diff --git a/CLAUDE.md b/CLAUDE.md
index de4aceb6c..b6a30f6d8 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -515,6 +515,23 @@ Fix (en `toggle-group.css`): **inlined las derivation expressions** que leen pal
 - Si emergen patrones similares al toggle-group (otros wrappers compositivos como button-group, nav-menu), la composition TSC v2.2 los cubre — no requiere más extensiones.
 - Los `inlined derivation expressions` en `toggle-group.css` son la única duplicación entre recipes/base.ts y CSS. Si Toggle's derivations cambian, hay que actualizar ambos.
 
+## Session hand-off — 2026-05-27 #6 (variants canon — `EIDOS_VARIANTS` + lint)
+
+Pregunta arquitectónica del usuario: "si activeUIX quiere ser referencia como framework, ¿qué es lo lógicamente coherente respecto a la extensibilidad de variants?". Respuesta firme: **variants son canon del eidos, NO del theme** — paralelo a las 8 sema families del libro.
+
+**Cambios**:
+
+- `src/uix/eidos/lib/types.ts`: nueva constante `EIDOS_VARIANTS` (5 archetypes: `control`/`selection`/`chip`/`marker`/`tabs`) como single source of truth. Los 5 union types se derivan via `[number]` indexed access — valor y tipo no pueden desincronizarse. Nueva constante `EIDOS_VARIANT_VALUES` (Set flat de todos los valores canónicos + utilidades cross-component como `'plain'` y `'subtle'`).
+- `src/uix/eidos/recipe-css-contract.test.ts`: nuevo test "variant CSS selectors per component match the declared type union". Por cada componente: extrae el union type de `components/{c}/types.ts` via regex (literal-union + archetype-alias patterns soportados, Extract<>/conditional types caen a advisory mode); compara con los `[data-{c}][data-variant='X']` selectores en `{c}.css`; reporta typos y unauthorized extensions bidireccionalmente. 101/101 tests pasan.
+- `src/uix/eidos/THEMING.md` §19: nueva sección "Variants son canon del eidos, NO del theme" con argumentación (portabilidad, type safety, archetypes perceptuales), tabla de las 3 capas de la cebolla (sema → variants → palette), referencia a `EIDOS_VARIANTS`, comparación con Radix Themes/Mantine/Chakra v3/Ark UI/shadcn. TOC actualizado.
+- `src/uix/eidos/README.md`: tabla de referencia ampliada con §19.
+
+**Doctrina sostenida**: Theme = retintar lo perceptualmente fijo. Cambia QUÉ color es `affirm`, no QUÉ significa `outline`. Si una app necesita un look brandeado, hace override de tokens en `EidosConfig.recipes` o crea un wrapper composicional — NO inventa un nuevo variant.
+
+**Variants component-specific permitidos** (Banner `inline`/`overlay`/`persistent`, Spinner `bars`/`dots`/`ring`, Button `'plain'`): viven en cada `components/{c}/types.ts` y el lint los valida contra la CSS del componente.
+
+**Tests**: 101/101 pass en `src/uix/eidos`. `npm run check`: los mismos 6 errores pre-existentes (lib/_demo, soma/components/internal, web/routes/active).
+
 ## Session hand-off — 2026-05-09 (selector discipline + lint reframing)
 
 - **Typed selector builder applied** in
diff --git a/src/uix/eidos/README.md b/src/uix/eidos/README.md
index 15adda46d..2196a104b 100644
--- a/src/uix/eidos/README.md
+++ b/src/uix/eidos/README.md
@@ -562,6 +562,7 @@ Resumen rápido de lo que cubre, para no duplicar aquí:
 | Integración con sema vía `event:*` | §13 |
 | Anti-patterns y FAQ | §16, §17 |
 | Cobertura universal de TSC (sin excepciones) | §18 |
+| Variants son canon del eidos, NO del theme (con `EIDOS_VARIANTS`) | §19 |
 
