feat(public): 主题切换修复 + 卡片图标服务端本地缓存

- 主题切换：菜单改为 fixed 定位并弹出在父菜单右侧；FIXED_THEMES 扩为 9 主题并统一校验；
  子菜单点击无响应修复（合并 IIFE 作用域使 applyTheme 对点击处理器可见）；删除死代码。
- 卡片图标：新增 GET /site/icon/<domain>?letter=X 接口，首次请求由服务端拉取 favicon
  并缓存到 data/icon/（运行时自动建目录，已加 .gitignore），之后直接读本地不再重复拉取；
  拉取失败或内网/不可达网址自动生成「站点名称首字母」SVG 头像兜底，杜绝空白图标。
- 模型 Nav.to_dict 新增 domain/scheme/letter/color 计算字段，供卡片与图标接口复用。

.gitignore

@@ -166,3 +166,6 @@ dedup_nav.py
 scripts/_verify_*.png
 scripts/screenshots/
 output/
+
+# 前台卡片图标本地缓存（首次拉取后自动生成，无需入库）
+data/icon/

applications/models/admin_nav.py

@@ -54,6 +54,38 @@ class Nav(db.Model):
 
     def to_dict(self):
         """方便模板直接读取"""
+        url = self.url or ''
+        # 提取域名 / 协议，用于加载 favicon 与生成确定性配色
+        domain = ''
+        scheme = 'https'
+        try:
+            from urllib.parse import urlparse
+            parsed = urlparse(url if '://' in url else 'http://' + url)
+            domain = parsed.netloc or parsed.path.split('/')[0]
+            if parsed.scheme:
+                scheme = parsed.scheme
+        except Exception:
+            domain = ''
+
+        # 取标题首个可见字符作为「无 favicon 时的兜底字母头像」
+        letter = ''
+        for ch in (self.title or ''):
+            if ch.strip():
+                letter = ch.upper()
+                break
+        if not letter:
+            letter = (domain[:1] or '·').upper()
+
+        # 按域名哈希得到稳定的渐变配色（同域名永远同色，跨域名尽量区分）
+        hue = 0
+        if domain:
+            s = 0
+            for ch in domain:
+                s = (s * 31 + ord(ch)) & 0xffffffff
+            hue = s % 360
+        color = 'linear-gradient(135deg, hsl(%d,62%%,56%%) 0%%, hsl(%d,72%%,46%%) 100%%)' % (
+            hue, (hue + 28) % 360)
+
         return {
             'id': self.id,
             'category': self.category,
@@ -61,6 +93,10 @@ class Nav(db.Model):
             'url': self.url,
             'description': self.description or '',
             'icon': self.icon or 'layui-icon-link',
+            'letter': letter,
+            'color': color,
+            'domain': domain,
+            'scheme': scheme,
             'sort': self.sort or 0,
             'enable': self.enable,
             'is_external': self.is_external,

applications/view/public/nav.py

@@ -12,8 +12,13 @@ URL 路径（挂在根路径下，便于匿名访问）：
 """
 from collections import OrderedDict
 import time
+import os
+import re
+import threading
+import urllib.request
+import urllib.error
 
-from flask import Blueprint, render_template, request, jsonify
+from flask import Blueprint, render_template, request, jsonify, current_app, send_file
 
