cmd/protoc-gen-connect-python: follow connect-python APIs: 2025-07-08

[zchee]

This pull request introduces significant enhancements to the Python code generation for the Connect RPC framework, focusing on supporting bidirectional streaming, improving code structure, and handling method options like idempotency. Below is a summary of the most important changes:

Enhancements to RPC Method Support:

• Added support for BidirectionalStreaming RPC type in the generate function, including updates to the Method struct and handling in generated client and handler classes. [1] [2] [3] [4]

Improvements to Generated Code Structure:

• Updated import statements in generated Python files to use grouped imports for better readability and maintainability. [1] [2]
• Modified the handler class to use abc.ABCMeta as a metaclass and added context parameters to handler methods for better extensibility. [1] [2]

Handling of Method Options:

• Incorporated logic to process MethodOptions in the generate function, including idempotency level checks, and merged them into client options in the generated code. [1] [2] [3]

Formatting and Code Generation:

• Improved formatting of generated Python imports and method definitions to follow Python conventions, such as aligning multi-line imports and method calls. [1] [2] [3]

Version Update:

• Updated the version of the protoc-gen-connect-python plugin in the generated files to reflect the latest changes.

These changes collectively enhance the usability, performance, and maintainability of the generated code for Connect RPC services.