fix(tui): align filter tab selection with default currentFilter

TabSelectRenderable has no constructor option for initial selection
and always highlights index 0 (Errors) on mount, while the screen's
currentFilter defaults to 'all'. This desynced the visible tab from
the actually-displayed issue list. Explicitly select the "All" tab
after construction, add setSelectedIndex to the TabSelectRenderable
test double (previously missing), and extend the Tab focus test to
cover the round-trip swap back.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: JasonWarrenUK

src/tui/screens/validation-explorer.ts

@@ -198,6 +198,8 @@ export class ValidationExplorerScreen implements Screen {
 				{ name: 'All', description: '', value: 'all' },
 			],
 		});
+		// TabSelectRenderable always highlights index 0 on mount; align it with currentFilter ('all').
+		this.tabs.setSelectedIndex(2);
 		this.filterPanel = panel(this.renderer, { title: 'Filter' });
 		this.filterPanel.add(this.tabs);
 		this.shell.content.add(this.filterPanel.box);

tests/fixtures/tui/opentui.ts

@@ -125,10 +125,14 @@ export class InputRenderable extends BaseRenderable {
 }
 
 export class TabSelectRenderable extends BaseRenderable {
+	selectedIndex = 0;
 	on = vi.fn();
 	focus = vi.fn();
 	moveLeft = vi.fn();
 	moveRight = vi.fn();
+	setSelectedIndex = vi.fn(function (this: TabSelectRenderable, index: number) {
+		this.selectedIndex = index;
+	});
 }
 
 export class ASCIIFontRenderable extends BaseRenderable {}

tests/tui/screens/validation-explorer.test.ts

@@ -139,6 +139,19 @@ describe('ValidationExplorerScreen', () => {
 			screen.cleanup();
 		});
 
+		it('aligns the tab bar selection with currentFilter (all) on mount', async () => {
+			const screen = new ValidationExplorerScreen(mockContext);
+			screen.render({ validation: validationWithIssues, sourceType: 'csv' });
+
+			await new Promise((resolve) => setTimeout(resolve, 10));
+
+			const tabs = (screen as any).tabs;
+			expect(tabs.setSelectedIndex).toHaveBeenCalledWith(2);
+			expect(tabs.selectedIndex).toBe(2);
+
+			screen.cleanup();
+		});
+
 		it('rebuilds the issue list when the filter tab changes', async () => {
 			const screen = new ValidationExplorerScreen(mockContext);
 			screen.render({ validation: validationWithIssues, sourceType: 'csv' });
@@ -180,6 +193,11 @@ describe('ValidationExplorerScreen', () => {
 			expect(issuesPanel.box.borderColor).toEqual(unfocusedColor);
 			expect(detailPanel.box.borderColor).toEqual(focusedColor);
 
+			// Pressing Tab again swaps back to the original focused/unfocused state.
+			handler({ name: 'tab' });
+			expect(issuesPanel.box.borderColor).toEqual(focusedColor);
+			expect(detailPanel.box.borderColor).toEqual(unfocusedColor);
+
 			screen.cleanup();
 		});