fix: 多单元并行 + 多车道正确弹药计算

- 所有单元以同基准时间并行发射(offset=0)
- 通道内 ch×ChannelInterval 独立错开
- CalcRoundsNeeded 恢复纯单机，yLanes 乘法在 Solve
- Piston: 33发=11×3车道, 2/3击毁

src/CounterDrone.Core/Algorithms/DefaultDefensePlanner.cs

@@ -162,13 +162,17 @@ namespace CounterDrone.Core.Algorithms
                 {
                     float salvoDelay = salvo * candidates[0].Unit.Cooldown;
 
-                    // 同平台飞行时间只算一次（平台飞到投放点后所有通道齐投）
+                // 车道参数
-                    var (effectiveR, _) = ComputeEffectiveRadius(threat, ammo, env);
+                var (laneEffR, _) = ComputeEffectiveRadius(threat, ammo, env);
-                    float cloudDiameter = effectiveR * 2f;
+                float cloudDiameter = laneEffR * 2f;
-                    float droneSpeed = (float)threat.Target.TypicalSpeed / 3.6f;
+                float droneSpeed = (float)threat.Target.TypicalSpeed / 3.6f;
-                    float physicsInterval = Math.Max(candidates[0].Unit.ChannelInterval,
+                float physicsInterval = Math.Max(candidates[0].Unit.ChannelInterval,
-                        cloudDiameter / droneSpeed);
+                    cloudDiameter / droneSpeed);
-                    float spacing = effectiveR * 1.5f;
+                float spacing = laneEffR * 1.5f;
+
+                // 所有弹药以中点偏移=0为基准计算基础发射时间
+                var refEvent = GenerateFireEventsAt(threat, candidates[0].Unit, neededAmmo, ammo, env, 0, 0, yLanes, formationWidth);
+                float globalBaseFireTime = refEvent[0].FireTime;
 
                     foreach (var c in candidates.OrderBy(c => c.EarliestInterceptTime)
                         .ThenByDescending(c => c.KillProbability))
@@ -181,21 +185,19 @@ namespace CounterDrone.Core.Algorithms
                         int toTake = Math.Min(maxSalvo, totalRoundsNeeded - roundsCollected);
                         if (toTake <= 0) continue;
 
-                        // 同单元所有弹药以中心点计算飞行时间，仅通过 eventIdx 错开间隔
+                        // 所有单元以航路中点计算相同的基准发射时间，仅通道间隔错开
-                        float centerOffset = (eventIdx + (toTake - 1) / 2f - (totalRoundsNeeded - 1) / 2f) * spacing;
+                        var refEvt = GenerateFireEventsAt(threat, c.Unit, c.AmmoType, ammo, env, 0, 0, yLanes, formationWidth);
-                        int yLane = eventIdx % yLanes;
+                        float unitBaseTime = refEvt[0].FireTime;
-                        var feTemplate = GenerateFireEventsAt(threat, c.Unit, c.AmmoType, ammo, env, centerOffset, yLane, yLanes, formationWidth);
-                        float baseFireTime = feTemplate[0].FireTime;
 
                         var fevents = new List<FireEvent>();
                         for (int ch = 0; ch < toTake; ch++)
                         {
                             float offset = (eventIdx - (totalRoundsNeeded - 1) / 2f) * spacing;
-                            int yLane2 = eventIdx % yLanes;
+                            int yLane = eventIdx % yLanes;
-                            var fe = GenerateFireEventsAt(threat, c.Unit, c.AmmoType, ammo, env, offset, yLane2, yLanes, formationWidth);
+                            var fe = GenerateFireEventsAt(threat, c.Unit, c.AmmoType, ammo, env, offset, yLane, yLanes, formationWidth);
                             foreach (var e in fe)
                             {
-                                e.FireTime = baseFireTime + salvoDelay + eventIdx * physicsInterval;
+                                e.FireTime = unitBaseTime + salvoDelay + ch * c.Unit.ChannelInterval;
                             }
                             fevents.AddRange(fe);
                             eventIdx++;
@@ -406,17 +408,7 @@ namespace CounterDrone.Core.Algorithms
             var aerosolType = (AerosolType)ammo.AerosolType;
             float neededExposure = aerosolType == AerosolType.ActiveMaterial ? 2f : 6f;
             float singleCoverage = neededExposure * avgSpeed;
-
+            float requiredCoverage = singleCoverage;
-            // 多架编队：覆盖范围需加上编队展开宽度
-            int quantity = Math.Max(1, threat.Target.Quantity);
-            float formationSpread = 0f;
-            if (quantity > 1 && threat.Route != null)
-            {
-                var mode = (FormationMode)threat.Route.FormationMode;
-                if (mode != FormationMode.Single)
-                    formationSpread = (quantity - 1) * (float)threat.Route.LateralSpacing;
-            }
-            float requiredCoverage = singleCoverage + formationSpread;
 
             return Math.Max(1,
                 (int)Math.Ceiling((requiredCoverage - 2f * effectiveR) / spacing) + 1);

test/unit/CounterDrone.Core.Tests/DefensePlannerTests.cs

@@ -95,15 +95,48 @@ namespace CounterDrone.Core.Tests
         // ═══════════════════════════════════════
 
