Drill: visible dust; pulses push loose material back and open a channel (t92)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/t_drill.js

@@ -206,6 +206,35 @@ check('115 grains of rubble prevent basalt breaking during sustained drilling',
 const through118 = rubbleShield(118);
 check('118 grains extinguish the ray before it can even shake basalt', through118 === 0 && !run('digp.some(d => d > 0)'), `${through118} basalt opened`);
 
+// A 35-grain-deep pile against basalt: compare with gravity alone, tracking only rubble.
+function channelPile(fire) {
+  flatWorld(run, 240, 160, 110);
+  return run(`(() => {
+    RS=12345; tick=0; lastPulseTick=-99; drillPulses=[]; player.bitTier=3;
+    bot.x=45; bot.y=88; EV.length=0;
+    for(let y=85;y<110;y++) {
+      for(let x=55;x<90;x++) setCell(y*W+x,RSTONE,20,0);
+      for(let x=90;x<150;x++) setCell(y*W+x,BASALT,20,F_NAT);
+    }
+    const measure=()=>{let n=0,sx=0,empty=0;for(let i=0;i<N;i++) if(mat[i]===RSTONE){n++;sx+=i%W;}
+      for(let x=55;x<90;x++) if(mat[90*W+x]===EMPTY) empty++;
+      return {n,cx:sx/n,empty};};
+    const before=measure(); let dust=0;
+    for(let t=0;t<480;t++) {
+      ${fire ? 'toolPulse(130,90,1,0);' : ''} simTick();
+      dust+=EV.filter(e=>e.t==='debris' && e.dust).length; EV.length=0;
+    }
+    return {before,after:measure(),dust};
+  })()`);
+}
+const channelRest=channelPile(false), channel=channelPile(true);
+check('medium pulses open most of the centre ray through a 35-grain pile within 480 ticks',
+  channel.after.empty>=28 && channel.after.empty>channelRest.after.empty+15,JSON.stringify(channel));
+check('the pile streams back toward the bot rather than just bouncing on its surface',
+  channel.after.cx<channel.before.cx-5 && channel.after.cx<channelRest.after.cx-5,JSON.stringify(channelRest));
+check('channel drilling retains every rubble grain',channel.after.n===channel.before.n,`${channel.before.n}->${channel.after.n}`);
+check('shaking loose grains emits dust puffs',channel.dust>0,`${channel.dust} puffs`);
+
 // Absorption over a fixed distance, isolated from gravity, kicks and cell breakage.
 function transmission(material, distance, step, tune = 0) {
   flatWorld(run, 240, 160, 150);
@@ -246,6 +275,18 @@ check('pulses fluidise a settled rubble pile so its height drops',
 check('shaking conserves the pile material',fluidPile.grains===fluidPile.left,`${fluidPile.grains}->${fluidPile.left}`);
 check('repeating a seeded pile gives the same result',JSON.stringify(shakenPile(true))===JSON.stringify(fluidPile));
 
+// A wave must still shake loose grains far behind its advancing front, throughout the path.
+flatWorld(run,240,160,150);
+const travelled=run(`(() => {
+  RS=12345; bot.x=0;bot.y=0;tickStamp=1;EV.length=0;
+  for(const x of [25,45,65]) setCell(80*W+x,RSTONE,20,0);
+  const p={ox:19.5,oy:80.5,ang:0,w:1,jit:0.5,n:1,damp:PULSE_W[1].damp,
+    en:new Float32Array([1.4]),s:new Float32Array([60]),r:60,range:100,tune:0};
+  drillPulses=[p];pulseTick();
+  return [25,45,65].filter(x=>mat[80*W+x-1]===RSTONE).length;
+})()`);
+check('the travelled ray path pushes interior grains one cell toward the bot',travelled>=2,`${travelled}/3 botward hops (probabilistic kicks)`);
+
 // One artificially long ray crosses many exposed grains in a single tick, exercising the caps.
 flatWorld(run,240,160,150);
 const kicks = run(`(() => {