feat(api): API keys + Redis rate limiting + usage stats

Add an optional API-key layer to the public read-only API. Keys grant
higher per-minute rate limits and attribute usage; anonymous callers are
still allowed at a lower IP-based budget.

- migration 0008_api_key: api_key table (sha256 hash only, plaintext shown once)
- apikey pkg: key generation + hashing
- ratelimit pkg: Redis fixed-window limiter + per-key usage counters; fails open
- public API middleware: X-API-Key / Bearer auth, X-RateLimit-* headers, 429+Retry-After
- admin: issue/list/revoke keys + usage view (API + UI tab)

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

api/internal/handler/handler.go

@@ -15,6 +15,7 @@ import (
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
 
+	"github.com/baicai2026-baicai/goods/api/internal/ratelimit"
 	"github.com/baicai2026-baicai/goods/api/internal/store"
 )
 
@@ -24,17 +25,35 @@ const APIVersion = "v1"
 const (
 	defaultPageSize = 20
 	maxPageSize     = 100
+
+	// defaultAnonLimit is the per-minute request budget for unauthenticated
+	// callers (identified by client IP) when none is configured.
+	defaultAnonLimit = 60
 )
 
 // Handler holds dependencies shared by the HTTP routes.
 type Handler struct {
-	store *store.Store
-	spa   fs.FS
+	store     *store.Store
+	spa       fs.FS
+	limiter   *ratelimit.Limiter
+	anonLimit int
 }
 
 // New constructs a Handler backed by the given store. spa may be nil (JSON-only).
+// Rate limiting is disabled until WithRateLimit is called.
 func New(s *store.Store, spa fs.FS) *Handler {
-	return &Handler{store: s, spa: spa}
+	return &Handler{store: s, spa: spa, anonLimit: defaultAnonLimit}
+}
+
+// WithRateLimit attaches a Redis-backed limiter and the anonymous per-minute
+// budget, enabling rate limiting + usage tracking on the public API routes.
+// A non-positive anonPerMin keeps the default.
+func (h *Handler) WithRateLimit(l *ratelimit.Limiter, anonPerMin int) *Handler {
+	h.limiter = l
+	if anonPerMin > 0 {
+		h.anonLimit = anonPerMin
+	}
+	return h
 }
 
 // Router builds the top-level HTTP handler with middleware and routes mounted.
@@ -47,6 +66,7 @@ func (h *Handler) Router() http.Handler {
 	r.Get("/healthz", h.Healthz)
 
 	r.Route("/api/"+APIVersion, func(r chi.Router) {
+		r.Use(h.rateLimit)
 		r.Route("/products", func(r chi.Router) {
 			r.Get("/barcode/{gtin}", h.ProductByBarcode)
 			r.Get("/search", h.SearchProducts)

api/internal/handler/middleware.go

@@ -0,0 +1,90 @@
+package handler
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/baicai2026-baicai/goods/api/internal/apikey"
+	"github.com/baicai2026-baicai/goods/api/internal/store"
+)
+
+type ctxKey int
+
+const apiKeyIDKey ctxKey = 0
+
+// rateLimit authenticates an optional API key and enforces a per-minute budget
+// on the public API. Anonymous callers are limited by client IP at a lower
+// budget; a valid key raises the budget and attributes usage. An API key that
+// is present but invalid or revoked is rejected with 401. Rate-limit headers
+// are set on every response; over-budget callers get 429 + Retry-After.
+func (h *Handler) rateLimit(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		id := "ip:" + clientIP(r)
+		limit := h.anonLimit
+		keyID := ""
+
+		if raw := presentedKey(r); raw != "" {
+			if !apikey.IsWellFormed(raw) {
+				writeError(w, r, http.StatusUnauthorized, "invalid_api_key", "API key 格式无效")
+				return
+			}
+			k, err := h.store.APIKeyByHash(r.Context(), apikey.Hash(raw))
+			if errors.Is(err, store.ErrNotFound) {
+				writeError(w, r, http.StatusUnauthorized, "invalid_api_key", "API key 无效或已吊销")
+				return
+			}
+			if err != nil {
+				writeError(w, r, http.StatusInternalServerError, "internal_error", "internal server error")
+				return
+			}
+			keyID = k.ID
+			limit = k.RateLimitPerMin
+			id = "key:" + k.ID
+		}
+
+		res := h.limiter.Allow(r.Context(), id, limit, time.Minute)
+		w.Header().Set("X-RateLimit-Limit", strconv.Itoa(res.Limit))
+		w.Header().Set("X-RateLimit-Remaining", strconv.Itoa(res.Remaining))
+		w.Header().Set("X-RateLimit-Reset", strconv.FormatInt(res.ResetUnix, 10))
+		if !res.Allowed {
+			retry := res.ResetUnix - time.Now().Unix()
+			if retry < 1 {
+				retry = 1
+			}
+			w.Header().Set("Retry-After", strconv.FormatInt(retry, 10))
+			writeError(w, r, http.StatusTooManyRequests, "rate_limited", "请求过于频繁，请稍后再试")
+			return
+		}
+
+		if keyID != "" {
+			h.limiter.RecordUsage(r.Context(), keyID)
+			next.ServeHTTP(w, r.WithContext(context.WithValue(r.Context(), apiKeyIDKey, keyID)))
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// presentedKey extracts an API key from the X-API-Key header or a Bearer token.
+func presentedKey(r *http.Request) string {
+	if v := strings.TrimSpace(r.Header.Get("X-API-Key")); v != "" {
+		return v
+	}
+	if v := r.Header.Get("Authorization"); strings.HasPrefix(v, "Bearer ") {
+		return strings.TrimSpace(strings.TrimPrefix(v, "Bearer "))
+	}
+	return ""
+}
+
+// clientIP returns the caller IP, preferring chi's RealIP-normalized RemoteAddr.
+func clientIP(r *http.Request) string {
+	if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
+		return host
+	}
+	return r.RemoteAddr
+}

