feat: M5 背景图上传/压缩+智能取色（FR-A8/A9，smart-color 下沉 shared，canvas 采样→analyzeImage 推导强调色/模糊/表面不透明尊重手动项，持久化+重开恢复）

packages/shared/src/index.ts

@@ -5,3 +5,4 @@ export * from './types/doc.js';
 export * from './types/search.js';
 export * from './types/graph.js';
 export * from './constants.js';
+export * from './utils/smart-color.js';

packages/shared/src/types/ipc.ts

@@ -58,8 +58,8 @@ export interface IpcMap {
   [IPC.winClose]: { args: void; result: void };
   [IPC.copyMd]: { args: { path: string }; result: string };
   [IPC.printPdf]: { args: void; result: void };
-  [IPC.appearanceLoad]: { args: void; result: { themeId: string; params: Record<string, unknown>; effect: string } | null };
-  [IPC.appearanceSave]: { args: { themeId: string; params: Record<string, unknown>; effect: string }; result: void };
+  [IPC.appearanceLoad]: { args: void; result: { themeId: string; params: Record<string, unknown>; effect: string; bgImage: string | null } | null };
+  [IPC.appearanceSave]: { args: { themeId: string; params: Record<string, unknown>; effect: string; bgImage: string | null }; result: void };
   [IPC.keymapLoad]: { args: void; result: { id: string; combo: string }[] | null };
   [IPC.keymapSave]: { args: { id: string; combo: string }[]; result: void };
 }

packages/shared/src/utils/smart-color.ts

@@ -0,0 +1,75 @@
+// 智能取色：分析背景图亮度/主色 → 推荐深浅模式与强调色（FR-A9）
+// 纯函数，输入采样后的像素数据，输出推荐参数
+
+export interface ImageSample {
+  /** 采样像素的 [r,g,b] 列表（已降采样） */
+  pixels: [number, number, number][];
+}
+
+export interface SmartColorResult {
+  mode: 'dark' | 'light';
+  accentHue: number;       // 0-360，约束在冷色/紫红区间
+  accent: string;          // hex 强调色
+  suggestedBgOpacity: number;   // 0-1
+  suggestedBlur: number;        // px
+  suggestedSurfaceOpacity: number; // 0-1
+}
+
+function luminance(r: number, g: number, b: number): number {
+  const f = (c: number) => { c /= 255; return c <= 0.03928 ? c / 12.92 : Math.pow((c + 0.055) / 1.055, 2.4); };
+  return 0.2126 * f(r) + 0.7152 * f(g) + 0.0722 * f(b);
+}
+
+function rgbToHsl(r: number, g: number, b: number): [number, number, number] {
+  r /= 255; g /= 255; b /= 255;
+  const max = Math.max(r, g, b), min = Math.min(r, g, b);
+  let h = 0; const l = (max + min) / 2; const d = max - min; const s = d === 0 ? 0 : d / (1 - Math.abs(2 * l - 1));
+  if (d !== 0) {
+    switch (max) {
+      case r: h = ((g - b) / d) % 6; break;
+      case g: h = (b - r) / d + 2; break;
+      default: h = (r - g) / d + 4;
+    }
+    h *= 60; if (h < 0) h += 360;
+  }
+  return [h, s, l];
+}
+
+function hslToHex(h: number, s: number, l: number): string {
+  const c = (1 - Math.abs(2 * l - 1)) * s; const x = c * (1 - Math.abs(((h / 60) % 2) - 1)); const m = l - c / 2;
+  let r = 0, g = 0, b = 0;
+  if (h < 60) [r, g, b] = [c, x, 0]; else if (h < 120) [r, g, b] = [x, c, 0];
+  else if (h < 180) [r, g, b] = [0, c, x]; else if (h < 240) [r, g, b] = [0, x, c];
+  else if (h < 300) [r, g, b] = [x, 0, c]; else [r, g, b] = [c, 0, x];
+  const to = (v: number) => Math.round((v + m) * 255).toString(16).padStart(2, '0');
+  return '#' + to(r) + to(g) + to(b);
+}
+
+function constrainHue(h: number): number {
+  if (h >= 180 && h <= 330) return h;
+  if (h < 180) return h < 90 ? 200 : 210;
+  return 290;
+}
+
+export function analyzeImage(sample: ImageSample): SmartColorResult {
+  const { pixels } = sample;
+  if (pixels.length === 0) {
+    return { mode: 'dark', accentHue: 210, accent: '#4a9eff', suggestedBgOpacity: 0.6, suggestedBlur: 20, suggestedSurfaceOpacity: 0.5 };
+  }
+  const avgLum = pixels.reduce((s, p) => s + luminance(p[0], p[1], p[2]), 0) / pixels.length;
+  const mode: 'dark' | 'light' = avgLum < 0.5 ? 'dark' : 'light';
+  const buckets = new Array(12).fill(0);
+  let dominantHue = 210;
+  for (const p of pixels) {
+    const [h, s] = rgbToHsl(p[0], p[1], p[2]);
+    if (s > 0.15) buckets[Math.floor(h / 30) % 12]++;
+  }
+  let max = 0;
+  for (let i = 0; i < 12; i++) if (buckets[i] > max) { max = buckets[i]; dominantHue = i * 30 + 15; }
+  const accentHue = constrainHue(dominantHue);
+  const accent = hslToHex(accentHue, 0.7, mode === 'dark' ? 0.6 : 0.45);
+  const suggestedBgOpacity = Math.round(Math.max(0.3, Math.min(0.8, 0.5 + (0.5 - avgLum) * 0.4)) * 100) / 100;
+  const suggestedBlur = avgLum < 0.4 ? 24 : avgLum > 0.7 ? 12 : 18;
+  const suggestedSurfaceOpacity = mode === 'dark' ? 0.5 : 0.7;
+  return { mode, accentHue, accent, suggestedBgOpacity, suggestedBlur, suggestedSurfaceOpacity };
+}