```
Update loop details:
```js
function frame(ts){
dt = min((ts-last)/1000, 1/30); last=ts; t+=dt;
updatePressure(dt); updateLava(dt); updateSmoke(dt); updateStreaks(dt);
render();
fps ema: f = 1/dt; ema = ema*0.92 + f*0.08;
if(t-lastStat>0.25){ update DOM }
rAF
}
```
Lava update pseudocode:
```js
for(i=lava.length-1;i>=0;i--){
p=lava[i];
p.age+=dt;
// heat
const grounded=p.g;
p.heat -= dt*(grounded? (p.slow?0.22:0.13) : 0.075) * p.cool; // p.cool variance 0.8-1.3
if(p.heat<=0){ p.fade-=dt/2.6; if(p.fade<=0){kill} }
if grounded:
gi = clamp
gY=groundY[gi];
d=(groundY[min(gi+2,W-1)]-groundY[max(gi-2,0)])/4;
p.vx += clamp(d,-3,3)*300*dt;
p.vx *= 1/(1+3.0*dt);
p.x += p.vx*dt; p.y = groundY[clamp(round? use gi from new x...)]
// snap
p.y = groundY[cl(p.x)]-1.5;
// drop-off: if groundY at new x much lower than old? snap handles.
// small hop on steep drop: if groundY ahead - current >30: p.g=false; p.vy=... keep simple: skip, snap slides down cliffs instantly = looks like flow. ok.
p.slow = |vx|<14;
else air:
p.vy += 380*dt; p.vx += windX*26*dt; p.vx*=1/(1+0.1*dt);
p.x+=vx*dt; p.y+=vy*dt;
const gy2=groundY[cl(p.x)];
if(p.y>=gy2-1){
if(p.vy>150 && rnd... ) { p.vy*=-0.18; p.vx*=0.55; p.y=gy2-1; maybe spark }
else { p.g=true; p.y=gy2-1.5; p.vx*=0.5; landing fx if heat>0.4&&vy>200 }
// if on nearly flat & hot, fine
}
bounds: if x<-40||x>W+40||y>H+40 kill (also fade)
}
```
Note heat cooling 0.075/s air → 13s in air; too long; air cooling 0.16 → ~6s hot in air. Grounded 0.13–0.22 → 5–8s glow, then fade 2.6s. With eruption every ~26s+2s, active lava between eruptions persists ~10s, fine. Spark: cool fast 1.6/s, life 0.6, fade quick.
Actually also cap: lava array cap 4200; if exceeded, remove oldest (shift is O(n); use swap with random index or just skip spawns — skip spawns beyond cap and also kill oldest via index swap: lava[lava.length-1] pattern... I'll just skip spawning when at cap and set slider max accordingly; plus emergency trim.
Rendering lava:
pass 0: rock (source-over): for p where heat<=0: alpha=p.fade; size=p.s*(1+ (1-p.fade)*0) drawImage(ROCK,...)
pass 1 (lighter): for p with heat>0: idx = min(24, heat*24|0); s=p.s*(1.6+heat*0.8)? size scale: base sprite 48px wide for glow falloff; draw at dsize = p.s * (2 + 2*heat) maybe. Particle sizes: normal s=2.2–3.6 (radius-ish), bombs s=5–7, sparks s=1.2–2.
Draw: ctx.globalAlpha = min(1, p.heat*1.4+0.15) * p.fade? While fading pre-rock? heat>0.06 → glow only. Use globalAlpha=Math.min(1,p.heat*1.6). drawImage(spr, x-d/2, y-d/2, d, d).
Set ctx.globalCompositeOperation per pass; reset after; also globalAlpha resets.
Count passes: iterate array twice — fine.
Smoke draw: source-over, for each: a = alphaProfile; dark then light? draw dark with a*(1-k), light with a*k where k=min(1,age/2). Two drawImages each — maybe only draw light when k>0.05, dark when k<0.95. size grows.
Smoke update:
```
p.age+=dt; if age>life kill.
buoy = 55*(1-p.age/p.life*0.9)... use (1 - age/life)
p.vy += (-85*(1-age/life) - 0) *dt??
```
Better: vy relax toward target vy_t = -(90*(1.2-age/life))-ish... Let me do forces: vy += (-70*(1 - age/life) )*dt (buoyancy fading); vy *= 1/(1+0.55*dt) (drag → terminal rise speed); wind: vx += (wind*3.2 - vx)*dt*0.9; turbulence: vx += Math.sin(p.age*1.7+p.sd)*22*dt; vy += Math.sin(p.age*2.3+p.sd*2)*10*dt.
x+=vx*dt;y+=vy*dt. size = p.s0 + p.age*p.gs (gs ~ 14–26). life 4.5–7.5s.
