Add sidebar-font-size Ghostty config option (closes #2643)

Sources/GhosttyConfig.swift

@@ -17,6 +17,13 @@ struct GhosttyConfig {
     var fontFamily: String = "Menlo"
     var fontSize: CGFloat = 12
     var surfaceTabBarFontSize: CGFloat = 11
+    // Primary sidebar workspace-label font size. Secondary sidebar text scales
+    // proportionally from this value (see SidebarFontScale). Default matches
+    // the hardcoded size used prior to this setting.
+    static let defaultSidebarFontSize: CGFloat = 12.5
+    static let minSidebarFontSize: CGFloat = 10
+    static let maxSidebarFontSize: CGFloat = 20
+    var sidebarFontSize: CGFloat = GhosttyConfig.defaultSidebarFontSize
     var theme: String?
     var workingDirectory: String?
     // Ghostty measures scrollback-limit in bytes, not lines.
@@ -394,6 +401,18 @@ struct GhosttyConfig {
                     if let size = Double(value) {
                         surfaceTabBarFontSize = CGFloat(size)
                     }
+                case "sidebar-font-size":
+                    // `Double(_:)` accepts "nan" / "inf" per IEEE 754 / Apple
+                    // docs. Reject non-finite values so they don't poison the
+                    // clamp (min/max of NaN → NaN → NaN-valued fontScale →
+                    // invisible sidebar text).
+                    if let size = Double(value), size.isFinite {
+                        let clamped = min(
+                            Double(GhosttyConfig.maxSidebarFontSize),
+                            max(Double(GhosttyConfig.minSidebarFontSize), size)
+                        )
+                        sidebarFontSize = CGFloat(clamped)
+                    }
                 case "theme":
                     theme = value
                     if let preferredColorScheme {

Sources/ShortcutHintPill.swift

@@ -70,11 +70,12 @@ extension View {
         text: String?,
         emphasis: Double,
         offsetX: Double,
-        offsetY: Double
+        offsetY: Double,
+        fontScale: CGFloat = 1.0
     ) -> some View {
         overlay(alignment: .topTrailing) {
             if let text {
-                ShortcutHintPill(text: text, fontSize: 10, emphasis: emphasis)
+                ShortcutHintPill(text: text, fontSize: 10 * fontScale, emphasis: emphasis)
                     .offset(
                         x: ShortcutHintDebugSettings.clamped(offsetX),
                         y: ShortcutHintDebugSettings.clamped(offsetY)

Sources/Sidebar/SidebarDirectoryText.swift

@@ -9,25 +9,26 @@ import SwiftUI
 struct SidebarDirectoryText: View {
     let candidates: [String]
     let color: Color
+    var fontScale: CGFloat = 1
 
     var body: some View {
         if candidates.count <= 1 {
             Text(candidates.first ?? "")
-                .font(.system(size: 10, design: .monospaced))
+                .font(.system(size: 10 * fontScale, design: .monospaced))
                 .foregroundColor(color)
                 .lineLimit(1)
                 .truncationMode(.tail)
         } else {
             ViewThatFits(in: .horizontal) {
                 ForEach(Array(candidates.dropLast().enumerated()), id: \.offset) { _, candidate in
                     Text(candidate)
-                        .font(.system(size: 10, design: .monospaced))
+                        .font(.system(size: 10 * fontScale, design: .monospaced))
                         .foregroundColor(color)
                         .lineLimit(1)
                         .fixedSize(horizontal: true, vertical: false)
                 }
                 Text(candidates.last ?? "")
-                    .font(.system(size: 10, design: .monospaced))
+                    .font(.system(size: 10 * fontScale, design: .monospaced))
                     .foregroundColor(color)
                     .lineLimit(1)
                     .truncationMode(.tail)

cmuxTests/GhosttyConfigTests.swift

@@ -4126,6 +4126,106 @@ final class GhosttyMouseFocusTests: XCTestCase {
     }
 }
 
