web/components/copilot.js

@@ -162,11 +162,8 @@ export class AppCopilot extends I18nMixin(ChatSession) {
     return this.querySelector('.copilot-textarea');
   }
 
-  _scrollToBottom() {
-    this.updateComplete.then(() => {
-      const el = this.querySelector('.copilot-messages');
-      if (el) el.scrollTop = el.scrollHeight;
-    });
+  _messagesContainer() {
+    return this.querySelector('.copilot-messages');
   }
 
   _onMessagePushed(item) {
@@ -389,6 +386,15 @@ export class AppCopilot extends I18nMixin(ChatSession) {
             ${t('chat.thinking')}
           </div>
         ` : nothing}
+
+        ${this._showJump ? html`
+          <button class="copilot-jump-btn" type="button"
+                  title=${t('chat.scroll_to_latest')}
+                  aria-label=${t('chat.scroll_to_latest')}
+                  @click=${() => this._jumpToBottom()}>
+            <i class="bi bi-arrow-down-circle-fill"></i>
+          </button>
+        ` : nothing}
       </div>
 
       <div class="copilot-input-area">

web/components/shared/chat-page.js

@@ -43,7 +43,7 @@ export class ChatPage extends ChatSession {
 
   updated(changed) {
     if (changed.has('visible') && this.visible) {
-      this._scrollToBottom();
+      this._forceScrollToBottom();
     }
     // The owner (mobile-app) re-points this chat by changing `source`. Switch the
     // live connection — base `_switchSource` tears down the WS, reloads that
@@ -72,11 +72,8 @@ export class ChatPage extends ChatSession {
     return this.querySelector('.chat-page-textarea');
   }
 
-  _scrollToBottom() {
-    this.updateComplete.then(() => {
-      const el = this.querySelector('.chat-page-messages');
-      if (el) el.scrollTop = el.scrollHeight;
-    });
+  _messagesContainer() {
+    return this.querySelector('.chat-page-messages');
   }
 
   _onMessagePushed(item) {
@@ -184,6 +181,15 @@ export class ChatPage extends ChatSession {
               ${t('chat.thinking')}
             </div>
           ` : nothing}
+
+          ${this._showJump ? html`
+            <button class="copilot-jump-btn" type="button"
+                    title=${t('chat.scroll_to_latest')}
+                    aria-label=${t('chat.scroll_to_latest')}
+                    @click=${() => this._jumpToBottom()}>
+              <i class="bi bi-arrow-down-circle-fill"></i>
+            </button>
+          ` : nothing}
         </div>
 
         <div class="chat-page-input-area">

web/css/copilot-messages.css

@@ -9,6 +9,39 @@
   gap: 0.7rem;
 }
 
+/* ── "Jump to latest" floating affordance ──────────────────────────────────── */
+/* Shown only while the reader is scrolled away from the bottom (auto-scroll has
+   yielded). Sticky to the scrollport bottom so it stays in view as they read;
+   removed from the DOM entirely while stuck to the bottom. */
+.copilot-jump-btn {
+  position: sticky;
+  bottom: 0.6rem;
+  align-self: flex-end;
+  width: 38px;
+  height: 38px;
+  display: grid;
+  place-items: center;
+  padding: 0;
+  border: 1px solid var(--card-border);
+  border-radius: 50%;
+  background: rgba(var(--accent-rgb), 0.92);
+  color: #fff;
+  box-shadow: var(--card-shadow);
+  cursor: pointer;
+  z-index: 5;
+  font-size: 1.1rem;
+  line-height: 1;
+  transition: transform 0.12s ease, background-color 0.12s ease;
+}
+.copilot-jump-btn:hover { background: var(--accent); transform: translateY(-1px); }
+.copilot-jump-btn:active { transform: translateY(0); }
+.copilot-jump-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
+
+@media (prefers-reduced-motion: reduce) {
+  .copilot-jump-btn { transition: none; }
+  .copilot-jump-btn:hover { transform: none; }
+}
+
 /* ── Message bubbles ───────────────────────────────────────────────────────── */
 