 from applications.models import Nav, NavCategory
 from plugins.siteStats.view.stat import get_nav_visit_counts, my_top_navs
@@ -227,4 +232,169 @@ def _grouped_navs() -> "OrderedDict[str, list]":
 def _category_meta() -> "dict[str, dict]":
     """返回分类元信息 {name: {icon, description, ...}}，用于抽屉图标等"""
     cats = NavCategory.query.filter(NavCategory.enable == 1).all()
-    return {c.name: {'icon': c.icon or 'layui-icon-list', 'description': c.description or ''} for c in cats}
+    return {c.name: {'icon': c.icon or 'layui-icon-list', 'description': c.description or ''} for c in cats}
+
+
+# ---------------------------------------------------------------------------
+# 卡片图标本地缓存
+# 首次请求某域名图标时，自动拉取并保存到 data/icon/，以后直接读本地文件，
+# 不再重复拉取。拉取失败（含内网/不可达网址）时自动生成「站点名称首字母」SVG 兜底。
+# ---------------------------------------------------------------------------
+_ICON_DIR = None
+_ICON_LOCKS = {}
+_ICON_LOCKS_GUARD = threading.Lock()
+_ICON_EXT_MIME = {
+    '.ico': 'image/x-icon',
+    '.png': 'image/png',
+    '.jpg': 'image/jpeg',
+    '.jpeg': 'image/jpeg',
+    '.gif': 'image/gif',
+    '.svg': 'image/svg+xml',
+}
+
+
+def _icon_dir():
+    global _ICON_DIR
+    if _ICON_DIR is None:
+        base = current_app.config.get('DATA_DIR')
+        if not base:
+            base = os.path.join(os.path.dirname(os.path.dirname(__file__)), '..', 'data')
+        _ICON_DIR = os.path.join(base, 'icon')
+    os.makedirs(_ICON_DIR, exist_ok=True)
+    return _ICON_DIR
+
+
+def _safe_name(domain: str) -> str:
+    return re.sub(r'[^A-Za-z0-9.\-_]', '_', domain or 'unknown')
+
+
+def _lock_for(key: str):
+    with _ICON_LOCKS_GUARD:
+        lock = _ICON_LOCKS.get(key)
+        if lock is None:
+            lock = threading.Lock()
+            _ICON_LOCKS[key] = lock
+        return lock
+
+
+def _domain_hue(domain: str) -> int:
+    """与 models.admin_nav.Nav.to_dict 中用于生成卡片字母头像的配色保持一致"""
+    s = 0
+    for ch in (domain or ''):
+        s = (s * 31 + ord(ch)) & 0xffffffff
+    return s % 360
+
+
+def _letter_svg(letter: str, domain: str) -> bytes:
+    hue = _domain_hue(domain)
+    c1 = "hsl(%d,62%%,56%%)" % hue
+    c2 = "hsl(%d,72%%,46%%)" % ((hue + 28) % 360)
+    ch = (letter or (domain or '·')[:1] or '·').upper()[:1] or '·'
+    ch = re.sub(r'[<>&"]', '', ch)  # 防止 SVG 注入
+    svg = (
+        '<svg xmlns="http://www.w3.org/2000/svg" width="64" height="64" viewBox="0 0 64 64">'
+        '<defs><linearGradient id="g" x1="0" y1="0" x2="1" y2="1">'
+        '<stop offset="0%%" stop-color="%s"/>'
+        '<stop offset="100%%" stop-color="%s"/>'
+        '</linearGradient></defs>'
+        '<rect width="64" height="64" rx="14" fill="url(#g)"/>'
+        '<text x="32" y="33" text-anchor="middle" dominant-baseline="central" '
+        'font-family="Arial, \'PingFang SC\', \'Microsoft YaHei\', sans-serif" '
+        'font-size="34" font-weight="700" fill="#ffffff">%s</text>'
+        '</svg>'
+    ) % (c1, c2, ch)
+    return svg.encode('utf-8')
+
+
+def _fetch_bytes(url: str, timeout: int = 5):
+    try:
+        req = urllib.request.Request(url, headers={'User-Agent': 'Mozilla/5.0'})
