From 999576b0c5802a67718c3954ac0d3342e49bb573 Mon Sep 17 00:00:00 2001
From: Steve Streza <s.streza@kickstarter.com>
Date: Tue, 24 Feb 2026 12:55:46 -0800
Subject: [PATCH 1/2] Enable Swift 6 for KDS

---
 KDS/Package.swift                            |  3 ---
 KDS/Sources/KDS/Colors/SemanticColor.swift   |  6 +++---
 KDS/Sources/KDS/Controllers/ColorsView.swift |  4 ++--
 KDS/Sources/KDS/Fonts/InterFont.swift        | 12 ++++++++----
 4 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/KDS/Package.swift b/KDS/Package.swift
index 7b13f18d17..fba98b0cd0 100644
--- a/KDS/Package.swift
+++ b/KDS/Package.swift
@@ -34,8 +34,5 @@ let package = Package(
         .product(name: "SnapshotTesting", package: "swift-snapshot-testing")
       ]
     )
-  ],
-  swiftLanguageModes: [
-    .v5
   ]
 )
diff --git a/KDS/Sources/KDS/Colors/SemanticColor.swift b/KDS/Sources/KDS/Colors/SemanticColor.swift
index 1d48a6046a..94857df181 100644
--- a/KDS/Sources/KDS/Colors/SemanticColor.swift
+++ b/KDS/Sources/KDS/Colors/SemanticColor.swift
@@ -1,7 +1,7 @@
 import SwiftUI
 import UIKit
 
-public protocol AdaptiveColor {
+public protocol AdaptiveColor: Sendable {
   /// Returns a dynamically-provided `UIColor`, which responds to light/dark mode.
   var dynamicColor: UIColor { get }
 }
@@ -30,7 +30,7 @@ public extension AdaptiveColor {
 
 /// A semantic color from the Kickstarter design system, like "surface/primary".
 /// Includes a light and dark mode color pair, as well as an identifying title.
-public struct SemanticColor: AdaptiveColor {
+public struct SemanticColor: AdaptiveColor, Sendable {
   public let dynamicColor: UIColor
 
   public let name: String
@@ -62,7 +62,7 @@ public struct SemanticColor: AdaptiveColor {
 }
 
 /// Used for old design system colors which can't be mapped directly to the Kickstarter color palette.
-public struct LegacyColor: AdaptiveColor {
+public struct LegacyColor: AdaptiveColor, Sendable {
   public let name: String
   public let dynamicColor: UIColor
 
diff --git a/KDS/Sources/KDS/Controllers/ColorsView.swift b/KDS/Sources/KDS/Controllers/ColorsView.swift
index f2575caa6c..924122a5fa 100644
--- a/KDS/Sources/KDS/Controllers/ColorsView.swift
+++ b/KDS/Sources/KDS/Controllers/ColorsView.swift
@@ -176,13 +176,13 @@ public struct ColorsView: View {
   }
 }
 
-extension SemanticColor: @retroactive Identifiable {
+extension SemanticColor: Identifiable {
   public var id: String {
     return self.name
   }
 }
 
-extension LegacyColor: @retroactive Identifiable {
+extension LegacyColor: Identifiable {
   public var id: String {
     return self.name
   }
diff --git a/KDS/Sources/KDS/Fonts/InterFont.swift b/KDS/Sources/KDS/Fonts/InterFont.swift
index 065aabaf92..592b443073 100644
--- a/KDS/Sources/KDS/Fonts/InterFont.swift
+++ b/KDS/Sources/KDS/Fonts/InterFont.swift
@@ -1,3 +1,4 @@
+import Synchronization
 import UIKit
 
 public enum InterFont: CustomFont, CaseIterable {
@@ -75,15 +76,18 @@ public enum InterFont: CustomFont, CaseIterable {
   }
 }
 
-var registeredInterfont = false
-
 extension InterFont: CustomFontAccessible {
+  private static let registeredInterfont = Mutex<Bool>(false)
   public static var isRegistered: Bool {
     get {
-      registeredInterfont
+      registeredInterfont.withLock { isRegistered in
+        isRegistered
+      }
     }
     set {
-      registeredInterfont = newValue
+      registeredInterfont.withLock { isRegistered in
+        isRegistered = newValue
+      }
     }
   }
 

From 572c7e1a5b80cead47bb5250dabb1c6a65302da4 Mon Sep 17 00:00:00 2001
From: Steve Streza <s.streza@kickstarter.com>
Date: Tue, 24 Feb 2026 13:55:13 -0800
Subject: [PATCH 2/2] Use an Atomic rather than a Mutex

---
 KDS/Sources/KDS/Fonts/InterFont.swift | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/KDS/Sources/KDS/Fonts/InterFont.swift b/KDS/Sources/KDS/Fonts/InterFont.swift
index 592b443073..0f1bebc63c 100644
--- a/KDS/Sources/KDS/Fonts/InterFont.swift
+++ b/KDS/Sources/KDS/Fonts/InterFont.swift
@@ -77,17 +77,13 @@ public enum InterFont: CustomFont, CaseIterable {
 }
 
 extension InterFont: CustomFontAccessible {
-  private static let registeredInterfont = Mutex<Bool>(false)
+  private static let registeredInterfont = Atomic(false)
   public static var isRegistered: Bool {
     get {
-      registeredInterfont.withLock { isRegistered in
-        isRegistered
-      }
+      registeredInterfont.load(ordering: .acquiring)
     }
     set {
-      registeredInterfont.withLock { isRegistered in
-        isRegistered = newValue
-      }
+      _ = registeredInterfont.exchange(newValue, ordering: .acquiringAndReleasing)
     }
   }