pi-fabric

A programmable tool and agent runtime for Pi

One program for tools, MCP, agents, workflows, actors, mesh, councils, and recursion.

🏆 100% on ARC-AGI-3. A Fabric-powered agent won all 25 environments in one 22.4-hour session with 4 minutes of human time ($1,349 in model spend).

Fabric gives Pi one programmable tool called fabric_exec, which composes core tools and MCP servers with captured extension tools. The default kernel runs checked TypeScript in isolated QuickJS; select sandboxed Python (Monty) with executor.kernel: "python". CPython is an explicit native escape hatch via executor.pythonRuntime: "cpython". The configured kernel is exclusive: there is no per-call language selector. Trusted TypeScript workloads can also use unsafe Node/Bun processes. Programs call host providers for agents, actors, and durable coordination, then return the result of their branches, loops, fan-out, and data flow. See [execution…