perf(queue): 限制大媒体任务内存并消除准入惊群

将同步与异步非文本任务的准入唤醒改为按任务和全局队首推进，批量续租等待者，避免大量请求同时争抢 advisory lock 和数据库连接。

对 Base64 请求解析、素材解码、上游媒体执行和结果物化增加分层并发限制，复用请求素材并释放重复 Gemini wire 数据；生产 API 默认入口解析并发 16，媒体物化并发 8。

新增 1000 个同步 Gemini 图像编辑请求的模拟上游压力验收，10 MiB 输入和输出下全部成功，Heap 峰值增长约 2.58 GiB，并验证共享上传哈希、单次 attempt 与本地零落盘。

验证：go test ./... -count=1；go vet ./...；gofmt -l 无输出；kubectl kustomize deploy/kubernetes/production；10 MiB Gemini Base64 千任务压力测试通过。

apps/api/internal/httpapi/request_preparation.go

@@ -9,9 +9,12 @@ import (
 	"fmt"
 	"mime"
 	"net/http"
+	"os"
 	"path/filepath"
 	"sort"
+	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/auth"
@@ -41,6 +44,11 @@ type requestAssetOptions struct {
 	Source           string
 }
 
+type requestAssetLock struct {
+	mu   sync.Mutex
+	refs int
+}
+
 func (s *Server) prepareTaskRequest(ctx context.Context, r *http.Request, user *auth.User, body map[string]any) (preparedTaskRequest, error) {
 	preparedBody, err := s.prepareRequestAssetRefs(ctx, body)
 	if err != nil {
@@ -120,13 +128,9 @@ func (s *Server) prepareRequestAssetValue(ctx context.Context, value any, path [
 		sort.Strings(keys)
 		for _, key := range keys {
 			item := typed[key]
-			if decoded, ok, err := requestAssetFromValue(key, path, item, typed); err != nil {
+			if ref, ok, err := s.prepareRequestAssetField(ctx, key, path, item, typed); err != nil {
 				return nil, err
 			} else if ok {
-				ref, err := s.ensureRequestAsset(ctx, decoded)
-				if err != nil {
-					return nil, err
-				}
 				next[key] = requestAssetWrapper(ref)
 				continue
 			}
@@ -152,6 +156,67 @@ func (s *Server) prepareRequestAssetValue(ctx context.Context, value any, path [
 	}
 }
 
+func (s *Server) prepareRequestAssetField(ctx context.Context, key string, path []string, value any, siblings map[string]any) (map[string]any, bool, error) {
+	text, ok := value.(string)
+	if !ok {
+		return nil, false, nil
+	}
+	raw := strings.TrimSpace(text)
+	if raw == "" || mediaURLString(raw) {
+		return nil, false, nil
+	}
+	if !strings.HasPrefix(strings.ToLower(raw), "data:") &&
+		!strictRequestBase64Field(key, path) &&
+		!likelyRequestBase64MediaField(key, path, raw) {
+		return nil, false, nil
+	}
+	if err := s.acquireMediaRequestSlot(ctx); err != nil {
+		return nil, false, err
+	}
+	defer s.releaseMediaRequestSlot()
+	decoded, ok, err := requestAssetFromValue(key, path, value, siblings)
+	if err != nil || !ok {
+		return nil, ok, err
+	}
+	ref, err := s.ensureRequestAsset(ctx, decoded)
+	return ref, true, err
+}
+
+func (s *Server) acquireMediaRequestSlot(ctx context.Context) error {
+	if s.mediaRequestSlots == nil {
+		return nil
+	}
+	select {
+	case s.mediaRequestSlots <- struct{}{}:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func (s *Server) releaseMediaRequestSlot() {
+	if s.mediaRequestSlots != nil {
+		<-s.mediaRequestSlots
+	}
+}
+
+func (s *Server) acquireMediaRequestBodySlot(ctx context.Context) (func(), error) {
+	if s.mediaRequestBodySlots == nil {
+		return func() {}, nil
+	}
+	select {
+	case s.mediaRequestBodySlots <- struct{}{}:
+		var once sync.Once
+		return func() {
+			once.Do(func() {
+				<-s.mediaRequestBodySlots
+			})
+		}, nil
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
 func requestAssetFromValue(key string, path []string, value any, siblings map[string]any) (decodedRequestAsset, bool, error) {
 	text, ok := value.(string)
 	if !ok {
@@ -215,6 +280,8 @@ func (s *Server) ensureRequestAssetWithOptions(ctx context.Context, decoded deco
 	if contentType == "" {
 		contentType = "application/octet-stream"
 	}
+	release := s.acquireRequestAssetLock(sha + "\x00" + contentType + "\x00" + options.UploadScene + "\x00" + strconv.FormatBool(options.RequirePublicURL))
+	defer release()
 	now := time.Now()
 	if existing, ok, err := s.store.FindRequestAsset(ctx, sha, contentType); err != nil && !store.IsUndefinedDatabaseObject(err) {
 		return nil, err
@@ -286,6 +353,31 @@ func (s *Server) ensureRequestAssetWithOptions(ctx context.Context, decoded deco
 	return requestAssetRef(asset), nil
 }
 
+func (s *Server) acquireRequestAssetLock(key string) func() {
+	s.requestAssetLocksMu.Lock()
+	if s.requestAssetLocks == nil {
+		s.requestAssetLocks = map[string]*requestAssetLock{}
+	}
+	entry := s.requestAssetLocks[key]
+	if entry == nil {
+		entry = &requestAssetLock{}
+		s.requestAssetLocks[key] = entry
+	}
+	entry.refs++
+	s.requestAssetLocksMu.Unlock()
+
+	entry.mu.Lock()
+	return func() {
+		entry.mu.Unlock()
+		s.requestAssetLocksMu.Lock()
+		entry.refs--
+		if entry.refs == 0 {
+			delete(s.requestAssetLocks, key)
+		}
+		s.requestAssetLocksMu.Unlock()
+	}
+}
+
 func requestConversationKey(r *http.Request, body map[string]any) string {
 	if r != nil {
 		if value := strings.TrimSpace(r.Header.Get("X-EasyAI-Conversation-ID")); value != "" {
@@ -397,6 +489,16 @@ func requestAssetStillUsable(asset store.RequestAsset, now time.Time) bool {
 	if asset.ExpiresAt != nil && !asset.ExpiresAt.After(now) {
 		return false
 	}
+	if strings.EqualFold(strings.TrimSpace(asset.StorageProvider), "local_static") {
+		localPath := strings.TrimSpace(asset.LocalPath)
+		info, err := os.Stat(localPath)
+		if localPath == "" || err != nil || !info.Mode().IsRegular() {
+			return false
+		}
+		if asset.ByteSize > 0 && info.Size() != asset.ByteSize {
+			return false
+		}
+	}
 	return strings.TrimSpace(asset.URL) != ""
 }