diff --git a/src/CounterDrone.Core/Algorithms/DefensePlanner.cs b/src/CounterDrone.Core/Algorithms/DefensePlanner.cs
index b52e27f..5a366d1 100644
--- a/src/CounterDrone.Core/Algorithms/DefensePlanner.cs
+++ b/src/CounterDrone.Core/Algorithms/DefensePlanner.cs
@@ -142,7 +142,6 @@ namespace CounterDrone.Core.Algorithms
                 for (int l = 0; l < yLanes; l++) laneNeeded[l] = singleNeeded;
                 int currentLane = 0;
                 int roundsCollected = 0;
-                int eventIdx = 0;
                 var assignedUnits = new List<(FireUnit unit, int rounds, List<FireEvent> events)>();
 
                 foreach (var c in candidates.OrderBy(c => c.EarliestInterceptTime)
@@ -170,19 +169,21 @@ namespace CounterDrone.Core.Algorithms
 
                     var fevents = new List<FireEvent>();
                     int unitIdx = fireUnits.IndexOf(c.Unit);
+                    int baseRoundInLane = singleNeeded - laneNeeded[currentLane];
                     for (int ch = 0; ch < toTake; ch++)
                     {
-                        float offset = (eventIdx - (totalRoundsNeeded - 1) / 2f) * spacing;
+                        // offset 基于车道内发序（不是全局 eventIdx），使每车道独立分布在同一航路段，
+                        // 多车道重叠覆盖而非沿航路连成长链
+                        int roundInLane = baseRoundInLane + ch;
+                        float offset = (roundInLane - (singleNeeded - 1) / 2f) * spacing;
                         var fe = GenerateFireEventsAt(threat, c.Unit, c.AmmoType, ammo, env, offset, yLane, yLanes, formationWidth);
-                        int baseRoundInLane = singleNeeded - laneNeeded[currentLane];
                         foreach (var e in fe)
                         {
-                            e.FireTime = laneBaseTime[yLane] + (baseRoundInLane + ch) * stagger;
+                            e.FireTime = laneBaseTime[yLane] + roundInLane * stagger;
                             // TargetX/Z 保留 GenerateFireEventsAt 算出的风偏补偿后抛撒点 cloudGenX/Z
                             e.PlatformIndex = unitIdx * c.Unit.TotalChannels + ch;
                         }
                         fevents.AddRange(fe);
-                        eventIdx++;
                     }
 
                     assignedUnits.Add((c.Unit, toTake, fevents));