#267: jump to top/bottom buttons for long pastes and the editor

Fixed-position Top/Bottom pills appear only when content exceeds 2x
viewport height (window scroll on paste view, textarea scroll on /new).
New static/jump.js drives them; markup added to paste.html and new.html.

internal/web/static/app.css

@@ -884,3 +884,17 @@ button[type="submit"]:focus-visible,
 .created-banner { display: block; }
 /* #167: gutter rows for wrapped paste view — one row per visual code line */
 .gutline { display: block; }
+
+/* #267: jump to top/bottom pills for long pastes and the editor.
+   Hidden unless JS (jump.js) detects content more than 2x the viewport. */
+.jumpnav {
+  position: fixed;
+  right: 18px;
+  bottom: 18px;
+  z-index: 50;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+.jumpnav.hidden { display: none; }
+.jump-btn { box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25); }

internal/web/static/jump.js

@@ -0,0 +1,41 @@
+/* #267: jump to top / bottom controls for long content.
+   Paste view scrolls the window; the /new editor scrolls its textarea.
+   The active scroller is chosen via data-jump-scroll on the script tag. */
+(function () {
+  var nav = document.getElementById('jumpnav');
+  if (!nav) return;
+  var scroller = window;
+  var sel = nav.dataset.jumpScroll;
+  if (sel) scroller = document.querySelector(sel);
+
+  function el() {
+    return scroller === window ? document.scrollingElement : scroller;
+  }
+  function isLarge() {
+    var e = el();
+    if (!e) return false;
+    var visible = scroller === window ? window.innerHeight : e.clientHeight;
+    return e.scrollHeight > visible * 2;
+  }
+  function refresh() {
+    nav.classList.toggle('hidden', !isLarge());
+  }
+  function jump(toTop) {
+    var e = el();
+    if (!e) return;
+    if (scroller === window) {
+      window.scrollTo({ top: toTop ? 0 : e.scrollHeight });
+    } else {
+      e.scrollTop = toTop ? 0 : e.scrollHeight;
+    }
+  }
+  nav.addEventListener('click', function (ev) {
+    var b = ev.target.closest('[data-jump]');
+    if (!b) return;
+    ev.preventDefault();
+    jump(b.dataset.jump === 'top');
+  });
+  window.addEventListener('resize', refresh);
+  if (scroller !== window && scroller) scroller.addEventListener('input', refresh);
+  refresh();
+})();