multi-mcp copilot-instructions.md

Copilot Code Review Instructions

These instructions define how GitHub Copilot should review pull requests in this repository. This is a production-grade Python MCP (Model Context Protocol) proxy server built on asyncio, anyio, Starlette, Pydantic, and loguru. Apply the following standards on every review.

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Architecture & Design

• This codebase uses an async-first architecture. Flag any blocking I/O calls (e.g., open(), requests.get(), time.sleep()) made outside of an executor — suggest anyio/asyncio async equivalents instead.
• All configuration must flow through Pydantic models (pydantic-settings). Flag any raw os.environ or os.getenv calls that bypass the settings layer.
• The proxy pattern (aggregating multiple MCP backends into one endpoint) is core to this project. Flag any code that tightly couples business logic to a specific backend transport (stdio vs SSE) — these should be abstracted.
• Prefer dependency injection over global state. Flag module-level mutable globals.

Security

• Flag any place where the --api-key value could be logged, printed, or exposed in tracebacks. API keys must never appear in log output at any level.
• Flag any use of subprocess or shell=True without explicit input sanitisation.
• Flag any dynamic eval(), exec(), or __import__() usage.
• Flag any file path construction that uses raw string concatenation instead of pathlib.Path.
• Ensure all external HTTP calls use httpx (the project standard) — flag use of requests in new code since requests is synchronous and not appropriate for this async codebase.

Code Quality

• All public functions and classes must have docstrings. Flag missing docstrings on anything that is not a private helper (_ prefix).
• Type annotations are required on all function signatures. Flag unannotated parameters or return types.
• Pydantic v2 patterns must be used throughout. Flag any Pydantic v1 patterns such as .dict(), .parse_obj(), validator decorators — suggest v2 equivalents (.model_dump(), .model_validate(), @field_validator).
• Flag bare except: or except Exception: clauses without logging or re-raising — silent swallowing of exceptions is not acceptable in a proxy server.
• Flag any TODO, FIXME, or HACK comments introduced in the PR diff.