/Terminal/IntrinsicSizeTimingTests.swift
@@ -12,7 +12,7 @@
 private struct OptionalIdealSizeView: View {
     let idealWidth: CGFloat?
     let idealHeight: CGFloat?
-    let titlebarStyle: String
+    let titlebarStyle: Ghostty.Config.MacOSTitlebarStyle
 
     var body: some View {
         VStack(spacing: 0) {
@@ -20,7 +20,7 @@
                 .frame(idealWidth: idealWidth, idealHeight: idealHeight)
         }
         // Matches TerminalView line 108: hidden style extends into titlebar
-        .ignoresSafeArea(.container, edges: titlebarStyle == "hidden" ? .top : [])
+        .ignoresSafeArea(.container, edges: titlebarStyle == .hidden ? .top : [])
     }
 }
 
@@ -28,18 +28,18 @@
 private let minReasonableHeight: CGFloat = 50
 
 /// All macos-titlebar-style values that map to different window nibs.
-private let allTitlebarStyles = ["native", "hidden", "transparent", "tabs"]
+private let allTitlebarStyles: [Ghostty.Config.MacOSTitlebarStyle] = [.native, .hidden, .transparent, .tabs]
 
 /// Window style masks that roughly correspond to each titlebar style.
 /// In real Ghostty these come from different nib files; in tests we
 /// approximate with NSWindow style masks.
-private func styleMask(for titlebarStyle: String) -> NSWindow.StyleMask {
+private func styleMask(for titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) -> NSWindow.StyleMask {
     switch titlebarStyle {
-    case "hidden":
+    case .hidden:
         return [.titled, .resizable, .fullSizeContentView]
-    case "transparent", "tabs":
+    case .transparent, .tabs:
         return [.titled, .resizable, .fullSizeContentView]
-    default:
+    case .native:
         return [.titled, .resizable]
     }
 }
@@ -67,7 +67,7 @@
     /// intrinsicContentSize returns a tiny value.
     @Test(.bug("https://github.com/ghostty-org/ghostty/issues/11256", "intrinsicContentSize too small before @FocusedValue propagates"),
           arguments: allTitlebarStyles)
-    func intrinsicSizeTooSmallWithNilIdealSize(titlebarStyle: String) async throws {
+    func intrinsicSizeTooSmallWithNilIdealSize(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let expectedSize = NSSize(width: 600, height: 400)
 
         // nil ideal sizes = @FocusedValue hasn't propagated lastFocusedSurface
@@ -106,7 +106,7 @@
     /// too-small window when intrinsicContentSize is based on nil ideal sizes.
     @Test(.bug("https://github.com/ghostty-org/ghostty/issues/11256", "apply() sets wrong window size due to racy intrinsicContentSize"),
           arguments: allTitlebarStyles)
-    func applyProducesWrongSizeWithNilIdealSize(titlebarStyle: String) async throws {
+    func applyProducesWrongSizeWithNilIdealSize(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let container = await TerminalViewContainer {
             OptionalIdealSizeView(idealWidth: nil, idealHeight: nil, titlebarStyle: titlebarStyle)
         }
@@ -150,7 +150,7 @@
     /// to propagate, so intrinsicContentSize is still tiny when apply() runs.
     @Test(.bug("https://github.com/ghostty-org/ghostty/issues/11256", "40ms async delay reads intrinsicContentSize before @FocusedValue propagates"),
           arguments: allTitlebarStyles)
-    func asyncAfterDelayProducesWrongSizeWithNilIdealSize(titlebarStyle: String) async throws {
+    func asyncAfterDelayProducesWrongSizeWithNilIdealSize(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let container = await TerminalViewContainer {
             OptionalIdealSizeView(idealWidth: nil, idealHeight: nil, titlebarStyle: titlebarStyle)
         }
@@ -195,7 +195,7 @@
     /// fallback value, not just adjust timing.
     @Test(.bug("https://github.com/ghostty-org/ghostty/issues/11256", "Synchronous apply also fails without fallback"),
           arguments: allTitlebarStyles)
-    func synchronousApplyAlsoFailsWithNilIdealSize(titlebarStyle: String) async throws {
+    func synchronousApplyAlsoFailsWithNilIdealSize(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let container = await TerminalViewContainer {
             OptionalIdealSizeView(idealWidth: nil, idealHeight: nil, titlebarStyle: titlebarStyle)
         }
@@ -233,7 +233,7 @@
     /// should be correct for every titlebar style. This is the "happy path" that
     /// works today when the 40ms delay is sufficient.
     @Test(arguments: allTitlebarStyles)
-    func intrinsicSizeCorrectWhenIdealSizesAvailable(titlebarStyle: String) async throws {
+    func intrinsicSizeCorrectWhenIdealSizesAvailable(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let expectedSize = NSSize(width: 600, height: 400)
 
