Clarify (1) whether updates made during aria-busy="true" should be announced once busy clears and (2) queue/coalescing expectations for rapid successive live-region updates #2906

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>PercA11y probe c2-007-l0v0p0a0r0b0u0c2f0n0k0</title>
<meta name="probe-vector" content='{"lifecycle":"pre_existing_empty","visibility":"none","politeness":"polite","atomic":"default","relevant":"default","busy":"none","update_kind":"text_content","cadence":"triple_50ms","focus":"none","container":"light_dom","channel":"live_region"}'>
<meta name="probe-expectation" content="OBSERVED">
<meta name="probe-allowed" content='{"presence":"OBSERVED","count_min":1,"count_max":3,"text_mode":"any_issued"}'>
</head>
<body data-probe="c2-007-l0v0p0a0r0b0u0c2f0n0k0">
<main>
<h1>Probe program c2-007-l0v0p0a0r0b0u0c2f0n0k0</h1>
<h2 id="editor" tabindex="-1">Editor</h2>
<button id="go">Run</button>
<div id="mount"></div>
<script>
var nonce=new URLSearchParams(location.search).get('nonce')||'NONCE0';
var T=function(i){return 'Item '+nonce+'-'+i;};
var OFF=[0,50,100],doc=document,root=null,reg=null;
function region(t,b){var e=doc.createElement('div');e.id='live';e.setAttribute('aria-live','polite');
var s=doc.createElement('span');s.textContent=t;e.appendChild(s);return e;}
function upd(i){var t=T(i);reg.textContent=t;}
function seq(){OFF.forEach(function(d,i){var f=function(){upd(i+1);if(i===OFF.length-1)done();};if(d){setTimeout(f,d);}else{f();}});}
function done(){}
function trigger(){seq();}
function setup(){root=document.getElementById('mount');reg=region('',false);root.appendChild(reg);document.body.setAttribute('data-probe-ready','1');}
addEventListener('load',setup);
document.getElementById('go').addEventListener('click',trigger);
</script>
</main>
</body>
</html>