Earendil Pi 1.0: MIT coding-agent harness with Codemode, MCP, and experimental Durable

Earendil shipped Pi 1.0 on Oct 1, 2026: a hardened, minimal, extensible coding-agent harness you can make your own. Both Pi and the same-day companion are MIT licensed. Install today from pi.dev; code lives at github.com/earendil-works/pi (announce).

Earendil says hundreds of thousands of people use Pi every week—treat that as a vendor claim, not an independently audited MAU figure here.

What’s in 1.0

Per Earendil’s feature list (primary):

• Codemode — native MCP support, plus support for non-LLM models (Earendil cites examples such as Jev and image models as capability color, not a separate product pitch)
• Extension support for virtual models (e.g. plan with one model, implement with another)
• Deferred tool loading
• Cache warming for Anthropic models (provider-specific as stated; not generalized to every vendor)
• Mid-conversation system messages — transcript-aware prompt and tool changes
• Full-screen mode by default (TUI), plus a new TUI theme

This is an agent harness / CLI—not a Raspberry Pi story, and not Magnitude’s on-device local-inference engine.

Install

Primary path from the announce:

curl -fsSL https://pi.dev/install.sh | sh

Docs at pi.dev. Windows PowerShell and npm/pnpm/bun global installs for @earendil-works/pi-coding-agent are also shown on the product site.

Same-day: experimental Pi Durable

Alongside 1.0, Earendil shipped Pi Durable as the experimental npm package @earendil-works/pi-durable—a substrate for long-running, crash-resumable, multiplayer agent apps (checkpointed tasks; multi-client attach and steer). It does not replace the Pi coding agent (Durable post).

Experimental: Earendil and the npm README state the API may change / changes without notice between releases. Do not read Durable as stable GA.

Install line from the announce (pulls companions @earendil-works/pi-ai and @earendil-works/chord as well):

npm install @earendil-works/pi-durable @earendil-works/pi-ai @earendil-works/chord

Prior Codemode context

Days earlier (Sep 29, 2026), Earendil published “You Said No MCP!”—the Codemode / MCP rethink essay. Today’s post is the numbered 1.0 ship plus Durable, not a re-run of that essay alone. Discussion also landed on HN.

Who should care

Builders who want a minimal MIT coding-agent harness with native MCP via Codemode, deferred tools, virtual-model extensions, and a fullscreen TUI can start at the Pi 1.0 post and pi.dev. Teams experimenting with long-running multiplayer agent apps can peek at Pi Durable—treat it as experimental: the API may still change. No paid SKUs were confirmed on this pass.