fix: protect publish path from mysql exhaustion

server/store/store.go

@@ -3147,6 +3147,29 @@ func (relationsMapper) GetRelationshipContext(tenantID types.TenantID, userID, p
 }
 
 func (relationsMapper) CanSendP2P(tenantID types.TenantID, userID, peerID types.Uid) (bool, string, error) {
+	if userID.IsZero() || peerID.IsZero() || userID == peerID {
+		return false, "", types.ErrMalformed
+	}
+	// A warm relationship cache is sufficient for the publish hot path. Block
+	// entries are checked first in both directions; friendship and block writes
+	// keep these sets coherent. Redis errors and cache misses fall back to the
+	// authoritative database path below.
+	blockCacheReady := true
+	if blocked, err := cachedBlockContains(tenantID, userID, peerID); err != nil {
+		blockCacheReady = false
+	} else if blocked {
+		return false, types.RelationshipBlockedByMe, nil
+	}
+	if blocked, err := cachedBlockContains(tenantID, peerID, userID); err != nil {
+		blockCacheReady = false
+	} else if blocked {
+		return false, types.RelationshipBlockedByPeer, nil
+	}
+	if blockCacheReady {
+		if friend, err := cachedFriendContains(tenantID, userID, peerID); err == nil && friend {
+			return true, types.RelationshipFriend, nil
+		}
+	}
 	ctx, err := (relationsMapper{}).GetRelationshipContext(tenantID, userID, peerID, "")
 	if err != nil {
 		return false, "", err
@@ -3168,6 +3191,9 @@ func (relationsMapper) BlockUser(tenantID types.TenantID, blockerID, blockedID t
 	block, err := tenantAdp.TenantUserBlockUpsert(tenantID, blockerID, blockedID, now)
 	if err == nil {
 		cacheBlockOneWay(tenantID, blockerID, blockedID)
+		// A positive friend cache must never outlive a new block. Removing both
+		// directions also makes a later block-cache eviction fall back to MySQL.
+		uncacheFriendPair(tenantID, blockerID, blockedID)
 	}
 	return block, err
 }