diff --git a/continue.md b/continue.md
index 1791e6bf7..eec60afb7 100644
--- a/continue.md
+++ b/continue.md
@@ -129,8 +129,14 @@ Actualizacion 2026-05-16:
      guard + widget + range order sin mover esa logica a `core`.
   2. Unificar paths sync/async de combinadores solo con tests amplios; es zona
      sensible por `SiumAsyncSchemaError`.
-  3. Documentar limites de `lazy()` con inputs ciclicos o anadir proteccion
-     `WeakSet` si empieza a recibir datos no confiables.
+  3. Cerrado: `lazy()` documenta limites de datos runtime autociclicos y lanza
+     `SiumLazyResolvingError` cuando el thunk usa el proxy mientras resuelve o
+     devuelve el mismo proxy como schema final. No se anade `WeakSet` global
+     porque la deteccion de ciclos de datos debe ser una capa de normalizacion
+     del dominio si entran datos no confiables.
+  4. Validado tras `lazy()`: `npx vitest run src/arts/sium/test` -> 18
+     archivos, 370 tests OK; `npm run check` -> 0 errores, 0 warnings;
+     `npm run test` -> 233 archivos, 2266 tests OK.
 - Validacion Sium domain factory:
   - `npx vitest run src/arts/sium/test/color.test.ts src/arts/sium/test/date.test.ts src/arts/sium/test/time.test.ts src/arts/sium/test/standard-schema.test.ts` -> 4 archivos, 122 tests OK.
   - `npm run check` -> 0 errores, 0 warnings.
diff --git a/src/arts/sium/README.md b/src/arts/sium/README.md
index 76c2be483..f439e9b21 100644
--- a/src/arts/sium/README.md
+++ b/src/arts/sium/README.md
@@ -613,6 +613,12 @@ export const Tree: Schema<TreeNode> = lazy(() =>
 );
 ```
 
+`lazy()` protege errores de construccion del schema: si el thunk intenta usar el propio proxy
+mientras resuelve, o devuelve ese mismo proxy como schema final, lanza `SiumLazyResolvingError`.
+Esto no es deteccion de ciclos en datos de usuario. Si pasas un objeto runtime autociclico a un
+schema recursivo, el decode/encode puede seguir desbordando la pila; valida esos datos antes o
+anade una capa de normalizacion especifica del dominio.
+
 ### Transform Y Codec
 
 ```ts
diff --git a/src/arts/sium/core/lazy.ts b/src/arts/sium/core/lazy.ts
index 146efba1b..29e1572d0 100644
--- a/src/arts/sium/core/lazy.ts
+++ b/src/arts/sium/core/lazy.ts
@@ -20,6 +20,7 @@ function createResolvingAccessError(): SiumLazyResolvingError {
 export function lazy<I, O>(getSchema: () => Schema<I, O>): Schema<I, O> {
 	let cached: Schema<I, O> | undefined;
 	let resolving = false;
+	let proxy: Schema<I, O>;
 
 	const unresolvedStandard = {
 		version: 1,
@@ -54,14 +55,19 @@ export function lazy<I, O>(getSchema: () => Schema<I, O>): Schema<I, O> {
 
 		resolving = true;
 		try {
-			cached = getSchema();
+			const resolved = getSchema();
+			if (resolved === proxy) {
+				throw createResolvingAccessError();
+			}
+
+			cached = resolved;
 			return cached;
 		} finally {
 			resolving = false;
 		}
 	};
 
-	const schema: Schema<I, O> = {
+	proxy = {
 		get '~standard'() {
 			if (cached !== undefined) {
 				return cached['~standard'];
@@ -91,5 +97,5 @@ export function lazy<I, O>(getSchema: () => Schema<I, O>): Schema<I, O> {
 		validateSync: (input, ctx) => getResolvedSchema().validateSync(input, ctx)
 	};
 
-	return schema;
+	return proxy;
 }
diff --git a/src/arts/sium/test/lazy.test.ts b/src/arts/sium/test/lazy.test.ts
index e4fcc8743..827ec98fb 100644
--- a/src/arts/sium/test/lazy.test.ts
+++ b/src/arts/sium/test/lazy.test.ts
@@ -2,7 +2,7 @@ import { describe, expect, it } from 'vitest';
 import { array, lazy, object, optional, string } from '../core';
 import { createSchema } from '../core/schema';
 import type { Schema } from '../core/types';
-import { SiumAsyncSchemaError } from '../errors';
+import { SiumAsyncSchemaError, SiumLazyResolvingError } from '../errors';
 
 type TreeNode = {
 	value: string;
@@ -219,8 +219,22 @@ describe('lazy()', () => {
 		expect(() => schema.decodeSync('x')).toThrow(SiumAsyncSchemaError);
 	});
 
+	it('throws SiumLazyResolvingError when the thunk uses the proxy while resolving', () => {
+		const schema: Schema<string, string> = lazy(() => {
+			schema.decodeSync('x');
+			return string();
+		});
+
+		expect(() => schema.decodeSync('x')).toThrow(SiumLazyResolvingError);
+	});
+
+	it('throws SiumLazyResolvingError when the thunk returns the same lazy proxy', () => {
+		const schema: Schema<string, string> = lazy(() => schema);
+
+		expect(() => schema.decodeSync('x')).toThrow(SiumLazyResolvingError);
+	});
+
 	it('is re-exported by the core barrel', () => {
 		expect(lazy).toBeTypeOf('function');
 	});
 });
-