Marvin - AI Engineering Toolkit

Marvin is a lightweight AI engineering toolkit for building natural language interfaces that are reliable, scalable, and easy to trust.

Reproductions

• use the repros folder to reproduce the results (e.g. uv run repros/1234.py)
• this folder is not checked into git

Architecture & Design Philosophy

• Aggressively minimal and elegant: Keep implementations simple and focused
• Functional first: Prefer functional approaches, use classes where justified
• Type-safe: Full type annotations, modern Python syntax (3.10+)
• Private internals: Keep implementation details "private" (e.g. def _impl)

Key Components

• Engine: Core AI interaction layer
• Tasks: Structured AI task definitions and execution
• Tools: Extensible function calling capabilities
• Agents: AI agents with tool access and memory
• Memory: Persistent conversation and context storage
• Handlers: Event processing and routing
• CLI: Command-line interface for common operations

Development Guidelines

Type Hints

• Use X | Y instead of Union[X, Y]
• Use builtins like list, dict instead of typing.List, typing.Dict
• Use T | None instead of Optional

Dependencies & Running

• Use uv for dependency management and script execution
• Install deps: uv sync or uv sync --extra foo
• Run scripts: uv run some/script.py or uv run --with pandas script.py
• Testing: uv run pytest or uv run pytest -n3 for parallel

Finding Things

• Use rg for searching, not grep
• Use ls and tree for navigation
• Check git context with using the GitHub MCP server
• Think like a hacker with good intentions - search in site-packages when needed

Linter Philosophy

• Empirically understand by running code
• Linter tells basic truths but may be orthogonal to goals
• Don't obsess over upstream linter errors, use as clues when relevant