perf: sync protocol and core hardening updates

internal/store/memory/album_group.go

@@ -0,0 +1,68 @@
+package memory
+
+import (
+	"bytes"
+	"context"
+
+	"telesrv/internal/domain"
+)
+
+type albumGroupKey struct {
+	senderUserID int64
+	peerType     domain.PeerType
+	peerID       int64
+	randomID     int64
+}
+
+type albumGroupRecord struct {
+	groupedID  int64
+	intentHash [32]byte
+}
+
+// ReserveAlbumGroup 在 MessageStore 的同一把互斥锁下完成读旧组、选胜者与补齐绑定，
+// 因而并发重叠批次不会产生拆组。
+func (s *MessageStore) ReserveAlbumGroup(_ context.Context, req domain.AlbumGroupReservationRequest) (int64, error) {
+	if err := req.Validate(); err != nil {
+		return 0, err
+	}
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.albumGroups == nil {
+		s.albumGroups = make(map[albumGroupKey]albumGroupRecord)
+	}
+
+	groupedID := int64(0)
+	type pendingBinding struct {
+		key        albumGroupKey
+		intentHash [32]byte
+	}
+	bindings := make([]pendingBinding, 0, len(req.Items))
+	for _, item := range req.Items {
+		key := albumGroupKey{
+			senderUserID: req.SenderUserID,
+			peerType:     req.Peer.Type,
+			peerID:       req.Peer.ID,
+			randomID:     item.RandomID,
+		}
+		var intentHash [32]byte
+		copy(intentHash[:], item.IntentHash)
+		bindings = append(bindings, pendingBinding{key: key, intentHash: intentHash})
+		if existing, exists := s.albumGroups[key]; exists {
+			if !bytes.Equal(existing.intentHash[:], item.IntentHash) {
+				return 0, domain.ErrMessageRandomIDDuplicate
+			}
+			if groupedID != 0 && groupedID != existing.groupedID {
+				return 0, domain.ErrMessageRandomIDDuplicate
+			}
+			groupedID = existing.groupedID
+		}
+	}
+	if groupedID == 0 {
+		groupedID = req.ProposedGroupedID
+	}
+	for _, binding := range bindings {
+		s.albumGroups[binding.key] = albumGroupRecord{groupedID: groupedID, intentHash: binding.intentHash}
+	}
+	return groupedID, nil
+}