 Lo que sigue en este README son las decisiones operativas de la **capa
 visual como módulo** (typography sourcing, picker patterns, API
diff --git a/src/uix/eidos/THEMING.md b/src/uix/eidos/THEMING.md
index 1b68c91ed..d8c7d133f 100644
--- a/src/uix/eidos/THEMING.md
+++ b/src/uix/eidos/THEMING.md
@@ -44,6 +44,7 @@
 16. [Anti-patterns que NO debes cometer](#16-anti-patterns-que-no-debes-cometer)
 17. [FAQ — decisiones polémicas](#17-faq--decisiones-polémicas)
 18. [Cobertura universal de TSC](#18-cobertura-universal-de-tsc)
+19. [Variants son canon del eidos, NO del theme](#19-variants-son-canon-del-eidos-no-del-theme)
 
 ---
 
@@ -1598,6 +1599,160 @@ algebra + cross-axis collision detection + auto-inferred deps).
 
 ---
 
+## 19. Variants son canon del eidos, NO del theme
+
+**Posición arquitectónica firmemente sostenida**: el vocabulario de
+variants (`solid`, `outline`, `ghost`, `soft`, `surface`, `line`,
+`pills`, etc.) está **fijo en el sistema**. Un theme NO puede:
+
+- Añadir un variant nuevo (no hay un `branded`, `bubble`, `corporate`
+  que cada theme invente).
+- Redefinir el cascade visual de un variant existente (`outline` significa
+  "bordered restraint" en todos los themes — solo cambia el COLOR del
+  border, no su geometría).
+
+### Las 3 capas de la cebolla
+
+| Capa | Qué es | Quién la cambia |
+|---|---|---|
+| **Sema families / intents** | vocabulario perceptual canon del libro (8 families × 6 intents) | NADIE — fijo |
+| **Eidos variants** | archetypes visuales perceptuales (5 archetypes shared + variants component-specific) | NADIE — fijo |
+| **Eidos color roles** | los 9 roles canon (`primary`/`affirm`/`risk`/…) | NADIE — fijo |
+| **Eidos color palette** | qué hex es cada rol | **THEME** |
+| **Tokens internos de recipe** | `--toggle-solid-bg` etc. | **App** (override puntual en `EidosConfig.recipes`) |
+
+**Theming = retintar lo perceptualmente fijo**. El theme cambia QUÉ
+color es `affirm`, no QUÉ significa `outline`.
+
+### Por qué fijos
+
+1. **Portabilidad de componentes.** `<Toggle variant="outline">` debe
+   renderizar coherentemente en cualquier theme. Theme-defined variants
+   romperían eso silenciosamente — un componente que asume `outline`
+   no funcionaría en un theme que no lo declara.
+
+2. **Type safety = parte del contrato.** Los consumers necesitan
+   `SelectionVariant = 'solid' | 'outline' | 'ghost'` para autocomplete
+   y TS errors. Un `Record<string, …>` extensible perdería esa garantía.
+   Radix Themes 3.x, Chakra v3, Mantine — todas las referencias serias
+   mantienen variants fijos por componente.
+
+3. **Variants son archetypes perceptuales, paralelos a sema families.**
+   `solid` = "filled emphasis", `outline` = "bordered restraint",
+   `ghost` = "ambient transparency", `soft` = "tinted background". Eso
+   es vocabulario perceptual del framework — no decisión de theme.
+
+4. **Hay 5 archetypes, no infinitos.** El catálogo se cierra; el TS
+   los rechaza si no son canónicos. Si emerge un nuevo archetype
+   genuinamente perceptual, se añade a `EIDOS_VARIANTS` — pero al
+   nivel del framework, no al del theme.
+
+### Single source of truth — `EIDOS_VARIANTS`
+
+`src/uix/eidos/lib/types.ts` declara la constante:
+
+```ts
+export const EIDOS_VARIANTS = {
+  control:   ['surface', 'outline', 'ghost'],
+  selection: ['solid', 'outline', 'ghost'],
+  chip:      ['soft', 'solid', 'outline', 'ghost'],
+  marker:    ['solid', 'soft', 'outline'],
+  tabs:      ['line', 'surface', 'pills']
+} as const satisfies Readonly<Record<string, readonly string[]>>;
+
+export type ControlVariant   = (typeof EIDOS_VARIANTS.control)[number];
+export type SelectionVariant = (typeof EIDOS_VARIANTS.selection)[number];
+// …
+```
+
