0.5.1

Added

• Message.stop_reason: New str | None field on the Message dataclass carrying the raw stop reason string returned by each provider.
  • OpenAI / OpenRouter: populated from choices[0].finish_reason (e.g. "stop", "tool_calls", "length").
  • Claude: populated from the top-level stop_reason field (e.g. "end_turn", "tool_use").
  • Google: populated from candidates[0].finishReason (e.g. "STOP", "MAX_TOKENS").
  • OpenAI Responses API: derived from the output items — "tool_calls" when a function_call item is present, "length" when incomplete_details is set, "stop" otherwise.

Changed

• Google _format_tools: Tool parameter schemas are now deep-cleaned to remove additionalProperties before being sent to the Gemini API, which rejects that field.
• ResponseSchema.for_google: Switched from the legacy responseSchema key to the modern responseJsonSchema key to align with the Gemini 2.0+ API specification.