 .copilot-msg {

web/i18n/en.js

@@ -68,6 +68,7 @@ export default {
   'chat.reasoning':     'Reasoning…',
   'chat.attach':        'Attach files',
   'chat.new_session':   'New conversation',
+  'chat.scroll_to_latest': 'Scroll to latest',
   'chat.security_group': 'Security group',
   'chat.collapse':      'Hide chat',
   'chat.close_tab':     'Close tab',

web/i18n/fr.js

@@ -68,6 +68,7 @@ export default {
   'chat.reasoning':     'Raisonnement…',
   'chat.attach':        'Joindre des fichiers',
   'chat.new_session':   'Nouvelle conversation',
+  'chat.scroll_to_latest': 'Aller aux derniers messages',
   'chat.security_group': 'Groupe de sécurité',
   'chat.collapse':      'Masquer la discussion',
   'chat.close_tab':     'Fermer l\'onglet',

web/i18n/it.js

@@ -68,6 +68,7 @@ export default {
   'chat.reasoning':     'Ragionamento…',
   'chat.attach':        'Allega file',
   'chat.new_session':   'Nuova conversazione',
+  'chat.scroll_to_latest': 'Vai agli ultimi messaggi',
   'chat.security_group': 'Gruppo di sicurezza',
   'chat.collapse':      'Nascondi la chat',
   'chat.close_tab':     'Chiudi scheda',

web/lib/chat-session.js

@@ -13,15 +13,24 @@ const SYSTEM_SLASH_COMMANDS = new Set([
   '/compact', '/resettools', '/sethome',
 ]);
 
+// Pixels from the bottom within which auto-scroll still "sticks". Scrolling
+// further up during streaming makes auto-scroll yield so the reader is left in
+// peace; scrolling back within this band re-arms it.
+const SCROLL_STICKY_PX = 80;
+
 /**
  * Base class for chat UI components (desktop copilot, mobile chat page).
  *
  * Contains all WebSocket logic, message state, and approval handling.
  * Subclasses implement the render() method and override the DOM hooks:
- *   - _scrollToBottom()
+ *   - _messagesContainer() → returns the scrollable message-list element
  *   - _getInputContent()   → returns current input value
  *   - _clearInput()        → empties the input
  *   - _onMessagePushed(item) → called after each push (scroll, focus, etc.)
+ *
+ * Auto-scroll is stick-to-bottom: it follows the stream only while the reader is
+ * within SCROLL_STICKY_PX of the bottom. Scrolling up to read pauses it, and a
+ * "jump to latest" affordance (driven by the `_showJump` state) is shown then.
  */
 export class ChatSession extends LightElement {
   static properties = {
@@ -42,6 +51,10 @@ export class ChatSession extends LightElement {
     // Voice recording state (shared by every chat surface).
     _hasTranscribe:      { state: true },
     _recording:          { state: true },
+    // Whether to show the "jump to latest" affordance: true only while the reader
+    // is scrolled away from the bottom (i.e. auto-scroll has yielded). Driven by
+    // the stickiness sensor in `_scrollToBottom`.
+    _showJump:           { state: true },
     // Pending attachments for the message being composed (shown as chips above
     // the textarea; uploaded to disk on selection, sent with the next message).
     _attachments:        { state: true },
@@ -85,6 +98,14 @@ export class ChatSession extends LightElement {
     this._shortcutRecording = false;
     this._mediaRecorder     = null;
     this._audioChunks       = [];
+    // Stick-to-bottom auto-scroll: `_stickToBottom` is `true` while the reader is
+    // within SCROLL_STICKY_PX of the bottom. A manual scroll-up flips it false so
+    // live streaming stops fighting the reader; scrolling back within the band
+    // re-arms it. `_scrollEl` tracks the bound container so the scroll sensor is
+    // attached exactly once (and re-attached if the element is recreated).
+    this._stickToBottom = true;
+    this._scrollEl      = null;
+    this._showJump      = false;
     // Each entry: { name, path, mimetype, filesize, uploading? }. While an upload
     // is in flight the entry has `uploading: true` and no `path` yet.
     this._attachments       = [];
@@ -168,7 +189,7 @@ export class ChatSession extends LightElement {
           if (m.kind === 'tool' && m.status === 'pending') expanded.add(m.tool_call_id);
         }
         this._expanded = expanded;
-        this._scrollToBottom();
+        this._forceScrollToBottom();
         // Set flag so ws.onopen sends a resume if there are pending tools
         // (approval/clarification waiting) or interrupted tools (status=error+Interrupted).
         this._hasPendingTools = items.some(
@@ -400,7 +421,7 @@ export class ChatSession extends LightElement {
       case 'approval_required':
         this._updateTool(msg.tool_call_id, { status: 'pending', request_id: msg.request_id });
         this._expanded = new Set([...this._expanded, msg.tool_call_id]);
-        this.updateComplete.then(() => this._scrollToBottom());
+        this._forceScrollToBottom();
         break;
 
