Remove @mainactor from CodeBlockHighlighter/Theme for background rendering, cache isDark

Author: macOS26

Sources/AgentColorSyntax/CodeBlockLangDef.swift

@@ -2,7 +2,7 @@ import AppKit
 
 // MARK: - Language Definition
 
-public struct LangDef {
+public struct LangDef: @unchecked Sendable {
     public let keywords: Set<String>
     public let declKeywords: Set<String>
     public let types: Set<String>

Sources/AgentColorSyntax/CodeBlockSyntax+Diff.swift

@@ -11,7 +11,7 @@ extension CodeBlockHighlighter {
         let result = NSMutableAttributedString(string: code, attributes: [
             .font: font, .foregroundColor: text
         ])
-        let isDark = NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        let isDark = CodeBlockTheme.isDark
 
         let removedBg = isDark
             ? NSColor(red: 0.4, green: 0.1, blue: 0.1, alpha: 1.0)    // dark red

Sources/AgentColorSyntax/CodeBlockSyntax+PathColor.swift

@@ -6,22 +6,22 @@ extension CodeBlockHighlighter {
 
     // Path segment colors for multi-color file path highlighting
     public static var pathHome: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.5, green: 0.5, blue: 0.55, alpha: 1)   // dim gray
             : NSColor(red: 0.45, green: 0.45, blue: 0.5, alpha: 1)
     }
     public static var pathTopDir: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.6, green: 0.75, blue: 0.55, alpha: 1)  // muted green
             : NSColor(red: 0.3, green: 0.5, blue: 0.25, alpha: 1)
     }
     public static var pathMiddle: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.816, green: 0.659, blue: 1.0, alpha: 1)  // lavender
             : NSColor(red: 0.4, green: 0.2, blue: 0.7, alpha: 1)
     }
     public static var pathFilename: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.35, green: 0.7, blue: 1.0, alpha: 1)   // bright blue
             : NSColor(red: 0.0, green: 0.3, blue: 0.8, alpha: 1)
     }

Sources/AgentColorSyntax/CodeBlockSyntax.swift

@@ -2,7 +2,7 @@ import AppKit
 
 // MARK: - Highlighter
 
-@MainActor public enum CodeBlockHighlighter {
+public enum CodeBlockHighlighter: Sendable {
     private static let wordRx: NSRegularExpression? = try? NSRegularExpression(pattern: #"\b(?:[a-zA-Z][a-zA-Z0-9_]*|_[a-zA-Z0-9][a-zA-Z0-9_]*)\b"#)
     private static let funcRx: NSRegularExpression? = try? NSRegularExpression(pattern: #"\b([a-zA-Z_][a-zA-Z0-9_]*)\s*(?=\()"#)
     private static let propRx: NSRegularExpression? = try? NSRegularExpression(pattern: #"\.([a-zA-Z_][a-zA-Z0-9_]*)"#)
@@ -516,42 +516,42 @@ import AppKit
 
     // Terminal output theme colors
     private static var termDir: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.35, green: 0.7, blue: 1.0, alpha: 1)   // bright blue
             : NSColor(red: 0.0, green: 0.3, blue: 0.8, alpha: 1)
     }
     private static var termExec: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.4, green: 0.9, blue: 0.4, alpha: 1)    // green
             : NSColor(red: 0.0, green: 0.5, blue: 0.0, alpha: 1)
     }
     private static var termSymlink: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.9, green: 0.5, blue: 0.9, alpha: 1)    // magenta
             : NSColor(red: 0.6, green: 0.0, blue: 0.6, alpha: 1)
     }
     private static var termSize: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.85, green: 0.85, blue: 0.5, alpha: 1)  // yellow
             : NSColor(red: 0.5, green: 0.4, blue: 0.0, alpha: 1)
     }
     private static var termDate: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.6, green: 0.6, blue: 0.7, alpha: 1)    // dim
             : NSColor(red: 0.4, green: 0.4, blue: 0.5, alpha: 1)
     }
     private static var termPerm: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.6, green: 0.7, blue: 0.6, alpha: 1)    // muted green
             : NSColor(red: 0.3, green: 0.4, blue: 0.3, alpha: 1)
     }
     private static var termPath: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 0.4, green: 0.85, blue: 0.85, alpha: 1)  // cyan
             : NSColor(red: 0.0, green: 0.5, blue: 0.5, alpha: 1)
     }
     private static var termError: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 1.0, green: 0.4, blue: 0.4, alpha: 1)    // red
             : NSColor(red: 0.8, green: 0.0, blue: 0.0, alpha: 1)
     }
@@ -565,7 +565,7 @@ import AppKit
     private static let termErrorRx: NSRegularExpression? = try? NSRegularExpression(pattern: #"\b(?:error|Error|ERROR|fatal|FATAL|failed|FAILED|No such file|Permission denied|not found|cannot)\b"#)
     private static let termWarningRx: NSRegularExpression? = try? NSRegularExpression(pattern: #"\b(?:warning|Warning|WARNING|deprecated|DEPRECATED|caution)\b"#)
     private static var termWarning: NSColor {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        CodeBlockTheme.isDark
             ? NSColor(red: 1.0, green: 0.8, blue: 0.2, alpha: 1)    // yellow
             : NSColor(red: 0.7, green: 0.5, blue: 0.0, alpha: 1)
     }
@@ -655,7 +655,7 @@ import AppKit
 
     /// Highlight a D1F diff line: background stripe for the diff marker, code syntax for the text.
     private static func highlightD1FLine(line: String, font: NSFont) -> NSAttributedString {
-        let isDark = NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+        let isDark = CodeBlockTheme.isDark
         let trimmed = line.trimmingCharacters(in: .whitespaces)
 
         // Strip emoji prefix to get the code content for syntax highlighting

Sources/AgentColorSyntax/CodeBlockTheme.swift

@@ -2,11 +2,16 @@ import AppKit
 
 // MARK: - Code Block Theme (Xcode Dark/Light palette from JibberJabber)
 
-@MainActor public enum CodeBlockTheme {
-    private static var isDark: Bool {
-        NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+public enum CodeBlockTheme: Sendable {
+    private nonisolated(unsafe) static var _isDark: Bool = false
+
+    /// Call from main thread on launch and appearance changes to cache dark mode state.
+    @MainActor public static func updateAppearance() {
+        _isDark = NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
     }
 
+    public static var isDark: Bool { _isDark }
+
     private static func c(_ d: UInt32, _ l: UInt32) -> NSColor {
         let h = isDark ? d : l
         return NSColor(