fix: show empty project thread state in sidebar

apps/web/src/components/ChatView.browser.tsx

@@ -1041,6 +1041,19 @@ describe("ChatView timeline estimator parity (full app)", () => {
     },
   );
 
+  it("shows an explicit empty state for projects without threads in the sidebar", async () => {
+    const mounted = await mountChatView({
+      viewport: DEFAULT_VIEWPORT,
+      snapshot: createDraftOnlySnapshot(),
+    });
+
+    try {
+      await expect.element(page.getByText("No threads yet")).toBeInTheDocument();
+    } finally {
+      await mounted.cleanup();
+    }
+  });
+
   it("opens the project cwd for draft threads without a worktree path", async () => {
     setDraftThreadWithoutWorktree();
 

apps/web/src/components/Sidebar.tsx

@@ -1050,6 +1050,7 @@ export default function Sidebar() {
         const renderedThreads = pinnedCollapsedThread
           ? [pinnedCollapsedThread]
           : visibleProjectThreads;
+        const showEmptyThreadState = project.expanded && projectThreads.length === 0;
 
         return {
           hasHiddenThreads,
@@ -1058,6 +1059,7 @@ export default function Sidebar() {
           projectStatus,
           projectThreads,
           renderedThreads,
+          showEmptyThreadState,
           shouldShowThreadPanel,
           isThreadListExpanded,
         };
@@ -1203,6 +1205,7 @@ export default function Sidebar() {
       projectStatus,
       projectThreads,
       renderedThreads,
+      showEmptyThreadState,
       shouldShowThreadPanel,
       isThreadListExpanded,
     } = renderedProject;
@@ -1535,6 +1538,16 @@ export default function Sidebar() {
           ref={attachThreadListAutoAnimateRef}
           className="mx-1 my-0 w-full translate-x-0 gap-0.5 overflow-hidden px-1.5 py-0"
         >
+          {shouldShowThreadPanel && showEmptyThreadState ? (
+            <SidebarMenuSubItem className="w-full" data-thread-selection-safe>
+              <div
+                data-thread-selection-safe
+                className="flex h-6 w-full translate-x-0 items-center px-2 text-left text-[10px] text-muted-foreground/60"
+              >
+                <span>No threads yet</span>
+              </div>
+            </SidebarMenuSubItem>
+          ) : null}
           {shouldShowThreadPanel && renderedThreads.map((thread) => renderThreadRow(thread))}
 
           {project.expanded && hasHiddenThreads && !isThreadListExpanded && (