Compose Preview Catalogs MCP server

Compose Preview Server

The server behind compose-preview serve: catalog hosting, live render sessions, the playground, and the browser viewer surfaces. Its history was extracted from yschimke/compose-ai-tools; the CLI remains there and launches this repository's distribution.

What this repository ships

Archives on each GitHub release, and nothing on Maven Central.

The Compose/Wasm frontend is not an asset of these releases. It is built and released by yschimke/compose-ui-builder as compose-preview-ui-builder-web-.zip on that repository's own releases, and this build resolves it from there — the server archive carries an unpacked copy either way, and the standalone zip is for serving the editor yourself or pointing an existing serve at with --ui-builder-dir.

Nothing here is a Maven coordinate. Six modules used to publish — compose-preview-serve, compose-preview-mcp, and four more that existed on Central only because the first one's POM named them — and the arrangement cost more than it bought. A project dependency reaches a published POM as a coordinate, so adding one to :server meant publishing the dependency too; getting that wrong shipped compose-preview-server:ui-builder-export-jvm:unspecified in 3.1.0 and an unresolvable compose-preview-serve from 3.3.0 through 3.8.0. Six releases nobody could resolve, for transitives nobody wanted.

The one library consumer was compose-ai-tools' :cli, which compiled two wire-drift tests against compose-preview-serve. Those tests launch the distribution now (compose-ai-tools#5436) — the artifact serve runs anyway, so they check the wire that actually ships. Released coordinates up to and including 3.24.0 stay resolvable on Central; there simply will not be new ones.

render-host exists because rendering a packed bundle and reading a preview timeline out of git open no sockets, and a caller doing only that should not link ktor-server-, jmdns and kotlin-reflect to do it. It is published from compose-ai-tools**, not from here: that is where everything it depends on lives, and offline behaviour belongs in that layer (#180). It used to be this repository's :render-host module, publishing as compose-preview-render-host; that coordinate stays resolvable at its final 2.x for anyone pinned to it, and the new one is on compose-ai-tools' version line. The measured before/after and the transitives it deliberately cannot drop are recorded in its build file there, and checkRenderHostIsServerFree moved with it.

The UI builder is a second repository — yschimke/compose-ui-builder — and :server consumes it as releases. Its :ui-builder-runtime owns authoritative persistent design state, exact catalog validation and revision-pinned export orchestration there; :server supplies HTTP/authentication and adapts its narrow render request onto the render host. The runtime therefore has no Ktor, daemon/render-host, MCP or Compose UI dependency, while the offline render host has no UI-builder protocol or service edge. Three jars and a BOM come from Maven Central at composeai-ui-builder in gradle/libs.versions.toml, and the editor archive from that repository's GitHub release; -PcomposeUiBuilderDir swaps all four for a checkout when working on both at once.

Shortened. The full README is on GitHub.