fix(eidos): el aviso al pie se lee donde se ve, y la fuente unica deja de mentir sobre si misma

Cierra los dos hallazgos que quedaban de la auditoria.

ORDEN DE LECTURA (a11y). `position: fixed` saca la tira del flujo VISUAL pero no
del DOM: se lee donde esta en el fuente. Con `affix="bottom"` el aviso se ve al
pie y la mini-pagina lo renderizaba primero, asi que un lector de pantalla lo
anunciaba ANTES que la cabecera — medido en la preview del propio block, era el
primer nodo del documento.

Quien decide eso es el APP, no el block: el block coloca, el documento ordena.
Asi que la correccion no es un prop, es que la demo deje de modelar el desajuste
— el aviso se renderiza donde se ve — mas la advertencia en el typedoc de `affix`
y una fila en los Gaps. Verificado en los dos bordes: con `bottom` el aviso va
DESPUES de la cabecera en el DOM y se ve al pie; con `top` va antes y se ve
arriba. En ambos, z 150 y pegado a su borde.

AFIRMACIONES OBSOLETAS. Cinco sitios seguian diciendo que `Fab` "ships a private
copy today" y que su migracion estaba pendiente — falso desde 1fc0a7a96, que es
mi propio commit. El fichero que declaro fuente unica mentia sobre su estado.
Corregidos `affix.svelte`, `index.ts`, la tabla de attrs del README y las dos
menciones de la demo. Lo que queda dicho es lo cierto: `Fab` la lee, `MenuDial`
sigue con copia propia.

check 69 = base intacta · blocks 0 · layer:check 0 violaciones · contrato de capa
10/10 · smoke 311/311.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/uix/blocks/banner/README.md

@@ -100,6 +100,7 @@ surfaces: it owns the `dismissed` state, as the canon requires.
 | **`role="banner"` cannot be overridden**                               | **canon** — the component stamps it AFTER its rest props, so a page that also has a header gets a second banner landmark. Measured in the preview: two. Mitigated only by naming both with `aria-label`                                                                                                                                                                                                               |
 | **~~Sticky / bottom notice~~ — RESUELTO 2026-08-14**                   | **shipped** — `affix="top" \| "bottom"` composes the canon `Affix`. The old disposition («app-land, compose `Sticky`») named a component that CANNOT do it: sticky unpins when its container ends, and a banner lives at the start of the document                                                                                                                                                                    |
 | **The affixed strip covers content**                                   | **app-land** — `fixed` reserves no space, exactly like a fixed header. The block cannot pad a page it does not own; the app adds the matching `padding-block` when it affixes                                                                                                                                                                                                                                         |
+| **Reading order of an `affix="bottom"` strip**                         | **app-land** — `fixed` takes the strip out of the VISUAL flow, never out of the DOM: it is read where it sits in the source. A bottom notice rendered at the top of the page is announced BEFORE the header — measured in this block's own preview, where it was the first node of the document. The block places; the document orders, and the demo now renders the notice where it is SEEN                          |
 | **An affixed strip inside a transformed ancestor stops being fixed**   | **canon** — any ancestor with `transform`/`filter`/`contain` becomes the containing block for a fixed descendant, silently. Registered in `Affix`'s own Gaps (its portal escape is deliberately out of v1); a page-level banner is rarely inside one                                                                                                                                                                  |
 | **Dismissal persistence** (cookie / storage)                           | **app-land** — the component's README discarded it explicitly                                                                                                                                                                                                                                                                                                                                                         |
 | **Animated entrance / exit**                                           | **deferred** — the component deferred it until ≥2 cases; here it would shift the page on load                                                                                                                                                                                                                                                                                                                         |

src/uix/blocks/banner/types.ts

@@ -22,6 +22,13 @@ export type SiteBannerProps = Omit<BannerProps, 'children'> & {
 	 * Out of flow, so the page does not reserve space for it: pad the page by
 	 * the strip's height if it must not cover content. Undefined = in flow.
 	 *
+	 * ⚠️ **Reading order is yours, not the block's.** `fixed` takes the strip out
+	 * of the visual flow but NOT out of the DOM — it is read where it sits in the
+	 * source. With `affix="bottom"` the notice is SEEN at the foot, so rendering
+	 * the block at the top of the page makes a screen reader announce it before
+	 * the header. Render it where it is seen; the block places, the document
+	 * orders.
+	 *
 	 * For the OTHER behaviour — a strip that scrolls with the page and then pins
 	 * — wrap the block in `Sticky` from the app; that stays composition, exactly
 	 * as it was before this prop existed.

src/uix/eidos/components/affix/README.md

@@ -116,11 +116,11 @@ undeclared `data-affix*`. If `Fab` and `MenuDial` stamped `data-affix` to get
 the geometry, their own elements would be welded into this component's contract
 (a `Fab placement="static"` would report a missing required attr). So:
 
