ThinHarness is a minimal, opinionated Python harness for purpose-built agents.
It gives you the agent-loop primitives that are tedious to rebuild — scoped filesystem tools, structured output, retries, approvals, subagents, MCP, streaming, and tracing — in under 8k LOC, and leaves orchestration, auth, storage, and deployment to your app.
Pre-1.0, open source (MIT), Python.
