tune: idle float scaled to the real display — 3mm bob (was 6cm), matching shimmer for wander and path modes

public/js/ghosts/behavior.js

@@ -4,6 +4,14 @@
  */
 import * as THREE from 'three';
 
+/* Idle float amplitudes, in cm. The display is a ~25cm table with ~4cm ghosts, so
+ * these are deliberately tiny — a few millimetres reads as "hovering" at this
+ * scale, while anything larger looks like the ghost is bouncing. Per-ghost
+ * overrides: rec.behavior.bobAmp / bobHz. */
+const BOB_AMP_CM = 0.3;    // 3mm
+const BOB_HZ = 0.4;
+const SHIMMER_CM = 0.3;    // secondary float used by wander + path modes
+
 function hashNoise(seed, k) {
   // cheap deterministic pseudo-noise in [-1, 1]
   const x = Math.sin(seed * 127.1 + k * 311.7) * 43758.5453;
@@ -27,7 +35,7 @@ export function ghostTransform(rec, nowMs, out) {
       base.x + R * 0.9 * Math.sin(ph * 1.0 + hashNoise(s, 1) * 6.28) * 0.7
              + R * 0.4 * Math.sin(ph * 2.3 + hashNoise(s, 2) * 6.28) * 0.3,
       base.y + (b.vertical ?? 10) * Math.sin(t * v * 1.3 + hashNoise(s, 3) * 6.28)
-             + 3 * Math.sin(t * 1.7 + hashNoise(s, 6) * 6.28),
+             + SHIMMER_CM * Math.sin(t * 1.7 + hashNoise(s, 6) * 6.28),
       base.z + R * 0.9 * Math.cos(ph * 0.8 + hashNoise(s, 4) * 6.28) * 0.7
              + R * 0.4 * Math.cos(ph * 1.9 + hashNoise(s, 5) * 6.28) * 0.3
     );
@@ -40,8 +48,8 @@ export function ghostTransform(rec, nowMs, out) {
     const dir = ahead(t + eps).sub(ahead(t));
     out.rotationY = Math.atan2(dir.x, dir.z);
   } else {
-    const amp = b.bobAmp ?? 6;     // cm
-    const hz = b.bobHz ?? 0.4;
+    const amp = b.bobAmp ?? BOB_AMP_CM;
+    const hz = b.bobHz ?? BOB_HZ;
     out.position.set(base.x, base.y + amp * Math.sin(t * hz * Math.PI * 2), base.z);
     out.rotationY = 0.25 * Math.sin(t * 0.3); // slow idle sway
   }
@@ -91,6 +99,6 @@ function pathTransform(b, t, out) {
   const dx = ahead.x - out.position.x, dz = ahead.z - out.position.z;
   if (dx * dx + dz * dz > 1e-4) out.rotationY = Math.atan2(dx, dz);
   // gentle float so walking still reads ghostly
-  out.position.y += 2 * Math.sin(t * 1.9 + (b.seed || 0));
+  out.position.y += SHIMMER_CM * Math.sin(t * 1.9 + (b.seed || 0));
 }
 const _look = new THREE.Vector3();