Release 4.20.0

🚀 Added

• Override server variable defaults via [servers.variables] in config. #4166
• Form-encoded payloads for dynamic auth via payload_content_type. #4167

🏎️ Performance

• ~50% lower coverage-phase wall on definition-heavy schemas.
• Cache repeated computations during the coverage phase.
• Faster schema bundling for specs with recursive references.

🐛 Fixed

• Emit an all-valid object baseline for properties declared next to a non-object type.
• Populate nested object templates referenced via $ref instead of generating null/{}.
• Honor servers[] declared at path-item and operation scopes. #4166
• Restore per-property negatives in coverage phase when an unsatisfiable optional property would otherwise sink the template draw.
• Emit minLength negatives for string schemas whose pattern requires more characters than minLength - 1.
• Emit minLength/maxLength negatives for string schemas whose format (e.g. email, uuid) makes the bounded length unsatisfiable.
• Cover the enum / const keywords when entries violate the declared type by emitting each entry as a negative case.
• Set Content-Type: application/json on JSON-serialized nested multipart/form-data parts.
• Emit a non-empty alphabetic string (e.g. AAA) as the string-type negative for non-string parameters so ?q= no longer collapses to absent on the wire.
• Skip report aggregation for crashed xdist workers instead of failing the whole controller with AttributeError.
• Emit maxLength negatives for string schemas whose format makes the exact length unsatisfiable when maxLength exceeds 100.
• False positive negative_data_rejection for integer enum entries under type: integer / type: number.