We need answer by creating index.html in /tmp/ws. Need implement single page web app self-contained no external. Need maybe inspect dir? We should write file. Need maybe use tools. Need create index.html. Need ensure full-screen canvas, clicks launch shells that explode into gravity-affected fading particle bursts. Single file CSS/JS inline. Could include instructions. Need maybe no external resources. Need produce final concise with path. Need maybe use bash to create? write is fine. Need maybe maybe ensure present. Let's write. Need careful code.

Need design: canvas full screen, handle resize, devicePixelRatio. Click launches shell from bottom, upward arc, explosion at apex maybe click target? "clicks launch shells that explode..." Click anywhere launches shell from bottom toward click target, with trail. Explosion creates particles with velocities random, gravity, drag, fade, color. Need full-screen canvas. No external.

Need maybe handle pointer events. We'll write robust HTML. Maybe include CSS reset, canvas display block. JS: state arrays shells and particles, click count, shell colors. Animation loop. On click, if mouse down? "clicks launch shells"; pointerdown maybe. Shell object x,y vx,vy, color, target, life. At click: target coordinates, launch from random bottom x maybe center? Shell velocity based on target, with gravity? Actually shell projectile affected by gravity too? Could. Launch shell from bottom, velocity target offset. We can set vx = dx / 1.55, vy = dy / 1.55 - maybe. But if target above, vy negative. Need ensure reaches near target. Use ballistic formula: time=1.6, vx=dx/time, vy=dy/time - 0.5*g*time maybe if gravity affects shell. But shell should fly up. Better: target y maybe above bottom. We'll set vy = dy/t - 0.5*shellGravity*t, with shellGravity 200 px/s^2; g=420. If target close, use random apex. Shell gravity. Update shell position with velocity, drag, gravity. Explode when vy < 10 or y <= target y or time > maybe. But if target is near bottom? Click bottom maybe explosion quickly. Need robust.

Explosion particles: n maybe 100+ based on distance, colors. Particle velocities from angle random, speed random. gravity 420, drag 0.99, life 1-2.5 s, fade alpha. Draw with additive? Use globalCompositeOperation 'lighter'. Draw background with semi-transparent fill to create trails, or clear each frame. For fireworks, use fade trails with rgba(5,8,18,0.25) to preserve trails. But full-screen canvas; if clear with alpha, need initial black. On resize, canvas full; ctx fill background. But if using alpha fill, prior transparent? Fine. We can fill rgba(2,5,15,0.22) each frame. But after resize? fill black.

Need maybe draw stars? no external. Could include subtle static stars as background? Not necessary.

Need maybe add "Click/tap to launch" overlay. Could have small HUD. Need accessible? Not necessary. But nice.

Need maybe avoid network. Good.

Need maybe use CSS style.

Need perhaps include "End with index.html present." We'll write and maybe ls. Need final mention.

Let's write file.

Need maybe verify file present. Use ls maybe.