+final class SidebarFontSizeConfigTests: XCTestCase {
+
+    func testDefaultSidebarFontSizeMatchesConstant() {
+        let config = GhosttyConfig()
+        XCTAssertEqual(config.sidebarFontSize, GhosttyConfig.defaultSidebarFontSize, accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeValid() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = 14")
+        XCTAssertEqual(config.sidebarFontSize, 14, accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeFractional() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = 13.5")
+        XCTAssertEqual(config.sidebarFontSize, 13.5, accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeClampedAboveMax() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = 9999")
+        XCTAssertEqual(config.sidebarFontSize,
+                       GhosttyConfig.maxSidebarFontSize,
+                       accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeClampedBelowMin() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = 1")
+        XCTAssertEqual(config.sidebarFontSize,
+                       GhosttyConfig.minSidebarFontSize,
+                       accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeIgnoresNonNumeric() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = huge")
+        XCTAssertEqual(config.sidebarFontSize,
+                       GhosttyConfig.defaultSidebarFontSize,
+                       accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeTrailingZero() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = 14.0")
+        XCTAssertEqual(config.sidebarFontSize, 14, accuracy: 0.0001)
+    }
+
+    func testLoadReadsSidebarFontSizeViaInjectedLoader() {
+        let loaded = GhosttyConfig.load(
+            preferredColorScheme: .dark,
+            useCache: false,
+            loadFromDisk: { _ in
+                var config = GhosttyConfig()
+                config.parse("sidebar-font-size = 14\n")
+                return config
+            }
+        )
+        XCTAssertEqual(loaded.sidebarFontSize, 14, accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeIgnoresNaN() {
+        // `Double("nan")` returns `.nan`. Without explicit rejection the
+        // min/max clamp would produce NaN, yielding an invisible sidebar.
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = nan")
+        XCTAssertEqual(config.sidebarFontSize,
+                       GhosttyConfig.defaultSidebarFontSize,
+                       accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeIgnoresInfinity() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = inf")
+        XCTAssertEqual(config.sidebarFontSize,
+                       GhosttyConfig.defaultSidebarFontSize,
+                       accuracy: 0.0001)
+    }
+
+    func testParseSidebarFontSizeIgnoresNegativeInfinity() {
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = -infinity")
+        XCTAssertEqual(config.sidebarFontSize,
+                       GhosttyConfig.defaultSidebarFontSize,
+                       accuracy: 0.0001)
+    }
+
+    func testParseLaterSidebarFontSizeWins() {
+        // When multiple config files are loaded in order, later paths
+        // should override earlier values for the same key — this is the
+        // contract that makes ~/Library/Application Support override
+        // ~/.config/ghostty on macOS.
+        var config = GhosttyConfig()
+        config.parse("sidebar-font-size = 11")
+        config.parse("sidebar-font-size = 18")
+        XCTAssertEqual(config.sidebarFontSize, 18, accuracy: 0.0001)
+    }
+}
+
 final class SidebarBackgroundConfigTests: XCTestCase {
 
     func testParseSidebarBackgroundSingleHex() {

cmuxTests/SidebarOrderingTests.swift

@@ -999,3 +999,87 @@ final class TerminalControllerSidebarDedupeTests: XCTestCase {
         )
     }
 }
+
+final class SidebarTabItemSettingsSnapshotFontScaleTests: XCTestCase {
+
+    /// A UserDefaults suite isolated to this test class so we don't mutate
+    /// the real user defaults used by other tests / the host app.
+    private var defaults: UserDefaults!
+    private var suiteName: String!
+
+    override func setUp() {
+        super.setUp()
+        suiteName = "cmux-tests-\(UUID().uuidString)"
+        defaults = UserDefaults(suiteName: suiteName)
+    }
+
+    override func tearDown() {
+        defaults.removePersistentDomain(forName: suiteName)
+        defaults = nil
+        suiteName = nil
+        super.tearDown()
+    }
+
+    func testDefaultConfigYieldsUnitScale() {
+        let snapshot = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { GhosttyConfig.defaultSidebarFontSize }
+        )
+        XCTAssertEqual(snapshot.sidebarFontScale, 1.0, accuracy: 0.0001)
+    }
+
+    func testPrimaryEighteenScalesProportionally() {
+        let snapshot = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { 18 }
+        )
+        let expected = 18 / GhosttyConfig.defaultSidebarFontSize
+        XCTAssertEqual(snapshot.sidebarFontScale, expected, accuracy: 0.0001)
+    }
+
+    func testBelowMinClampsUp() {
+        let snapshot = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { 4 }
+        )
+        let expected = GhosttyConfig.minSidebarFontSize / GhosttyConfig.defaultSidebarFontSize
+        XCTAssertEqual(snapshot.sidebarFontScale, expected, accuracy: 0.0001)
+    }
+
+    func testAboveMaxClampsDown() {
+        let snapshot = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { 9999 }
+        )
+        let expected = GhosttyConfig.maxSidebarFontSize / GhosttyConfig.defaultSidebarFontSize
+        XCTAssertEqual(snapshot.sidebarFontScale, expected, accuracy: 0.0001)
+    }
+
+    /// If this test ever passes incorrectly (i.e. two snapshots with
+    /// different scales compare equal), TabItemView's
+    /// `.equatable()` will skip re-rendering on font-size changes and the
+    /// live-reload path will silently break.
+    func testSnapshotEqualityReflectsScaleDifference() {
+        let base = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { GhosttyConfig.defaultSidebarFontSize }
+        )
+        let bigger = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { 18 }
+        )
+        XCTAssertNotEqual(base, bigger)
+    }
+
+    func testSnapshotEqualityHoldsWhenScaleMatches() {
+        let a = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { 14 }
+        )
+        let b = SidebarTabItemSettingsSnapshot(
+            defaults: defaults,
+            sidebarFontSizeProvider: { 14 }
+        )
+        XCTAssertEqual(a, b)
+    }
+}