Loose walls slump to a natural slope instead of eroding layer by layer (t93)

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

test/t_pile_collapse.js

@@ -0,0 +1,48 @@
+// Tall loose faces release together; supported heaps stop moving, including when revisited.
+const {load, suite, flatWorld} = require('./harness');
+const {createHash} = require('node:crypto');
+const {run} = load();
+const {check, done} = suite();
+function wall(material, offset = 0) {
+  flatWorld(run, 192, 600, 96);
+  run(`RS=123; worldSeed=7; bot.x=500; bot.y=40;
+    for(let y=56;y<96;y++)for(let x=${80+offset};x<${100+offset};x++)setCell(y*W+x,${material},20,0);`);
+}
+function motion(n, revisit = false) {
+  run(`for(let k=0;k<${n};k++) {
+    tick++;tickStamp=tickStamp%255+1;
+    if (${revisit}) awake.fill(3);
+    simMove();
+    for(let c=0;c<NCH;c++)if(awake[c])awake[c]--;
+  }`);
+}
+function profile() {
+  return run(`(()=>{const h=[];let n=0,top=96;
+    for(let x=0;x<W;x++){let y=0;while(y<96&&PH[mat[y*W+x]]!==PH_POWDER)y++;
+      h.push(96-y);top=Math.min(top,y);
+      for(;y<96;y++)if(PH[mat[y*W+x]]===PH_POWDER)n++;
+    }
+    let cliff=0;for(let x=1;x<W;x++)cliff=Math.max(cliff,Math.abs(h[x]-h[x-1]));
+    return {cliff,height:96-top,n};})()`);
+}
+const hash = () => createHash('sha256').update(run('mat')).digest('hex');
+const rubble = '[RSTONE,CUORE,FEORE,LDIRT][(x+y)%4]';
+let sandHeight;
+for(const [name, material] of [['sand','SAND'],['mixed rubble',rubble],['rubble with clay',`(x+y)%5===0?LCLAY:${rubble}`],['clay','LCLAY']]) {
+  for(const offset of [0,17]) {
+    wall(material,offset);
+    const maxCliff = name==='clay' ? 3 : 2;
+    let slopedAt=0;
+    for(let k=1;k<=180;k++) {motion(1);if(profile().cliff<=maxCliff&&!slopedAt)slopedAt=k;}
+    const p=profile();
+    check(`${name} face slumps within 180 ticks (offset ${offset})`,slopedAt>0&&p.cliff<=maxCliff&&p.n===800,JSON.stringify({slopedAt,...p}));
+    motion(1200,true);
+    if(name==='sand'&&offset===0)sandHeight=profile().height;
+    if(name==='clay'&&offset===0)check('sticky clay holds a steeper settled heap than sand',profile().height>sandHeight,`sand ${sandHeight}, clay ${profile().height}`);
+    const settled=hash();
+    // Force visits so sleeping cannot hide continued creeping.
+    motion(600,true);motion(3);
+    check(`${name} settled heap stays put and sleeps (offset ${offset})`,hash()===settled&&run('awake.every(v=>v===0)')&&profile().n===800);
+  }
+}
+done();

test/t_threads.js

@@ -26,6 +26,9 @@ function setup() {
       const m=materials[(random()*materials.length)|0];
       setCell(y*W+x,m,m===MAGMA?1450:m===MCU?1200:m===STEAM?110:20,0);
     }
+    // A cohesive vertical face spans chunk rows and must collapse identically in every pool.
+    for(let y=50;y<90;y++)for(let x=260;x<280;x++)
+      setCell(y*W+x,(x+y)%5===0?LCLAY:RSTONE,20,0);
     addMachine('wheel',40,35,0);
     for(let x=0;x<W;x++)setCell(31*W+x,STONE,20,F_NAT);
     setCell(31*W+W-10,EMPTY,20,0);