       case 'approval_resolved': {
@@ -441,7 +462,7 @@ export class ChatSession extends LightElement {
           suggested_answers: msg.suggested_answers ?? [],
         });
         this._expanded = new Set([...this._expanded, msg.tool_call_id]);
-        this.updateComplete.then(() => this._scrollToBottom());
+        this._forceScrollToBottom();
         break;
 
       case 'agent_start':
@@ -657,6 +678,10 @@ export class ChatSession extends LightElement {
       ({ name, path, mimetype, filesize }));
     this._attachments = [];
 
+    // Sending implies the reader wants to follow the conversation: always land at
+    // the latest, even if they had scrolled up to read before sending.
+    this._forceScrollToBottom();
+
     // System slash commands reply with a `Done` and never echo back as a
     // `user_message`, so render them optimistically. Regular messages and custom
     // slash commands use telnet-style echo: no local push — the bubble appears only
@@ -910,8 +935,56 @@ export class ChatSession extends LightElement {
     el.style.height = el.scrollHeight + 'px';
   }
 
-  /** Scrolls the message list to the bottom. */
-  _scrollToBottom() {}
+  /** Returns the scrollable message-list element. Subclasses must override. */
+  _messagesContainer() { return null; }
+
+  /**
+   * Scrolls the message list to the bottom — unless the reader has scrolled away
+   * from the bottom, in which case streaming is left to flow without yanking them
+   * back. Pass `force=true` for cases that must always land at the latest content
+   * (history load, the chat becoming visible, interactive approval/clarification
+   * prompts).
+   *
+   * Stickiness is tracked as a flag updated by a passive `scroll` listener on the
+   * container (attached lazily), NOT by re-measuring the distance on every call:
+   * a single fast flush can add more than the threshold of new content, which
+   * would otherwise make a stuck reader look "far from the bottom" and kill the
+   * auto-scroll. The listener recomputes the flag from the live scroll position,
+   * so scrolling back within the band re-arms it.
+   */
+  _scrollToBottom(force = false) {
+    this.updateComplete.then(() => {
+      const el = this._messagesContainer();
+      if (!el) return;
+      // Lazily bind the stickiness sensor to the (possibly recreated) container.
+      if (el !== this._scrollEl) {
+        this._scrollEl = el;
+        el.addEventListener('scroll', () => {
+          if (this._scrollEl !== el) return;
+          this._stickToBottom =
+            (el.scrollHeight - el.scrollTop - el.clientHeight) <= SCROLL_STICKY_PX;
+          this._updateJumpButton();
+        }, { passive: true });
+      }
+      if (force || this._stickToBottom) {
+        el.scrollTop = el.scrollHeight;
+        this._stickToBottom = true;
+        this._updateJumpButton();
+      }
+    });
+  }
+
+  /** Always scrolls to the bottom regardless of the reader's position. */
+  _forceScrollToBottom() { this._scrollToBottom(true); }
+
+  /** "Jump to latest" handler: force-scroll and re-stick. */
+  _jumpToBottom() { this._forceScrollToBottom(); }
+
+  /** Toggles the `_showJump` state from the current stickiness (only on change). */
+  _updateJumpButton() {
+    const show = !this._stickToBottom && this._messages.length > 0;
+    if (show !== this._showJump) this._showJump = show;
+  }
 
   // ── Voice recording (shared by every chat surface) ────────────────────────────