fix: reduce combat separation to SC2-level tightness

public/config/collision.config.json

@@ -20,8 +20,8 @@
     "strengthArriving": 1.0,
     "_strengthArriving_description": "Separation at destination. Gentle spread, not sudden explosion.",
 
-    "strengthCombat": 0.3,
-    "_strengthCombat_description": "Separation during combat. Minimal - units should focus on attacking, not spreading.",
+    "strengthCombat": 0.1,
+    "_strengthCombat_description": "Separation during combat. Near-zero so units stack tightly like SC2 while fighting.",
 
     "maxForce": 2.0,
     "_maxForce_description": "Maximum separation force. Low cap prevents jerky movement.",
@@ -62,11 +62,11 @@
   "combat": {
     "_description": "Combat movement - minimal spreading, focus on attacking",
 
-    "spreadSpeedMultiplier": 0.25,
-    "_spreadSpeedMultiplier_description": "Speed when spreading in combat. Slow to maintain formation.",
+    "spreadSpeedMultiplier": 0.1,
+    "_spreadSpeedMultiplier_description": "Speed when spreading in combat. Very slow - SC2 units barely move while attacking.",
 
-    "separationThreshold": 0.3,
-    "_separationThreshold_description": "High threshold - don't spread for minor overlaps during combat."
+    "separationThreshold": 0.8,
+    "_separationThreshold_description": "High threshold - only spread when severely overlapping. Most combat units stay put."
   },
 
   "arrival": {

src/data/collisionConfig.ts

@@ -89,7 +89,7 @@ const DEFAULT_CONFIG: CollisionConfig = {
     strengthMoving: 0.15,
     strengthIdle: 1.2,
     strengthArriving: 1.2,
-    strengthCombat: 0.3,
+    strengthCombat: 0.1,
     maxForce: 2.0,
     flyingMultiplier: 1.2,
   },
@@ -105,8 +105,8 @@ const DEFAULT_CONFIG: CollisionConfig = {
     settleThreshold: 0.85,
   },
   combat: {
-    spreadSpeedMultiplier: 0.25,
-    separationThreshold: 0.3,
+    spreadSpeedMultiplier: 0.1,
+    separationThreshold: 0.8,
   },
   arrival: {
     spreadRadius: 3.0,
@@ -157,7 +157,9 @@ class CollisionConfigLoader {
     try {
       const response = await fetch('/config/collision.config.json');
       if (!response.ok) {
-        debugInitialization.warn('[CollisionConfig] Failed to load collision.config.json, using defaults');
+        debugInitialization.warn(
+          '[CollisionConfig] Failed to load collision.config.json, using defaults'
+        );
         this.config = DEFAULT_CONFIG;
         return;
       }

tests/data/collisionConfig.test.ts

@@ -332,21 +332,28 @@ describe('Collision Configuration', () => {
   });
 
   describe('config value relationships', () => {
-    it('idle separation is stricter than combat', () => {
+    it('combat separation threshold is higher than idle (more overlap-tolerant)', () => {
       const config = collisionConfig.getConfig();
-      expect(config.idle.separationThreshold).toBeGreaterThan(config.combat.separationThreshold);
+      // Combat units tolerate more overlap before spreading - SC2-style tight stacking
+      expect(config.combat.separationThreshold).toBeGreaterThanOrEqual(
+        config.idle.separationThreshold
+      );
     });
 
     it('arriving strength is strongest', () => {
       const config = collisionConfig.getConfig();
-      expect(config.separation.strengthArriving).toBeGreaterThanOrEqual(config.separation.strengthIdle);
+      expect(config.separation.strengthArriving).toBeGreaterThanOrEqual(
+        config.separation.strengthIdle
+      );
       expect(config.separation.strengthArriving).toBeGreaterThan(config.separation.strengthMoving);
       expect(config.separation.strengthArriving).toBeGreaterThan(config.separation.strengthCombat);
     });
 
     it('soft margin is larger than hard margin for buildings', () => {
       const config = collisionConfig.getConfig();
-      expect(config.buildingAvoidance.softMargin).toBeGreaterThan(config.buildingAvoidance.hardMargin);
+      expect(config.buildingAvoidance.softMargin).toBeGreaterThan(
+        config.buildingAvoidance.hardMargin
+      );
     });
 
     it('building avoidance is strong compared to separation', () => {