AI 面试官网页版实战：Go + SSE 流式输出（三）

GET  /              面试页面（embed 的 index.html）
POST /api/start     开始面试：生成计划，返回首题
GET  /api/answer    SSE：提交回答，流式返回面试官点评
GET  /api/question  取下一题
GET  /api/report    取最终评分报告（Markdown）

// internal/llm/client.go — ChatStream 边读边回调
func (c *OpenAIClient) ChatStream(ctx context.Context, system, user string,
    onToken func(string)) (string, error) {
    stream := c.cli.Chat.Completions.NewStreaming(ctx, c.chatParams(system, user))
    defer stream.Close()
    var full strings.Builder
    for stream.Next() {
        for _, choice := range stream.Current().Choices {
            if tok := choice.Delta.Content; tok != "" {
                full.WriteString(tok)
                onToken(tok) // 逐 token 回调给 HTTP 层
            }
        }
    }
    return full.String(), stream.Err()
}

// internal/web/server.go — SSE 事件发送
w.Header().Set("Content-Type", "text/event-stream")
flusher := w.(http.Flusher)
send := func(event string, data any) {
    b, _ := json.Marshal(data)
    fmt.Fprintf(w, "event: %s\ndata: %s\n\n", event, b)
    flusher.Flush() // 立即推送，不缓冲
}
_, _ = s.client.ChatStream(ctx, sys, commentary, func(tok string) {
    send("token", map[string]string{"t": tok})
})
send("result", result) // 追问 or 下一题 or 结束
send("done", map[string]bool{})

// 按 SSE 空行分隔解析事件块
const resp = await fetch('/api/answer?session='+session+'&a='+encodeURIComponent(a));
const reader = resp.body.getReader(), dec = new TextDecoder();
let buf = '';
while (true) {
  const {done, value} = await reader.read(); if (done) break;
  buf += dec.decode(value, {stream: true});
  let p;
  while ((p = buf.indexOf('\n\n')) >= 0) {
    const block = buf.slice(0, p); buf = buf.slice(p + 2);
    handleEvent(block); // 解析 event: / data: 行
  }
}

export OPENAI_API_KEY=你的Key
go run ./cmd/coach web --addr :8080
# 打开 http://localhost:8080