api/internal/handler/middleware_db_test.go

@@ -0,0 +1,120 @@
+package handler
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/baicai2026-baicai/goods/api/internal/apikey"
+	"github.com/baicai2026-baicai/goods/api/internal/ratelimit"
+	"github.com/baicai2026-baicai/goods/api/internal/store"
+)
+
+// newRateLimitedHandler builds a handler backed by the test DB and a live Redis
+// limiter, plus a freshly issued API key with the given per-minute limit. It
+// skips when either backend is unavailable.
+func newRateLimitedHandler(t *testing.T, keyLimit int) (h *Handler, plaintextKey string) {
+	t.Helper()
+	dsn := os.Getenv("OPENGOODS_DATABASE_URL")
+	if dsn == "" {
+		dsn = "postgres://opengoods:opengoods@localhost:5432/opengoods?sslmode=disable"
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	pool, err := pgxpool.New(ctx, dsn)
+	if err != nil {
+		t.Skipf("no database: %v", err)
+	}
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		t.Skipf("database not reachable: %v", err)
+	}
+	var hasTable bool
+	if err := pool.QueryRow(ctx, "SELECT to_regclass('public.api_key') IS NOT NULL").Scan(&hasTable); err != nil || !hasTable {
+		pool.Close()
+		t.Skip("migrations not applied (api_key missing)")
+	}
+
+	redisURL := os.Getenv("OPENGOODS_REDIS_URL")
+	if redisURL == "" {
+		redisURL = "redis://localhost:6379/0"
+	}
+	limiter := ratelimit.New(redisURL)
+	pingCtx, pingCancel := context.WithTimeout(context.Background(), time.Second)
+	defer pingCancel()
+	if err := limiter.Ping(pingCtx); err != nil {
+		pool.Close()
+		t.Skipf("redis not reachable: %v", err)
+	}
+
+	key, hash, prefix, err := apikey.Generate()
+	if err != nil {
+		pool.Close()
+		t.Fatal(err)
+	}
+	name := fmt.Sprintf("test-key-%d", time.Now().UnixNano())
+	if _, err := pool.Exec(context.Background(),
+		`INSERT INTO api_key (name, key_prefix, key_hash, rate_limit_per_min) VALUES ($1,$2,$3,$4)`,
+		name, prefix, hash, keyLimit); err != nil {
+		pool.Close()
+		t.Fatalf("insert api_key: %v", err)
+	}
+	t.Cleanup(func() {
+		_, _ = pool.Exec(context.Background(), "DELETE FROM api_key WHERE key_hash=$1", hash)
+		pool.Close()
+	})
+
+	return New(store.New(pool), nil).WithRateLimit(limiter, 60), key
+}
+
+func TestRateLimitHeadersAndKeyAuth(t *testing.T) {
+	h, key := newRateLimitedHandler(t, 100)
+	req := httptest.NewRequest(http.MethodGet, "/api/"+APIVersion+"/categories", nil)
+	req.Header.Set("X-API-Key", key)
+	rec := httptest.NewRecorder()
+	h.Router().ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+	if got := rec.Header().Get("X-RateLimit-Limit"); got != "100" {
+		t.Fatalf("X-RateLimit-Limit = %q, want 100 (key limit)", got)
+	}
+	if rec.Header().Get("X-RateLimit-Remaining") == "" {
+		t.Fatal("missing X-RateLimit-Remaining header")
+	}
+}
+
+func TestInvalidKeyRejected(t *testing.T) {
+	h, _ := newRateLimitedHandler(t, 100)
+	req := httptest.NewRequest(http.MethodGet, "/api/"+APIVersion+"/categories", nil)
+	req.Header.Set("X-API-Key", "og_live_thiskeydoesnotexist123456")
+	rec := httptest.NewRecorder()
+	h.Router().ServeHTTP(rec, req)
+	if rec.Code != http.StatusUnauthorized {
+		t.Fatalf("status = %d, want 401; body = %s", rec.Code, rec.Body.String())
+	}
+}
+
+func TestRateLimitExceeded(t *testing.T) {
+	h, key := newRateLimitedHandler(t, 1)
+	do := func() int {
+		req := httptest.NewRequest(http.MethodGet, "/api/"+APIVersion+"/categories", nil)
+		req.Header.Set("X-API-Key", key)
+		rec := httptest.NewRecorder()
+		h.Router().ServeHTTP(rec, req)
+		return rec.Code
+	}
+	if code := do(); code != http.StatusOK {
+		t.Fatalf("first request status = %d, want 200", code)
+	}
+	if code := do(); code != http.StatusTooManyRequests {
+		t.Fatalf("second request status = %d, want 429", code)
+	}
+}