uix(palabras): F-A · doc.languages = fuente de verdad de multilenguaje (cableado)

El rework Camino A (461be12d9, otra sesion) dejaba `multilingual` derivado de la
PROP `languages`; el schema `doc.languages` (9223956a9) estaba puesto pero sin
cablear. Ahora el DOCUMENTO se auto-describe:
- resolvedLanguages: `doc.languages` (si presente) manda; la prop = seed/override.
- constructor: deriva de `initialDoc.languages ?? prop`; SELLA `doc.languages` en el
  doc cuando se siembra desde la prop (asi se auto-describe en adelante).
- foldPalabrasLanguages ahora sella `doc.languages` (predataba el campo).
- languageSpecs (etiquetas del switcher) reconciliado con resolvedLanguages.

2 tests nuevos (doc.languages SIN prop → multilingual; prop-seeded → sella
doc.languages). 62/62 provider · 502/502 motor · 0 errores. Verificado Playwright:
misma estructura en es/en (compartida por construccion), contenido por idioma.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/uix/soma/components/palabras/engine/i18n.ts

@@ -212,6 +212,7 @@ export function foldPalabrasLanguages(
 	};
 	return {
 		...base,
+		languages: [primary, ...others],
 		activeLang: primary,
 		children: base.children.map((block, i) =>
 			mapLeavesZip(

src/uix/soma/components/palabras/palabras-provider.svelte.test.ts

@@ -2704,6 +2704,43 @@ describe('PalabrasProvider · multilingual (F-A)', () => {
 		dom.dispose();
 	});
 
+	it('doc.languages is the SOURCE OF TRUTH — multilingual WITHOUT the languages prop', () => {
+		const { dom } = installSomaHarness();
+		const root = document.createElement('div');
+		document.body.append(root);
+		// The folded doc carries `doc.languages`; the `languages` PROP is left unset.
+		const opts = palabrasOpts(root, foldPalabrasLanguages({ es: doc('Hola'), en: doc('Hello') }, 'es'));
+		const { result, cleanup } = withEffectRoot(() => {
+			const provider = PalabrasProvider.create(opts);
+			vi.spyOn(PalabrasProvider, 'require').mockReturnValue(provider);
+			return { provider };
+		});
+		expect(result.provider.multilingual).toBe(true); // from doc.languages, not a prop
+		expect(result.provider.resolvedLanguages).toEqual(['es', 'en']);
+		result.provider.setActiveLang('en');
+		expect(result.provider.plainText).toBe('Hello');
+		cleanup();
+		dom.dispose();
+	});
+
+	it('a prop-seeded multilingual doc self-describes (stamps doc.languages)', () => {
+		const { dom } = installSomaHarness();
+		const root = document.createElement('div');
+		document.body.append(root);
+		const opts = palabrasOpts(root, doc('Hola')); // MONO doc, no doc.languages
+		opts.languages.current = ['es', 'en']; // the prop SEEDS the language set
+		const { result, cleanup } = withEffectRoot(() => {
+			const provider = PalabrasProvider.create(opts);
+			vi.spyOn(PalabrasProvider, 'require').mockReturnValue(provider);
+			return { provider };
+		});
+		expect(result.provider.multilingual).toBe(true);
+		// The doc got STAMPED with `languages`, so it self-describes going forward.
+		expect((opts.value.current as { languages?: string[] }).languages).toEqual(['es', 'en']);
+		cleanup();
+		dom.dispose();
+	});
+
 	it('setActiveLang swaps the active content; ONE doc carries both languages', () => {
 		const { provider, opts, cleanup, dom } = multiProvider({ es: doc('Hola'), en: doc('Hello') }, [
 			'es',

src/uix/soma/components/palabras/palabras-provider.svelte.ts

@@ -209,9 +209,14 @@ export class PalabrasProvider {
 	// the tree (`switchDocumentLanguage`). `doc.activeLang` records the current one.
 	private activeLangState = $state<LangCode>('');
 
-	readonly resolvedLanguages = $derived.by<readonly LangCode[]>(() =>
-		(this.opts.languages.current ?? []).map(langCodeOf)
-	);
+	// `doc.languages` (the document's own list) is the SOURCE OF TRUTH for whether a
+	// document is multilingual — it self-describes. The `languages` prop is only a
+	// seed / override for a document that lacks the field.
+	readonly resolvedLanguages = $derived.by<readonly LangCode[]>(() => {
+		const fromDoc = this.document.languages;
+		if (fromDoc && fromDoc.length > 0) return fromDoc;
+		return (this.opts.languages.current ?? []).map(langCodeOf);
+	});
 	get multilingual(): boolean {
 		return this.resolvedLanguages.length > 0;
 	}
@@ -347,11 +352,17 @@ export class PalabrasProvider {
 		// here (and writing the id-stamped doc back to `value`) is the single
 		// point that guarantees ids exist before the first paint.
 		let initialDoc = normalizeDocument(opts.value.current).document;
-		if (this.multilingual) {
+		// `doc.languages` is the source of truth; the `languages` prop seeds a doc that
+		// lacks it. `this.document` isn't set yet, so derive from `initialDoc` here.
+		const initLangs =
+			initialDoc.languages && initialDoc.languages.length > 0
+				? initialDoc.languages
+				: (opts.languages.current ?? []).map(langCodeOf);
+		if (initLangs.length > 0) {
 			// One document carries every language (`block.i18n`); `doc.activeLang`
 			// records which one lives in `children`. Reconcile the requested active
 			// language with the doc's, swapping content into place if they differ.
-			const langs = this.resolvedLanguages;
+			const langs = initLangs;
 			const childrenLang = initialDoc.activeLang ?? langs[0];
 			const requested = opts.activeLang.current;
 			const desired =
@@ -364,6 +375,9 @@ export class PalabrasProvider {
 				initialDoc = switchDocumentLanguage(initialDoc, childrenLang, desired);
 			else if (initialDoc.activeLang !== desired)
 				initialDoc = { ...initialDoc, activeLang: desired };
+			// Stamp `languages` so a prop-seeded document self-describes from here on.
+			if (!initialDoc.languages || initialDoc.languages.length === 0)
+				initialDoc = { ...initialDoc, languages: langs };
 			this.activeLangState = desired;
 			this.opts.activeLang.current = desired;
 		}
@@ -1701,7 +1715,9 @@ export class PalabrasProvider {
 	readonly snippetProps = $derived.by(() => ({
 		multilingual: this.multilingual,
 		languages: this.resolvedLanguages,
-		languageSpecs: this.opts.languages.current ?? [],
+		languageSpecs: this.resolvedLanguages.map(
+			(code) => (this.opts.languages.current ?? []).find((s) => langCodeOf(s) === code) ?? code
+		),
 		activeLang: this.activeLang,
 		setActiveLang: (code: LangCode) => this.setActiveLang(code),
 		missingRequiredLangs: this.missingRequiredLangs,