diff --git a/packages/core/package.json b/packages/core/package.json
index 93f6cb51..c542a3bb 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -47,6 +47,7 @@
   "scripts": {
     "build": "tsup",
     "dev": "tsup --watch",
+    "check-types": "tsc -p tsconfig.check.json",
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
diff --git a/packages/core/src/schema.test.ts b/packages/core/src/schema.test.ts
index 9629de1a..2f567892 100644
--- a/packages/core/src/schema.test.ts
+++ b/packages/core/src/schema.test.ts
@@ -1,6 +1,7 @@
 import { describe, it, expect } from "vitest";
 import { z } from "zod";
 import { defineSchema, defineCatalog } from "./schema";
+import type { Spec } from "./types";
 
 // =============================================================================
 // Shared test schema (mirrors the React schema shape)
@@ -565,6 +566,21 @@ describe("catalog.validate", () => {
     actions: {},
   });
 
+  it("returns data assignable to Spec", () => {
+    const result = catalog.validate({
+      root: "card-1",
+      elements: {
+        "card-1": { type: "Card", props: { title: "Hello" }, children: [] },
+      },
+    });
+    expect(result.success).toBe(true);
+    if (result.success && result.data) {
+      // s.any() fields such as `visible` must not infer as unknown.
+      const spec: Spec = result.data;
+      expect(spec.root).toBe("card-1");
+    }
+  });
+
   it("validates a valid spec", () => {
     const spec = {
       root: "card-1",
diff --git a/packages/core/src/schema.ts b/packages/core/src/schema.ts
index e5aa0bf4..a5e954dd 100644
--- a/packages/core/src/schema.ts
+++ b/packages/core/src/schema.ts
@@ -355,7 +355,7 @@ type InferSpecField<T, TCatalog> =
                 : T extends SchemaType<"propsOf", infer Path>
                   ? InferPropsOfType<Path, TCatalog>
                   : T extends SchemaType<"any">
-                    ? unknown
+                    ? any
                     : unknown;
 
 type InferRefType<Path, TCatalog> = Path extends "catalog.components"
diff --git a/packages/core/tsconfig.check.json b/packages/core/tsconfig.check.json
new file mode 100644
index 00000000..d7993566
--- /dev/null
+++ b/packages/core/tsconfig.check.json
@@ -0,0 +1,9 @@
+{
+  // Type-checks the tests that assert inferred types. The full core
+  // project is not type-checked in CI yet.
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "noEmit": true
+  },
+  "include": ["src/schema.test.ts"]
+}