The trail reads as motion, never as residue: the ghosts fade with the sprint

The lingering doubles were a real bug, not a taste problem: racketAI's
!incoming return kept the last chase's vx/vz on the body, so the speed
ghosts trailed a zombie that had already stopped. The velocity dies with
the chase now (tested). The look is halved with it: ghost alphas
0.22/0.10 -> 0.11/0.05, trailK 0.05 -> 0.035 — a hint of speed in the
corner of the eye, never a second body.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/config.js

@@ -622,7 +622,8 @@ export const TUNE = {
   // back along the velocity). Procedural register only — dust and afterimage, never painted into
   // a sprite, and nothing draws at walking pace: trailMin sits above every shamble.
   trailMin: 3.6,       // m/s of ground speed before a body earns dust + ghosts (0 = both off)
-  trailK: 0.05,        // s each ghost trails behind along the velocity (two samples: 1x and 2x)
+  trailK: 0.035,       // s each ghost trails behind along the velocity (two samples: 1x and 2x).
+                       // 0.05 on the first cut — "der Effekt sollte dezenter sein": shorter smear
   runDustEvery: 0.5,   // m of ground covered per dust puff while sprinting
   fps: 60,          // frame cap — 30 halves battery/heat but Oliver felt it; smoothness wins (0 = uncapped)
   lowPower: 1,      // >= 0.5 caps RES at 3 (−44% of pixels painted per frame) — the battery saver,

src/gameplay.js

@@ -1425,7 +1425,10 @@ function racketAI(rz, dt) {
   rz.swingCool -= dt;
   const incoming = ball.active && ball.lastHit === 'P' && ball.vz < 0
     && (G.interlude || (ball.pow || 0) < TUNE.zSplatQ); // in the duel it plays EVERY ball — it's tennis now
-  if (!incoming) { if (rz.pose === 'run') rz.pose = 'idle'; return; }
+  // ...and the sprint velocity dies WITH the chase. This return kept the last chase's vx/vz on
+  // the body, so the speed ghosts trailed a zombie that had already stopped ("teilweise bleiben
+  // die doppelten ghosts länger sichtbar") — the trail must read as motion, never as residue.
+  if (!incoming) { rz.vx = 0; rz.vz = 0; if (rz.pose === 'run') rz.pose = 'idle'; return; }
   // ANTICIPATION. He used to run at the ball's LIVE position, and against a serve that is a
   // trap: for the first third of the flight the ball is still up by YOUR baseline, so he ran
   // deep and straight while the ball was already leaving sideways, and only started sliding

src/render.js

@@ -814,7 +814,9 @@ function drawZombie(zb, ghost) {
   // during a named frame — a collapsing corpse must not smear on stale velocity.
   if (!ghost && TUNE.trailMin && !zb.showFrame
       && Math.hypot(zb.vx || 0, zb.vz || 0) > TUNE.trailMin) {
-    for (const [k, a] of [[2, 0.10], [1, 0.22]]) {
+    // alphas halved from 0.10/0.22 on the first phone verdict ("dezenter"): a hint of speed in
+    // the corner of the eye, never a second body
+    for (const [k, a] of [[2, 0.05], [1, 0.11]]) {
       ctx.save(); ctx.globalAlpha *= a;
       drawZombie({ ...zb, x: zb.x - zb.vx * TUNE.trailK * k, z: zb.z - (zb.vz || 0) * TUNE.trailK * k }, true);
       ctx.restore();
@@ -1801,7 +1803,7 @@ function drawChar(ch, ghost) {
   // MOVEMENT READS: the same two-ghost speed streak the bodies wear (see drawZombie) — gameplay's
   // mover writes P.vx/vz, so only a genuine sprint (auto-run chase, horde steer) ever draws one.
   if (!ghost && TUNE.trailMin && Math.hypot(ch.vx || 0, ch.vz || 0) > TUNE.trailMin) {
-    for (const [k, a] of [[2, 0.10], [1, 0.22]]) {
+    for (const [k, a] of [[2, 0.05], [1, 0.11]]) { // halved with drawZombie's — one look, both bodies
       ctx.save(); ctx.globalAlpha *= a;
       drawChar({ ...ch, x: ch.x - ch.vx * TUNE.trailK * k, z: ch.z - ch.vz * TUNE.trailK * k }, true);
       ctx.restore();