fix: harden mode state machine + per-duck randomized chirps

State machine:
- sit/stand hand-over timers are now cancellable and cleared by every
transition entry point (setMode, triggerRoll, resetSim); a stale 2 s
stand-up timer could previously flip a sitting or rolling duck to the
walking policy mid-motion
- resetSim cancels any roll in flight and pending timers, always lands
on walk (R mid-roll no longer replays the roll on the reset duck)
- rolls only launch from a standing walk, not from a sit
- RT quack uses a Schmitt trigger (fire at 0.35, re-arm below 0.2):
analog jitter around a single threshold caused multiple quacks

Sound:
- ship the runtime's four chirp voice banks (12 takes each); each
colourway has its own duck voice and every quack picks a random take

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

assets/{quack.wav → voices/duck1/chirp_a.wav}

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:71c1a42876e55ade7e0dc72a5b2d68244bb192a3bf24caf18cc8645eece6bdee
-size 46840
+oid sha256:450d807c1e6f535f30a1e50491df9b57567b8b8be357148de731de8b7582c8c2
+size 5336

assets/voices/duck1/chirp_b.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:660fa601e43eb7f05e67903446ccb11b9205bec31fdf4695a824c885e1da621e
+size 5510

assets/voices/duck1/chirp_c.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:2451a1286f28eaa5f54875c54486e03dd234c425c70c62ecc35c37f1bc745fc8
+size 8658

assets/voices/duck1/chirp_d.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:070253cd8fd2323226677935a6a7f6bb664e556a2292493e9269c8bc50cda188
+size 11002

assets/voices/duck1/chirp_e.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:9f0225bf39edae00420250f26610b923ca369eacaae97d775ca6e0d68d0789f2
+size 7214

assets/voices/duck1/chirp_f.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:41bb6b9105669e0d297ab4e396491ff4798d0092c9f67911858cc970bb6e2fee
+size 6460

assets/voices/duck1/chirp_g.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c33fe26fc9491564c12a2ab4d49da7d5502d02e097067e1ca7b5e48078a5f2c8
+size 11068

assets/voices/duck1/chirp_h.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:47a7a3b9d6e06b601daaa47c3426c5dab963c9a05bd9878ca39155fbe7a55f8b
+size 10512

assets/voices/duck1/chirp_i.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0114c825dec129ae02fbd2aacf0595497d919108865e25e57b6610dd2f41e270
+size 6578

assets/voices/duck1/chirp_j.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3a7a18a47c5a18d9fd21a78ea25dcb657feb7460680171357c5f123fc05ec454
+size 7278

assets/voices/duck1/chirp_k.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:bd64c51c26fe8f311e41ef9e949ca5a47718b529ce973d32d9490b2a350c89db
+size 9542

assets/voices/duck1/chirp_l.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:cecbff6accd2f0d525d302db9c6582d695e31e907bcee14bb82ede4db1d204e0
+size 8632

assets/voices/duck2/chirp_a.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:9f7aa1decf578eab8c05b1fc2ed5205439d19541bf270d26762440d0a8ca0aa9
+size 8702

assets/voices/duck2/chirp_b.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:2fa61541951c240fa9e94cfb3582bf61f6a57254b1233e6c7342b852474bd33e
+size 7032

assets/voices/duck2/chirp_c.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:4ae92893fe916f96629c26ded93e71855fd0cee490c1690027ce0a19b3a29284
+size 16544

assets/voices/duck2/chirp_d.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:971282d4fa0ab372713bc42bc510d03d6f033e8760e7592658cfec8c4ceace71
+size 10252

assets/voices/duck2/chirp_e.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a1d662e8b23203d5622984e698e9ed67a749133416fee6ddc59a3552675259b9
+size 8972

assets/voices/duck2/chirp_f.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d340696b480ae7cc2cc5b85de00741e86bd29ce766ad8eaa5f305726a079ae35
+size 8576

assets/voices/duck2/chirp_g.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d79c3369e113a4323ec8afe3a4ca22b7a47e3867266af233974ff423d8fc134a
+size 13824

assets/voices/duck2/chirp_h.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b04e48823c5b41f61c60633644bb3ffbf20611de9dcdc9bcdaff3c02ed5b2b5b
+size 13046

assets/voices/duck2/chirp_i.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d34507b77bbab2a1ca9a467c19089e4605c6836194bc4a56b2dbd1890ad0f487
+size 5716

assets/voices/duck2/chirp_j.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e7c217684a7fb0f27acb3a06052c784f3a66f775122bb368c2be4c27a50ac3f2
+size 9098

assets/voices/duck2/chirp_k.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:00d2a8938313ea05addc67743d36dd21ba466601817c7ad891bd0ea15dfc1ec2
+size 11676

assets/voices/duck2/chirp_l.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a1fc77cdb7c00e5ed7ebe618452c11c517b7f3f647dfaa70566896ec2bfae084
+size 13124