-| Attr                   | Stamped by                                          | Selected by                                                 |
-| ---------------------- | --------------------------------------------------- | ----------------------------------------------------------- |
-| `data-affix`           | `<Affix>` only                                      | nothing — it is the identity, and morfo-check's entry point |
-| `data-affix-placement` | `<Affix>` today; `Fab` / `MenuDial` after migration | every rule in the layer                                     |
-| `data-affix-stretch`   | `<Affix>`                                           | the one full-bleed rule (block edges only)                  |
+| Attr                   | Stamped by                                      | Selected by                                                 |
+| ---------------------- | ----------------------------------------------- | ----------------------------------------------------------- |
+| `data-affix`           | `<Affix>` only                                  | nothing — it is the identity, and morfo-check's entry point |
+| `data-affix-placement` | `<Affix>` and `Fab`; `MenuDial` after migration | every rule in the layer                                     |
+| `data-affix-stretch`   | `<Affix>`                                       | the one full-bleed rule (block edges only)                  |
 
 morfo-check skips any attr that does not start with the morfo's own kebab, so a
 `Fab` carrying `data-affix-placement` is never judged against `affixMorfo`. This

src/uix/eidos/components/affix/affix.svelte

@@ -15,8 +15,9 @@
 	 *
 	 * scope:['eidos'] — no runtime. `affixMorfo` declares the `data-affix`
 	 * identity and the two knobs; this wrapper stamps them. The geometry lives
-	 * in `affix.css`, keyed on `data-affix-placement` so `Fab` / `MenuDial` can
-	 * migrate onto the same rules without inheriting this morfo's contract.
+	 * in `affix.css`, keyed on `data-affix-placement` so a consumer gets the same
+	 * rules without inheriting this morfo's contract. `Fab` did on 2026-08-14;
+	 * `MenuDial` is the one still carrying a private copy.
 	 */
 	import { ActiveEidos } from '$uix/eidos';
 	import { composeInlineStyle } from '$uix/eidos/lib/style';

src/uix/eidos/components/affix/index.ts

@@ -9,7 +9,8 @@
 // The companion of <Sticky>, not a variant of it — sticky unpins when its
 // container ends, fixed never does. It POSITIONS; the surface is the child's.
 // The geometry is a shared layer keyed on `data-affix-placement` (affix.css),
-// the single source `Fab` and `MenuDial` migrate onto. scope:['eidos'].
+// the single source of that geometry: `Fab` reads it (2026-08-14), `MenuDial`
+// still carries its own copy. scope:['eidos'].
 import Affix from './affix.svelte';
 
 export { Affix };

web/routes/blocks/banner/BannerSite.svelte

@@ -49,7 +49,7 @@
 	const pagePad = $derived(!dismissed && affix ? `${padSide}: 3.5rem;` : '');
 </script>
 
-{#if !dismissed}
+{#snippet notice()}
 	<!--
 		`aria-label` porque la página tiene DOS landmarks `banner`: este strip (que
 		fija `role="banner"` y no deja sobreescribirlo) y el `<header>` del
@@ -72,6 +72,18 @@
 			<Link href="#novedades" size="sm" color="currentColor">Ver qué cambia →</Link>
 		{/snippet}
 	</SiteBanner>
+{/snippet}
+
+<!--
+	El aviso se renderiza donde SE VE, no siempre arriba. `position: fixed` saca la
+	tira del flujo visual pero NO del DOM: se lee donde está en el fuente. Con
+	`affix="bottom"` el aviso se ve al pie, así que ponerlo primero haría que un
+	lector de pantalla lo oyera antes que la cabecera — medido en esta misma
+	preview, era el primer nodo del documento. Quién decide esto es el APP, no el
+	block: el block coloca, el documento ordena.
+-->
+{#if !dismissed && affix !== 'bottom'}
+	{@render notice()}
 {/if}
 
 <div style={pagePad}>
@@ -157,3 +169,7 @@
 		</Section>
 	{/each}
 </div>
+
+{#if !dismissed && affix === 'bottom'}
+	{@render notice()}
+{/if}

web/routes/uix/components/affix/+page.svelte

@@ -145,7 +145,7 @@
 			away with it; an element anchored to a viewport edge is <code>fixed</code>, and that is a
 			different component. It POSITIONS and nothing else: the surface is the child's. Its geometry
 			is a <strong>shared layer</strong> keyed on <code>data-affix-placement</code> — the single
-			source <code>Fab</code> and <code>MenuDial</code> migrate onto.
+			source <code>Fab</code> already reads, and <code>MenuDial</code> still has to.
 		</p>
 		<div data-uix-page-meta>
 			<span data-uix-meta-pill><span data-uix-meta-key>zones</span>{placements.length}</span>
@@ -639,9 +639,11 @@
 			<p data-uix-section-desc>
 				<code>src/uix/eidos/components/affix/affix.css</code> is both this component's recipe AND
 				the shared viewport-placement layer. <code>Fab</code> (4 zones) and <code>MenuDial</code>
-				(9) ship private copies of these rules today, with divergent tokens; they migrate onto this file
-				by importing it and stamping <code>data-affix-placement</code>, the way the menu / listbox
-				recipes consume <code>lib/list-surface.css</code>.
+				(9) each shipped a private copy. <code>Fab</code> migrated on 2026-08-14;
+				<code>MenuDial</code>
+				is the one left, and it migrates onto this file by importing it and stamping
+				<code>data-affix-placement</code>, the way the menu / listbox recipes consume
+				<code>lib/list-surface.css</code>.
 			</p>
 			<div data-uix-table-wrap>
 				<table data-uix-table>