WorkItemDetail.labels validation fails when API returns unexpanded label IDs

Summary

work_items.retrieve() (and any code path returning a WorkItemDetail) raises a pydantic.ValidationError for any work item that has labels attached, when labels is not explicitly expanded.

Repro

Call the retrieve endpoint for a work item that has one or more labels, without expand=labels:

client.work_items.retrieve(
    workspace_slug=workspace_slug,
    project_id=project_id,
    work_item_id=work_item_id,
)

Result: pydantic.ValidationError — Input should be a valid dictionary or instance of Label — deterministic, not intermittent, for every work item that has labels.

Root cause

The Plane API returns labels as an array of label ID strings when the field isn't expanded (the normal/default response shape). The WorkItemDetail model types labels as list[Label] unconditionally, so pydantic rejects the plain ID strings instead of accepting either shape.

Expected behavior

labels should accept both shapes depending on whether the caller expanded it — e.g. list[Label] | list[str], or the model should coerce string IDs into a minimal Label reference, consistent with how the API actually behaves when expand isn't requested.

Environment

• plane-sdk==0.2.19 (PyPI)
• Found via makeplane/plane-mcp-server (retrieve_work_item / retrieve_work_item_by_identifier tools), but the bug is in the SDK's model, not the MCP server.
• Server tested against: self-hosted Plane Community 1.3.1.

Workaround in use

Using list_work_items (which doesn't hit this validation path) instead of retrieve_work_item*, and filtering client-side.

Tìm model WorkItemDetail trong SDK và tái hiện lỗi thông qua work_items.retrieve mà không có expand=labels. Xác minh rằng labels chấp nhận cả các chuỗi ID label chưa được mở rộng của API lẫn các đối tượng Label đã được mở rộng, đồng thời xác nhận rằng các đường dẫn retrieve_work_item không còn gây ra ValidationError.