         let container = await TerminalViewContainer {
@@ -274,7 +274,7 @@
     /// Verifies that apply() sets a correctly sized window when ideal sizes
     /// are available, for each titlebar style.
     @Test(arguments: allTitlebarStyles)
-    func applyProducesCorrectSizeWhenIdealSizesAvailable(titlebarStyle: String) async throws {
+    func applyProducesCorrectSizeWhenIdealSizesAvailable(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let expectedSize = NSSize(width: 600, height: 400)
 
         let container = await TerminalViewContainer {
@@ -319,7 +319,7 @@
     /// This should always pass — it validates the delay works when @FocusedValue
     /// has already propagated.
     @Test(arguments: allTitlebarStyles)
-    func asyncAfterDelayProducesCorrectSizeWhenIdealSizesAvailable(titlebarStyle: String) async throws {
+    func asyncAfterDelayProducesCorrectSizeWhenIdealSizesAvailable(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let expectedSize = NSSize(width: 600, height: 400)
 
         let container = await TerminalViewContainer {
@@ -364,7 +364,7 @@
     /// (never .contentIntrinsicSize). The window uses its initial frame.
     /// This should work for all titlebar styles regardless of the bug.
     @Test(arguments: allTitlebarStyles)
-    func framePathWorksWithoutWindowSize(titlebarStyle: String) async throws {
+    func framePathWorksWithoutWindowSize(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let expectedFrame = NSRect(x: 100, y: 100, width: 800, height: 600)
 
         let container = await TerminalViewContainer {
@@ -399,7 +399,7 @@
     /// Verifies isChanged correctly detects mismatch for contentIntrinsicSize
     /// across titlebar styles when ideal sizes are available.
     @Test(arguments: allTitlebarStyles)
-    func isChangedDetectsMismatch(titlebarStyle: String) async throws {
+    func isChangedDetectsMismatch(titlebarStyle: Ghostty.Config.MacOSTitlebarStyle) async throws {
         let expectedSize = NSSize(width: 600, height: 400)
 
         let container = await TerminalViewContainer {
diff --git a/macos/Sources/Features/Terminal/TerminalController.swift b/macos/Sources/Features/Terminal/TerminalController.swift
--- a/macos/Sources/Features/Terminal/TerminalController.swift
+++ b/macos/Sources/Features/Terminal/TerminalController.swift
@@ -19,10 +19,10 @@
         }
 
         let nib = switch config.macosTitlebarStyle {
-        case "native": "Terminal"
-        case "hidden": "TerminalHiddenTitlebar"
-        case "transparent": "TerminalTransparentTitlebar"
-        case "tabs":
+        case .native: "Terminal"
+        case .hidden: "TerminalHiddenTitlebar"
+        case .transparent: "TerminalTransparentTitlebar"
+        case .tabs:
 #if compiler(>=6.2)
             if #available(macOS 26.0, *) {
                 "TerminalTabsTitlebarTahoe"
@@ -32,7 +32,6 @@
 #else
             "TerminalTabsTitlebarVentura"
 #endif
-        default: defaultValue
         }
 
