Cloudflare's three-layer agent stack puts the host at the bottom and the framework on top

The figure is three: the number of layers Cloudflare says production agents now require, set out in the post introducing its new framework, Flue ^[1]. Cloudflare supplies the bottom layer, and since 16 January it employs the team that supplies the top one ^[2][3].

The stack it draws is framework, harness, runtime ^[1]. What sits underneath is a constraint rather than a taxonomy: Cloudflare argues that the hard parts of running agents, including resuming after an interruption without losing context, executing untrusted code securely, and reaching the tools a model was trained for, are tied to state, storage and compute, so a harness cannot solve them on its own ^[6]. It has therefore pushed durable execution, dynamic code execution, a durable filesystem and dynamic workflows into the Agents SDK as a base layer ^[7]. Flue, open source, from the team behind Astro, and built on the Pi harness that also underpins OpenClaw, is the first framework to build on it ^[4][5].

Vercel published the same shape a different way. eve is in public preview, open source, and ships with durable execution, sandboxed compute, human-in-the-loop approvals, subagents and evals built in ^[10]. It is the framework Vercel builds and runs its own agents on ^[11], and an eve agent is an ordinary Vercel project that `vercel deploy` sends to production unchanged ^[12]. Both frameworks advertise durable execution, a sandbox and drop-in channels for Slack, GitHub and Discord ^[16]. That leaves the feature list as the thing they share and the host's primitives as the thing they do not. Two infrastructure vendors now maintain their own open-source agent framework ^[15].

The acquisition prices that trade. Astro remains open source under Cloudflare's stewardship ^[8], and Fred Schott, CEO of The Astro Technology Company, says Astro will stay the best way to build content-driven websites "whether they host on Cloudflare or elsewhere" ^[9]. Neutrality at the framework layer is cheap to promise; durable execution is the layer Cloudflare itself describes as dependent on the platform underneath ^[6].

Watch whether Flue and eve run where their vendors do not. Astro 6's beta adds support for additional JavaScript runtimes ^[20], and the Astro Ecosystem Fund still lists Webflow, Netlify, Wix and Sentry as partners ^[18].