serve is the command you leave running while you work.
One process covers every selected folder, and both halves of each:
- client modules go through Vite, with HMR
- API routes run in the same process, hot-reloaded on change
- requests are dispatched between the two by the folder's
backend.base
No second command to start, no proxy to configure.
pnpm dev # every folder
pnpm dev admin front # just these twoListens on devPort (default 4556, configured in package.json).
Dev is always client-rendered
serve is Vite + HMR + client-side rendering, whether or not the folder has SSR enabled.
Server rendering happens in the production build, so there is no server-rendered markup to look at here.
This catches people out coming from Next, Nuxt or TanStack Start, where dev mirrors production rendering. To see anything server-rendered, use kosmo preview.
Selecting folders
With no arguments, every source folder is served. Name one or more to narrow the scope - the names are directory names under src/.
A name with no src/<name>/kosmo.config.ts stops the command before anything runs, and a project with no folders at all reports No source folders detected.
Narrowing changes what the one process serves: folders you left out are not mounted, so their paths 404 on devPort rather than falling through.
Ports
devPort is the only port you address.
Each folder's Vite server and HMR socket get their own, picked from a free range derived from devPort - which is why the command insists on a devPort below 64000, so that range still fits.
devPort is not negotiated.
If something else holds it, the dev server reports Failed to start dev server on port 4556 and exits rather than moving, so the URL you have open never silently changes under you.