Add thinking mode support for anthropic client

[SrikarMannepalli]

⏺ Summary of Changes

Problem Solved

AutoGen’s Anthropic client did not support thinking mode—Claude’s ability to show its reasoning process before providing a final answer.
Without this, users could not access the internal thought process that makes Claude’s responses more accurate and transparent.

Changes Made

Core Implementation (_anthropic_client.py)

• Added _get_thinking_config() method to handle thinking parameter validation.
• Added thinking content extraction for both regular and streaming responses.
• Added support for thinking parameter in API calls.
• Fixed pre-existing bug: _last_used_tools initialization.

Configuration Support (config/init.py)

• Added ThinkingConfig TypedDict and ThinkingConfigModel for type safety.
• Integrated thinking config into existing configuration structures.

Test Coverage (test_anthropic_model_client.py)

• Added 4 comprehensive tests covering validation, basic usage, streaming, and tool integration.

Key Design Decisions

• API-First Validation: Let Anthropic API handle all validation (budget_tokens, model support, temperature requirements).
• User Responsibility: Users must set temperature=1.0 themselves — no automatic overrides.
• Model-Agnostic: Works with any model name format (API validates support).
• Clean Integration: Follows AutoGen’s existing extra_create_args pattern.

---

⏺ Usage Example

thinking_config = {
    "thinking": {
        "type": "enabled",
        "budget_tokens": 2000
    }
}

result = await client.create(messages, extra_create_args=thinking_config)

print(result.thought)   # reasoning process
print(result.content)   # final answer

---

⏺ Result

AutoGen users can now access Claude’s reasoning process, leading to more transparent and explainable AI interactions, while maintaining clean, maintainable code that follows AutoGen’s architectural principles.

---

⏺ Related Issue

Closes #6095

---

⏺ Checks

• I’ve included any doc changes needed for https://microsoft.github.io/autogen/.
• I’ve added tests corresponding to the changes introduced in this PR.
• I’ve made sure all auto checks have passed.

[SrikarMannepalli]

@microsoft-github-policy-service agree

[SrikarMannepalli]

Hi @ekzhu,
This change introduces support for Claude’s reasoning (“thinking”) mode in the Anthropic client, along with validation, configuration updates, and tests.
I kindly request you to review the PR whenever you get a chance. Please let me know if there are any additional adjustments or clarifications you’d like.
Thanks so much for your time 🙏

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.93%. Comparing base (0df6be1) to head (9cfb218).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../autogen_ext/models/anthropic/_anthropic_client.py	40.00%	24 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7002      +/-   ##
==========================================
- Coverage   80.99%   80.93%   -0.07%     
==========================================
  Files         237      237              
  Lines       18198    18240      +42     
==========================================
+ Hits        14739    14762      +23     
- Misses       3459     3478      +19     

Flag	Coverage Δ
unittests	80.93% <50.00%> (-0.07%)	⬇️

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