@seamstack/core

Core types and host-adapter contracts for SeamStack — pair any frontend with any backend.

pnpm add @seamstack/core

If you're building a SeamStack project, you don't install this directly — it comes in transitively via @seamstack/cli and the adapter packages. Install it explicitly only if you're authoring a new adapter (a frontend host or backend) and need the contracts.

What's in here

• The contracts every adapter implements: Serveable, DevContext, BuildContext, StartContext.
• Host-adapter utilities for spawning user backend processes (PATH normalization, wire-env construction, port handshaking).
• The shared types the CLI and adapters speak to each other through.

Authoring an adapter

A SeamStack adapter is a function returning an object that implements Serveable. The CLI calls it three times — once per phase (dev, build, start) — passing the resolved topology. The adapter's job is to start a frontend dev server, run a frontend build, or spawn a backend process — and tell the seam where it's listening.

The existing adapters (@seamstack/vite, @seamstack/hono, etc.) are the canonical examples of how to consume these types.

More

See the SeamStack README for the user-facing picture, the mix-and-match support table, and CLI docs.