A MishkaGervaz custom form template: the "Save as snippet" box at the top of the Studio's Snippets tab.

It owns the whole box and nothing below it — the saved list is a Gervaz TABLE, MishkaCmsCoreWeb.Templates.StudioSnippets.

The scope control is the point

Before this, scope was decided FOR the author: a node selected saved :page, nothing selected saved :shared, and there was no way to say otherwise. The three radios here are that choice made explicit, in the same chip idiom as the list's own filter chips.

They are radios rather than buttons so the browser holds the selection: no phx-change round trip per click, which also means clicking one cannot disturb a half-typed name. The selected styling is peer-checked:, so it is CSS rather than a re-render.

What each one means, and why visibility is not simply the stored scope:

"All sites" is a site_id decision, not a scope one — which is why the radio posts a visibility param that MishkaCmsCore.Runtime.Snippet's before_save hook translates, rather than posting scope directly. It is offered to a master only: a tenant's :create action forces site_id to its own tenant, so showing the choice would be a promise the action cannot keep.

The markup the source rides in on

source — the serialised subtree, recomputed on every canvas edit — is NOT a form field. It reaches the action through a hidden input that Panels renders OUTSIDE this component and associates with form="pb-snippet-form"; FormData collects form-associated controls wherever they sit in the DOM, so LiveView serialises it with the rest. Passing it through the component's defaults instead would rebuild the form on every keystroke-adjacent edit and wipe the name the author was typing.