Tardigrade: an open-source framework building agent harnesses as components over an immutable event log

viksit · x · 2026-09-04

Developer arjunkmrm released Tardigrade, an open-source framework that treats agent harness authoring like frontend UI development. Typical agent loops (compaction at context limits, turn limits, tool permissions, subagent budgets) accrete stateful conditions that make behavior hard to reason about.

Tardigrade defines a harness as a composition of components, each a typed state machine projecting from an immutable event log — "React for harnesses". Built with EffectTS, it runs locally or self-hosts as durable objects on Cloudflare. Details and code walkthrough at tardigrade.sh.

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