assets/voices/duck3/chirp_a.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:4ed6496a3208db4057f1547e2cc5c18a078d4200abdd1b564d7a502640448854
+size 5896

assets/voices/duck3/chirp_b.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b701381ae6aaa98a46114ad96847fcd4b087a4b3f1f02b5f1f2bbda7219dd183
+size 8448

assets/voices/duck3/chirp_c.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f4e678fe44d371931ce323495a2e9bf9957fda5a382526acc58c1a82cc3e9eef
+size 13430

assets/voices/duck3/chirp_d.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6f52cab48cb6eb9566e40da17023d8365064848746be2b444786431e8d8bd092
+size 12864

assets/voices/duck3/chirp_e.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:95f839d2c444acfa5bf823d9b8c65e84774f82650f4d8e3b5c7aa80cd4f242a0
+size 5496

assets/voices/duck3/chirp_f.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f6e581b10f2b4e81f13ffa186f9761285e581dda161614008a922ed59f46079a
+size 6528

assets/voices/duck3/chirp_g.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f78916cbdc2065d914f20c509ef0157500d14d386c1d8e2be00c018a99a8e942
+size 17304

assets/voices/duck3/chirp_h.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c9a4c5a0b36cc2e684b7e00e95f9e6ec02f6dc2799337a2cddb1e791f84278e2
+size 12524

assets/voices/duck3/chirp_i.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:4dc2ef2ce703297da12fbe5f9722236df4a5faa907142cfc00e56970c75bc445
+size 8418

assets/voices/duck3/chirp_j.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:97931d92be70e1448d6bed56515b8ffb1a439a6e44ae6c35b8c5e3ae7b400c00
+size 5182

assets/voices/duck3/chirp_k.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:5d68b91b7b6ae44a24b693183587dd27f1c8d8e9c6fd94e0f5c7c0931d9f98f0
+size 17800

assets/voices/duck3/chirp_l.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0f874aacabad93a0f706695874260dc421b3624e716ba4bfbc3e83e5ba840af6
+size 13884

assets/voices/duck4/chirp_a.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:356abe1da47758ab6df17954975123c53be79a9bcc919b5adf06d7ac8a602fb2
+size 7350

assets/voices/duck4/chirp_b.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:63c6dba54db0a001e7ed9376cdccb9bd47a9e255fa7fd909e2505dc9fd332193
+size 9116

assets/voices/duck4/chirp_c.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:22804c3f59ff7eccef58aacbfd855fe9808f35cbe21ff4cd72264c2e30fd156a
+size 13554

assets/voices/duck4/chirp_d.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8158e8e9d118037bd03bed4d564dd9e70b07ade5acf8cb56b7d52cbe77dc53cd
+size 11580

assets/voices/duck4/chirp_e.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:836664d06509dbe43daddef6bd3415372774158145d950139b0e30f4057be41a
+size 8552

assets/voices/duck4/chirp_f.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:2839e0865a5e42aff830b2d1ccf113fba60c28e403c42886ba1b1e5bd470ce52
+size 7752

assets/voices/duck4/chirp_g.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3ba26ccde31aafa4d43df34058da9a7b53aacdeaa847b2a9f12660b31a022a1e
+size 12176

assets/voices/duck4/chirp_h.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:28231a6ec54e9fabf53c6add53987b8b946ded9b384e7d0af5a9bca5fe0c0f57
+size 13742

assets/voices/duck4/chirp_i.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d028418fb90dcf2b91efb8bc034ac6a934a302e50243271cc9cd272f956d3810
+size 6604

assets/voices/duck4/chirp_j.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e768b952f37f22c2852e06ae1c88ef84d662721b7b518204b79292fbd794b543
+size 6472

assets/voices/duck4/chirp_k.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:80ccda91a3632145bfa6a750f8f1230ab59e94e541b82fb81c74810a56802c24
+size 17340

assets/voices/duck4/chirp_l.wav

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:5a683cdb89ec94c655e900275a5afbd0a618e7523888d6bc681de4bbffe30f3d
+size 11280

index.html

@@ -468,7 +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 = "23"; // bump on rl.js changes to defeat heuristic caching
+      const V = "24"; // 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

@@ -197,7 +197,7 @@ const velCmd = new Float32Array(3); // twist command, driven by held keys
 // the control loop reads it before the input section below has evaluated.
 const padCmd = new Float32Array(3);
 let padActive = false;
-const padPrev = { x: false, dpadDown: false, dpadUp: false, rt: 0 };
+const padPrev = { x: false, dpadDown: false, dpadUp: false, rtArmed: true };
 // Declared before the control loop starts: buildObs reads it via
 // effectiveCmd on the very first control step.
 const held = new Set();
@@ -220,7 +220,24 @@ function effectiveCmd() {
 let rollRun = null;
 let rollSource = "kb"; // which hint lights up: keyboard Space or pad X
 
