diff --git a/macos/Ghostty.sdef b/macos/Ghostty.sdef
index cf95c5004..6948fdfb2 100644
--- a/macos/Ghostty.sdef
+++ b/macos/Ghostty.sdef
@@ -127,16 +127,23 @@
     </record-type>
 
     <enumeration name="tab color" code="GTbC" description="The color of a Ghostty tab.">
-      <enumerator name="none" code="GTcN" description="No color."/>
-      <enumerator name="blue" code="GTcB" description="Blue."/>
-      <enumerator name="purple" code="GTcP" description="Purple."/>
-      <enumerator name="pink" code="GTcK" description="Pink."/>
-      <enumerator name="red" code="GTcR" description="Red."/>
-      <enumerator name="orange" code="GTcO" description="Orange."/>
-      <enumerator name="yellow" code="GTcY" description="Yellow."/>
-      <enumerator name="green" code="GTcG" description="Green."/>
-      <enumerator name="teal" code="GTcT" description="Teal."/>
-      <enumerator name="graphite" code="GTcX" description="Graphite."/>
+      <!-- Color enumerators use a 4-bit-per-channel ASCII hex RGBA as their code
+           (one hex digit per channel: R, G, B, A). Values are the nearest 4-bit
+           rounding of Apple's published Human Interface Guidelines light-mode
+           system color hex (https://developer.apple.com/design/human-interface-guidelines/color).
+           They serve as stable identifiers; the actual rendered color comes from
+           the corresponding system color and may shift between OS releases.
+           The "none" enumerator uses a literal code. -->
+      <enumerator name="none" code="none" description="No color."/>
+      <enumerator name="blue" code="08FF" description="Blue."/>
+      <enumerator name="purple" code="C3DF" description="Purple."/>
+      <enumerator name="pink" code="F35F" description="Pink."/>
+      <enumerator name="red" code="F34F" description="Red."/>
+      <enumerator name="orange" code="F82F" description="Orange."/>
+      <enumerator name="yellow" code="FC0F" description="Yellow."/>
+      <enumerator name="green" code="3C5F" description="Green."/>
+      <enumerator name="teal" code="0CBF" description="Teal."/>
+      <enumerator name="graphite" code="889F" description="Graphite."/>
     </enumeration>
 
     <enumeration name="split direction" code="GSpD" description="Direction for a new split.">
diff --git a/macos/Sources/Features/AppleScript/ScriptTab.swift b/macos/Sources/Features/AppleScript/ScriptTab.swift
index b58c021e4..d0d2dd709 100644
--- a/macos/Sources/Features/AppleScript/ScriptTab.swift
+++ b/macos/Sources/Features/AppleScript/ScriptTab.swift
@@ -203,21 +203,20 @@ extension ScriptTab {
 }
 
 /// Maps `TerminalTabColor` to and from the `tab color` enumeration in `Ghostty.sdef`.
-///
-/// Cocoa scripting passes enumerator FourCharCodes as integers via KVC.
+/// See `Ghostty.sdef` for how the codes are derived.
 private extension TerminalTabColor {
     var appleScriptCode: UInt32 {
         switch self {
-        case .none:     "GTcN".fourCharCode
-        case .blue:     "GTcB".fourCharCode
-        case .purple:   "GTcP".fourCharCode
-        case .pink:     "GTcK".fourCharCode
-        case .red:      "GTcR".fourCharCode
-        case .orange:   "GTcO".fourCharCode
-        case .yellow:   "GTcY".fourCharCode
-        case .green:    "GTcG".fourCharCode
-        case .teal:     "GTcT".fourCharCode
-        case .graphite: "GTcX".fourCharCode
+        case .none:     "none".fourCharCode
+        case .blue:     "08FF".fourCharCode
+        case .purple:   "C3DF".fourCharCode
+        case .pink:     "F35F".fourCharCode
+        case .red:      "F34F".fourCharCode
+        case .orange:   "F82F".fourCharCode
+        case .yellow:   "FC0F".fourCharCode
+        case .green:    "3C5F".fourCharCode
+        case .teal:     "0CBF".fourCharCode
+        case .graphite: "889F".fourCharCode
         }
     }