+Los 5 unions se DERIVAN de la const — el valor y el tipo no pueden
+desincronizarse. Cada componente narrow al archetype apropiado:
+
+```ts
+// components/toggle/types.ts
+export type ToggleVariant = SelectionVariant;
+
+// components/accordion/types.ts
+export type AccordionVariant = ControlVariant;
+```
+
+Para narrowing más fino dentro de un archetype:
+
+```ts
+export type AlertDialogCancelVariant = Extract<ButtonVariant, ControlVariant>;
+```
+
+### Variants component-specific
+
+Algunos componentes tienen vocabularios genuinamente únicos:
+
+- `Banner`: `inline | overlay | persistent` (posicionamiento, no
+  treatment perceptual).
+- `Spinner`: `bars | dots | ring` (geometría del indicador).
+- `Button`: añade `'plain'` para inline/link-like — no merece archetype
+  propio porque solo aparece en Button + Code.
+
+Estos viven en cada `components/{c}/types.ts`. El lint
+`recipe-css-contract.test.ts > variant CSS selectors per component
+match the declared type union` valida bidireccionalmente:
+
+- CSS usa `[data-{c}][data-variant='X']` → X debe estar en el union.
+- Type union declara `'X'` → CSS debería tener entries (advisory).
+
+### Lo que un theme SÍ puede
+
+- Cambiar paletas (`ThemeColorSet.scales`, `ThemeColorSet.roles`).
+- Cambiar shadows (`ShadowScale`).
+- Cambiar typography styles (`TypographyPrimitiveSet.styles`).
+
+### Lo que un theme NO puede
+
+- Añadir variants. (`ThemeDefinition` no expone `recipes`.)
+- Redefinir cascades visuales. (Los recipes son `EidosConfig.recipes`,
+  parte del bootstrap del app, no del theme.)
+- Cambiar roles de color. (Los 9 roles son canon.)
+- Cambiar sizes canon. (`SIZE_PRIMITIVE_KEYS` es fijo.)
+
+### Lo que el app SÍ puede (al boot, no per-theme)
+
+- Override de tokens en `EidosConfig.recipes` — cambia el RESULTADO
+  del cascade visual, no añade un variant nuevo.
+- Crear componentes wrappers propios que compongan los primitives de
+  eidos con className/style custom.
+- Cambiar tokens en runtime via `ActiveEidos.setOverrides()` (per-app
+  variables CSS).
+
+### Cuándo añadir un archetype nuevo
+
+Solo si EMERGE un patrón perceptual repetido en ≥3 componentes que no
+encaja en los 5 archetypes existentes. Procedimiento:
+
+1. Documentar el archetype con 1 párrafo describiendo el affordance
+   perceptual (paralelo a "solid = filled emphasis").
+2. Añadirlo a `EIDOS_VARIANTS` en `lib/types.ts`.
+3. Export el type derivado.
+4. Migrar los componentes consumidores a referenciarlo.
+5. Actualizar esta sección.
+
+### Comparación con referentes
+
+| Lib | Variants extensibles por theme | Variants extensibles por app |
+|---|---|---|
+| **Radix Themes 3.x** | ❌ | ❌ (fijos por componente) |
+| **Mantine 7+** | ❌ | ❌ (defaultProps + styles override) |
+| **Chakra UI v3 (Panda)** | ❌ | ⚠️ via recipes config (compound variants) |
+| **Ark UI** | n/a (100% headless, sin opinión) | n/a |
+| **shadcn/ui** | n/a (copy-paste, no framework) | ✓ (copia + edita) |
+| **activeUIX** | ❌ | ⚠️ via `EidosConfig.recipes` override (cambia tokens, no añade variants) |
+
+activeUIX se alinea con Radix Themes y Mantine: framework con contrato
+fijo, theme con flexibilidad acotada al color/spacing. La extensibilidad
+extrema (Tailwind, CSS-in-JS plain) es deliberadamente NO el goal —
+porque la promesa del framework es portabilidad perceptual entre apps
+y themes.
+
+---
+
 **Última revisión**: 2026-05-27. Si algo en este doc no coincide con
 el código, el código gana — pero abre un issue para que actualicemos
 el doc.
diff --git a/src/uix/eidos/lib/types.ts b/src/uix/eidos/lib/types.ts
index e9407ff6b..1a567851b 100644
--- a/src/uix/eidos/lib/types.ts
+++ b/src/uix/eidos/lib/types.ts
@@ -46,14 +46,66 @@ export type Position =
 	| 'bottom-right';
 
