Python: Preserve tool call IDs in chat history XML

[Gali (Jokasa7)]

Motivation and Context

Python ChatHistory.to_prompt() / str(history) followed by ChatHistory.from_rendered_prompt() drops call_id from function calls and results. For Responses API content, the item id and the tool-call correlation call_id are distinct. After this XML round trip, the existing Responses request adapter emits call_id=None for tool outputs (and for function calls when store_enabled=False). The JSON round trip already preserves these fields.

Description

Serialize the existing optional call_id field as an XML attribute in FunctionCallContent and FunctionResultContent, and read it when reconstructing each object. XML without the attribute continues to deserialize with call_id=None. This does not change the existing id field or introduce an ID fallback.

Regression tests exercise both public XML serialization entry points, legacy content without a correlation ID, and the actual Responses request preparation for both store_enabled modes.

Validation

• New regression cases against the original implementation: 4 failed, 2 passed.
• pytest tests/unit/contents tests/unit/agents/openai_responses: 438 passed, with 71 existing deprecation warnings.
• Official Python pre-commit checks passed both for all changed files and for the whole repository in a clean worktree with this same patch.
• Full-package mypy semantic_kernel: 23 errors in 6 files, identical line-for-line in a clean worktree at the original commit using the same environment. These errors are in unchanged code; this is not a claim of a clean full-package type check.
• An independent agent review also checked XML escaping, multiple calls, and backward compatibility. No live provider request was sent; request payload generation was verified locally.

Contribution Checklist

• The code builds clean without any errors or warnings — the full-package type-check limitation is recorded above.
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations.
• All unit tests pass, and I have added new tests where possible — the relevant 438 tests passed; the entire optional-provider suite was not run.
• The added tests preserve legacy XML behavior and keep item IDs separate from tool-call correlation IDs.

Prepared with AI assistance, including the implementation, tests, and this description. Local regression verification and an independent agent review are recorded above.

[Copilot]

🟢 Approval recommended

All reviewed changes and regression coverage are complete with no unresolved blocking issues.

Pull request overview

Preserves Responses API tool-call call_id values through chat-history XML serialization and deserialization.

Changes:

• Adds XML serialization and restoration for call_id.
• Adds XML round-trip and legacy compatibility tests.
• Verifies Responses request payloads for both storage modes.

File summaries

File	Description
python/tests/unit/contents/test_chat_history.py	Tests XML round-trip preservation and legacy behavior.
python/tests/unit/agents/openai_responses/test_openai_responses_thread_actions.py	Tests prepared Responses payloads.
python/semantic_kernel/contents/function_result_content.py	Persists function-result call_id in XML.
python/semantic_kernel/contents/function_call_content.py	Persists function-call call_id in XML.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 0
• Review effort level: Lite

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