diff --git a/packages/language/package.json b/packages/language/package.json
index 3f4cca8c..2344404b 100644
--- a/packages/language/package.json
+++ b/packages/language/package.json
@@ -56,6 +56,7 @@
     },
     "dependencies": {
         "@zenstackhq/common-helpers": "workspace:*",
+        "@zenstackhq/schema": "workspace:*",
         "langium": "catalog:",
         "pluralize": "^8.0.0",
         "ts-pattern": "catalog:",
diff --git a/packages/language/src/validators/function-invocation-validator.ts b/packages/language/src/validators/function-invocation-validator.ts
index 8ce1035e..b1e285c7 100644
--- a/packages/language/src/validators/function-invocation-validator.ts
+++ b/packages/language/src/validators/function-invocation-validator.ts
@@ -1,3 +1,4 @@
+import { ID_GENERATOR_FUNCTIONS } from '@zenstackhq/schema';
 import { AstUtils, type AstNode, type ValidationAcceptor } from 'langium';
 import { match, P } from 'ts-pattern';
 import { ExpressionContext } from '../constants';
@@ -88,7 +89,7 @@ export default class FunctionInvocationValidator implements AstValidator<Express
             }
         }
 
-        if (['uuid', 'ulid', 'cuid', 'nanoid'].includes(funcDecl.name)) {
+        if (ID_GENERATOR_FUNCTIONS.includes(funcDecl.name as typeof ID_GENERATOR_FUNCTIONS[number])) {
             const formatParamIdx = funcDecl.params.findIndex((param) => param.name === 'format');
             const formatArg = getLiteral<string>(expr.args[formatParamIdx]?.value);
             if (
diff --git a/packages/orm/src/client/crud-types.ts b/packages/orm/src/client/crud-types.ts
index 1b6f3d3c..f9dafb2e 100644
--- a/packages/orm/src/client/crud-types.ts
+++ b/packages/orm/src/client/crud-types.ts
@@ -35,6 +35,7 @@ import type {
 import type {
     AtLeast,
     MapBaseType,
+    MapStringWithFormat,
     MaybePromise,
     NonEmptyArray,
     NullableIf,
@@ -970,14 +971,16 @@ type MapModelFieldType<
 
 type MapFieldDefType<
     Schema extends SchemaDef,
-    T extends Pick<FieldDef, 'type' | 'optional' | 'array'>,
+    T extends Pick<FieldDef, 'type' | 'optional' | 'array' | 'default'>,
     Partial extends boolean = false,
 > = WrapType<
     T['type'] extends GetEnums<Schema>
         ? keyof GetEnum<Schema, T['type']>
         : T['type'] extends GetTypeDefs<Schema>
           ? TypeDefResult<Schema, T['type'], Partial> & Record<string, unknown>
-          : MapBaseType<T['type']>,
+          : T['type'] extends 'String'
+            ? MapStringWithFormat<T['default']>
+            : MapBaseType<T['type']>,
     T['optional'],
     T['array']
 >;
diff --git a/packages/orm/src/utils/type-utils.ts b/packages/orm/src/utils/type-utils.ts
index f1ad3d35..7713fa02 100644
--- a/packages/orm/src/utils/type-utils.ts
+++ b/packages/orm/src/utils/type-utils.ts
@@ -1,4 +1,5 @@
 import type Decimal from 'decimal.js';
+import type { IdGeneratorFunction } from '@zenstackhq/schema';
 import type { JsonObject, JsonValue } from '../common-types';
 
