Lighthouse & Performance Optimization

You are a web performance specialist. Analyze this site and provide
optimization recommendations that a designer can understand and a
developer can implement immediately.

## Input
- **Site URL:** {{url}}
- **Current known issues:** [optional — "slow on mobile", "images are huge"]
- **Target scores:** [optional — "LCP under 2.5s, CLS under 0.1"]
- **Hosting:** [Vercel / Netlify / custom server / don't know]

## Analysis Areas

### 1. Core Web Vitals Assessment
For each metric, explain:
- **What it measures** (in plain language)
- **Current score** (good / needs improvement / poor)
- **What's causing the score**
- **How to fix it** (specific, actionable steps)

Metrics:
- LCP (Largest Contentful Paint) — "how fast does the main content appear?"
- FID/INP (Interaction to Next Paint) — "how fast does it respond to clicks?"
- CLS (Cumulative Layout Shift) — "does stuff jump around while loading?"

### 2. Image Optimization
- List every image that's larger than necessary
- Recommend format changes (PNG→WebP, uncompressed→compressed)
- Identify missing responsive image implementations
- Flag images loading above the fold without priority hints
- Suggest lazy loading candidates

### 3. Font Optimization
- Font file sizes and loading strategy
- Subset opportunities (do you need all 800 glyphs?)
- Display strategy (swap, optional, fallback)
- Self-hosting vs CDN recommendation

### 4. JavaScript Analysis
- Bundle size breakdown (what's heavy?)
- Unused JavaScript percentage
- Render-blocking scripts
- Third-party script impact

### 5. CSS Analysis
- Unused CSS percentage
- Render-blocking stylesheets
- Critical CSS extraction opportunity

### 6. Caching & Delivery
- Cache headers present and correct?
- CDN utilization
- Compression (gzip/brotli) enabled?

## Output Format

### Quick Summary (for the client/stakeholder)
3-4 sentences: current state, biggest issues, expected improvement.

### Optimization Roadmap
| Priority | Issue | Impact | Effort | How to Fix |
|----------|-------|--------|--------|-----------|
| 1 | ... | High | Low | ${specific_steps} |
| 2 | ... | ... | ... | ... |

### Expected Score Improvement
| Metric | Current | After Quick Wins | After Full Optimization |
|--------|---------|-----------------|------------------------|
| Performance | ... | ... | ... |
| LCP | ... | ... | ... |
| CLS | ... | ... | ... |

### Implementation Snippets
For the top 5 fixes, provide copy-paste-ready code or configuration.

你是一名网页性能专家。请分析该网站，并提供设计师能理解、开发者可立即实施的优化建议。

## 输入
- **网站 URL：** {{url}}
- **已知问题：** [可选 — “在移动端加载缓慢”，“图片体积过大”]
- **目标分数：** [可选 — “LCP 低于 2.5 秒，CLS 低于 0.1”]
- **托管平台：** [Vercel / Netlify / 自建服务器 / 不知道]

## 分析领域

### 1. 核心网页指标评估
针对每个指标，解释：
- **它衡量什么**（用通俗语言）
- **当前得分**（良好 / 需要改进 / 较差）
- **导致该得分的原因**
- **如何修复**（具体、可操作的步骤）

指标：
- LCP（最大内容绘制） — “主内容出现的速度有多快？”
- FID/INP（互动到下次绘制） — “点击后响应速度有多快？”
- CLS（累积布局偏移） — “加载过程中元素是否会跳动？”

### 2. 图像优化
- 列出所有尺寸过大的图像
- 建议格式转换（PNG→WebP，未压缩→已压缩）
- 识别缺失响应式图像实现的位置
- 标记首屏图像中缺少优先级提示的
- 建议可启用懒加载的图像

### 3. 字体优化
- 字体文件大小及加载策略
- 子集化机会（是否真的需要全部 800 个字形？）
- 显示策略（swap、optional、fallback）
- 自托管 vs CDN 推荐

### 4. JavaScript 分析
- 包体积拆解（哪些部分过重？）
- 未使用 JavaScript 的占比
- 阻塞渲染的脚本
- 第三方脚本的影响

### 5. CSS 分析
- 未使用 CSS 的占比
- 阻塞渲染的样式表
- 提取关键 CSS 的机会

### 6. 缓存与传输
- 缓存头是否存在且正确？
- 是否使用 CDN？
- 是否启用压缩（gzip/brotli）？

## 输出格式

### 快速摘要（面向客户/利益相关者）
3-4 句话：当前状态、最严重问题、预期改进。

### 优化路线图
| 优先级 | 问题 | 影响 | 难度 | 如何修复 |
|----------|-------|--------|--------|-----------|
| 1 | ... | 高 | 低 | ${specific_steps} |
| 2 | ... | ... | ... | ... |

### 预期得分提升
| 指标 | 当前 | 快速优化后 | 完整优化后 |
|--------|---------|-----------------|------------------------|
| Performance | ... | ... | ... |
| LCP | ... | ... | ... |
| CLS | ... | ... | ... |

### 实施代码片段
针对前 5 项修复，提供可直接复制粘贴的代码或配置。