fix(box): validate and export explicitly selected files (#2641)

* fix(box): retain outbox files when export fails

* test(box): retain ownership evidence in CI logs

* test(box): exercise LocalAgent export repair through real runtime and Docker

Co-authored-by: multica-agent <[email protected]>

* fix(box): complete bounded outbox recovery contract

* feat(box): export explicitly selected files

Co-authored-by: multica-agent <[email protected]>

* test(box): exercise explicit export on real Docker

Co-authored-by: multica-agent <[email protected]>

* test(box): verify explicit exports with live model and Docker

Co-authored-by: multica-agent <[email protected]>

* fix(box): align explicit export SDK and integration contracts

* docs(box): describe selected-file export contract

---------

Co-authored-by: HaiYangBG1 <[email protected]>
Co-authored-by: Chin Rock <[email protected]>
Co-authored-by: multica-agent <[email protected]>

src/langbot/pkg/plugin/box_actions.py

@@ -3,6 +3,7 @@
 from langbot_plugin.entities.io.actions.enums import PluginToRuntimeAction as Action
 from langbot_plugin.runtime.io.handler import ActionResponse
 from ..box.runner import RunnerBoxService
+from ..box.export_errors import BoxExportError
 from .agent_run_support import _validate_agent_run_session
 
 
@@ -45,7 +46,7 @@ def register(h):
         if action == Action.IMPORT_BOX_ATTACHMENTS:
             return ActionResponse.success(await service.import_attachments(query, data.get('attachment_ids')))
         if action == Action.EXPORT_BOX_FILES:
-            return ActionResponse.success(await service.export_files(query))
+            return ActionResponse.success(await service.export_files(query, data.get('paths')))
         raise ValueError('Unsupported Box action')
 
     def register_action(action):
@@ -53,6 +54,8 @@ def register(h):
         async def invoke(data):
             try:
                 return await dispatch(action, data)
+            except BoxExportError as exc:
+                return ActionResponse.error(str(exc), data={'error': exc.error.model_dump(mode='json')})
             except Exception as exc:
                 return ActionResponse.error(f'{type(exc).__name__}: {exc}')