Earendil defines a harness as "storage plus the machinery needed to run one or more conversations with large language models in parallel." In Pi Durable, "everything the harness runs, from calling the model to executing a tool, is a…
In the News: October 1, 2026 (Evening)
Earendil ships Pi Durable, an experimental harness that checkpoints every model call and tool call so agents resume after a crash, alongside Pi 1.0.
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Pi Durable makes crash recovery a harness primitive
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Pi 1.0 adds deferred tool loading and mid-conversation system messages
Earendil lists what 1.0 adds: Codemode with native MCP support, extension support for virtual models, deferred tool loading, cache warming for Anthropic models, mid-conversation system messages ("transcript-aware prompt and tool…