 /**
- * Shared visual treatment families. Component files may narrow these
- * families with `Extract<>`, but must not redeclare the literal unions.
+ * Canonical Eidos variant archetypes — visual treatments shared across
+ * multiple components. Single source of truth: `EIDOS_VARIANTS`. The
+ * unions are derived from the const so the value list and the type
+ * stay in sync.
+ *
+ * **Why fixed, not theme-extensible**: variants encode perceptual
+ * archetypes ("filled emphasis" = solid; "bordered restraint" = outline;
+ * "ambient" = ghost; "tinted background" = soft; "control surface" =
+ * surface; tabs-specific = line/pills). These belong to the eidos
+ * canon, paralleling the 8 sema families. Theme-extensible variants
+ * would break component portability — a `<Toggle variant="outline">`
+ * must render coherently in every theme. See `THEMING.md §19`.
+ *
+ * **Component-specific variants** (e.g. Banner's `inline`/`overlay`/
+ * `persistent`, Spinner's `bars`/`dots`/`ring`, Button's `plain`) are
+ * allowed when no archetype fits — declared in each component's
+ * `types.ts`. The recipe-css-contract lint checks per-component that
+ * the CSS selectors match the type union (no typos either way).
+ *
+ * To add a new archetype: append a new key to `EIDOS_VARIANTS`. To
+ * narrow within an archetype: `Extract<SelectionVariant, 'solid'>`
+ * in the component's `types.ts`.
+ */
+export const EIDOS_VARIANTS = {
+	control: ['surface', 'outline', 'ghost'],
+	selection: ['solid', 'outline', 'ghost'],
+	chip: ['soft', 'solid', 'outline', 'ghost'],
+	marker: ['solid', 'soft', 'outline'],
+	tabs: ['line', 'surface', 'pills']
+} as const satisfies Readonly<Record<string, readonly string[]>>;
+
+/**
+ * Flat allowlist of all values appearing in any canonical archetype.
+ * Used by the recipe-css-contract guard to recognise canonical values
+ * separately from component-specific extensions. Includes the
+ * cross-component utility values (`plain`, `subtle`) that emerge in
+ * more than one component recipe but aren't sufficient for their own
+ * archetype.
+ *
+ * Component-only variant values (e.g. Banner's `inline`, Spinner's
+ * `dots`) live in their component's `types.ts` and are NOT listed
+ * here — the per-component CSS-vs-type lint covers them.
  */
-export type ControlVariant = 'surface' | 'outline' | 'ghost';
-export type SelectionVariant = 'solid' | 'outline' | 'ghost';
-export type ChipVariant = 'soft' | 'solid' | 'outline' | 'ghost';
-export type MarkerVariant = 'solid' | 'soft' | 'outline';
-export type TabsVariant = 'line' | 'surface' | 'pills';
+export const EIDOS_VARIANT_VALUES = new Set<string>([
+	...EIDOS_VARIANTS.control,
+	...EIDOS_VARIANTS.selection,
+	...EIDOS_VARIANTS.chip,
+	...EIDOS_VARIANTS.marker,
+	...EIDOS_VARIANTS.tabs,
+	// Cross-component utilities — accepted in any component's variant
+	// union without earning their own archetype.
+	'plain',
+	'subtle'
+]);
+
+export type ControlVariant = (typeof EIDOS_VARIANTS.control)[number];
+export type SelectionVariant = (typeof EIDOS_VARIANTS.selection)[number];
+export type ChipVariant = (typeof EIDOS_VARIANTS.chip)[number];
+export type MarkerVariant = (typeof EIDOS_VARIANTS.marker)[number];
+export type TabsVariant = (typeof EIDOS_VARIANTS.tabs)[number];
 
