pydantic-ai-harness

Why we included this project

Agents that run for hours, fixing a codebase or researching a question, need more around the model than a typed loop. Pydantic AI Harness is the official library that supplies that structure for Pydantic AI: a filesystem workspace, a shell with an allowlist, planning, cross-session memory, sub-agents, and context compaction that keeps a session coherent into hour ten. Each piece is a capability you add to an agent, and complete agents like Coder and Researcher are just those blocks combined, so you can start from a whole coding agent and strip it down or assemble your own stack. Durable execution means a long job survives a restart, which makes it a practical fit for teams already on Pydantic AI whose agents have outgrown the basic loop.