An open page takes up a new version by itself after a deploy (#388)

The live stream already came back after a deploy and the lists caught
up, but the page kept running the script it had loaded, in a tab or the
home-screen app, until reloaded by hand. Back after a drop, the page now
asks for / again without the cache; another app.js named there is a new
version. With nothing to lose it reloads, and the item that was open,
carried across in sessionStorage whole since a read one is off the
Unread list, is opened again. While an episode plays, a dialog is open,
a search is set or a field is typed in, it offers a reload in a toast.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/events.ts

@@ -13,7 +13,7 @@ let dropped=false;
 function connect(){
   sse=new EventSource('/api/events');
   // Back after a drop: whatever was sent meanwhile went to nobody.
-  sse.onopen=()=>{ if(dropped){ dropped=false; catchUp(); } };
+  sse.onopen=()=>{ if(dropped){ dropped=false; catchUp(); checkVersion(); } };
   const soon=(fn: ()=>void,ms=500)=>{ let t: number; return ()=>{ clearTimeout(t); t=setTimeout(fn,ms); }; };
   // Caught: a network gone when one fires (a laptop asleep) was an unhandled rejection (#219).
   const refreshEntries=soon(()=>{ if(S.feed) loadEntries(false,true).catch(()=>{}); });
@@ -84,5 +84,51 @@ function connect(){
   };
   sse.onerror=()=>{ sse.close(); dropped=true; setTimeout(connect,4000); };
 }
+
+/// A deploy of ipx-web drops the stream and the page kept running the script it loaded, in an
+/// open tab or the home-screen app, until reloaded by hand (#388). Back after a drop, the page
+/// asks for itself again: a different app.js named there is a new version.
+const runningScript=document.querySelector('script[src^="/app.js"]')?.getAttribute('src');
+async function checkVersion(){
+  if(!runningScript) return;
+  let page: string;
+  // Mid-deploy, / can be a 502 or the sign-in page: no script named, nothing to compare.
+  try{ const r=await fetch('/',{cache:'no-store'}); if(!r.ok) return; page=await r.text(); }catch{ return; }
+  const live=page.match(/\/app\.js\?v=[0-9a-f]+/)?.[0];
+  if(!live||live===runningScript) return;
+  if(reloadWouldLose()) offerReload();
+  else reloadKeepingPlace();
+}
+/// Something a reload throws away: an episode playing, a dialog open, a search or a field typed in.
+function reloadWouldLose(){
+  const typing=document.activeElement instanceof HTMLTextAreaElement
+    || (document.activeElement instanceof HTMLInputElement && document.activeElement.type!=='range'
+        && document.activeElement.type!=='checkbox' && document.activeElement.value!=='');
+  return !audio.paused || !!$('#modal')?.classList.contains('on') || !!S.q || typing;
+}
+/// The feed and tab come back from localStorage; the item open is carried across in the session,
+/// whole: read, it is off the Unread list the server sends after the reload.
+function reloadKeepingPlace(){
+  try{ const e=cur(); if(e) sessionStorage.setItem('ipx.reopen',JSON.stringify(e)); }catch{}
+  location.reload();
+}
+/// The item open before a reload for a new version, once, for showList to open again.
+function takeReopen(): Entry|null{
+  try{
+    const j=sessionStorage.getItem('ipx.reopen'); sessionStorage.removeItem('ipx.reopen');
+    return j ? JSON.parse(j) as Entry : null;
+  }catch{ return null; }
+}
+let offered=false;
+function offerReload(){
+  if(offered) return;
+  offered=true;
+  const t=document.createElement('div'), b=document.createElement('button');
+  t.className='toast'; t.setAttribute('role','status'); t.textContent='A new version of iPX is ready. ';
+  b.type='button'; b.className='btn'; b.textContent='Reload';
+  b.onclick=reloadKeepingPlace;
+  t.appendChild(b);
+  $('#toasts')?.appendChild(t);
+}
 connect();
 loadFeeds().then(preloadLists).catch(()=>{});