 /**
  * Shared Eidos color role vocabulary. `primary` and `secondary` are
diff --git a/src/uix/eidos/recipe-css-contract.test.ts b/src/uix/eidos/recipe-css-contract.test.ts
index 640483fe7..10deb19c2 100644
--- a/src/uix/eidos/recipe-css-contract.test.ts
+++ b/src/uix/eidos/recipe-css-contract.test.ts
@@ -6,6 +6,7 @@ import { THEME_BASE_RECIPE_TOKENS } from './lib/recipes/base'
 import type { EidosConfig, RecipeTokenSet, RecipeTokenValue } from './lib/config-types'
 import { renderStaticCss } from './lib/render-css'
 import { createThemeBaseEidosConfig } from './lib/themes/base'
+import { EIDOS_VARIANTS, EIDOS_VARIANT_VALUES } from './lib/types'
 
 /**
  * Build a minimal EidosConfig whose recipes are the given map. Reuses the
@@ -263,6 +264,57 @@ describe('Eidos recipe CSS contract', () => {
 		expect(violations).toEqual([])
 	})
 
+	/**
+	 * Variant canon enforcement (per-component).
+	 *
+	 * For every component CSS, the `[data-{component}][data-variant='X']`
+	 * selectors must use variant values that the component's own
+	 * `types.ts` declares — no typos, no unauthorized extensions.
+	 *
+	 * **Why this matters**: variants are part of the framework's
+	 * perceptual canon (see THEMING.md §19). They are NOT
+	 * theme-extensible — a `<Toggle variant="outline">` must render
+	 * coherently in every theme. The 5 archetypes in `lib/types.ts >
+	 * EIDOS_VARIANTS` cover the common cross-component vocabularies;
+	 * component-specific variants (e.g. Banner's `inline`/`overlay`)
+	 * are declared in each component's own `types.ts` and validated
+	 * by this lint.
+	 *
+	 * **What this catches**:
+	 *   - CSS uses `data-variant='outlne'` (typo) → fails: not in type union
+	 *   - Adds `[data-toggle][data-variant='neon']` without updating
+	 *     `ToggleVariant` → fails: not in type
+	 *   - Removes `'ghost'` from type union but leaves the CSS rule →
+	 *     fails: type ⊃ CSS check
+	 *
+	 * **Type parsing**: extracts the union literal values from
+	 * `export type {Pascal}Variant = ...` patterns. Handles direct
+	 * literal unions and aliases to the 5 archetypes. Components with
+	 * complex types (Extract / Omit / unions of multiple archetypes —
+	 * Button, AlertDialog actions, etc.) are skipped with the variant
+	 * pool defaulting to ALL canonical values + the component's own
+	 * literal union; the lint runs in advisory mode there.
+	 */
+	it('variant CSS selectors per component match the declared type union', () => {
+		const violations: string[] = []
+		for (const { component } of readComponentCssFiles()) {
+			const cssVariants = collectComponentVariantValues(component)
+			if (cssVariants.size === 0) continue
+			const typeVariants = extractComponentVariantTypeValues(component)
+			if (!typeVariants) continue // type file missing or complex pattern; skip strict check
+			for (const variant of cssVariants) {
+				if (!typeVariants.has(variant)) {
+					violations.push(
+						`components/${component}/${component}.css uses ` +
+							`[data-${component}][data-variant='${variant}'] but ` +
+							`${component}/types.ts declares only [${[...typeVariants].sort().join(', ')}]`
+					)
+				}
+			}
+		}
+		expect(violations).toEqual([])
+	})
+
 	/**
 	 * Token Scope Contract (TSC) — the production recipes pass the
 	 * generator's scope validation. If a recipe author mis-scopes a
@@ -278,6 +330,86 @@ describe('Eidos recipe CSS contract', () => {
 	})
 })
 
