Simple Coding Agent

gistfile1.txt

# Simplified version of https://martinfowler.com/articles/build-own-coding-agent.html

import asyncio
import subprocess

from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStdio



instructions = """
You are a specialised agent for maintaining and developing the XXXXXX codebase.

## Development Guidelines:

1. **Test Failures:**
   - When tests fail, fix the implementation first, not the tests
   - Tests represent expected behavior; implementation should conform to tests
   - Only modify tests if they clearly don't match specifications

2. **Code Changes:**
   - Make the smallest possible changes to fix issues
   - Focus on fixing the specific problem rather than rewriting large portions
   - Add unit tests for all new functionality before implementing it

3. **Best Practices:**
   - Keep functions small with a single responsibility
   - Implement proper error handling with appropriate exceptions
   - Be mindful of configuration dependencies in tests

Remember to examine test failure messages carefully to understand the root cause before making any changes.
"""


# MCP Servers
internet_search = MCPServerStdio(
    command="uvx", args=["duckduckgo-mcp-server"]
)
code_reasoning = MCPServerStdio(
    command="npx",
    args=["-y", "@mettamatt/code-reasoning"],
    tool_prefix="code_reasoning",
)
desktop_commander = MCPServerStdio(
    command="npx",
    args=["-y", "@wonderwhy-er/desktop-commander"],
    tool_prefix="desktop_commander",
)
context7 = MCPServerStdio(
    command="npx", args=["-y", "@upstash/context7-mcp"],
    tool_prefix="context"
)


# Agent Setup
agent = Agent(
    instructions=instructions,
    model="gpt-4o-mini",
    mcp_servers=[
        internet_search,
        code_reasoning,
        context7,
        desktop_commander,
    ],
)


@agent.tool_plain()
def run_unit_tests() -> str:
    """Run unit tests using uv."""
    result = subprocess.run(
        ["uv", "run", "pytest", "-xvs", "tests/"],
        capture_output=True, text=True
    )
    return result.stdout


@agent.instructions
def better_coding() -> str:
    """Guidelines for better coding."""
    import this
    return ''.join(this.d.get(i, i) for i in this.s)


async def main():
    async with agent:
        await agent.to_cli()


if __name__ == "__main__":
    asyncio.run(main())