editorPanel

local edui = require("@builtin::~edui.framework")

return {
    title = "My Tab",        -- the tab's label (`label` is accepted too)
    order = 60,              -- sort position in the menu
    dock = "bottom",         -- seeds the FIRST arrangement: left | right | bottom | center
    menu = "scene",          -- which top-bar menu lists it; an unknown name creates that menu
    startClosed = true,      -- registered closed; opened from the menu
    build = function()       -- the tab's body, called again whenever it should change
        return edui.panel{ body = edui.text{ text = "hello" } }
    end,
}

build is the only required field. The tab id defaults to the folder stem (myTab.editorPanel → myTab); an explicit id overrides it, and a duplicate id replaces the prior registration. An init may return a LIST of specs when one asset carries several tabs — a spec this registration no longer declares has its tab taken down.

The spec is forwarded whole to edui.shell.addPanel, so anything the shell accepts (badge, badgeColor, …) works here; man edui.shell is its contract.

build may return nil to mean "nothing changed, keep what is drawn" — the shell rebuilds open tabs on a timer, and a panel that re-publishes an identical tree pays for it. Only the ACTIVE tab of a dock leaf is rebuilt at all.

An init.luau that fails to load does not break the editor: its tab comes up carrying the failure — the path and the error, selectable — so a panel that will not compile says so where you would look for it.

Every instance of this type becomes a tab: the ones in the open world, and the ones the built-in library ships, on the same terms.

Adding a tab to a project is creating a new editorPanel asset: it comes from the template above and registers its tab at once, wherever under /source it was made (editorPanels/ is the type's conventional folder). Editing the init.luau re-registers the tab, deleting the folder removes it. Nothing registers panels by name anywhere.

guides { path = "editor/edui/edui" } — the guide beside this type, inside the edui package — covers the build model, where panel state lives, and the edui.* surface a body draws with.

In the Inspector

Panels: each panel id this file registers (panelRef:panelIds()), whether it is open, an Open action for it, and Open for the source. A file whose init.luau does not load says why.