Pi 1.0: a minimal, MIT-licensed agent harness hits stable
Earendil's harness, used by hundreds of thousands weekly, goes MIT: Codemode for MCP and non-LLM models, cache warming, and a crash-proof durable runtime.
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Pi 1.0: the minimal harness, now MIT
Earendil shipped Pi 1.0, a hardened, minimal coding-agent harness already run by hundreds of thousands of developers weekly, now MIT-licensed and installable with a single curl command from pi.dev. It runs the latest models from every major provider and is built to be reshaped around your workflow instead of locking you into one vendor's CLI.
Codemode wires MCP and non-LLM models into one loop
The headline 1.0 feature is Codemode: native support for MCP tools plus non-LLM models like Jev decision models and image generators, all inside the same agent. You could stand up an agent this weekend that routes with a fast decision model and returns images, no glue code required.
The token and latency tricks, finally readable
Pi 1.0 bakes in deferred tool loading, Anthropic prompt-cache warming, and mid-conversation system messages, the same efficiency tricks big proprietary CLIs use to hold down your token bill and latency, but in MIT code you can read and copy. If you've wondered how agents keep cache hits high across long sessions, it's now open.
Pi Durable: crash-proof, forkable long-running agents
A companion package, Pi Durable (experimental, via npm), extends Pi to long-running agents with checkpoint recovery, replayable tools, hot-swappable extensions, conversation forks, and persistent state, and runs beyond the terminal. It's the missing piece for agents that must survive restarts or branch mid-task.