         return nib
@@ -1537,7 +1536,7 @@
     struct DerivedConfig {
         let backgroundColor: Color
         let macosWindowButtons: Ghostty.MacOSWindowButtons
-        let macosTitlebarStyle: String
+        let macosTitlebarStyle: Ghostty.Config.MacOSTitlebarStyle
         let maximize: Bool
         let windowPositionX: Int16?
         let windowPositionY: Int16?
@@ -1545,7 +1544,7 @@
         init() {
             self.backgroundColor = Color(NSColor.windowBackgroundColor)
             self.macosWindowButtons = .visible
-            self.macosTitlebarStyle = "system"
+            self.macosTitlebarStyle = .default
             self.maximize = false
             self.windowPositionX = nil
             self.windowPositionY = nil
diff --git a/macos/Sources/Features/Terminal/TerminalView.swift b/macos/Sources/Features/Terminal/TerminalView.swift
--- a/macos/Sources/Features/Terminal/TerminalView.swift
+++ b/macos/Sources/Features/Terminal/TerminalView.swift
@@ -105,7 +105,7 @@
                                idealHeight: lastFocusedSurface?.value?.initialSize?.height)
                 }
                 // Ignore safe area to extend up in to the titlebar region if we have the "hidden" titlebar style
-                .ignoresSafeArea(.container, edges: ghostty.config.macosTitlebarStyle == "hidden" ? .top : [])
+                .ignoresSafeArea(.container, edges: ghostty.config.macosTitlebarStyle == .hidden ? .top : [])
 
                 if let surfaceView = lastFocusedSurface?.value {
                     TerminalCommandPaletteView(
diff --git a/macos/Sources/Features/Terminal/Window Styles/TerminalWindow.swift b/macos/Sources/Features/Terminal/Window Styles/TerminalWindow.swift
--- a/macos/Sources/Features/Terminal/Window Styles/TerminalWindow.swift
+++ b/macos/Sources/Features/Terminal/Window Styles/TerminalWindow.swift
@@ -588,7 +588,7 @@
         let backgroundColor: NSColor
         let backgroundOpacity: Double
         let macosWindowButtons: Ghostty.MacOSWindowButtons
-        let macosTitlebarStyle: String
+        let macosTitlebarStyle: Ghostty.Config.MacOSTitlebarStyle
         let windowCornerRadius: CGFloat
 
         init() {
@@ -597,7 +597,7 @@
             self.backgroundOpacity = 1
             self.macosWindowButtons = .visible
             self.backgroundBlur = .disabled
-            self.macosTitlebarStyle = "transparent"
+            self.macosTitlebarStyle = .default
             self.windowCornerRadius = 16
         }
 
@@ -613,7 +613,7 @@
             // Native, transparent, and hidden styles use 16pt radius
             // Tabs style uses 20pt radius
             switch config.macosTitlebarStyle {
-            case "tabs":
+            case .tabs:
                 self.windowCornerRadius = 20
             default:
                 self.windowCornerRadius = 16
diff --git a/macos/Sources/Features/Terminal/Window Styles/TransparentTitlebarTerminalWindow.swift b/macos/Sources/Features/Terminal/Window Styles/TransparentTitlebarTerminalWindow.swift
--- a/macos/Sources/Features/Terminal/Window Styles/TransparentTitlebarTerminalWindow.swift
+++ b/macos/Sources/Features/Terminal/Window Styles/TransparentTitlebarTerminalWindow.swift
@@ -92,8 +92,8 @@
             // For glass background styles, use a transparent titlebar to let the glass effect show through
             // Only apply this for transparent and tabs titlebar styles
             let isGlassStyle = derivedConfig.backgroundBlur.isGlassStyle
-            let isTransparentTitlebar = derivedConfig.macosTitlebarStyle == "transparent" ||
-                                       derivedConfig.macosTitlebarStyle == "tabs"
+            let isTransparentTitlebar = derivedConfig.macosTitlebarStyle == .transparent ||
+            derivedConfig.macosTitlebarStyle == .tabs
 
             titlebarView.layer?.backgroundColor = (isGlassStyle && isTransparentTitlebar)
                 ? NSColor.clear.cgColor