# `AshUi.Phoenix.RootLayout`
[🔗](https://github.com/hyperbob-labs/ash_ui/blob/main/lib/ash_ui/phoenix/root_layout.ex#L1)

Document assembly for routed AshUi resources (DESIGN.md §9).

The layout is a framework function of declared data — there are no
`root_layout_*` env/assign channels and no fallback hrefs:

- `<base href>` derived from the mount scope (`conn.script_name`), so
  relative stylesheet hrefs resolve correctly at any route depth.
- One `<link rel="stylesheet">` per EFFECTIVE stylesheet of the routed
  resource (`AshUi.Info.stylesheets/1`), linked in declared order.
  Each declared entry is served as-declared, resolved against the base.
- The framework runtime scripts (`blueprint_runtime_script_paths/0`),
  unconditional.
- Runtime-state stamping (see below).

## Runtime state contract

Runtime state is host-stamped, never compiled: a map with the optional keys
`:scheme`, `:fonts`, and `:zoom`, provided under the SINGLE key
`:ash_ui_runtime_state` — as a layout assign, or in the Plug session
under `"ash_ui_runtime_state"` (assign wins):

    %{scheme: "dark", fonts: %{ui: "Inter", mono: "Iosevka"}, zoom: 1.25}

Stamping (each key only when present; absent runtime state stamps nothing):

- `scheme` → `data-theme="<scheme>"` on `<html>`. Palette blocks live in
  token stylesheets keyed on `:root[data-theme=…]`.
- `fonts` → one `--font-<name>: <value>` custom property per entry, inline
  on `<html>`.
- `zoom` → the `<html>` root `font-size` (`16px * zoom`). Generated layout
  sizing is rem-based, so this is the single document scale knob.

A theme or font change is an attribute/token flip — never a re-link, never
a recompile.

# `blueprint_runtime_script_paths`

The framework runtime script paths, linked unconditionally in every
AshUi document.

# `render`

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*Consult [api-reference.md](api-reference.md) for complete listing*