[Suhas Aggarwal (suhasagg)]

Summary

Honor tool_choice="none" when preparing Ollama chat requests.

Problem

OllamaChatClient._prepare_options() excludes tool_choice from the
provider request because Ollama does not accept that option directly.

However, tools were still processed by the generic option path and
included in the Ollama request even when the caller explicitly selected
tool_choice="none".

Changes

• Treat tools as a specially handled option instead of passing it
  through the generic option-processing path.
• Omit tools when tool_choice="none".
• Preserve existing tool behavior when tool use is enabled.
• Add regression tests covering disabled and automatic tool choice.

Testing

• Focused regression tests: 2 passed
• Ollama non-integration tests: 49 passed, 5 deselected
• Ruff check: passed
• Ruff format check: passed
• MyPy reports two existing TypedDict ** expansion errors in
  _chat_client.py; the same errors reproduce on the unmodified baseline.

Fixes #8986

[Copilot]

Copilot review overview

🟡 Changes recommended

ToolMode mappings remain unsupported and the public options type contradicts the new behavior.

Review effort: Balanced
Findings: 1

Open (1)

• Handle ToolMode mapping when disabling tools · New

What changed in this PR

Updates Ollama request preparation to honor disabled tool choice.

Changes:

• Handles tools separately from generic options.
• Omits tools for tool_choice="none".
• Adds regression tests for none and auto.

File	Description
_chat_client.py	Conditionally includes Ollama tools.
test_ollama_chat_client.py	Tests disabled and automatic tool choice.

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[Suhas Aggarwal (suhasagg)]

@microsoft-github-policy-service agree

[Eduard van Valkenburg (eavanvalkenburg)]

Suhas Aggarwal (@suhasagg) Thanks for the contribution. This implements the same change as #8987, so we'll continue the work there and close this duplicate.