Fred Schott, creator of Astro, has released Flue 2, the first stable version of his agent framework, introducing React-inspired 'Agent Hooks' for building dynamic, composable agents. Flue functions re-render on every conversational turn, and 16 built-in hooks (useSkill, useTool, useSubagent, etc.) let developers attach capabilities dynamically at runtime instead of statically configuring agents upfront. Schott explains the pivot away from file-based routing (borrowed from web frameworks) toward React-style composability, since many customers run a single agent rather than multiple routed ones. The framework is built on Pi, an open-source minimal harness, with Schott arguing 'there is no agent without a harness' — a philosophy shared by Vercel's competing eve framework. Despite Cloudflare (Schott's employer) backing, Flue remains host-portable, and Schott discusses positioning against 'OG' frameworks like Vercel AI SDK, Cloudflare Agents SDK, and Mastra, as well as emerging meta-harness concepts like Databricks' Omnigent and Exo.
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File based magic is an antipatternFlue’s central proposition: agents need a harnessBuilding Flue agents with coding agentsWhere Flue fits in the agent development stackThe Cloudflare connectionQuestions this post answers
What are Agent Hooks in Flue 2 and how do they work?
Agent Hooks are React-inspired TypeScript hooks in Flue 2, the first stable release of Fred Schott's agent framework, that let agents manage their own state, listen to lifecycle events, and dynamically attach resources or capabilities at runtime. Flue 2 ships 16 built-in hooks, including useSkill(), useTool(), and useSubagent(), plus support for custom hooks, and an agent function re-renders on every conversational turn before each model call. Developers evaluating agent frameworks can track Flue's evolution and comparisons on daily.dev.
What is the difference between Flue and Vercel's eve agent framework?
Both Flue and Vercel's eve treat the harness as a built-in, foundational part of the framework rather than an add-on feature, unlike older frameworks such as Vercel AI SDK, Cloudflare Agents SDK, or Mastra. The main distinction is portability: eve is optimized to take advantage of Vercel's platform features even though it can be self-hosted, while Flue is designed as an open source framework meant to work equally well across any host. Teams choosing between agent frameworks can compare Flue and eve tradeoffs on daily.dev.
What is a harness in the context of AI agent frameworks like Flue?
A harness is the environment that gives an agent access to the context and capabilities it needs to accomplish tasks, letting the agent drive itself through problems rather than being scripted step by step by code. Flue is built on Pi, an open source minimal harness, with Schott comparing Pi's foundational role to how Vite underlies Astro, and arguing there is no agent without a harness. Developers building on agent harnesses can follow this fast-moving space on daily.dev.