[PD] let toy proxy handle /chat/completions

[lk-chen]

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
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Purpose

Let proxy forward not only /completions/ but also /chat/completions/ endpoint

Test Plan

Test Result

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Summary of Changes

Hello @lk-chen, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request extends the functionality of the toy_proxy_server by adding support for the /v1/chat/completions API endpoint. To achieve this, the existing request handling logic was refactored into a reusable function, which now serves both the new chat completions endpoint and the pre-existing completions endpoint, improving code maintainability and extensibility.

Highlights

• New API Endpoint Support: The toy_proxy_server now supports the /v1/chat/completions API endpoint, allowing it to handle chat-specific completion requests.
• Code Refactoring for Reusability: The core logic for handling completion requests has been refactored into a new private helper function, _handle_completions. This function now centralizes the processing for both the original /v1/completions and the newly added /v1/chat/completions endpoints, reducing code duplication.
• Dynamic Endpoint Routing: Internal calls to send_request_to_service and stream_service_response within the proxy now dynamically use the requested API path, making the handling logic more flexible.

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[gemini-code-assist]

Code Review

This pull request refactors the toy_proxy_server.py to support the /v1/chat/completions endpoint in addition to the existing /v1/completions endpoint. This is achieved by generalizing the request handling logic into a new internal function _handle_completions, which is a good strategy for reducing code duplication and improving maintainability. The changes appear functionally correct and enhance the server's versatility for testing.

My main suggestion is to leverage the existing logger for error reporting within the _handle_completions function instead of using print statements. This aligns with standard practices for server applications, offering more robust and configurable logging.

While docstrings for the new public endpoint handlers (handle_completions and handle_chat_completions) are not included as formal comments due to the requested severity filter (medium+), adding them would be beneficial for long-term clarity and maintainability.

Please also consider filling out the PR description template to provide more context for this change.

The code generally adheres to PEP 8 style guidelines.

[gemini-code-assist]

This error message has been updated to be dynamic using an f-string, which is a good improvement.

For more robust error handling in server applications, consider using the existing logger instance (available as logger in this file, initialized on line 16) instead of print. For example, using logger.error() or logger.exception().

If logger.exception(f"Error occurred in disagg prefill proxy server - {api} endpoint: {e!r}") were used here, it would also capture and log the full traceback automatically. This could simplify the subsequent print(e) (line 239) and print(traceback.format_exception(...)) (line 240) calls, though those specific lines are outside the scope of this particular change.

        logger.error(f"Error occurred in disagg prefill proxy server - {api} endpoint. Exception: {e!r}")