fix: don't set nullable modifier when nullable is embedded in LowCardinality type string

src/generator/datasource.test.ts

@@ -142,7 +142,7 @@ describe('Datasource Generator', () => {
       expect(result.content).toContain('country LowCardinality(String)');
     });
 
-    it('formats LowCardinality(Nullable) correctly', () => {
+    it('formats LowCardinality(Nullable) correctly with .lowCardinality().nullable()', () => {
       const ds = defineDatasource('test_ds', {
         schema: {
           country: t.string().lowCardinality().nullable(),
@@ -151,6 +151,19 @@ describe('Datasource Generator', () => {
 
       const result = generateDatasource(ds);
       expect(result.content).toContain('country LowCardinality(Nullable(String))');
+      expect(result.content).not.toContain('Nullable(LowCardinality');
+    });
+
+    it('formats LowCardinality(Nullable) correctly with .nullable().lowCardinality()', () => {
+      const ds = defineDatasource('test_ds', {
+        schema: {
+          country: t.string().nullable().lowCardinality(),
+        },
+      });
+
+      const result = generateDatasource(ds);
+      expect(result.content).toContain('country LowCardinality(Nullable(String))');
+      expect(result.content).not.toContain('Nullable(LowCardinality');
     });
 
     it('includes default values', () => {

src/schema/types.test.ts

@@ -87,10 +87,18 @@ describe("Type Validators (t.*)", () => {
       expect(type._tinybirdType).toBe("LowCardinality(Nullable(String))");
     });
 
-    it("preserves both modifiers when chained", () => {
+    it("preserves lowCardinality modifier and omits nullable when combined (nullable is in the type string)", () => {
       const type = t.string().lowCardinality().nullable();
       expect(type._modifiers.lowCardinality).toBe(true);
-      expect(type._modifiers.nullable).toBe(true);
+      expect(type._modifiers.nullable).toBeUndefined();
+      expect(type._tinybirdType).toBe("LowCardinality(Nullable(String))");
+    });
+
+    it("omits nullable modifier when nullable().lowCardinality() is chained", () => {
+      const type = t.string().nullable().lowCardinality();
+      expect(type._modifiers.lowCardinality).toBe(true);
+      expect(type._modifiers.nullable).toBeUndefined();
+      expect(type._tinybirdType).toBe("LowCardinality(Nullable(String))");
     });
   });
 

src/schema/types.ts

@@ -106,7 +106,6 @@ function createValidator<TType, TTinybirdType extends string>(
           `LowCardinality(Nullable(${string}))`
         >(newType as `LowCardinality(Nullable(${string}))`, {
           ...modifiers,
-          nullable: true,
         }) as unknown as TypeValidator<
           TType | null,
           `Nullable(${TTinybirdType})`,
@@ -129,9 +128,10 @@ function createValidator<TType, TTinybirdType extends string>(
         // Extract base type from Nullable(X) and wrap as LowCardinality(Nullable(X))
         const baseType = tinybirdType.replace(/^Nullable\((.+)\)$/, "$1");
         const newType = `LowCardinality(Nullable(${baseType}))`;
+        const { nullable: _, ...rest } = modifiers;
         return createValidator<TType, `LowCardinality(Nullable(${string}))`>(
           newType as `LowCardinality(Nullable(${string}))`,
-          { ...modifiers, lowCardinality: true },
+          { ...rest, lowCardinality: true },
         ) as unknown as TypeValidator<
           TType,
           `LowCardinality(${TTinybirdType})`,