Green Tea: declare intent, derive execution

Expressive Tea Software publishes two frameworks. Green Tea is the one being built.

It is not a successor to Expressive Tea, and it is not a rewrite of it. It is a different answer to a problem that the decorator-and-middleware approach never solved.

The problem

const user = req.user;

It compiles. TypeScript is satisfied. And it is a prayer.

req.user exists only if some middleware ran before this handler — which depends on where the router got mounted, which line app.use() sits on, and whether a package installed last sprint quietly inserted itself into the middle of the chain. So the whole request has to stay in someone’s head: what ran, what is on req by now, what order things fire in, which plugin replaced the body parser.

That bookkeeping is where the bugs live, and neither the tests nor the types catch them, because nothing is wrong. Every line is correct and the application is still broken.

The idea

Green Tea puts the request on the page instead. Each step declares what it needs and what it produces; the framework derives the order from those declarations, type-checks the wiring before it serves traffic, and runs only the slice a given route actually depends on.

• Order is derived from dependencies, never maintained by hand.
• Boot fails loudly when nothing provides a key, so a handler never receives undefined.
• A route runs only the steps its handler depends on.
• app.explain('/users/:id') prints the whole chain. Onboarding becomes reading rather than archaeology.

A handler that reads ctx.user does not compile if no step produces user. “It was undefined in production” stops being a category of incident.

Where it runs

Node, Deno, Bun and Cloudflare Workers, over web-standard Request and Response. Every CI run exercises all four — the Deno, Bun and workerd suites are not an afterthought that gets skipped when they are inconvenient.

Where it stands

Green Tea is in beta, and the honest version of that is worth stating rather than softening.

Releases carry a -beta.N suffix on a calendar version; 26.8.0-beta.1 went out on 19 August 2026, to npm and to JSR. The API can still change between betas, and when it does the change is named in the changelog rather than discovered on upgrade. Install with the explicit tag:

npm install @green-tea/core@beta

latest resolves to the same version today, because there is nothing else to install. The day a stable release ships, latest moves and an implicit install silently changes channel — asking for @beta now means you stay on the channel you meant.

Only the newest beta receives security fixes; there is no backport channel yet. Anything exploitable goes to security@expressive-tea.io, not to a public issue.

What ends the beta is an API freeze and a first stable release — not a version number. Green Tea versions by calendar, so there is no 1.0 milestone on the way to wait for.

What is next

The API freeze and the first stable release. Beyond them: the mesh sub-specifications (discovery, load-balancing, failover), official plugins, and a radix-tree matcher for very large route tables.

Expressive Tea is not being retired in Green Tea’s favour. It stays in maintenance with its security patches, and a framework in maintenance is a reasonable thing to keep in production.

Green Tea is simply where the new work is.

Site · Docs · GitHub

The most recent release is covered in Green Tea 26.8.0-beta.1. The engineering story — first person, from the person who wrote it — is on the Green Tea blog.