Yielded Agent

An agent harness toolkit for TypeScript built on Effect and Effect AI. It builds durable agent Threads: you define schemas, instructions and tools, and the runtime runs the model/tool loop, validates output and can retain accepted work across process restarts.

A Thread is the conversation, a Run is one logical execution of it, and an Attempt is one period advancing that Run. Additional input can join an active Run, and model context, history and recovery state have separate lifetimes.

bun add @yielded/agent@beta effect. The getting-started guide covers provider setup and an executable entry point; the runtime needs a model and history Layer supplied by your application.

Process-local conversations use InMemory.layer, retained successful history uses SQLite or PostgreSQL adapters, durable Node services use a supplied SQLite host or a custom PostgreSQL host, and durable Cloudflare services use SQLite-backed Thread Objects.

No. The README says a durable receipt means the runtime owes a terminal settlement, recorded results are reused, uncertain ordinary mutations require reconciliation, and Durable Steps need external idempotency — there is no exactly-once external execution guarantee.

Your application supplies authorization, tool handlers, model services and storage. Yielded Agent supplies typed execution, bounded work, approvals and recovery under a single owner per Thread, with native Effect AI tools and provider Layers working directly.

It is published at beta (@yielded/agent@beta) with an MIT licence, CI on GitHub, a durability contract document and example applications such as a travel planner and a durable benchmark.