Keep TUI cursor stable after plugin toggle

tests/test_plugin_helper.py

@@ -1471,6 +1471,75 @@ sha256 = "{sha256_file(asset)}"
     return PluginHelperTui(choices=[choice], repo_root=repo), instance, state
 
 
+def _make_two_plugin_tui_fixture(root: Path) -> tuple[PluginHelperTui, Path, Path]:
+    repo = root / "repo"
+    instance_root = root / "instances"
+    instance = instance_root / "1.40.8"
+    state = root / "state"
+    (repo / "registry").mkdir(parents=True)
+    (repo / "locks").mkdir()
+    (instance / "Beat Saber_Data").mkdir(parents=True)
+    (instance / "Plugins").mkdir()
+
+    plugins_state: dict[str, dict] = {}
+    lock_entries: list[str] = []
+    registry_entries: list[str] = []
+    for plugin_id, name, filename in (
+        ("alpha", "Alpha", "Alpha.dll"),
+        ("beta", "Beta", "Beta.dll"),
+    ):
+        asset = plugin_downloads_dir(state, "1.40.8", plugin_id) / filename
+        asset.write_bytes(f"{plugin_id} dll".encode())
+        (instance / "Plugins" / filename).write_bytes(f"{plugin_id} dll".encode())
+        registry_entries.append(
+            f"""
+[[plugins]]
+id = "{plugin_id}"
+name = "{name}"
+repo = "owner/{plugin_id}"
+asset_patterns = ["*.dll"]
+install_strategy = "dll-to-plugins"
+""".lstrip()
+        )
+        lock_entries.append(
+            f"""
+[[plugins]]
+id = "{plugin_id}"
+repo = "owner/{plugin_id}"
+tag = "v1.0.0"
+asset = "{filename}"
+sha256 = "{sha256_file(asset)}"
+""".lstrip()
+        )
+        plugins_state[plugin_id] = {
+            "installedAt": "2026-06-14T17:18:40Z",
+            "files": [{"path": f"Plugins/{filename}", "sha256": sha256_file(asset), "size": asset.stat().st_size}],
+        }
+
+    (repo / "registry" / "plugins.toml").write_text("".join(registry_entries), encoding="utf-8")
+    (repo / "locks" / "1.40.8.lock.toml").write_text(
+        f"""
+beat_saber_version = "1.40.8"
+instance = "1.40.8"
+{"".join(lock_entries)}
+""".lstrip(),
+        encoding="utf-8",
+    )
+    save_installed_state(
+        state,
+        "1.40.8",
+        {"instance": "1.40.8", "plugins": plugins_state, "disabledPlugins": {}},
+    )
+    choice = InstallationChoice(
+        install_id="test",
+        install_label="Test Install",
+        instance_name="1.40.8",
+        instance_path=instance,
+        state_root=state,
+    )
+    return PluginHelperTui(choices=[choice], repo_root=repo), instance, state
+
+
 class PluginHelperTuiTests(unittest.IsolatedAsyncioTestCase):
     async def test_installation_picker_shows_duplicate_instances_with_state_dirs(self) -> None:
         choices = [
@@ -1523,6 +1592,25 @@ class PluginHelperTuiTests(unittest.IsolatedAsyncioTestCase):
             self.assertNotIn("example", updated["plugins"])
             self.assertIn("example", updated["disabledPlugins"])
 
+    async def test_space_toggle_keeps_cursor_on_selected_plugin(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            app, instance, _state = _make_two_plugin_tui_fixture(Path(tmp))
+
+            async with app.run_test() as pilot:
+                table = app.query_one(DataTable)
+                self.assertEqual(table.row_count, 2)
+                await pilot.press("down")
+                await pilot.pause()
+                self.assertEqual(table.cursor_row, 1)
+                self.assertEqual(app.plugin_rows[table.cursor_row]["id"], "beta")
+                await pilot.press("space")
+                await pilot.pause()
+                self.assertEqual(table.cursor_row, 1)
+                self.assertEqual(app.plugin_rows[table.cursor_row]["id"], "beta")
+
+            self.assertFalse((instance / "Plugins" / "Beta.dll").exists())
+            self.assertTrue((instance / "Plugins" / "Alpha.dll").exists())
+
     async def test_space_enables_disabled_plugin_from_asset(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             app, instance, state = _make_tui_fixture(Path(tmp), disabled=True)