+        with urllib.request.urlopen(req, timeout=timeout) as resp:
+            data = resp.read()
+            ctype = resp.headers.get('Content-Type', '') or ''
+            return data, ctype
+    except Exception:
+        return None
+
+
+def _ext_from(ctype: str, data: bytes) -> str:
+    ct = (ctype or '').lower()
+    if 'png' in ct:
+        return '.png'
+    if 'jpeg' in ct or 'jpg' in ct:
+        return '.jpg'
+    if 'gif' in ct:
+        return '.gif'
+    if 'svg' in ct:
+        return '.svg'
+    if 'icon' in ct:
+        return '.ico'
+    if data[:4] == b'\x00\x00\x01\x00':
+        return '.ico'
+    if data[:8] == b'\x89PNG\r\n\x1a\n':
+        return '.png'
+    if data[:3] == b'GIF':
+        return '.gif'
+    return '.ico'
+
+
+def _resolve_icon(domain: str, letter: str):
+    """返回 (file_path, mimetype)。优先读本地缓存，否则拉取/生成并落盘。"""
+    safe = _safe_name(domain)
+    d = _icon_dir()
+    # 1) 命中本地缓存（任意已知扩展名）
+    for ext in ('.svg', '.ico', '.png', '.jpg', '.jpeg', '.gif'):
+        p = os.path.join(d, safe + ext)
+        if os.path.isfile(p):
+            return p, _ICON_EXT_MIME.get(ext, 'application/octet-stream')
+    # 2) 加锁后再次检查（避免并发重复拉取）
+    with _lock_for(safe):
+        for ext in ('.svg', '.ico', '.png', '.jpg', '.jpeg', '.gif'):
+            p = os.path.join(d, safe + ext)
+            if os.path.isfile(p):
+                return p, _ICON_EXT_MIME.get(ext, 'application/octet-stream')
+        # 3) 循序尝试：站点自身 https → http（含内网）→ DuckDuckGo
+        candidates = [
+            'https://%s/favicon.ico' % domain,
+            'http://%s/favicon.ico' % domain,
+            'https://icons.duckduckgo.com/ip3/%s.ico' % domain,
+        ]
+        for url in candidates:
+            res = _fetch_bytes(url)
+            if not res:
+                continue
+            data, ctype = res
+            if not data or len(data) < 32:   # 过小多半是错误页/空响应
+                continue
+            # 必须是真正的图片（按 Content-Type 或二进制魔数判断），
+            # 否则跳过——避免把 200 的 HTML 错误页当图标缓存下来
+            ct = (ctype or '').lower()
+            is_image = (
+                ct.startswith('image/')
+                or data[:4] == b'\x00\x00\x01\x00'
+                or data[:8] == b'\x89PNG\r\n\x1a\n'
+                or data[:3] == b'GIF'
+            )
+            if not is_image:
+                continue
+            ext = _ext_from(ctype, data)
+            p = os.path.join(d, safe + ext)
+            try:
+                with open(p, 'wb') as f:
+                    f.write(data)
+                return p, _ICON_EXT_MIME.get(ext, 'application/octet-stream')
+            except OSError:
+                continue
+        # 4) 全部失败：生成字母头像 SVG 兜底并缓存
+        p = os.path.join(d, safe + '.svg')
+        with open(p, 'wb') as f:
+            f.write(_letter_svg(letter, domain))
+        return p, 'image/svg+xml'
+
+
+@bp.get('/icon/<string:domain>')
+def icon(domain):
+    """卡片图标：本地缓存优先，拉取失败时返回字母头像 SVG。"""
+    letter = request.args.get('letter', '') or ''
+    path, mime = _resolve_icon(domain, letter)
+    return send_file(path, mimetype=mime, max_age=86400)