         [Fact]
-        public void Ground_FireTime_VariesPerRound()
+        public void Ground_FireTime_VariesPerUnitPosition()
         {
-            var result = Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat(speed: 120));
+            // 两个单元不同位置 → 飞行时间不同 → 发射时间不同
-            var events = result.Best.MergedSchedule.OrderBy(e => e.FireTime).ToList();
+            var u0 = MakeGroundUnit("u0", 5000);
-            Assert.True(events.Count >= 3);
+            var u1 = MakeGroundUnit("u1", 8000);
-            // 地基弹道：目标更近的弹飞行时间更短，FireTime 更晚（更接近 recommendedTiming）
+            var threat = MakeThreat(speed: 120);
-            float first = events[0].FireTime;
+
-            float last = events[^1].FireTime;
+            var r0 = Plan(new() { u0 }, threat);
-            Assert.True(last > first, "远目标 FireTime 应 > 近目标");
+            var r1 = Plan(new() { u1 }, threat);
+
+            float t0 = r0.Best.MergedSchedule[0].FireTime;
+            float t1 = r1.Best.MergedSchedule[0].FireTime;
+            Assert.NotEqual(t0, t1); // 位置不同 → 弹道不同 → 发射时刻不同
+        }
+
+        [Fact]
+        public void MultiUnit_Parallel_ShorterThanSingle()
+        {
+            var threat = MakeThreat(speed: 200);
+            threat.Waypoints.Clear();
+            threat.Waypoints.Add(new Waypoint { PosX = 0, PosY = 500, PosZ = 0, Speed = 200 });
+            threat.Waypoints.Add(new Waypoint { PosX = 20000, PosY = 500, PosZ = 0, Speed = 200 });
+
+            // 每个单元只有 6 通道，单机需求 11 发 → 一个不够，必须两个并射
+            var unitSmall = new FireUnit { Id = "u0", Type = PlatformType.GroundBased,
+                Position = new Vector3(5000, 0, 50), GunCount = 1, ChannelsPerGun = 6,
+                MuzzleVelocity = 800, TotalMunitions = 11, Cooldown = 5f,
+                AmmoTypes = new() { AerosolType.InertGas } };
+            var unitSmall2 = new FireUnit { Id = "u1", Type = PlatformType.GroundBased,
+                Position = new Vector3(5100, 0, 50), GunCount = 1, ChannelsPerGun = 6,
+                MuzzleVelocity = 800, TotalMunitions = 11, Cooldown = 5f,
+                AmmoTypes = new() { AerosolType.InertGas } };
+
+            var r1 = Plan(new() { unitSmall }, threat);
+            var r2 = Plan(new() { unitSmall, unitSmall2 }, threat);
+
+            float s1 = r1.Best.MergedSchedule.Max(e => e.FireTime) - r1.Best.MergedSchedule.Min(e => e.FireTime);
+            float s2 = r2.Best.MergedSchedule.Max(e => e.FireTime) - r2.Best.MergedSchedule.Min(e => e.FireTime);
+
+            // 2 单元并射应短于 1 单元
+            var msg = $"2单元={s2:F1}s({r2.Best.MergedSchedule.Count}发) 1单元={s1:F1}s({r1.Best.MergedSchedule.Count}发)";
+            Assert.True(s2 < s1, msg);
         }
 
         [Fact]
@@ -146,13 +179,12 @@ namespace CounterDrone.Core.Tests
             var events = result.Best.MergedSchedule.OrderBy(e => e.FireTime).ToList();
             Assert.True(events.Count >= 3);
 
-            // 间隔应稳定 ≈ physicsInterval（1.2s），不应因目标位置变化而波动
+            // 间隔应稳定 ≈ ChannelInterval（1s），不应因目标位置变化而波动
-            // physicsInterval = max(1, 40.38/33.33) = 1.21s
             for (int i = 1; i < events.Count; i++)
             {
                 float gap = events[i].FireTime - events[i - 1].FireTime;
-                Assert.True(Math.Abs(gap - 1.21f) < 0.2f,
+                Assert.True(Math.Abs(gap - 1.0f) < 0.2f,
-                    $"gap[{i}]={gap:F3}, expected 1.21±0.2");
+                    $"gap[{i}]={gap:F3}, expected 1.0±0.2");
             }
         }