feat: add semantic admin palette

src/lib/theme-contrast.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { contrastRatio, derivePublicForegrounds, readableColor } from "@/lib/theme-contrast";
+import { contrastRatio, deriveAdminPalette, derivePublicForegrounds, readableColor } from "@/lib/theme-contrast";
 import { PRESETS, THEME_COLOR_KEYS } from "@/lib/theme-presets";
 
 describe("contrastRatio", () => {
@@ -76,6 +76,26 @@ describe("readableColor", () => {
   });
 });
 
+describe("deriveAdminPalette", () => {
+  it.each(Object.entries(PRESETS))("keeps admin text readable for %s", (_name, preset) => {
+    for (const palette of [preset.light, preset.dark]) {
+      const admin = deriveAdminPalette(palette);
+      expect(contrastRatio(admin.text, admin.canvas)).toBeGreaterThanOrEqual(4.5);
+      expect(contrastRatio(admin.text, admin.surface)).toBeGreaterThanOrEqual(4.5);
+      expect(contrastRatio(admin.muted, admin.surface)).toBeGreaterThanOrEqual(4.5);
+      expect(contrastRatio(admin.accentForeground, admin.accent)).toBeGreaterThanOrEqual(4.5);
+    }
+  });
+
+  it("does not copy hostile public structural colors into admin surfaces", () => {
+    const admin = deriveAdminPalette({
+      color_background: "#ff00ff", color_surface: "#00ff00", color_primary: "#ffff00",
+    });
+    expect(admin.canvas).not.toBe("#ff00ff");
+    expect(admin.surface).not.toBe("#00ff00");
+  });
+});
+
 describe("derivePublicForegrounds", () => {
   it.each(Object.entries(PRESETS))("makes every semantic pair readable for %s", (_name, preset) => {
     for (const palette of [preset.light, preset.dark]) {