Problem

core.cases.update_case returned HTTP 500 when a workflow closed a case and supplied required dropdowns by definition_ref/option_ref in the same payload.

Two issues:

1. The closure-requirements validator resolved definition_ref but not option_ref, so it wrote option_id=None into the merged map and falsely flagged the
   dropdown as missing.
2. update_case_simple didn't catch TracecatValidationError, so it bubbled to the global handler as a 500 instead of a 4xx.

Solution

• Resolve option_ref → option_id inside the validator before merging.
• Catch TracecatValidationError in update_case_simple and return 400, matching the file's existing convention for validation failures.
• Add a regression test that closes a case using definition_ref + option_ref for a required-on-closure dropdown.

Summary by cubic

Fix case closure validation to accept dropdown refs and return clear 400 errors for invalid closure data. You can now close a case by sending definition_ref + option_ref for required dropdowns.

• Bug Fixes
  • Resolve option_ref to option ID when validating required dropdowns on close.
  • Map TracecatValidationError to HTTP 400 in update_case_simple.
  • Add unit test to verify closing with dropdown refs satisfies closure requirements.

^{Written for commit aa4dd29. Summary will update on new commits. Review in cubic}