templates/public/base.html

@@ -241,10 +241,10 @@
         .theme-picker-trigger { position: relative; }
         .theme-menu {
             display: none;
-            position: absolute;
+            position: fixed;
-            top: calc(100% + 6px);
+            top: 0;
             left: 0;
-            min-width: 150px;
+            min-width: 160px;
             margin: 0; padding: 4px;
             list-style: none;
             background: var(--card-bg);
@@ -601,13 +601,28 @@
         .cat-drawer-list a.cat-drawer-mine { color: #8b5cf6; font-weight: 600; }
 
         .card .icon-wrap {
+            position: relative;
             width: 42px; height: 42px;
-            background: rgba(22, 186, 170, 0.1);
-            color: var(--brand);
             border-radius: 10px;
-            display: flex; align-items: center; justify-content: center;
+            overflow: hidden;
-            font-size: 20px;
             flex-shrink: 0;
+            box-shadow: inset 0 0 0 1px rgba(0,0,0,0.05);
+            background: var(--card-bg);
+        }
+        .card .nav-letter {
+            position: absolute; inset: 0;
+            display: flex; align-items: center; justify-content: center;
+            color: #fff; font-weight: 700; font-size: 18px;
+            text-transform: uppercase;
+            user-select: none;
+            letter-spacing: 0.5px;
+        }
+        .card .nav-favicon {
+            position: absolute; inset: 0;
+            width: 100%; height: 100%;
+            object-fit: contain;
+            background: #fff;
+            z-index: 1;
         }
         .card-body { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 4px; }
         .card .title-row { display: flex; align-items: center; gap: 8px; min-width: 0; }
@@ -845,7 +860,8 @@
                 gap: 9px;
                 align-items: flex-start;
             }
-            .card .icon-wrap { width: 32px; height: 32px; font-size: 16px; border-radius: 8px; flex-shrink: 0; }
+            .card .icon-wrap { width: 32px; height: 32px; border-radius: 8px; flex-shrink: 0; }
+            .card .nav-letter { font-size: 14px; }
             .card-body { gap: 2px; min-width: 0; }
             .card .title { font-size: 13px; line-height: 1.3; }
             .card .desc {
@@ -1131,7 +1147,7 @@
   // ===== 主题切换：多主题选择 + localStorage 持久化 + 跟随系统 =====
     (function(){
         var THEME_KEY = 'bw-theme';
-        var FIXED_THEMES = ['default', 'sunset', 'forest', 'dark'];
+        var FIXED_THEMES = ['default', 'sunset', 'forest', 'dark', 'lavender', 'ocean', 'sky', 'rose'];
         var ALL = FIXED_THEMES.concat(['auto']);
 
         function isSystemDark(){
@@ -1141,7 +1157,7 @@
         // 把"auto"解析为实际生效的主题
         function resolveTheme(name){
             if (name === 'auto') return isSystemDark() ? 'dark' : 'default';
-            return FIXED_THEMES.indexOf(name) !== -1 ? name : 'default';
+            return ALL.indexOf(name) !== -1 ? name : 'default';
         }
 
         // 应用主题（persist=true 表示记住用户选择）
@@ -1176,25 +1192,7 @@
             applyTheme('default', false);
         }
 
-        // 顶部按钮：展开/收起菜单
+        // 注：主题切换入口在侧栏(#side-theme-toggle)与抽屉(#drawer-theme-toggle)，下方单独绑定
-        var btn = document.getElementById('theme-toggle');
-        var menu = document.getElementById('theme-menu');
-        if (btn && menu) {
-            btn.addEventListener('click', function(e){
-                e.stopPropagation();
-                menu.classList.toggle('open');
-            });
-            menu.querySelectorAll('li').forEach(function(li){
-                li.addEventListener('click', function(e){
-                    e.stopPropagation();
-                    applyTheme(this.getAttribute('data-theme'), true);
-                    menu.classList.remove('open');
-                });
-            });
-            document.addEventListener('click', function(){
-                menu.classList.remove('open');
-            });
-        }
 
         // 跟随系统：监听系统暗色偏好变化，自动重应用
         if (window.matchMedia) {
@@ -1206,7 +1204,6 @@
             if (mq.addEventListener) mq.addEventListener('change', listener);
             else if (mq.addListener) mq.addListener(listener);   // 旧 Safari 兼容
         }
-    })();
         // 回到顶部
         var top = document.getElementById('to-top');
         if (top) {
@@ -1346,6 +1343,28 @@
             }
         })();
 
+        // 卡片图标增强：统一走本地缓存接口 /site/icon/<domain>。
+        // 服务端负责拉取并落盘到 data/icon/，拉取失败的自动返回「站点名称首字母」SVG，
+        // 因此既有真实 favicon、也不会再出现空白图标，且后续不再重复拉取。
+        window.enhanceFavicons = function(root){
+            var scope = root || document;
+            var imgs = scope.querySelectorAll('img.nav-favicon');
+            for (var i = 0; i < imgs.length; i++){
+                var img = imgs[i];
+                if (img.getAttribute('data-fav-wired')) continue;
+                img.setAttribute('data-fav-wired', '1');
+                var domain = img.getAttribute('data-domain');
+                if (!domain) continue;
+                var letter = img.getAttribute('data-letter') || '';
+                var url = '/site/icon/' + encodeURIComponent(domain);
+                if (letter) url += '?letter=' + encodeURIComponent(letter);
+                // 接口始终返回图片：成功为 favicon，失败为字母头像 SVG
+                img.onerror = function(){ img.style.display = 'none'; };
+                img.src = url;
+                img.style.display = 'block';
+            }
+        };
+
         // ===== 「我常访问」：localStorage 本地累计 + 服务端匿名榜合并 =====
         (function(){
             var KEY = 'wk_mine_clicks';
@@ -1510,6 +1529,8 @@
             } else {
                 render();
             }
+            // 首屏渲染后，为所有卡片加载 favicon（失败的自动回退到字母头像）
+            if (window.enhanceFavicons) window.enhanceFavicons(document);
         })();
 
