feat: duck-head modal logo, input lockout mid-roll, quieter quack

- welcome modal uses the site's duck-head mark (open variant on hover)
instead of the wordmark sticker
- all movement/mode inputs are ignored while a roll is in flight; the
existing deterministic completion check (tipped then upright, 3 s cap)
releases the lock, no arbitrary timer
- quack.wav only plays on the gamepad right trigger; mode/colour changes
keep the silent jaw flap

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitattributes

@@ -36,4 +36,5 @@ saved_model/**/* filter=lfs diff=lfs merge=lfs -text
 *.stl filter=lfs diff=lfs merge=lfs -text
 *.wav filter=lfs diff=lfs merge=lfs -text
 *.png filter=lfs diff=lfs merge=lfs -text
+*.webp filter=lfs diff=lfs merge=lfs -text
 *.jpg filter=lfs diff=lfs merge=lfs -text

index.html

@@ -281,12 +281,18 @@
         from { transform: translateY(18px) scale(0.94); opacity: 0; }
         to { transform: none; opacity: 1; }
       }
-      #welcome .logo-wordmark {
-        display: block;
-        width: min(78%, 300px);
+      /* Duck-head mark from the site header: closed by default, open on
+         hover (same swap as the site). */
+      #welcome .logo-head {
+        position: relative;
+        width: 7.2rem;
         margin: 0.3rem auto 0;
         filter: drop-shadow(0 10px 24px rgba(0, 0, 0, 0.45));
       }
+      #welcome .logo-head img { display: block; width: 100%; }
+      #welcome .logo-head .open { position: absolute; inset: 0; opacity: 0; }
+      #welcome .logo-head:hover .open { opacity: 1; }
+      #welcome .logo-head:hover .closed { opacity: 0; }
       #welcome .subtitle {
         margin-top: 0.55rem;
         font-size: 0.62rem;
@@ -400,7 +406,10 @@
 
     <div id="welcome" hidden>
       <div class="card" role="dialog" aria-modal="true" aria-label="Microduck playground">
-        <img class="logo-wordmark" id="logo-wordmark" alt="Microduck" />
+        <div class="logo-head">
+          <img class="closed" id="logo-head-closed" alt="Microduck" />
+          <img class="open" id="logo-head-open" alt="" aria-hidden="true" />
+        </div>
         <div class="subtitle">RL playground</div>
         <p class="tagline">
           A real robot brain in your browser: MuJoCo physics compiled to
@@ -427,7 +436,8 @@
         // on the private Space (rl.js hasn't installed its signer yet).
         const sign = new URLSearchParams(location.search).get("__sign");
         const signedUrl = (u) => (sign ? `${u}?__sign=${encodeURIComponent(sign)}` : u);
-        document.getElementById("logo-wordmark").src = signedUrl("./assets/logo-wordmark.png");
+        document.getElementById("logo-head-closed").src = signedUrl("./assets/duck-head-mark.webp");
+        document.getElementById("logo-head-open").src = signedUrl("./assets/duck-head-mark-open.webp");
         const open = () => {
           modal.hidden = false;
           modal.classList.remove("closing");
@@ -458,7 +468,7 @@
          appended: a plain src attribute can 401 when the browser blocks the
          *.static.hf.space auth cookie inside the hub iframe. -->
     <script type="module">
-      const V = "22"; // bump on rl.js changes to defeat heuristic caching
+      const V = "23"; // bump on rl.js changes to defeat heuristic caching
       const sign = new URLSearchParams(location.search).get("__sign");
       const suffix = sign ? `&__sign=${encodeURIComponent(sign)}` : "";
       import(`./rl.js?v=${V}${suffix}`);

rl.js

@@ -208,7 +208,11 @@ let sitFlag = 0;
 // The twist the policy actually receives: live gamepad sticks win over the
 // held keys. No input means zero command - the duck stands in place.
 // Shared by buildObs and the HUD mini-sticks so they can never disagree.
+// Mid-roll every movement input is ignored (zero twist) until the roll
+// hands back to walk on its own - steering would only knock the roll over.
+const ZERO_CMD = new Float32Array(3);
 function effectiveCmd() {
+  if (mode === "roll") return ZERO_CMD;
   return padActive ? padCmd : velCmd;
 }
 // One-shot roll tracking: trigger time + whether the trunk actually
@@ -465,8 +469,13 @@ let padJaw = 0;
 // is swallowed and sound simply starts working after the first click/key.
 const quackSound = new Audio(signed("./assets/quack.wav"));
 quackSound.volume = 0.7;
+// Silent jaw flap for mode/colour changes; the actual quack sound only
+// plays on the gamepad right trigger (anything more gets noisy fast).
 const quack = () => {
   quackAt = performance.now();
+};
+const quackLoud = () => {
+  quack();
   quackSound.currentTime = 0;
   quackSound.play().catch(() => {});
 };
@@ -505,7 +514,7 @@ function renderStats() {
 
   // Mini sticks: the dot mirrors the effective twist, lit yellow while the
   // user is actually driving.
-  const manual = padActive || held.size > 0;
+  const manual = (padActive || held.size > 0) && mode !== "roll";
   const yN = vx >= 0 ? vx / VEL_FWD : vx / -VEL_BACK;
   dotMove.style.transform = `translate(${(-vy / VEL_LAT) * STICK_R}px, ${-yN * STICK_R}px)`;
   dotTurn.style.transform = `translate(${(-wz / VEL_ANG) * STICK_R}px, 0px)`;
@@ -636,7 +645,7 @@ pollPad = function pollGamepad() {
   const rt = gp.buttons[7]?.value ?? 0;
   const lt = gp.buttons[6]?.value ?? 0;
   padJaw = Math.max(rt, lt);
-  if (padPrev.rt < 0.3 && rt >= 0.3) quack();
+  if (padPrev.rt < 0.3 && rt >= 0.3) quackLoud();
   padPrev.rt = rt;
 };
 
@@ -645,6 +654,9 @@ pollPad = function pollGamepad() {
 const modeLabel = document.getElementById("mode-label");
 
 function setMode(next) {
+  // No policy switching mid-roll: the roll ends on its own (upright again
+  // or expired) and returns to walk - switching now would floor the duck.
+  if (mode === "roll" && rollRun) return;
   quack();
   rollRun = null;
   if (next !== "sit") {