fix(webui): sp6 third review round, a held message line stays steady between polls, only a pane's latest render decides the line, the held preview cuts on whole characters (#1873, lane sp6-threads)

packages/webui/src/public/assistant.js

@@ -224,8 +224,16 @@
       why = `Nothing is read for this thread while ${name}'s bus is ${how}.`; readable = false; back = true;
     }
     else if (i?.threads && !thread) line = `This thread is not in ${name}'s thread list.`;
-    setText(e.line, line); e.line.hidden = !line;
+    // A held message the last render had no composer for stays in the line between polls, so the
+    // status line neither flickers nor is announced again on every read.
+    const withHeld = () => {
+      const cps = [...p.draft.replace(/\s+/g, ' ').trim()];
+      return `${line ? `${line} ` : ''}Your unsent message is kept until this thread can send: “${cps.length > 200 ? `${cps.slice(0, 200).join('')}…` : cps.join('')}”`;
+    };
+    const shown = readable && p.held && p.draft ? withHeld() : line;
+    setText(e.line, shown); e.line.hidden = !shown;
     if (!readable) {
+      p.held = false;
       // An unsent message outlives the chat view: it is held on the pane and put back when the
       // thread reads again.
       const typed = p.chat && e.body.querySelector('form textarea')?.value;
@@ -236,19 +244,21 @@
       return;
     }
     if (!p.chat) { p.chat = window.MosaicChat.pane(p.org); p.first = true; }
-    const first = p.first, chat = p.chat; p.first = false;
+    const first = p.first, chat = p.chat, seq = ++p.seq; p.first = false;
     void chat.render({ path: `/chat/threads/${p.id}`, container: e.body, canSend: !!list && i?.chatSend === true, navigated: first }).then(() => {
-      if (!p.draft || p.chat !== chat || !p.el.isConnected) return;
-      const field = e.body.querySelector('form textarea');
-      if (!field) {
+      // Only the latest render of this pane decides: an earlier one that a newer render cut short
+      // has no composer yet and must not claim the thread cannot send.
+      if (seq !== p.seq || p.chat !== chat || !p.el.isConnected) return;
+      const field = p.draft ? e.body.querySelector('form textarea') : null;
+      if (p.draft && !field) {
         // The thread reads but offers no composer: the held message stays visible here, never silently held.
-        const held = p.draft.length > 200 ? `${p.draft.slice(0, 200)}…` : p.draft;
-        setText(e.line, `${line ? `${line} ` : ''}Your unsent message is kept until this thread can send: “${held}”`); e.line.hidden = false;
+        p.held = true; const text = withHeld(); setText(e.line, text); e.line.hidden = false;
         return;
       }
       // Put the held message back only into an empty composer; text typed meanwhile is never overwritten.
-      if (!field.value) { field.value = p.draft; field.dispatchEvent(new Event('input', { bubbles: true })); }
-      if (field.value === p.draft) p.draft = '';
+      if (field && !field.value) { field.value = p.draft; field.dispatchEvent(new Event('input', { bubbles: true })); }
+      if (field && field.value === p.draft) p.draft = '';
+      if (p.held && (field || !p.draft)) { p.held = false; setText(e.line, line); e.line.hidden = !line; }
     }, () => {});
   }
   function paintTabs() {
@@ -281,7 +291,7 @@
   // ---------- panes ----------
   function makePane(key) {
     const { org, id } = split(key);
-    const p = { key, org, id, n: ++paneSeq, el: null, chat: null, first: true, title: null, draft: '' };
+    const p = { key, org, id, n: ++paneSeq, el: null, chat: null, first: true, title: null, draft: '', held: false, seq: 0 };
     const box = mounted.root.querySelector('[data-assist-panes]');
     box.insertAdjacentHTML('beforeend', paneShell(p));
     p.el = box.lastElementChild;