Effect lifecycle

<div class="scene"><div class="title">DEPENDENCY: <span id="dep">A</span></div><div class="lane"><span class="pill" id="connectA">connect A</span><span class="pill" id="cleanup">cleanup A</span><span class="pill" id="connectB">connect B</span></div><div class="wire"><span id="dot"></span></div><div class="label" id="note">A is subscribed</div></div>

.scene{width:min(94vw,800px);height:min(86vh,320px);position:relative;overflow:hidden;display:flex;flex-direction:column;justify-content:space-between;border:1px solid var(--line);border-radius:14px;background:var(--surface);padding:clamp(9px,2.4vmin,20px);font:500 clamp(15px,4vmin,18px)/1.3 var(--font-sans,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif)}.scene b,.scene strong{font-weight:700}.label{color:var(--muted)}.code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace}.pill{border:1px solid var(--line);border-radius:8px;padding:.4em .65em;background:var(--bg)}.active{border-color:var(--accent)!important;color:var(--accent)!important;background:color-mix(in srgb,var(--accent) 10%,var(--surface))!important}.title{font:700 clamp(12px,2.8vmin,17px) ui-monospace,monospace}.title span{color:var(--accent)}.lane{display:flex;justify-content:space-between;gap:5px;margin:clamp(15px,7vmin,48px) 0 15px}.lane .pill{flex:1;text-align:center}.wire{height:4px;background:var(--line);position:relative;margin:0 8% 18px}.wire span{position:absolute;top:-6px;width:16px;height:16px;border-radius:50%;background:var(--accent);left:0;transition:left .5s}.label{text-align:center}

const ids=["connectA","cleanup","connectB"];let n=0;function tick(){const step=n%3;ids.forEach((id,i)=>document.getElementById(id).classList.toggle("active",i===step));document.getElementById("dot").style.left=(step*50)+"%";document.getElementById("dep").textContent=step===2?"B":"A";document.getElementById("note").textContent=["A is subscribed","A is disconnected","B is subscribed"][step];n++}tick();setInterval(tick,950)