Fix #5: center import export modals

tests/test_import_export_workflow.py

@@ -13,7 +13,7 @@ from hosts.core.import_export import (
 )
 from hosts.core.models import HostEntry, HostsFile
 from hosts.tui.app import HostsManagerApp
-from hosts.tui.import_export_modal import ExportModal, ImportModal
+from hosts.tui.import_export_modal import ExportModal, FileBrowserModal, ImportModal
 
 
 @pytest.mark.asyncio
@@ -42,6 +42,52 @@ async def test_export_shortcut_opens_a_format_chooser_and_reports_validation():
         )
 
 
+@pytest.mark.asyncio
+async def test_export_modal_is_centered_in_the_terminal_viewport():
+    """The export form is centered rather than pinned to a terminal corner."""
+    app = HostsManagerApp()
+    app.load_hosts_file = Mock()
+
+    async with app.run_test(size=(120, 40)) as pilot:
+        await pilot.press("ctrl+x")
+        await pilot.pause()
+
+        container = app.screen.query_one("#format-container")
+        assert container.region.x == (app.size.width - container.region.width) // 2
+
+        assert container.region.y == (app.size.height - container.region.height) // 2
+
+
+@pytest.mark.asyncio
+async def test_export_browser_lets_the_user_choose_a_destination_directory():
+    """Browse opens a centered directory tree rather than requiring a typed path."""
+    app = HostsManagerApp()
+    app.load_hosts_file = Mock()
+
+    async with app.run_test(size=(120, 40)) as pilot:
+        await pilot.press("ctrl+x")
+        await pilot.pause()
+        await pilot.press("tab")
+        await pilot.press("enter")
+        await pilot.pause()
+        await pilot.pause()
+
+        assert isinstance(app.screen, FileBrowserModal)
+        assert app.screen.query_one("#file-browser-tree") is not None
+        container = app.screen.query_one("#file-browser-container")
+        assert container.region.x == (app.size.width - container.region.width) // 2
+
+        await pilot.press("tab")
+        await pilot.press("tab")
+        await pilot.press("enter")
+        await pilot.pause()
+        await pilot.pause()
+        assert isinstance(app.screen, ExportModal)
+        assert app.screen.query_one("#path-input", Input).value.endswith(
+            "hosts-export.hosts"
+        )
+
+
 @pytest.mark.asyncio
 async def test_export_requires_overwrite_confirmation_before_calling_service(tmp_path):
     """An existing output file is not replaced until the user confirms it."""