Resting faces steeper than the angle of repose topple: blown sand towers collapse (t93)

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

test/t_blow_collapse.js

@@ -0,0 +1,48 @@
+// Owner's upward nozzle recipe, inline and with real shared-memory helpers.
+const fs = require('fs');
+const {createHash} = require('crypto');
+const {load, suite, enableThreads} = require('./harness');
+const {run} = load(), {check, done} = suite();
+for (const file of ['pile-cut', 'pile-blow']) run(fs.readFileSync(require.resolve('./'+file+'.js'), 'utf8'));
+const hash = () => {const h=createHash('sha256');for(const a of run('[mat,flags,life]'))h.update(a);return h.digest('hex');};
+// A supported grain must release immediately, without relying on gravity underneath it.
+run(`pileBlowSetup();for(let y=270;y<340;y++)for(let x=356;x<376;x++)setCell(y*W+x,SAND,20,0);
+  powder(300*W+356,356,300,SAND);`);
+check('a resting tall face topples promptly',run('mat[300*W+356]===EMPTY && mat[308*W+348]===SAND && (flags[299*W+356]&F_AVALANCHE)'));
+run(`pileBlowSetup();for(let y=270;y<340;y++)for(let x=356;x<376;x++)setCell(y*W+x,SAND,20,0);
+  cleatMask[300*W+352]=1;powder(300*W+356,356,300,SAND);`);
+check('resting face spill stops at a cross-chunk cleat',run('mat[308*W+353]===SAND && mat[308*W+348]===EMPTY'));
+(async () => {
+  let expected;
+  for (const workers of [0, 1, 2, 8]) {
+    run('pileBlowSetup()');
+    const stop = workers ? await enableThreads(run, workers) : null;
+    try {
+      run('for(let k=0;k<1200;k++){pileBlowStroke();simTick();}');
+      const before = run('pileBlowProfile()');
+      check(`fast upward nozzle builds a large pile (${workers} helpers)`, before.grains > 15000 && before.height > 100, JSON.stringify(before));
+      run('bot.x=700;bot.y=100;for(let k=0;k<480;k++)simTick();');
+      const after = run('pileBlowProfile()');
+      check(`blown sand slumps within eight seconds (${workers} helpers)`, after.cliff <= 2, JSON.stringify(after));
+      check('all blown sand is retained', after.grains + after.flying + after.bag === 40000);
+      if (workers) {
+        check('helpers actually process the blown pile', run('simPool.activeMax') > 0);
+        check('blown collapse matches inline material and motion flags', hash() === expected);
+      } else expected = hash();
+      run('for(let k=0;k<1200;k++){awake.fill(3);simTick();}');
+      const resting = hash();
+      run('for(let k=0;k<600;k++){awake.fill(3);simTick();}for(let k=0;k<3;k++)simTick();');
+      check('settled blown sand stays put and sleeps', hash() === resting && run('awake.every(v=>!v)'));
+    } finally { if(stop) await stop(); }
+  }
+  const heights = [];
+  for (const material of ['SAND','LCLAY']) {
+    run(`pileBlowSetup();bag.fill(0);bagTotal=0;bot.x=700;
+      for(let y=360;y<480;y++)for(let x=350;x<410;x++)setCell(y*W+x,${material},20,0);
+      for(let k=0;k<1800;k++){awake.fill(3);simTick();}`);
+    heights.push(run(`(()=>{let height=0;for(let x=0;x<W;x++){let y=0;
+      while(y<480&&mat[y*W+x]!==${material})y++;height=Math.max(height,480-y);}return height;})()`));
+  }
+  check('large clay heaps remain steeper than equal sand heaps',heights[1]>heights[0],JSON.stringify(heights));
+  done();
+})().catch(e => { console.error(e); process.exitCode = 1; });