feat(govai): 0617 优化首批 — 安全/私有化/深度研究/服务层/可观测性

借鉴 odysseus 的能力设计，全程净室实现、零 AGPL 代码、不引入 AGPL 依赖。

T1 提示注入防护: pkg/promptguard 包裹外部/知识库内容为不可信数据，buildMessages 移出 system 指令区。 T2 安全 CI: .github/workflows(ci+security: govulncheck/gitleaks/actionlint/hadolint/trivy)+dependabot+.hadolint.yaml；go.mod 加 toolchain go1.25.11 修复 20 个 stdlib CVE。 T3 管理员 2FA: 迁移 000016 + RFC6238 TOTP/备份码(pkg/auth, 零依赖) + 登录流程集成(后端)。 T4 本地模型: LLM/embedding 支持本地 vLLM/Ollama(OpenAI 兼容, 鉴权头条件发送, NoAuth) + docs/local-deploy.md。 T6 深度研究: 迁移 000017 + Python research-worker(净室多步流水线, 检索避开 SearXNG) + Go research 服务/handler/路由。 T7 service 层: 新增 internal/service/{research,twofa}, 2FA 业务逻辑从胖 handler 下沉, 接口注入可单测。 T10 缓存/可观测性: internal/cache(Redis+内存, 优雅降级) 接入 store 热点列表; Prometheus 指标+/metrics; docs/openapi.yaml。 验证: go build/vet/test ./... 全绿(8 包); research-worker 12 单测过; 真实 PG 应用迁移并烟测。

server/internal/middleware/metrics.go

@@ -0,0 +1,52 @@
+package middleware
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	chimw "github.com/go-chi/chi/v5/middleware"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	httpRequestsTotal = promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "govai_http_requests_total",
+			Help: "HTTP 请求总数，按方法、路由模板、状态码统计。",
+		},
+		[]string{"method", "route", "status"},
+	)
+	httpRequestDuration = promauto.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "govai_http_request_duration_seconds",
+			Help:    "HTTP 请求耗时（秒），按方法与路由模板统计。",
+			Buckets: prometheus.DefBuckets,
+		},
+		[]string{"method", "route"},
+	)
+)
+
+// Metrics 是记录 Prometheus 指标的全局中间件。
+// 使用 chi 的路由模板（而非原始路径）作为标签，避免高基数。
+func Metrics(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		ww := chimw.NewWrapResponseWriter(w, r.ProtoMajor)
+
+		next.ServeHTTP(ww, r)
+
+		route := chi.RouteContext(r.Context()).RoutePattern()
+		if route == "" {
+			route = "unmatched"
+		}
+		status := ww.Status()
+		if status == 0 {
+			status = http.StatusOK
+		}
+		httpRequestsTotal.WithLabelValues(r.Method, route, strconv.Itoa(status)).Inc()
+		httpRequestDuration.WithLabelValues(r.Method, route).Observe(time.Since(start).Seconds())
+	})
+}

server/internal/middleware/metrics_test.go

@@ -0,0 +1,50 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestMetricsMiddleware_RecordsRequestWithRouteTemplate(t *testing.T) {
+	r := chi.NewRouter()
+	r.Use(Metrics)
+	r.Get("/things/{id}", func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	})
+
+	// 用路由模板（而非具体路径）作为标签，避免高基数
+	before := testutil.ToFloat64(httpRequestsTotal.WithLabelValues("GET", "/things/{id}", "200"))
+
+	rec := httptest.NewRecorder()
+	r.ServeHTTP(rec, httptest.NewRequest("GET", "/things/42", nil))
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("状态码应为 200，实际 %d", rec.Code)
+	}
+	after := testutil.ToFloat64(httpRequestsTotal.WithLabelValues("GET", "/things/{id}", "200"))
+	if after != before+1 {
+		t.Fatalf("请求计数应 +1：before=%v after=%v", before, after)
+	}
+}
+
+func TestMetricsMiddleware_RecordsErrorStatus(t *testing.T) {
+	r := chi.NewRouter()
+	r.Use(Metrics)
+	r.Get("/boom", func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+	})
+
+	before := testutil.ToFloat64(httpRequestsTotal.WithLabelValues("GET", "/boom", "500"))
+	rec := httptest.NewRecorder()
+	r.ServeHTTP(rec, httptest.NewRequest("GET", "/boom", nil))
+
+	after := testutil.ToFloat64(httpRequestsTotal.WithLabelValues("GET", "/boom", "500"))
+	if after != before+1 {
+		t.Fatalf("500 计数应 +1：before=%v after=%v", before, after)
+	}
+}