- Add extensions field to HTTPRoute class to store x-* fields
- Extract extensions from operation's model_extra in parser
- Add test to verify extensions are properly parsed
Previously, external schema references (URLs) in OpenAPI schemas were
silently passed through and only failed during JSON schema validation
with confusing "failed to match exactly one schema" errors.
This change:
- Detects external references in _replace_ref_with_defs() and raises clear error messages
- Updates exception handlers to propagate external reference errors while preserving other error handling
- Adds comprehensive test coverage for external reference detection
- Provides helpful error messages explaining that FastMCP only supports local schema references
Fixes#926🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
