Fix workspace route navigation

src/ui/app-header.ts

@@ -25,17 +25,20 @@ export function routeButton(
 }
 
 function surfaceSwitch(app: App): HTMLElement {
-  const key = app.currentWorkspace?.key ?? app.state.workspaceKey;
   const dashboard = app.sqlRoute.surface === 'dashboard';
+  // The header stays mounted when File → New workspace swaps the active
+  // aggregate. Resolve at click time so its route never retains the workspace
+  // key from the header's original render.
+  const workspaceKey = (): string => app.currentWorkspace?.key ?? app.state.workspaceKey;
   return h('div', {
     class: 'editor-mode-switch app-surface-switch',
     role: 'group', 'aria-label': 'Application surface',
   },
   routeButton('SQL Browser', !dashboard, () => {
-    void app.navigateSqlRoute({ surface: 'workspace', workspaceKey: key }, 'push');
+    void app.navigateSqlRoute({ surface: 'workspace', workspaceKey: workspaceKey() }, 'push');
   }),
   routeButton('Dashboard', dashboard, () => {
-    void app.navigateSqlRoute({ surface: 'dashboard', workspaceKey: key, mode: 'edit' }, 'push');
+    void app.navigateSqlRoute({ surface: 'dashboard', workspaceKey: workspaceKey(), mode: 'edit' }, 'push');
   }));
 }
 

tests/unit/app.test.ts

@@ -972,10 +972,18 @@ describe('renderApp shell', () => {
       .toEqual(['SQL Browser', 'Dashboard']);
     expect(qs(app.root, '.dashboard-mode-switch')).toBeNull();
     app.navigateSqlRoute = vi.fn(async () => {});
+    // File → New workspace replaces the active aggregate without rebuilding
+    // this header. Its surface controls must route to the replacement, not
+    // the key captured when the header first mounted.
+    app.currentWorkspace = {
+      storageVersion: 2, id: 'new-workspace', key: 'sql_library_7',
+      name: 'SQL Library', queries: [], dashboard: null,
+    };
+    app.state.workspaceKey = 'sql_library_7';
     qsa<HTMLButtonElement>(app.root, '.app-surface-switch .editor-mode-btn')
       .find((button) => button.textContent === 'Dashboard')!.click();
     expect(app.navigateSqlRoute).toHaveBeenCalledWith({
-      surface: 'dashboard', workspaceKey: app.state.workspaceKey, mode: 'edit',
+      surface: 'dashboard', workspaceKey: 'sql_library_7', mode: 'edit',
     }, 'push');
     expect(qs(app.root, '.sidebar')).not.toBeNull();
     expect(qs(app.root, '.cm-editor')).not.toBeNull();