feat(webui): add native workspace folder picker

tests/utils/test_webui_workspaces.py

@@ -72,6 +72,7 @@ def test_workspace_payload_is_config_data_dir_scoped(tmp_path, monkeypatch) -> N
     assert payload["default_scope"]["access_mode"] == "full"
     assert payload["default_access_mode"] == "default"
     assert payload["controls"]["can_change_project"] is True
+    assert payload["controls"]["can_pick_folder"] is False
 
 
 def test_workspace_payload_hides_mutable_state_when_controls_unavailable(
@@ -91,6 +92,22 @@ def test_workspace_payload_hides_mutable_state_when_controls_unavailable(
     assert payload["default_scope"]["project_path"] == str(default.resolve())
     assert payload["controls"]["can_change_project"] is False
     assert payload["controls"]["can_use_full_access"] is False
+    assert payload["controls"]["can_pick_folder"] is False
+
+
+def test_workspace_payload_advertises_native_folder_picker(tmp_path, monkeypatch) -> None:
+    monkeypatch.setattr("nanobot.webui.workspaces.get_webui_dir", lambda: tmp_path / "webui")
+    default = tmp_path / "default"
+    default.mkdir()
+
+    payload = workspaces_payload(
+        default_workspace=default,
+        default_restrict_to_workspace=False,
+        controls_available=True,
+        folder_picker_available=True,
+    )
+
+    assert payload["controls"]["can_pick_folder"] is True
 
 
 def test_workspace_payload_uses_webui_default_access_mode(tmp_path, monkeypatch) -> None: