fix

static/www/1.html

@@ -202,7 +202,7 @@
             z-index: 1100;
             /* above composer/footer */
             display: none;
-            /* hidden initially */
+            /* hard-hidden until armed */
             align-items: center;
             justify-content: center;
             border: 1px solid #ced4da;
@@ -324,6 +324,9 @@
         let firstRequestDone = false;
         let controller = null;
 
+        // HARD STOP guard: do not show button until conversation starts
+        let scrollBtnArmed = false;
+
         // --- render helpers ---
         function renderMarkdown(targetEl, md) {
             const html = marked.parse(md, { breaks: true, gfm: true, headerIds: false });
@@ -382,8 +385,12 @@
         }
 
         function updateScrollButton() {
+            // Hard stop: never show until armed
+            if (!scrollBtnArmed) {
+                scrollDownBtn.style.display = 'none';
+                return;
+            }
             const needs = isOverflowingAny() && !atBottom();
-            // hidden initially (no overflow) and whenever you’re at the bottom
             scrollDownBtn.style.display = needs ? 'inline-flex' : 'none';
         }
 
@@ -405,6 +412,9 @@
 
             if (!firstRequestDone) { welcomeLogo?.remove(); firstRequestDone = true; }
 
+            // Arm the scroll button the moment a real conversation starts
+            scrollBtnArmed = true;
+
             const autoStick = atBottom();
 
             const userMsg = document.createElement('div');
@@ -496,7 +506,7 @@
         window.addEventListener('scroll', updateScrollButton, { passive: true });
         window.addEventListener('resize', updateScrollButton);
 
-        // Observe content changes to recalc button visibility
+        // Observe content changes to recalc button visibility (only after armed)
         const threadObserver = new MutationObserver(() => {
             requestAnimationFrame(updateScrollButton);
         });
@@ -507,7 +517,10 @@
             try { await fetch('/api/clear', { method: 'GET' }); } catch (_) { }
             await loadLocale(CURRENT_LOCALE);
             inputText.focus();
-            updateScrollButton(); // initial -> hidden if no overflow
+            // Force-hide at startup no matter what
+            scrollBtnArmed = false;
+            scrollDownBtn.style.display = 'none';
+            updateScrollButton();
         });
     </script>
 </body>