+// Pending mode-transition timers (sit hand-over, stand-up hand-back).
+// Every transition entry point clears them: a stale timer firing after
+// the state has moved on is exactly how a sitting or rolling duck ends
+// up handed to the walking policy mid-motion.
+let sitTimer = null;
+let standTimer = null;
+function clearModeTimers() {
+  clearTimeout(sitTimer); sitTimer = null;
+  clearTimeout(standTimer); standTimer = null;
+}
+
 function resetSim() {
+  // A reset is a full transition to the walking stand: cancel any roll in
+  // flight and any pending sit/stand hand-over, or they'd replay on the
+  // freshly reset duck.
+  clearModeTimers();
+  rollRun = null;
+  mode = "walk";
   mujoco.mj_resetDataKeyframe(model, data, standKeyId);
   mujoco.mj_forward(model, data);
   lastAction.fill(0);
@@ -461,14 +478,28 @@ function syncRig() {
 const QUACK_MS = 480;
 let quackAt = -Infinity;
 let padJaw = 0;
-// Same sound as the robot: the runtime plays its voice-bank chirp on every
-// mouth-open edge and falls back to the stock quack.wav — the only audio
-// asset in the repo, so that's what we ship. Restarting playback on each
-// trigger matches the runtime's "cut off any still-playing sound".
+// Voice banks from the robot runtime: each printed duck ships a different
+// voice, so each colourway gets its own bank and every quack draws a
+// random chirp take from it - same as the real ducks all sounding
+// slightly different. Audio elements are created lazily and cached.
 // Browsers block audio until the first user gesture; the rejected play()
 // is swallowed and sound simply starts working after the first click/key.
-const quackSound = new Audio(signed("./assets/quack.wav"));
-quackSound.volume = 0.7;
+const CHIRP_TAKES = "abcdefghijkl";
+const VOICE_BANK = { classic: "duck1", charcoal: "duck2", purple: "duck3", blue: "duck4" };
+const chirpCache = new Map();
+function playChirp() {
+  const bank = VOICE_BANK[currentVariant] ?? "duck1";
+  const take = CHIRP_TAKES[(Math.random() * CHIRP_TAKES.length) | 0];
+  const url = signed(`./assets/voices/${bank}/chirp_${take}.wav`);
+  let a = chirpCache.get(url);
+  if (!a) {
+    a = new Audio(url);
+    a.volume = 0.7;
+    chirpCache.set(url, a);
+  }
+  a.currentTime = 0;
+  a.play().catch(() => {});
+}
 // 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 = () => {
@@ -476,8 +507,7 @@ const quack = () => {
 };
 const quackLoud = () => {
   quack();
-  quackSound.currentTime = 0;
-  quackSound.play().catch(() => {});
+  playChirp();
 };
 function jawOpenNow() {
   const t = (performance.now() - quackAt) / QUACK_MS;
@@ -642,11 +672,14 @@ pollPad = function pollGamepad() {
 
   // Triggers drive the mouth like the runtime (max of both), and the right
   // one quacks on its rising edge — same as the robot's chirp.
+  // Schmitt trigger on the analog RT value: fire at 0.35, re-arm only once
+  // it drops below 0.2. A single threshold re-fires on every jitter around
+  // it, which is how one squeeze used to quack several times.
   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) quackLoud();
-  padPrev.rt = rt;
+  if (padPrev.rtArmed && rt >= 0.35) { quackLoud(); padPrev.rtArmed = false; }
+  else if (!padPrev.rtArmed && rt < 0.2) padPrev.rtArmed = true;
 };
 
 // Read-only state label (bottom-left): reflects the active policy,
@@ -657,13 +690,19 @@ 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;
+  clearModeTimers();
   quack();
   rollRun = null;
   if (next !== "sit") {
     // Leaving a sit: let the sitstand policy stand the duck back up first.
     if (mode === "sitstand" && sitFlag === 1) {
       sitFlag = 0;
-      setTimeout(() => { mode = next; lastAction.fill(0); syncButtons(); }, 2000);
+      standTimer = setTimeout(() => {
+        standTimer = null;
+        mode = next;
+        lastAction.fill(0);
+        syncButtons();
+      }, 2000);
       syncButtons();
       return;
     }
@@ -676,7 +715,8 @@ function setMode(next) {
     mode = "sitstand";
     sitFlag = 0;
     lastAction.fill(0);
-    setTimeout(() => {
+    sitTimer = setTimeout(() => {
+      sitTimer = null;
       if (mode === "sitstand") { sitFlag = 1; syncButtons(); }
     }, 800);
   }
@@ -688,7 +728,10 @@ function setMode(next) {
 // continuous action history across policy switches, and the roll initiates
 // more reliably mid-gait with the true last actions in the obs.
 function triggerRoll(source = "kb") {
-  if (mode === "roll") return;
+  // Rolls only launch from a standing walk: from a sit (or mid sit/stand
+  // hand-over) the roll policy just faceplants the duck.
+  if (mode !== "walk" || standTimer) return;
+  clearModeTimers();
   rollSource = source;
   quack();
   mode = "roll";