updated the collision for jumps and terrain

src/scene/PartyPopulation.tsx

@@ -81,6 +81,7 @@ const BREADCRUMB_REACHED_DISTANCE = 0.04;
 const PARTY_COLLISION_RADIUS = 0.34;
 const PARTY_COLLISION_HALF_HEIGHT = 0.48;
 const PARTY_COLLISION_CENTER_HEIGHT = PARTY_COLLISION_RADIUS + PARTY_COLLISION_HALF_HEIGHT + 0.04;
+const PARTY_WALKABLE_STEP_HEIGHT = 0.32;
 const PARTY_OBJECTIVE_APPROACH_SNAP_DISTANCE = 6;
 const PARTY_FLOOR_SAMPLE_SPACING = 0.6;
 const PARTY_FLOOR_RAY_HEIGHT = 1.25;
@@ -291,7 +292,12 @@ function PartyActors({
   const resetRevision = useGameStore((state) => state.resetRevision);
   const { rapier, world } = useRapier();
   const navigationCapsule = useMemo(
-    () => new rapier.Capsule(PARTY_COLLISION_HALF_HEIGHT, PARTY_COLLISION_RADIUS),
+    // Trim the lower leg band while keeping the capsule top at normal head
+    // height. This supplies step clearance without demanding extra ceiling.
+    () => new rapier.Capsule(
+      PARTY_COLLISION_HALF_HEIGHT - PARTY_WALKABLE_STEP_HEIGHT * 0.5,
+      PARTY_COLLISION_RADIUS,
+    ),
     [rapier],
   );
   const navigationRotation = useMemo(() => new Quaternion(), []);
@@ -319,13 +325,20 @@ function PartyActors({
     const dz = end[2] - start[2];
     const distance = Math.hypot(dx, dy, dz);
     if (!Number.isFinite(distance)) return false;
-    if (distance <= 0.04) return true;
+    const planarDistance = Math.hypot(dx, dz);
+    // Collision and navigation surfaces commonly disagree by a few centimeters.
+    // Treat a same-column height correction as grounding, not a blocked move.
+    if (planarDistance <= 0.04) {
+      return Math.abs(dy) <= PARTY_WALKABLE_STEP_HEIGHT;
+    }
     const queryFlags = rapier.QueryFilterFlags.EXCLUDE_SENSORS
       | rapier.QueryFilterFlags.EXCLUDE_DYNAMIC;
     const obstacle = world.castShape(
       {
         x: start[0],
-        y: start[1] + PARTY_COLLISION_CENTER_HEIGHT,
+        // Raise only the trimmed lower band over walkable relief. The floor
+        // samples below still reject real ledges and excessive elevation.
+        y: start[1] + PARTY_COLLISION_CENTER_HEIGHT + PARTY_WALKABLE_STEP_HEIGHT * 0.5,
         z: start[2],
       },
       navigationRotation,