Kit-trees — `composite: 1` (frozen)

A kit-tree is a JSON element tree over the Element Contract: the only way extensions, themes, stores and agents add storefront UI without shipping code. It is rendered through the active theme's kit, so it looks native everywhere; it is validated statically (elements, props, bindings, caps) before it can ever render. Anything beyond this language is a P2 sealed section.

Node

{ "el": "Box", "props": { "surface": "surface-alt", "padding": "m" },
  "children": [ { "el": "Heading", "props": { "level": 3 }, "children": [ { "$bind": "$config.baslik" } ] },
                { "el": "KeyValueList", "each": "$ext.ibans", "as": "hesap",
                  "props": { "rows": [ { "key": { "$bind": "$hesap.banka" }, "value": { "$bind": "$hesap.iban" } } ] } } ] }

el — an element name from the contract (required + optional elements); unknown = rejected.
props — the element's props (see the contract table); values are scalars, bindings, arrays or objects of those. Platform-reserved props (id, hook, sid, type, island) are refused.
variants — section-variant axes; children — text, bindings or nodes; each + as — repeat over a list binding (≤ 50); if — "$x" / { "not": "$x" } / { "eq": ["$x", value] }; slot: "blocks" — where a composite's block instances go.
caps: ≤ 200 nodes, depth ≤ 6. No HTML in text (use the markdown formatter into Prose).

Bindings

prefix	source
`$props.*`	a composite instance's props (the owner's form, from the composite's JSON Schema)
`$config.*`	a block fill's per-placement config (`configSchema`)
`$ext.*`	the extension's OWN config, only the pointers listed in `exposeConfig`
`$data.*`	declared data the platform prefetches: `productList`, `productByHandle`, `collectionList`, `metafields`
`$ctx.*`	`storeName`, `payments.{cardEnabled,kapidaEnabled,havaleEnabled,taksitAvailable}`, `route.{path,kind,handle}`
`$blocks`	a composite instance's block list (`{ type, props }[]`)
`$item` / `$<as>`	the current `each` item

Formatters on a binding: money (kuruş → "1.249,90 TL"), href (a bundle link → URL), media (a media ref → the kit's image source), markdown (→ safe HTML for Prose).

Where trees come from

Extensions: manifest ui.storefront — blocks (≤ 4, placed in zones), sections (≤ 3 composites in the add-picker, type <ext>.<key>@1), pages (≤ 3, under /ek/{slug}). Validated at registry load (D-T1-TREE) and rendered on every first-party kit in CI (G-EXT-UI).
Stores: layout.composites in the bundle, type c.<name>@1 — authored as JSON by agents / the assistant, offered under "Benim bölümlerim".
Themes: sections/*.composite.json in a theme package.

Generated from the live platform registries at build time — reference pages cannot go stale. Markdown variant: /reference/kit-trees.md

Kit-trees — composite: 1 (frozen)

Node

Bindings

Where trees come from

Kit-trees — `composite: 1` (frozen)