Add rate limiting for import

**Description**
Currently services lacks proper serialization support.

**Proposed solution**
Add configurable serialization with sensible defaults.

**Priority**: Low/Medium

The title asks for rate limiting for import, while the description asks for configurable serialization and says services lacks serialization support. Confirm which change is intended before locating the relevant import or services entry point; no files or tests are named. Done should be a clearly scoped requirement with sensible defaults and coverage for the selected behavior.

Written by the indexing model from the issue text.