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Earendil has released Pi 1.0, a stable update to its minimal, extensible agent harness, with features including Codemode, virtual-model extensions and deferred tool loading. The company also introduced Pi Durable, a separate experimental package for building longer-running agent applications.
Earendil has released Pi 1.0, an update to its minimal, extensible agent harness, adding features for connecting tools and models, changing prompts during a session and customizing the interface. The company also released Pi Durable, a separate experimental package intended as a foundation for longer-running agent applications.
Earendil says Pi 1.0 is the result of months of development and feedback from users submitting issues and code contributions. The company describes the release as a hardened, stable version of software used by hundreds of thousands of people each week. That usage figure comes from Earendil; the announcement does not give a measurement method or a narrower time period.
The release adds Codemode, which Earendil describes as native support for MCP and for non-language-model models, including Jev and image models. Other additions include support for extensions that create virtual models, deferred tool loading, and cache warming for Anthropic models. Pi can also now receive system messages during a conversation with transcript-aware prompt and tool changes.
Interface changes include a new terminal user-interface theme and full-screen mode by default. Earendil says it considered potential additions over several months and adopted features it believed had proved useful, while rejecting others to keep the product minimal. The announcement provides a feature list and examples, but not independent performance results or comparative tests.
New Ways to Extend Pi
The update broadens how developers can configure and use Pi without, according to Earendil, abandoning its minimal design. Virtual-model extensions can combine different models for different tasks, while Codemode adds routes for working with tools and non-LLM models. Deferred tool loading and cache warming are also intended to change how an agent manages its available tools and model interactions.
For users building agent-based software, the separate Pi Durable package points to a different use case: applications that need to support longer-running tasks and conversations, and that can be reached beyond a coding agent or terminal. Earendil describes it as a substrate for builders and users to steer underlying intelligence. Because the package is experimental, its longer-term reliability and suitability for production use are not established in the announcement.
The practical impact will depend on how the new features behave in real projects and how developers adopt them. Earendil has made both packages available under the MIT license, which permits broad use under that license’s terms. The release itself does not establish how widely the new capabilities will be used or whether they outperform alternatives.
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Pi’s Minimalist Design Approach
Earendil presents Pi as a coding agent and a flexible base for building other agentic applications. The company says Pi already works with the latest models from major providers, though the release announcement does not list those providers or specify model versions. It also says users have made Pi a daily coding tool and used it as a customizable foundation for other applications.
The company frames the 1.0 release around a deliberate approach to adding features: wait for an approach to prove itself, then weigh its usefulness against the complexity it adds. Earendil says it has discussed that process and its relationship to Codemode and MCP in an earlier post. It does not provide a detailed account in this announcement of the features it rejected or the evidence used to make each decision.
Earendil says some people wanted to use Pi beyond a terminal-based coding agent, including for longer conversations and tasks. Rather than reshape Pi itself around those needs, it says it created Pi Durable as a separate package that carries forward Pi’s principles of minimalism and flexibility into a different application-building setting.
“A hardened, minimal, extensible agent harness that you can make your own.”
— Earendil, in its Pi 1.0 announcement
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Open Questions on Adoption
The announcement does not specify the calendar date of the release, provide independent verification of the reported weekly user count, or publish benchmarks for the new features. It also does not give detailed compatibility requirements, model coverage or performance measurements for Codemode, cache warming, deferred tool loading or virtual-model extensions.
Pi Durable is explicitly experimental. Earendil does not state when it might be considered stable, what service or support commitments apply, or which production workloads it has been tested against. The announcement also does not clarify how the package handles persistence, recovery or operational requirements for long-running applications. Those details may be available in separate documentation, but they are not established in the supplied release information.
long-running AI application framework
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Documentation and User Feedback
Both 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. Pi can be installed through the shell and PowerShell commands listed in the release announcement; Pi Durable is available through npm as the packages @earendil-works/pi-durable, @earendil-works/pi-ai and @earendil-works/chord.
Earendil says it wants feedback from users as it continues developing the tools. The company has not announced a date for a follow-up release or a timeline for Pi Durable to move beyond experimental status. Near-term indications of progress are likely to come from the published documentation, code changes and how users report working with the new features.
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Key Questions
What is Pi 1.0?
Pi 1.0 is an update to Earendil’s minimal, extensible agent harness. It adds features including Codemode, virtual-model extensions, deferred tool loading and mid-conversation system-message changes.
What is Pi Durable?
Pi Durable is a separate experimental package for building longer-running agent applications. Earendil says it is intended to extend Pi’s minimal and flexible approach beyond terminal-based coding agents.
Is Pi Durable a stable release?
No. Earendil describes Pi Durable as experimental. The announcement does not provide a schedule for a stable release or details of production-readiness testing.
Where can developers get Pi?
Earendil says Pi 1.0 is available through its installation instructions, with documentation at pi.dev and source code at the Earendil Works GitHub repository. Pi Durable’s listed packages are available through npm.
Source: hn
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