Earendil ships Pi 1.0 agent harness and Pi Durable package
Earendil has announced Pi 1.0, which it describes as a hardened, minimal, extensible agent harness that users can make their own. The authors say hundreds of thousands of people around the world use Pi every week, and that many of them submit issues and pull requests. Over many months, they say, that feedback was used to improve, harden and evolve Pi into a stable piece of software that people and businesses can depend on.
The post leans on Pi's reputation for being minimal. Its authors say agentic tooling changes every week and many of the changes do not last, so Pi waits until something has proven itself and only then considers adopting it, weighing its real functionality against the complexity it adds. They point to an earlier post from the same week about how that process applied to Codemode and MCP. Before 1.0, Pi already ran the latest models from every major provider, had become a daily driver coding agent for people around the world, and served as a highly malleable base for building agentic applications.
Pi 1.0 adds seven things: Codemode, with native support for MCP and for non-LLM models such as Jev and image models; extension support for virtual models; deferred tool loading; cache warming for anthropic models; mid-conversation system messages, meaning transcript-aware prompt and tool changes; a new TUI theme; and full-screen mode by default. The authors say they thought about many of these features for months, that they were "thrown up against the wall and stuck", and that the list of ideas that fell off is much longer. In their words, Pi with these features feels like a major step forward but still feels simple.
The second announcement is Pi Durable. Earendil says some aspects of Pi did not fit how many people wanted to use it. The company wants Pi's minimalism to work outside the coding agent and outside the terminal: reachable from different surfaces, and able to support longer-running conversations and tasks. "In short, Pi must become more durable." Rather than stretch Pi into something it was not, the team put that work into a separate, experimental package. Pi Durable is described as a new substrate for building long-running agentic applications, one that lets both the builders and the users of those applications steer the underlying intelligence. It shares Pi's principles of minimalism and malleability while extending them in new directions. Mario, whose surname the post does not give, writes about how Pi Durable was crafted in a separate post.
The post closes with the company's stated purpose: Earendil was formed to craft software and open protocols that strengthen human agency. Both releases are available the day of the post and are MIT licensed. Pi 1.0 installs with a shell script (curl -fsSL https://pi.dev/install.sh | sh) or, on Windows, a PowerShell command (powershell -c "irm https://pi.dev/install.ps1 | iex"). Pi Durable is an npm package installed together with @earendil-works/pi-ai and @earendil-works/chord. Documentation is at pi.dev and code at github.com/earendil-works/pi.
Key facts
- Earendil ships Pi 1.0, described as a hardened, minimal, extensible agent harness; the authors claim hundreds of thousands of weekly users.
- New in 1.0: Codemode (native MCP plus non-LLM models like Jev and image models), extension support for virtual models, deferred tool loading, cache warming for anthropic models, mid-conversation system messages, a new TUI theme, and full-screen mode by default.
- Pi Durable is a separate experimental package, a substrate for long-running agentic applications that reach beyond the coding agent and the terminal.
- Both are MIT licensed. Pi 1.0 installs via a curl script or PowerShell command; Pi Durable via npm alongside @earendil-works/pi-ai and @earendil-works/chord.
- The authors say Pi adopts features only after they have proven themselves, weighing functionality against added complexity.
Why it matters
Pi 1.0 marks the point where Earendil calls its agent harness stable enough for people and businesses to depend on. The pitch is restraint: in a field where, in the authors' words, tooling changes every week and many changes do not last, Pi adds a feature only after it has proven itself. The 1.0 list is short for that reason, and the authors say far more ideas were dropped than kept. The second release, Pi Durable, shows where they want to go next: Pi's minimalism applied to long-running work and to surfaces other than the terminal, built as a separate package so Pi itself does not change shape.
Who it affects
Existing Pi users get the new features and the 1.0 label; the authors say hundreds of thousands of people already use Pi every week. Developers who run Pi as a daily coding agent will see a new TUI theme and full-screen mode as the default. People building agentic applications on Pi as a base are the audience for Pi Durable, which targets longer-running conversations and tasks. Users who work with MCP servers, non-LLM models or image models are the ones Codemode is aimed at.
How to use it
On Unix-like systems, install Pi 1.0 with curl -fsSL https://pi.dev/install.sh | sh. On Windows, run powershell -c "irm https://pi.dev/install.ps1 | iex". To try Pi Durable, run npm install @earendil-works/pi-durable @earendil-works/pi-ai @earendil-works/chord. Both are MIT licensed. Documentation is at pi.dev and the code is at github.com/earendil-works/pi. For the design of Pi Durable, the announcement points to a separate post by Mario.
How solid is it
This is a release announcement written by the makers of Pi, so every claim about quality, stability and usage is the authors' own. The weekly-user figure is given only as "hundreds of thousands", with no method stated. No benchmarks, performance figures or pricing are given. The post does not explain what Jev is, and it does not describe Pi Durable's architecture or API; that is deferred to Mario's separate post. The software is available now under the MIT licence, so the claims can be tested directly.
Risks and caveats
Pi Durable is explicitly labelled experimental, and the post states no stability or roadmap commitment for it. Pi 1.0 changes some defaults, with full-screen mode now on by default and a new TUI theme, so existing users will notice the difference. The post names no businesses that depend on Pi, so the claim that businesses can rely on it rests on the authors' word. Details of how Codemode and virtual-model extensions behave are not covered in this post.
“Rather than stray from our minimal roots and try to make Pi something it wasn't, we combined that work into a new experimental package that we are shipping today, Pi Durable.”
— Earendil, Pi 1.0 announcement