Call your html_render tool exactly once (do not run shell commands) with title "Clipboard proof 27402" and exactly this HTML body:
<pre id="code">echo hello-27402</pre><button id="copy">Copy</button><output id="status">idle</output><script>document.getElementById('copy').addEventListener('click',async()=>{try{await navigator.clipboard.writeText(document.getElementById('code').textContent);document.getElementById('status').textContent='copied'}catch(error){document.getElementById('status').textContent='failed: '+error.name+' '+error.message}})</script>
Then reply "done".