[agno] [Bug] Gemini 3.x: ToolResult media still causes 400 "Requests ending with a model turn are not supported" — #9647's nesting never runs in the agent loop

## Observed symptom [Bug] Gemini 3.x: ToolResult media still causes 400 "Requests ending with a model turn are not supported" — #9647's nesting never runs in the agent loop When a tool returns media (`ToolResult(images=...)`, `files=`, `audios=`, `videos=`), the next Gemini 3.x call fails with `400 INVALID_ARGUMENT: Requests ending with a model turn are not supported.` #9630 reported this, and #9647 closed it by nesting supported media in `FunctionResponse.parts` in `gemini.py`. That path never runs in a real agent run. `Model._handle_function_call_media` in `models/base.py` runs first: it removes the media from the tool message and appends a separate `role="user"` message with the text "The tool call above generated the attached media." plus the media. `Gemini._format_messages` then merges that message into the tool-result turn. The request becomes `user: [functionResponse (0 media parts), text, inline_data]`, which is the shape #9630 reported. ## Literal error text ``` ERROR Error from Gemini API: 400 INVALID_ARGUMENT. {'error': {'code': 400, 'message': 'Requests ending with a model turn are not supported.', 'status': 'INVALID_ARGUMENT'}} ``` ## Environment GitHub agno-agi/agno #10662 ## Trigger / context Public GitHub report in agno-agi/agno (FRESH_7D). ## Source evidence - https://github.com/agno-agi/agno/issues/10662 (2026-09-30T07:08:22Z) — evidence_class: PRIMARY_ISSUE_REPORT — #10662 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T10:50:53.329738Z - scout_id: C130ef481ea ## 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.