E0720: A page declared outside pages/

A page is a .vuka.html file under pages/: the file's path is its URL (pages/pets/[id].vuka.html serves /pets/{id}), and vuka writes its registration in pages/route.go. A page is declared nowhere else — not with @web.Live, not with a route decorator on a type, and not by registering its struct from Go with app.Get, app.Live, app.Page or web.Routes.

A route is a page when what it registers is a struct that renders: Live and Page always; otherwise a constructor, func(deps…) *T, whose *T is a ui.Node or whose T embeds ui.Live, or a route with ui.Island(…). A function is a handler — an API — whatever it returns: data, nothing, an error, or a ui.Node it builds from components, such as a fragment a form post answers with. Handlers stay app.Get and the other verbs in Go, or a file of GET/POST/… functions under pages/api/.

Reported by the compiler (a decorator), by vukavet (a registration from Go, outside a generated file or a test, which may mount the page it tests), and at start-up (a decorator on a constructor).

Wrong

// pets.vuka
package app

@web.Live("/pets/{id}")
type Pet struct {
	ui.Live
	ID int
}

// main.go
app.Get("/about", NewAbout)

Right

<!-- pages/pets/[id].vuka.html -->
<script lang="go">
package pets

type Pet struct {
	ui.Live
	ID int
}
</script>

<h1>Pet {ID}</h1>

<!-- pages/about.vuka.html -->
<script lang="go">
package pages

type About struct{}
</script>

<h1>About</h1>