fix(chat): resync sidebar after panel switch

static/panels.js

@@ -182,6 +182,18 @@ function _consumeSettingsTargetPanel(fallback = 'chat') {
   return target;
 }
 
+function _resyncChatSidebarAfterPanelSwitch() {
+  if (_currentPanel !== 'chat') return;
+  if (typeof renderSessionListFromCache !== 'function') return;
+  const run = () => {
+    if (_currentPanel !== 'chat') return;
+    if (typeof _renamingSid !== 'undefined' && _renamingSid) return;
+    renderSessionListFromCache();
+  };
+  if (typeof requestAnimationFrame === 'function') requestAnimationFrame(run);
+  else run();
+}
+
 async function switchPanel(name, opts = {}) {
   const nextPanel = name || 'chat';
   const prevPanel = _currentPanel;
@@ -251,6 +263,7 @@ async function switchPanel(name, opts = {}) {
     if (sidebar) sidebar.classList.add('mobile-open');
     if (overlay) overlay.classList.add('visible');
   }
+  _resyncChatSidebarAfterPanelSwitch();
   syncAppTitlebar();
   return true;
 }

tests/test_chat_panel_sidebar_resync.py

@@ -0,0 +1,71 @@
+"""Regression coverage for chat sidebar virtualization after panel navigation."""
+from pathlib import Path
+
+PANELS_JS = Path(__file__).parent.parent / "static" / "panels.js"
+
+
+def _read_source() -> str:
+    return PANELS_JS.read_text(encoding="utf-8")
+
+
+def _function_block(src: str, name: str) -> str:
+    marker = f"function {name}"
+    start = src.find(marker)
+    if start == -1:
+        marker = f"async function {name}"
+        start = src.find(marker)
+    assert start != -1, f"{name} not found"
+    paren = src.find("(", start)
+    assert paren != -1, f"{name} signature not found"
+    paren_depth = 1
+    j = paren + 1
+    while j < len(src) and paren_depth:
+        if src[j] == "(":
+            paren_depth += 1
+        elif src[j] == ")":
+            paren_depth -= 1
+        j += 1
+    assert paren_depth == 0, f"{name} signature did not close"
+    brace = src.find("{", j)
+    assert brace != -1, f"{name} body not found"
+    depth = 1
+    i = brace + 1
+    while i < len(src) and depth:
+        if src[i] == "{":
+            depth += 1
+        elif src[i] == "}":
+            depth -= 1
+        i += 1
+    assert depth == 0, f"{name} body did not close"
+    return src[start:i]
+
+
+def test_switching_back_to_chat_schedules_sidebar_resync_after_panel_is_visible():
+    """Chat navigation must re-render the sidebar after layout becomes visible.
+
+    The sidebar session list is virtualized. After switching away to Settings,
+    Logs, etc. and then back to Chat, the browser can clamp the preserved
+    scrollTop during the layout transition. If no render runs after the chat
+    view is visible again, stale virtual spacer/header DOM can remain until the
+    next manual scroll event.
+    """
+    src = _read_source()
+    switch_body = _function_block(src, "switchPanel")
+
+    assert "_resyncChatSidebarAfterPanelSwitch();" in switch_body
+    assert switch_body.index("if (panelEl) panelEl.classList.add('active');") < switch_body.index(
+        "_resyncChatSidebarAfterPanelSwitch();"
+    )
+
+
+def test_chat_sidebar_resync_helper_is_guarded_and_bounded_to_one_animation_frame():
+    """The resync must not poll or destroy rename state; one guarded rAF is enough."""
+    src = _read_source()
+    helper = _function_block(src, "_resyncChatSidebarAfterPanelSwitch")
+
+    assert "if (_currentPanel !== 'chat') return;" in helper
+    assert "typeof renderSessionListFromCache !== 'function'" in helper
+    assert "requestAnimationFrame" in helper
+    assert "setInterval" not in helper
+    assert "setTimeout" not in helper
+    assert "renderSessionListFromCache();" in helper