diff --git a/packages/plugins/openapi/tests/openapi-rpc.test.ts b/packages/plugins/openapi/tests/openapi-rpc.test.ts
index 845116ac3..930341ffb 100644
--- a/packages/plugins/openapi/tests/openapi-rpc.test.ts
+++ b/packages/plugins/openapi/tests/openapi-rpc.test.ts
@@ -457,6 +457,36 @@ model post_Item {
 
         await OpenAPIParser.validate(output);
     });
+
+    it('auth() in @default()', async () => {
+        const { projectDir } = await loadSchema(`
+plugin openapi {
+    provider = '${normalizePath(path.resolve(__dirname, '../dist'))}'
+    output = '$projectRoot/openapi.yaml'
+    flavor = 'rpc'
+}
+
+model User {
+    id Int @id
+    posts Post[]
+}
+
+model Post {
+    id Int @id
+    title String
+    author User @relation(fields: [authorId], references: [id])
+    authorId Int @default(auth().id)
+}
+        `);
+
+        const output = path.join(projectDir, 'openapi.yaml');
+        console.log('OpenAPI specification generated:', output);
+
+        await OpenAPIParser.validate(output);
+        const parsed = YAML.parse(fs.readFileSync(output, 'utf-8'));
+        expect(parsed.components.schemas.PostCreateInput.required).not.toContain('author');
+        expect(parsed.components.schemas.PostCreateManyInput.required).not.toContain('authorId');
+    });
 });
 
 function buildOptions(model: Model, modelFile: string, output: string) {
diff --git a/packages/schema/src/plugins/enhancer/enhance/index.ts b/packages/schema/src/plugins/enhancer/enhance/index.ts
index 404c16cd8..51f100557 100644
--- a/packages/schema/src/plugins/enhancer/enhance/index.ts
+++ b/packages/schema/src/plugins/enhancer/enhance/index.ts
@@ -1,3 +1,4 @@
+import { ReadonlyDeep } from '@prisma/generator-helper';
 import { DELEGATE_AUX_RELATION_PREFIX } from '@zenstackhq/runtime';
 import {
     PluginError,
@@ -6,8 +7,10 @@ import {
     getAuthDecl,
     getDataModelAndTypeDefs,
     getDataModels,
+    getForeignKeyFields,
     getLiteral,
     getRelationField,
+    hasAttribute,
     isDelegateModel,
     isDiscriminatorField,
     normalizedRelative,
@@ -311,7 +314,8 @@ export function enhance(prisma: any, context?: EnhancementContext<${authTypePara
         // make a bunch of typing fixes to the generated prisma client
         await this.processClientTypes(path.join(this.outDir, LOGICAL_CLIENT_GENERATION_PATH));
 
-        const dmmf = await getDMMF({ datamodel: fs.readFileSync(logicalPrismaFile, { encoding: 'utf-8' }) });
+        // get the dmmf of the logical prisma schema
+        const dmmf = await this.getLogicalDMMF(logicalPrismaFile);
 
         try {
             // clean up temp schema
@@ -329,6 +333,56 @@ export function enhance(prisma: any, context?: EnhancementContext<${authTypePara
         };
     }
 
+    private async getLogicalDMMF(logicalPrismaFile: string) {
+        const dmmf = await getDMMF({ datamodel: fs.readFileSync(logicalPrismaFile, { encoding: 'utf-8' }) });
+
+        // make necessary fixes
+
+        // fields that use `auth()` in `@default` are not handled by Prisma so in the DMMF
+        // they may be incorrectly represented as required, we need to fix that for input types
+        // also, if a FK field is of such case, its corresponding relation field should be optional
+        const createInputPattern = new RegExp(`^(.+?)(Unchecked)?Create.*Input$`);
+        for (const inputType of dmmf.schema.inputObjectTypes.prisma) {
+            const match = inputType.name.match(createInputPattern);
+            const modelName = match?.[1];
+            if (modelName) {
+                const dataModel = this.model.declarations.find(
+                    (d): d is DataModel => isDataModel(d) && d.name === modelName
+                );
+                if (dataModel) {
+                    for (const field of inputType.fields) {
+                        if (field.isRequired && this.shouldBeOptional(field, dataModel)) {
+                            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+                            (field as any).isRequired = false;
+                        }
+                    }
+                }
+            }
+        }
+        return dmmf;
+    }
+
+    private shouldBeOptional(field: ReadonlyDeep<DMMF.SchemaArg>, dataModel: DataModel) {
+        const dmField = dataModel.fields.find((f) => f.name === field.name);
+        if (!dmField) {
+            return false;
+        }
+
+        if (hasAttribute(dmField, '@default')) {
+            return true;
+        }
+
+        if (isDataModel(dmField.type.reference?.ref)) {
+            // if FK field should be optional, the relation field should too
+            const fkFields = getForeignKeyFields(dmField);
+            if (fkFields.length > 0 && fkFields.every((f) => hasAttribute(f, '@default'))) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     private getPrismaClientGeneratorName(model: Model) {
         for (const generator of model.declarations.filter(isGeneratorDecl)) {
             if (