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Earendil released Pi 1.0, a minimal, extensible agent harness that the company says has been hardened through months of user feedback. The update adds Codemode, extension support for virtual models and several workflow features; Earendil also released Pi Durable as an experimental package for building long-running agent applications.
Earendil has released Pi 1.0, a hardened, minimal and extensible agent harness, adding features including Codemode, virtual-model extensions and deferred tool loading. The company also made Pi Durable, a separate experimental package for building long-running agentic applications, available alongside the release.
In its announcement, Earendil said Pi has been used by hundreds of thousands of people each week and that feedback, issues and pull requests informed months of work on the 1.0 release. The company described the update as a step toward a stable tool that people and businesses can depend on, while retaining Pi’s minimal design. Those descriptions are Earendil’s assessment; the announcement does not provide independent reliability measurements or service-level commitments.
The listed additions include Codemode, which the announcement describes as native support for MCP and non-LLM models such as Jev and image models, as well as extension support for virtual models. Other changes include deferred tool loading, cache warming for Anthropic models, mid-conversation system messages that account for transcript and tool changes, a new terminal user-interface theme, and full-screen mode by default.
Earendil said it had considered many candidate features over several months and included those it believed added useful functionality without unnecessary complexity. The source gives no benchmark results, performance measurements or detailed compatibility matrix for the new features. It says Pi 1.0 is available through installation instructions for macOS, Linux and Windows, and that both Pi and Pi Durable are MIT licensed, with documentation at pi.dev and code at the Earendil Works GitHub repository.
New Tools for Agent Builders
Pi 1.0’s release matters to developers who want to shape an agent harness around their own workflows rather than adopt a larger, fixed application. Codemode and extensions for virtual models broaden the kinds of models and tools users can connect, while deferred loading and cache warming address tool availability and model interaction within the system. The announcement presents these as additions to an intentionally minimal base, rather than a move toward an all-in-one agent product.
The simultaneous release of Pi Durable as an experimental package marks a separate direction: supporting applications and tasks that persist beyond a conventional coding-agent session. Earendil says it is intended as a substrate that lets builders and users steer the underlying intelligence. Since the package is explicitly experimental and the announcement offers no deployment results, its practical readiness and limits are not established by the source.
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From Coding Agent to Durable Systems
Before the 1.0 release, Earendil said Pi already worked with the latest models from major providers and was used as a daily coding agent, as well as a foundation for custom agentic applications. These are statements from the company; the announcement does not name every provider or specify the models and dates covered.
Earendil framed the release around a preference for adopting new agent features only after they have demonstrated lasting value, weighing their functionality against added complexity. The company also said some users wanted to use Pi beyond a coding agent and terminal, including through different interfaces and in longer-running conversations and tasks. Rather than reshape Pi itself to meet those needs, Earendil said it put that work into the separate Pi Durable package.
“Pi is known for being minimal. We care about holding that line.”
— Earendil, in the Pi 1.0 announcement
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Limits and Adoption Still Unclear
The announcement does not specify the exact release date beyond saying Pi 1.0 is shipping “today,” and no calendar date is included in the supplied material. It also does not provide independent adoption figures, testing results, model-compatibility details, or evidence of how the new features perform in production. The claim that hundreds of thousands of people use Pi weekly is Earendil’s figure; the source gives no measurement method or reporting period.
Pi Durable is described as experimental, but the announcement does not set out a development roadmap, stability guarantees, supported deployment environments or a date for any later production-ready status. It remains unclear how broadly its approach will be adopted, and whether users will find the new Pi features easy to integrate into existing workflows.
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Installation and User Feedback
Pi 1.0 and Pi Durable are available now, according to Earendil. The company directs users to pi.dev for documentation and to its GitHub repository for the code; its announcement provides installation commands for Pi on Unix-like systems and Windows, and an npm command for the experimental Durable packages.
Earendil said it wants feedback from users and plans to continue developing the tools in the open. The announcement does not identify a specific follow-up release or milestone. For now, the next indications of how the launch is progressing will be the project’s documentation, repository activity and feedback from developers trying the new capabilities.
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Key Questions
What is Pi 1.0?
Pi 1.0 is an agent harness that Earendil describes as minimal, hardened and extensible. The release adds features for connecting tools and models and for customizing agent workflows.
What new features are included?
Earendil lists Codemode, 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.
What is Pi Durable?
Pi Durable is a separate experimental package that Earendil says provides a substrate for building long-running agentic applications. The announcement does not describe it as a production-ready replacement for Pi.
How can developers access Pi?
Earendil says Pi 1.0 is available through installation instructions at pi.dev, with code on its GitHub repository. Pi and Pi Durable are described as MIT licensed; the Durable packages can be installed through npm.
Source: hn
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