React for Agents: Astro Creator Brings Hooks to his Meta-Harness, Flue
Latent Space Richard MacManus
Astro creator Fred Schott just shipped Flue 2, built around React-style agent hooks. He’s betting the big idea isn’t routing — it’s giving agents a harness so they can adapt live.
Based on reporting by Latent Space, Richard MacManus — read the original for the full story.
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Agent frameworks are still young enough that the rules are being written in public. Fred Schott’s Flue, now at version 2 and its first stable release, is one of the clearest attempts yet to define them. The Astro creator, whose company was acquired by Cloudflare in January, is building around a React-inspired idea: agents should be composed with hooks, not just wrapped in scripts.
In Flue, an agent is a JavaScript function that re-renders on every turn, before each model call. The hook system is written in TypeScript and, according to the launch post, lets developers add state, respond to lifecycle events, and attach resources or capabilities as the agent runs. There are 16 built-in hooks, including useSkill(), useTool(), and useSubagent(), and developers can add their own.
That shift came from Schott realizing that the web-framework instincts he started with were too narrow. He had first tried to map familiar patterns like file-based routing onto Flue, but the early users pushed him toward something else. For a lot of teams, he said, the whole company is effectively one agent. Routing doesn’t matter much when the real problem is letting that agent change shape as the work changes.
That is why the word Schott keeps returning to is harness. Flue sits on top of Pi, an open source minimal harness, and Schott treats that layer as fundamental rather than optional. The point is to put the agent in an environment where it can access the context and capabilities it needs, instead of having code constantly poke it with instructions. Flue 2’s hosted agents are built with Vite, and Schott compares Pi’s role to the base layer Vite plays under Astro.
The pitch is also a quiet answer to the current scramble in agent tooling. Schott calls Vercel’s eve the closest competitor, and he’s fine with that comparison because both frameworks treat the harness as built in. He’s less interested in the newer “meta-harness” buzz, saying Flue’s framework and harness are too intertwined for that abstraction to be the whole story. For now, he says, the only roadmap item that matters is building the best harness.
My take — AI-written commentary, not fact-checked reporting
This is the right argument at the right time: stop pretending an agent is just a prompt with a cute wrapper. The industry loves pretending the hard part is the front end, then discovers the real work is state, tools, and boring control flow. Open source plus host portability still looks like the sensible bet here, especially when the alternative is yet another platform-shaped cage.
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