[pydantic-ai] google_model_profile sends invalid MINIMAL thinking_level for gemini-3.5-pro / gemini-3.1-pro and fails to strip Vertex regional prefixes

## Observed symptom google_model_profile sends invalid MINIMAL thinking_level for gemini-3.5-pro / gemini-3.1-pro and fails to strip Vertex regional prefixes `google_model_profile` in `pydantic_ai/profiles/google.py` currently has two issues with Gemini 3 / 3.5 and Vertex AI regional model identifiers: 1. **Non-preview Gemini 3+ Pro models (`gemini-3.5-pro`, `gemini-3.1-pro`, `gemini-3-pro`) receive `google_supports_minimal_thinking_level=True`:** - `_MODEL_THINKING_LEVELS` only lists `'gemini-3.1-pro-preview'` and `'gemini-3-pro-preview'`. - For `'gemini-3.5-pro'` or `'gemini-3.1-pro'`, `_resolve_thinking_levels` returns `None`, and line 264 sets `google_supports_minimal_thinking_level=thinking_levels is None or 'MINIMAL' in thinking_levels`, which evaluates to `True`. - As a result, passing `thinking='minimal'` or `thinking=False` on `gemini-3.5-pro` or `gemini-3.1-pro` sends `thinking_level='MINIMAL'`, which the Gemini API rejects with HTTP 400 (`INVALID_ARGUMENT`, as Gemini 3+ Pro models only support `LOW`, `MEDIUM`, and `HIGH`). ## Environment GitHub pydantic/pydantic-ai #9623 ## Trigger / context Public GitHub report in pydantic/pydantic-ai (FRESH_7D). ## Source evidence - https://github.com/pydantic/pydantic-ai/issues/9623 (2026-10-02T05:23:26Z) — evidence_class: PRIMARY_ISSUE_REPORT — #9623 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T10:50:53.329738Z - scout_id: C025f81cfd6 ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.