feat(ui): polish chat and git workflows with mobile UX and reliability fixes (#569)

* feat: add chat option for user message rendering mode

* feat: add chat option to toggle sticky user header

* feat(ui): overhaul context panel with reusable tabs and embedded session chat

Enable parallel context workflows with persistent tabbed views and isolated session chat while reducing resize and background runtime overhead.

* feat: polish context panel and git sidebar tabs

Refined context panel tab behavior and visuals for smoother switching and resizing
Reused the new tabs component in right sidebar and git sidebar with fit layout
Improved git section spacing, selection controls, and bulk revert confirmation flow

* feat: open diff files in editor at changed lines

Add edit actions in diff views to open files at the first changed line
Support per-file open-in-editor from All Files headers and icon-only action in single-file view
Improve file jump UX with load-aware navigation and reduced visual blink during line targeting

* fix: stabilize pill tabs and prevent git commit pathspec failures

Unified sortable tab variants to match animated styling behavior with responsive spacing and cleaner sidebar chrome
Fixed active tab pill measurement so size/position recalculates correctly when dropdowns reopen
Commit API now filters stale file paths before staging to avoid pathspec errors on deleted files

* fix: align user message action row spacing and hover behavior

* fix: persist user message view preferences in settings

Save plain-text and sticky-header toggles to settings.json when changed
Restore both chat display preferences from settings.json on startup
Validate and accept both preference fields in the settings API

* fix: improve git and sidebar tab layout on mobile

* fix: refine mobile user message action row spacing

Show mobile user-message actions in a consistent external row for sticky and non-sticky modes
Tune button row height and vertical position to match both mobile variants
Reduce sticky-header gradient tail and tighten assistant gap after user messages

* fix: improve chat action hover zones and mobile top shadow logic

Expand desktop trigger area so user action buttons reveal across the full row
Add sticky-header phantom hover row so inline actions appear from the whole button lane
Hide chat top scroll shadow on mobile only when sticky user headers are enabled

* fix: remove commit message input scrollbar flicker

Added optional scrollbar class support to shared textarea wrapper.
Disabled overlay scrollbar for Git commit message input.
Kept auto-resize behavior while preventing one-line empty-state micro-scroll.

* feat: make model provider groups collapsible in selector

Add collapsible provider headers in the chat model dropdown
Persist expanded/collapsed provider state across sessions
Refine provider header UX with inline chevrons and no hover highlight

* feat: arrange chat settings into a compact two-column layout

Places User Message Rendering next to Mermaid Rendering.
Places Diff Layout next to Diff View Mode.
Reduces right-column spacing to better match other settings sections.

* fix: show worktree branch edit controls in draft sessions

Detect worktree mode from current directory when session metadata is not yet bound
Enable immediate branch rename UI in Git sidebar without session switching

* feat: add beta badge to side panel menu action

packages/ui/src/components/session/SessionSidebar.tsx

@@ -50,6 +50,7 @@ import {
   RiAddLine,
   RiArrowDownSLine,
   RiArrowRightSLine,
+  RiChat4Line,
   RiCheckboxBlankLine,
   RiCheckboxLine,
   RiCheckLine,
@@ -859,6 +860,7 @@ export const SessionSidebar: React.FC<SessionSidebarProps> = ({
   const renameProject = useProjectsStore((state) => state.renameProject);
 
   const setActiveMainTab = useUIStore((state) => state.setActiveMainTab);
+  const openContextPanelTab = useUIStore((state) => state.openContextPanelTab);
   const deviceInfo = useDeviceInfo();
   const setSessionSwitcherOpen = useUIStore((state) => state.setSessionSwitcherOpen);
   const openMultiRunLauncher = useUIStore((state) => state.openMultiRunLauncher);
@@ -2552,6 +2554,27 @@ export const SessionSidebar: React.FC<SessionSidebarProps> = ({
                         </>
                       );
                     })() : null}
+                    <DropdownMenuItem
+                      disabled={!sessionDirectory}
+                      onClick={() => {
+                        if (!sessionDirectory) {
+                          return;
+                        }
+
+                        openContextPanelTab(sessionDirectory, {
+                          mode: 'chat',
+                          dedupeKey: `session:${session.id}`,
+                          label: sessionTitle,
+                        });
+                      }}
+                      className="[&>svg]:mr-1"
+                    >
+                      <RiChat4Line className="mr-1 h-4 w-4" />
+                      <span className="truncate">Open in Side Panel</span>
+                      <span className="shrink-0 typography-micro px-1 rounded leading-none pb-px text-[var(--status-warning)] bg-[var(--status-warning)]/10">
+                        beta
+                      </span>
+                    </DropdownMenuItem>
                     <DropdownMenuSeparator />
                     <DropdownMenuItem
                       className="text-destructive focus:text-destructive [&>svg]:mr-1"
@@ -2604,6 +2627,7 @@ export const SessionSidebar: React.FC<SessionSidebarProps> = ({
       addSessionToFolder,
       removeSessionFromFolder,
       createFolderAndStartRename,
+      openContextPanelTab,
       notifyOnSubtasks,
     ],
   );