fix(sidebar): show collapse chevron on pinned section headers (#12147)

src/renderer/src/components/sidebar/WorktreeList.lineage-child-card.test.ts

@@ -917,6 +917,30 @@ describe('WorktreeList lineage child card renderer', () => {
     expect(markup).toContain('aria-expanded="true"')
   })
 
+  it('renders a collapse chevron on the pinned section header with worktrees', async () => {
+    setPinnedFixtureState()
+    const markup = await renderWorktreeListMarkup()
+
+    expect(markup).toContain('Pinned')
+    expect(markup).toContain('data-workspace-pin-drop-target=""')
+    expect(markup).toContain('data-repo-header-collapse-affordance=""')
+    expect(markup).toContain('aria-expanded="true"')
+  })
+
+  it('renders collapsed pinned section header affordance state', async () => {
+    setPinnedFixtureState()
+    mockStore.state = {
+      ...mockStore.state,
+      collapsedGroups: new Set(['pinned'])
+    }
+    const markup = await renderWorktreeListMarkup()
+
+    expect(markup).toContain('data-workspace-pin-drop-target=""')
+    expect(markup).toContain('data-repo-header-collapse-affordance=""')
+    expect(markup).toContain('aria-expanded="false"')
+    expect(markup).toContain('-rotate-90')
+  })
+
   it('renders a collapse chevron on grouped repo headers with worktrees', async () => {
     setLineageFixtureState('repo')
     const markup = await renderWorktreeListMarkup()

src/renderer/src/components/sidebar/WorktreeList.tsx

@@ -4196,10 +4196,13 @@ const VirtualizedWorktreeViewport = React.memo(function VirtualizedWorktreeViewp
                   projectGroupPathStatus.reason === 'ambiguous-connection')
               const projectGroupDepth = row.projectGroupDepth ?? 0
               const isHeaderCollapsed = collapsedGroups.has(row.key)
-              // Why: repo/project and status headers share compact section chrome; flat "All" stays a simple label.
+              // Why: repo/project/status/pinned share compact section chrome; flat "All" stays a simple label.
               const showHeaderCollapseAffordance =
                 row.count > 0 &&
-                (isRepoHeader || isProjectGroupHeader || headerWorkspaceStatus !== null)
+                (isRepoHeader ||
+                  isProjectGroupHeader ||
+                  headerWorkspaceStatus !== null ||
+                  isPinnedHeader)
               // Why: non-project headers like "All" are flat-list labels; don't reserve project hierarchy indent.
               const headerPaddingLeft =
                 isRepoHeader || isProjectGroupHeader