fix(desktop): Cmd+W honors pinned / only-tab close guards

Address review: the Cmd/Ctrl+W path reused closeActiveTab(), an
unconditional force-close reserved for route-crash recovery, so the
shortcut could close a pinned tab or reseed the sole tab — both of which
the TabBar deliberately hides the close button for. Add a guarded
closeActiveTabIfClosable() that no-ops for pinned / only tabs and wire
the shortcut to it. (MUL-2987)

Co-authored-by: multica-agent <github@multica.ai>

apps/desktop/src/renderer/src/components/desktop-layout.tsx

@@ -71,11 +71,13 @@ function useNativeNavigationGestures() {
 }
 
 // Cmd/Ctrl+W closes the active tab. The main process owns the keystroke (it
-// must swallow the OS "Close Window" accelerator) and forwards it here.
+// must swallow the OS "Close Window" accelerator) and forwards it here. Uses
+// the guarded close so the shortcut honors the same pinned / only-tab rules
+// as the TabBar's close button — never the unconditional force-close.
 function useCloseActiveTabShortcut() {
   useEffect(() => {
     return window.desktopAPI.onCloseActiveTab(() => {
-      useTabStore.getState().closeActiveTab();
+      useTabStore.getState().closeActiveTabIfClosable();
     });
   }, []);
 }

apps/desktop/src/renderer/src/stores/tab-store.test.ts

@@ -320,6 +320,54 @@ describe("useTabStore actions", () => {
   });
 });
 
+describe("closeActiveTabIfClosable (Cmd/Ctrl+W guard — MUL-2987)", () => {
+  it("closes the active tab when it is unpinned and not the only tab", () => {
+    const store = useTabStore.getState();
+    store.switchWorkspace("acme");
+    const closableId = store.addTab("/acme/projects", "Projects", "FolderKanban");
+    store.setActiveTab(closableId);
+
+    store.closeActiveTabIfClosable();
+
+    const s = useTabStore.getState();
+    expect(s.byWorkspace.acme.tabs.some((t) => t.id === closableId)).toBe(false);
+    expect(s.byWorkspace.acme.tabs).toHaveLength(1);
+  });
+
+  it("no-ops on the only tab (never reseeds a default the user didn't ask for)", () => {
+    const store = useTabStore.getState();
+    store.switchWorkspace("acme");
+    const onlyTabId = useTabStore.getState().byWorkspace.acme.tabs[0].id;
+
+    store.closeActiveTabIfClosable();
+
+    const s = useTabStore.getState();
+    expect(s.byWorkspace.acme.tabs).toHaveLength(1);
+    expect(s.byWorkspace.acme.tabs[0].id).toBe(onlyTabId); // untouched, not reseeded
+  });
+
+  it("no-ops when the active tab is pinned (requires explicit Unpin first)", () => {
+    const store = useTabStore.getState();
+    store.switchWorkspace("acme");
+    store.addTab("/acme/projects", "Projects", "FolderKanban");
+    const pinnedId = useTabStore.getState().byWorkspace.acme.tabs[0].id;
+    store.togglePin(pinnedId);
+    store.setActiveTab(pinnedId);
+
+    store.closeActiveTabIfClosable();
+
+    const s = useTabStore.getState();
+    expect(s.byWorkspace.acme.tabs.some((t) => t.id === pinnedId)).toBe(true);
+    expect(s.byWorkspace.acme.tabs).toHaveLength(2);
+  });
+
+  it("no-ops when no workspace is active", () => {
+    const store = useTabStore.getState();
+    expect(() => store.closeActiveTabIfClosable()).not.toThrow();
+    expect(useTabStore.getState().byWorkspace).toEqual({});
+  });
+});
+
 describe("togglePin", () => {
   it("flips a tab's pinned state", () => {
     const store = useTabStore.getState();

apps/desktop/src/renderer/src/stores/tab-store.ts

@@ -96,6 +96,15 @@ interface TabStore {
    * (or a reseeded default if it was the last tab).
    */
   closeActiveTab: () => void;
+  /**
+   * Close the active tab in response to the user Cmd/Ctrl+W shortcut. Mirrors
+   * the TabBar's close-affordance rules (tab-bar.tsx `showCloseButton`):
+   * no-ops when the active tab is pinned or is the only tab in its workspace,
+   * so the shortcut can never destroy a tab the UI intentionally exposes no
+   * close button for. Distinct from closeActiveTab(), which is an
+   * unconditional force-close reserved for route-crash recovery.
+   */
+  closeActiveTabIfClosable: () => void;
   /**
    * Reorder within the active workspace's group only. Clamped so a tab can
    * never cross the pinned / unpinned boundary — a drag that would move a
@@ -517,6 +526,20 @@ export const useTabStore = create<TabStore>()(
         closeTab(group.activeTabId);
       },
 
+      closeActiveTabIfClosable() {
+        const { activeWorkspaceSlug, byWorkspace, closeTab } = get();
+        if (!activeWorkspaceSlug) return;
+        const group = byWorkspace[activeWorkspaceSlug];
+        if (!group) return;
+        // Match the TabBar close-button guard: the sole tab never closes
+        // (its X is hidden; closing would reseed a default the user didn't
+        // ask for) and pinned tabs require an explicit Unpin first.
+        if (group.tabs.length === 1) return;
+        const active = group.tabs.find((t) => t.id === group.activeTabId);
+        if (!active || active.pinned) return;
+        closeTab(active.id);
+      },
+
       moveTab(fromIndex, toIndex) {
         if (fromIndex === toIndex) return;
         const { activeWorkspaceSlug, byWorkspace } = get();