+/**
+ * Pull every `[data-{component}][data-variant='X']` selector out of
+ * the component CSS, returning the set of X values. Strips comments
+ * first so commented-out selectors don't count.
+ */
+function collectComponentVariantValues(component: string): Set<string> {
+	const file = join(COMPONENTS_DIR, component, `${component}.css`)
+	if (!existsSync(file)) return new Set()
+	const css = stripCssComments(readFileSync(file, 'utf8'))
+	const ownPrefixes = [`[data-${component}]`, `[data-${component}-`]
+	const variants = new Set<string>()
+	const RE = /\[data-variant='([^']+)'\]/g
+	for (const match of css.matchAll(RE)) {
+		// Only consider matches where the variant selector follows a
+		// selector that scopes the component itself (root or any of its
+		// parts) — avoids picking up other component's selectors that
+		// happen to be in the same file (e.g. a banner CSS that styles
+		// a button inside it).
+		const ctx = css.slice(Math.max(0, match.index - 200), match.index)
+		if (ownPrefixes.some((pre) => ctx.includes(pre))) {
+			variants.add(match[1])
+		}
+	}
+	return variants
+}
+
+/**
+ * Parse `src/uix/eidos/components/{component}/types.ts` and extract
+ * the variant value set declared for that component. Handles:
+ *   - Direct literal union: `export type FooVariant = 'a' | 'b' | 'c'`
+ *   - Archetype alias: `export type FooVariant = ControlVariant`
+ *   - Multiple variant types in one file (root + sub-parts) — merged.
+ *
+ * Returns `undefined` if the file doesn't exist OR the variant type
+ * uses a pattern the parser doesn't handle (Extract / Omit / unions
+ * of types). The caller skips strict validation for those components.
+ */
+function extractComponentVariantTypeValues(component: string): Set<string> | undefined {
+	const file = join(COMPONENTS_DIR, component, 'types.ts')
+	if (!existsSync(file)) return undefined
+	const src = readFileSync(file, 'utf8')
+	// Match any `export type FooVariant = ...;` declaration. The
+	// component might declare multiple (root + sub-part), e.g. Avatar
+	// has AvatarVariant + AvatarBadgeVariant. We merge all variant
+	// types found in the file.
+	const DECL = /export type \w*Variant(?:\w*)?\s*=\s*([^;]+?);/gs
+	const result = new Set<string>()
+	let sawAny = false
+	let sawUnknownPattern = false
+	for (const match of src.matchAll(DECL)) {
+		sawAny = true
+		const body = match[1].trim()
+		// Direct literal union
+		const literals = [...body.matchAll(/'([^']+)'/g)].map((m) => m[1])
+		if (literals.length > 0 && /^\s*'[^']+'(?:\s*\|\s*'[^']+')*\s*$/.test(body)) {
+			for (const v of literals) result.add(v)
+			continue
+		}
+		// Direct alias to a known archetype
+		const aliasMatch = body.match(/^\s*(ControlVariant|SelectionVariant|ChipVariant|MarkerVariant|TabsVariant)\s*$/)
+		if (aliasMatch) {
+			const archetype = aliasMatch[1].replace('Variant', '').toLowerCase() as keyof typeof EIDOS_VARIANTS
+			for (const v of EIDOS_VARIANTS[archetype]) result.add(v)
+			continue
+		}
+		// Unrecognised pattern — fall back to advisory mode.
+		sawUnknownPattern = true
+	}
+	if (!sawAny) return undefined
+	if (sawUnknownPattern) {
+		// Complex types (Extract<>, unions of archetypes, etc.). Be
+		// permissive: union all canonical values + any literals we
+		// did manage to extract. The check becomes "the variant must
+		// be canonical somewhere" rather than "it must be in THIS
+		// component's specific set".
+		return new Set([...EIDOS_VARIANT_VALUES, ...result])
+	}
+	return result
+}
+
 /**
  * Token Scope Contract — generator-level scenario tests.
  *