         // ===== 全局搜索：前端实时过滤卡片，并高亮分类 Tab =====
@@ -1596,6 +1617,23 @@
             filter(q || '');
         })();
 
+        // 将主题菜单定位到触发元素右侧（fixed 浮层，避免被侧栏 overflow 裁剪）
+        function positionThemeMenu(trigger, menu){
+            var rect = trigger.getBoundingClientRect();
+            var prevDisplay = menu.style.display;
+            menu.style.visibility = 'hidden';
+            menu.style.display = 'block';
+            var mw = menu.offsetWidth, mh = menu.offsetHeight;
+            menu.style.display = prevDisplay;
+            menu.style.visibility = '';
+            var left = rect.right + 8;
+            if (left + mw > window.innerWidth - 8) left = rect.left - mw - 8;
+            var top = rect.top;
+            if (top + mh > window.innerHeight - 8) top = Math.max(8, window.innerHeight - mh - 8);
+            menu.style.top = top + 'px';
+            menu.style.left = left + 'px';
+        }
+
         // ===== 侧栏「切换主题」：弹出下拉菜单 =====
         (function(){
             var btn = document.getElementById('side-theme-toggle');
@@ -1609,7 +1647,7 @@
                 e.stopPropagation();
                 var wasOpen = menu.classList.contains('open');
                 closeAll();
-                if (!wasOpen) menu.classList.add('open');
+                if (!wasOpen) { positionThemeMenu(btn, menu); menu.classList.add('open'); }
             });
             menu.addEventListener('click', function(e){
                 var li = e.target.closest('li[data-theme]');
@@ -1635,7 +1673,7 @@
                 e.stopPropagation();
                 var wasOpen = menu.classList.contains('open');
                 closeAll();
-                if (!wasOpen) menu.classList.add('open');
+                if (!wasOpen) { positionThemeMenu(btn, menu); menu.classList.add('open'); }
             });
             menu.addEventListener('click', function(e){
                 var li = e.target.closest('li[data-theme]');
@@ -1650,6 +1688,7 @@
             document.addEventListener('click', closeAll);
             document.addEventListener('keydown', function(e){ if (e.key === 'Escape') closeAll(); });
         })();
+    })();
     </script>
 </body>
 </html>

templates/public/category.html

@@ -29,7 +29,12 @@
                        data-nav-id="{{ item.id }}"
                        {% if item.is_external %}target="_blank" rel="noopener noreferrer"{% endif %}>
                         <div class="icon-wrap">
-                            <i class="layui-icon {{ item.icon }}"></i>
+                            <span class="nav-letter" style="background:{{ item.color }}">{{ item.letter }}</span>
+                            {% if item.domain %}
+                            <img class="nav-favicon" alt="" loading="lazy" referrerpolicy="no-referrer"
+                                 data-domain="{{ item.domain }}" data-letter="{{ item.letter }}"
+                                 style="display:none">
+                            {% endif %}
                         </div>
                         <div class="card-body">
                             <div class="title-row">

templates/public/index.html

@@ -8,7 +8,13 @@
    {%- if mine is not none %} data-mine="{{ mine }}"{% endif %}
    {%- if item.is_external %} target="_blank" rel="noopener noreferrer"{% endif %}>
     <div class="icon-wrap">
-        <i class="layui-icon {{ item.icon }}"></i>
+        <span class="nav-letter" style="background:{{ item.color }}">{{ item.letter }}</span>
+        {% if item.domain %}
+        {# 图标走本地缓存接口 /site/icon/<domain>，由服务端拉取并落盘到 data/icon/，失败自动生成字母头像 #}
+        <img class="nav-favicon" alt="" loading="lazy" referrerpolicy="no-referrer"
+             data-domain="{{ item.domain }}" data-letter="{{ item.letter }}"
+             style="display:none">
+        {% endif %}
     </div>
     <div class="card-body">
         <div class="title-row">