Fold long answers and offer a way back to the newest line

Plugin/unraid/include/ai_chat.php

@@ -164,6 +164,24 @@ function vv_ai_chat_assets(): void {
    15" panels with no pointer near them, so a control that only exists on hover does not exist. */
 /* Sits directly above the composer, so what it acts on — the exchange just above — reads left to
    right into the box you would retype it in. */
+/* Purely a positioning context. Deliberately NOT a flex item that grows: the parent is a column
+   flex container, .vv-ai-chat was flex:0 1 auto there, and it carries its own height — set inline
+   by setHeights() for the placements whose size is a share of a panel. A wrapper with flex:1 1
+   auto would stretch past the transcript and leave a dead strip under it, which is the same shape
+   of bug as the grid-stretch one. Block-level, no padding, no flex: the geometry is unchanged and
+   only the coordinate system is new. min-height:0 because flex items default to auto and would
+   refuse to shrink. */
+.vv-ai-chat-wrap { position:relative; min-width:0; min-height:0; }
+.vv-ai-jump { position:absolute; left:50%; transform:translateX(-50%); bottom:8px; z-index:3;
+              background:#242424; border:1px solid #3a3a3a; color:#ccc; font-size:10px;
+              padding:3px 12px; border-radius:11px; cursor:pointer; opacity:.94; }
+.vv-ai-jump:hover { background:#2e2e2e; color:#fff; }
+
+/* Folded answers cap at a readable height with a hard bottom edge rather than a fade — a fade
+   over a code block reads as a rendering fault. */
+.vv-ai-fold { max-height:420px; overflow:hidden; }
+.vv-ai-more { display:block; margin:4px 0 2px; }
+
 .vv-ai-last { display:flex; gap:10px; padding:0 2px 4px; }
 .vv-ai-lnk { background:none; border:none; padding:0; font-size:10px; color:#4a4a4a;
              cursor:pointer; text-decoration:underline; text-underline-offset:2px; }
@@ -550,6 +568,15 @@ vv_ai_profiles_script();
       return (c.scrollHeight - c.scrollTop - c.clientHeight) < 40;
     };
 
+    // The other half of stick-to-bottom. Scrolling up during a stream deliberately stops the
+    // transcript chasing you, which means text is now arriving off-screen with nothing saying so.
+    // The pill is that acknowledgement, and the way back.
+    function syncJump() {
+      const p = $('jump');
+      if (!p) return;
+      p.hidden = nearBottom();
+    }
+
     // Rendered through the same fmt() as a finished answer, so a fence that is still being written
     // formats as it arrives rather than snapping from plain text to a code block at the end. fmt
     // escapes, so a half-written tag cannot break out of the bubble mid-stream.
@@ -561,6 +588,7 @@ vv_ai_profiles_script();
       s.hidden = false;
       s.innerHTML = fmt(text);
       if (stick) scroll();
+      syncJump();
     }
 
     // Paths ride in data attributes rather than an onclick. They come out of the index, and a
@@ -616,7 +644,25 @@ vv_ai_profiles_script();
         h += `<div class="vv-ai-meta">${t.tokens} tok · ${t.tok_s} tok/s · `
            + `retrieve ${t.retrieve_ms}ms · generate ${(t.generate_ms/1000).toFixed(1)}s</div>`;
       }
-      chatEl().appendChild(el(h + '</div>')); scroll();
+      const node = el(h + '</div>');
+      chatEl().appendChild(node);
+      // Measured after it is in the DOM — scrollHeight is 0 on a detached node, so a fold decided
+      // before appending would either never fire or fire on everything.
+      foldIfLong(node);
+      scroll();
+    }
+
+    // A long answer buries the composer on a 15" panel, and the composer is where the next thing
+    // happens. Folded to a readable height with the control always visible — never hover-revealed,
+    // because the surfaces this runs on have no pointer near them.
+    const FOLD_PX = 420;
+    function foldIfLong(node) {
+      const body = node.querySelector('.vv-ai-body');
+      if (!body || body.scrollHeight <= FOLD_PX) return;
+      body.classList.add('vv-ai-fold');
+      body.insertAdjacentHTML('afterend',
+        `<button type="button" class="vv-ai-lnk vv-ai-more" data-more>Show the rest`
+        + ` (${Math.round(body.scrollHeight / 20)} lines)</button>`);
     }
 
     function addError(msg) {
@@ -663,6 +709,14 @@ vv_ai_profiles_script();
         }
         return;
       }
+      const more = e.target.closest('[data-more]');
+      if (more) {
+        const body = more.previousElementSibling;
+        if (body) body.classList.remove('vv-ai-fold');
+        more.remove();
+        return;
+      }
+
       const stog = e.target.closest('[data-src-toggle]');
       if (stog) {
         const box = stog.parentElement;
@@ -1311,6 +1365,13 @@ vv_ai_profiles_script();
     $('input').addEventListener('input', saveDraft);
     restoreDraft();
     syncLast();
+
+    const jumpEl = $('jump');
+    if (jumpEl) {
+      jumpEl.addEventListener('click', () => { scroll(); syncJump(); });
+      // passive: this only reads scroll position, so it must never delay the scroll itself.
+      chatEl().addEventListener('scroll', syncJump, { passive: true });
+    }
     const newBtn = $('new'); if (newBtn) newBtn.addEventListener('click', newChat);
 
     // ── Expand / collapse ────────────────────────────────────────────────
@@ -1786,8 +1847,13 @@ function vv_ai_chat_markup(string $prefix, array $o = []): void {
     </div>
   </div>
 
-  <div class="vv-ai-chat" id="<?= $p ?>-chat"<?= $style ?>>
+  <!-- Positioned wrapper so the jump pill can sit over the transcript's bottom edge without
-    <div class="vv-ai-empty"><?= htmlspecialchars($empty) ?></div>
+       being clipped by its overflow, and without taking a row of its own when hidden. -->
+  <div class="vv-ai-chat-wrap">
+    <div class="vv-ai-chat" id="<?= $p ?>-chat"<?= $style ?>>
+      <div class="vv-ai-empty"><?= htmlspecialchars($empty) ?></div>
+    </div>
+    <button type="button" class="vv-ai-jump" id="<?= $p ?>-jump" hidden>↓ newest</button>
   </div>
 
   <div class="vv-ai-composer">