fix(mobile): inkSubtle 三主题达 WCAG AA 对比度

app/mobile-rn/src/theme/tokens.test.ts

@@ -11,6 +11,27 @@ function resolvePath(source: unknown, path: string): unknown {
   ), source);
 }
 
+function hexToRgb(hex: string): [number, number, number] {
+  const normalized = hex.replace('#', '');
+  const r = parseInt(normalized.slice(0, 2), 16) / 255;
+  const g = parseInt(normalized.slice(2, 4), 16) / 255;
+  const b = parseInt(normalized.slice(4, 6), 16) / 255;
+  return [r, g, b];
+}
+
+function relativeLuminance(hex: string): number {
+  const [r, g, b] = hexToRgb(hex);
+  const linearize = (c: number) => (c <= 0.03928 ? c / 12.92 : Math.pow((c + 0.055) / 1.055, 2.4));
+  return 0.2126 * linearize(r) + 0.7152 * linearize(g) + 0.0722 * linearize(b);
+}
+
+function contrastRatio(foreground: string, background: string): number {
+  const l1 = relativeLuminance(foreground);
+  const l2 = relativeLuminance(background);
+  const [lighter, darker] = l1 > l2 ? [l1, l2] : [l2, l1];
+  return (lighter + 0.05) / (darker + 0.05);
+}
+
 describe('AgentHub mobile tokens', () => {
   it('keeps light mode as the default white-first mobile surface', () => {
     expect(getAgentHubTheme('light', true)).toBe(agentHubThemes.light);
@@ -125,4 +146,11 @@ describe('AgentHub mobile tokens', () => {
     expect(getAgentHubTheme('system', true).scheme).toBe('dark');
     expect(getAgentHubTheme('system', false).scheme).toBe('light');
   });
+
+  it('keeps inkSubtle at or above WCAG AA contrast (4.5:1) on canvas for every theme', () => {
+    for (const theme of Object.values(agentHubThemes)) {
+      const ratio = contrastRatio(theme.color.inkSubtle, theme.color.canvas);
+      expect(ratio, `${theme.scheme} inkSubtle/canvas`).toBeGreaterThanOrEqual(4.5);
+    }
+  });
 });

app/mobile-rn/src/theme/tokens.ts

@@ -196,7 +196,7 @@ export const agentHubThemes = {
       tint: 'rgba(41, 171, 226, 0.14)',
       ink: '#e3e4e6',
       inkMuted: '#a0a1aa',
-      inkSubtle: '#666875',
+      inkSubtle: '#8a8d98',
       line: 'rgba(255, 255, 255, 0.075)',
       focus: 'rgba(41, 171, 226, 0.42)',
       accent: '#29ABE2',
@@ -243,7 +243,7 @@ export const agentHubThemes = {
       tint: 'rgba(0, 113, 188, 0.08)',
       ink: '#171720',
       inkMuted: '#525463',
-      inkSubtle: '#8a8d98',
+      inkSubtle: '#6b6e78',
       line: 'rgba(15, 23, 42, 0.1)',
       focus: 'rgba(0, 113, 188, 0.32)',
       accent: '#0071BC',
@@ -290,7 +290,7 @@ export const agentHubThemes = {
       tint: 'rgba(41, 171, 226, 0.16)',
       ink: '#e3e4e6',
       inkMuted: '#a0a1aa',
-      inkSubtle: '#666875',
+      inkSubtle: '#8a8d98',
       line: 'rgba(255, 255, 255, 0.065)',
       focus: 'rgba(41, 171, 226, 0.42)',
       accent: '#29ABE2',