Eruption smoke: s0 bigger 14–30, initial vy -(120..240), gs 30, life 6–9, color darker (k offset slower).
Ambient smoke: rate = 1.5 + pressure*8 per second (wisps). Also when pressure>0.7 occasional stronger puff.
Cap smoke 750.
Spawn smoke position: (CX + rnd*30-15, craterY - 4).
Streaks: 40 items; if |wind|<5 alpha 0. skip else move x += wind*4.5*dt (+ their own factor), wrap 0..W; y fixed random in sky area (0..H*0.55); draw line length 30+|wind|*0.3, alpha 0.04+|wind|*0.0006. color 'rgba(200,200,220,α)'. Update positions only when wind active; draw always if alpha>0.
Shake: shake decays: shake *= Math.exp(-2.6*dt). During eruption: shake = max(shake, 7*pm). Pre-eruption: if p>0.8: shake=max(shake,(p-0.8)*8). offset ox=(Math.random()*2-1)*shake, oy likewise *0.6.
Render:
```
ctx.setTransform(1,0,0,1,0,0); ctx.clearRect? drawImage bg covers all → no clear needed except alpha? bg opaque → fine, skip clear.
ctx.translate(ox,oy);
drawImage(bg)
stars (before bg?? stars must be behind terrain — but bg contains terrain! So stars must be drawn onto... problem: bg includes terrain silhouette; dynamic stars would need drawing between sky and terrain. Options: draw stars onto bg offscreen (no twinkle) OR split: bgSky (gradient+moon) then dynamic stars then bgTerrain (transparent offscreen with ridges+ground). Two offscreens — easy. Do that: bgSky, bgTer.
Then magmaGlow (lighter), streaks, rockPass, glowPass, smoke, then reset transform → gauge, done.
```
Wait stars twinkle above terrain? Stars drawn after bgSky but before bgTer — correct occlusion.
Also faint horizon warm glow near volcano base in bgSky: gradient already has warm band; fine.
Star colors slight variation: white/#cfd6ff/#ffe9c8.
DOM stat: total = lava.length + smoke.length (+streaks? no, particles = lava+smoke). Show "LAVA n / ASH m" maybe in one line under big numbers.
Pressure build: rate = 0.032 + 0.016*Math.sin(t*0.31+1) + occasional surge: use second sine for irregularity: +0.012*Math.sin(t*0.13*7.7)... let's: rate=0.030+0.014*Math.sin(t*0.37)+0.010*Math.sin(t*1.61). Min ~0.006 → slow moments, max 0.054. Cycle ~ 20–40s. During eruption, pressure -= dt/dur (dur=2.3+0.8*pm? keep 2.4). After eruption residual small: set pressure to 0 at end exactly (drain computed to hit 0: track eruptLeft; pressure = eruptLeft/dur). Spawn window tied to eruptLeft.
Eruption spawn: while erupting: emitAcc += (amount/dur)*dt*(power curve?) just amount/dur; also first 0.3s extra: multiply rate by (1+1.5*max(0,(eruptLeft-dur+0.4)/0.4))? Simpler: rate factor = 1 + 1.2*Math.exp(-(dur-eruptLeft)*3) (strong start). ok.
Bomb chance 1.5%: s 5.5+2*rnd, cool slower 0.75, speed*0.85.
Also spawn sparks at crater continuously during eruption (rate 60/s): tiny fast particles heat bright — they add sparkle inside fountain; they're just lava particles with small s and high cool. Budget: sparks short-lived.
Muzzle flash: at eruption start, draw bright glow sprite at crater big for 0.5s: glowFlash=1 at trigger, decay 3/s; render GLOW sprite size 260*pm alpha flash*0.8 'lighter'.
Sound none.
Fonts: define stack: `ui-monospace,'Cascadia Mono','SF Mono',Menlo,Consolas,monospace`.
UI styles:
```
body{background:#08070a;color:#e6dccf;font-family:mono;overflow:hidden}
#panel{position:absolute;left:18px;bottom:18px;width:250px;padding:14px 16px;background:rgba(13,11,14,.78);border:1px solid rgba(230,215,200,.13); backdrop-filter:blur(4px)? maybe}
row label{font-size:10px;letter-spacing:.14em;color:#9a8f83}
value{color:#ffb35c}
input[type=range] custom: -webkit-appearance:none;height:2px;background:#3a332e; thumb: 11px square? circle #ff7a29 border.
button: transparent bg, 1px border #ff7a29-ish, color #ffb35c, hover fill rgba.
```
Square thumbs feel instrument-like; circle is fine. I'll use a small circle with border.
Title block:
```