Required Changes for Client Libraries

As a result of PR #1291, client libraries must update their filter construction and parsing to work with the server's new filter validation logic and properties-JSON format:

Summary

• Field validation is now strict. Filters with unknown/unqualified fields will cause 400 errors (was previously ignored).
• User metadata fields MUST be prefixed (e.g., m.category) when sending filter dicts or query parameters to the server.
• Code relying on implicit field mapping or omitting the m./metadata. prefix will break.

Action Items for Client Developers

1. Update filter construction:
   • Wherever the client builds filter dicts for server queries, ensure user metadata keys are prefixed with m. (e.g., {"m.time": "morning"} not {"time": "morning"}).
   • Audit existing usages (Python dicts, TypeScript types, etc.) to confirm consistency.
2. Error handling:
   • Raise or propagate user-facing errors when the server returns messages about unknown filter fields.
   • Update test suites to expect explicit errors for unknown fields (previously, missing fields were ignored, possibly allowing data leaks).
3. Interface documentation:
   • Update or clarify inline/helptext for all filter construction functions and method signatures.
4. Coordinate with backend:
   • If in doubt about field names or required prefixes, consult the backend API or open a discussion for ambiguous cases.

For further context, see the PR diff and the PR summary.

This change is required to support the new server implementation rolled out in PR #1291.