fix: enforce public contrast and audit rank errors

src/lib/theme-contrast.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { contrastRatio, readableColor } from "@/lib/theme-contrast";
+import { contrastRatio, derivePublicForegrounds, readableColor } from "@/lib/theme-contrast";
 import { PRESETS } from "@/lib/theme-presets";
 
 describe("contrastRatio", () => {
@@ -64,3 +64,27 @@ describe("readableColor", () => {
     expect(readableColor("rgb(1, 2, 3)", ["#ffffff"], 4.5)).toBe("rgb(1, 2, 3)");
   });
 });
+
+describe("derivePublicForegrounds", () => {
+  it.each(Object.entries(PRESETS))("makes every semantic pair readable for %s", (_name, preset) => {
+    const result = derivePublicForegrounds(preset);
+    for (const pair of result.pairs) {
+      expect(contrastRatio(pair.foreground, pair.background), pair.name).toBeGreaterThanOrEqual(4.5);
+    }
+  });
+
+  it("repairs hostile white-on-white custom colors", () => {
+    const result = derivePublicForegrounds({
+      color_background: "#ffffff", color_surface: "#ffffff", color_dropdown: "#ffffff",
+      color_navbar: "#ffffff", color_navbar_text: "#ffffff", color_text: "#ffffff",
+      color_text_muted: "#ffffff", color_primary: "#ffffff", color_accent: "#ffffff",
+      button_primary_color: "#ffffff", button_text_color: "#ffffff",
+      button_secondary_color: "#ffffff", button_secondary_text_color: "#ffffff",
+      button_danger_color: "#ffffff", button_danger_text_color: "#ffffff",
+      button_outline_color: "#ffffff", button_outline_text_color: "#ffffff",
+      link_color: "#ffffff", link_hover_color: "#ffffff",
+    });
+    expect(result.pairs.length).toBeGreaterThan(10);
+    for (const pair of result.pairs) expect(contrastRatio(pair.foreground, pair.background), pair.name).toBeGreaterThanOrEqual(4.5);
+  });
+});