 export type Optional<T extends object, K extends keyof T = keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
@@ -88,3 +89,57 @@ export type OrUndefinedIf<T, Condition extends boolean> = Condition extends true
 export type UnwrapTuplePromises<T extends readonly unknown[]> = {
     [K in keyof T]: Awaited<T[K]>;
 };
+
+//#region Format string to template literal conversion
+
+/**
+ * Converts a format string like "user_%s" to a template literal type like `user_${string}`.
+ * Supports multiple %s placeholders: "pre_%s_mid_%s" -> `pre_${string}_mid_${string}`
+ * Handles escaped \%s which becomes literal %s: "\\%s_%s" -> `%s_${string}`
+ */
+export type FormatToTemplateLiteral<F extends string> = F extends `${infer Prefix}%s${infer Suffix}`
+    ? Prefix extends `${infer P}\\`
+        ? `${P}%s${FormatToTemplateLiteral<Suffix>}` // Escaped \%s -> literal %s
+        : `${Prefix}${string}${FormatToTemplateLiteral<Suffix>}` // Unescaped %s -> ${string}
+    : F;
+
+/**
+ * Extracts the format string from an ID generator call expression's args.
+ * For uuid/cuid/nanoid: format is in args[1]
+ * For ulid: format is in args[0]
+ */
+type ExtractFormatFromArgs<
+    Func extends string,
+    Args extends readonly unknown[],
+> = Func extends 'ulid'
+    ? Args extends readonly [{ kind: 'literal'; value: infer V }, ...unknown[]]
+        ? V extends string
+            ? V
+            : never
+        : never
+    : Args extends readonly [unknown, { kind: 'literal'; value: infer V }, ...unknown[]]
+      ? V extends string
+          ? V
+          : never
+      : never;
+
+/**
+ * Extracts the format string from a field's default expression if it's an ID generator call.
+ * Returns the format string if found, never otherwise.
+ */
+export type ExtractIdFormat<Default> = Default extends {
+    kind: 'call';
+    function: infer F extends IdGeneratorFunction;
+    args: infer A extends readonly unknown[];
+}
+    ? ExtractFormatFromArgs<F, A>
+    : never;
+
+/**
+ * Maps a String type to either a template literal (if format exists) or plain string.
+ */
+export type MapStringWithFormat<Default> = ExtractIdFormat<Default> extends never
+    ? string
+    : FormatToTemplateLiteral<ExtractIdFormat<Default>>;
+
+//#endregion
diff --git a/packages/orm/test/type-utils.test.ts b/packages/orm/test/type-utils.test.ts
new file mode 100644
index 00000000..8e8fb052
--- /dev/null
+++ b/packages/orm/test/type-utils.test.ts
@@ -0,0 +1,285 @@
+import { describe, expectTypeOf, it } from 'vitest';
+import type {
+    ExtractIdFormat,
+    FormatToTemplateLiteral,
+    MapStringWithFormat,
+} from '../src/utils/type-utils';
+import type { CreateInput } from '../src/client/crud-types';
+import type { SchemaDef } from '../src/schema';
+
+describe('FormatToTemplateLiteral', () => {
+    it('converts simple prefix format to template literal', () => {
+        expectTypeOf<FormatToTemplateLiteral<'user_%s'>>().toEqualTypeOf<`user_${string}`>();
+    });
+
+    it('converts simple suffix format to template literal', () => {
+        expectTypeOf<FormatToTemplateLiteral<'%s_suffix'>>().toEqualTypeOf<`${string}_suffix`>();
+    });
+
+    it('converts multiple placeholders to template literal', () => {
+        expectTypeOf<FormatToTemplateLiteral<'pre_%s_mid_%s'>>().toEqualTypeOf<`pre_${string}_mid_${string}`>();
+    });
+
+    it('preserves string without placeholders', () => {
+        expectTypeOf<FormatToTemplateLiteral<'no_placeholder'>>().toEqualTypeOf<'no_placeholder'>();
+    });
+
+    it('handles escaped \\%s as literal %s', () => {
+        expectTypeOf<FormatToTemplateLiteral<'\\%s_end'>>().toEqualTypeOf<'%s_end'>();
+    });
+
+    it('handles mixed escaped and unescaped - unescaped first', () => {
+        expectTypeOf<FormatToTemplateLiteral<'%s_\\%s'>>().toEqualTypeOf<`${string}_%s`>();
+    });
+
+    it('handles mixed escaped and unescaped - escaped first', () => {
+        expectTypeOf<FormatToTemplateLiteral<'\\%s_%s'>>().toEqualTypeOf<`%s_${string}`>();
+    });
+
+    it('handles multiple escaped placeholders', () => {
+        expectTypeOf<FormatToTemplateLiteral<'\\%s_\\%s'>>().toEqualTypeOf<'%s_%s'>();
+    });
+
+    it('handles complex mixed pattern', () => {
+        expectTypeOf<FormatToTemplateLiteral<'pre_\\%s_%s_\\%s_end'>>().toEqualTypeOf<`pre_%s_${string}_%s_end`>();
+    });
+});
+
+describe('ExtractIdFormat', () => {
+    it('extracts format from uuid call with format arg', () => {
+        type UuidCall = {
+            kind: 'call';
+            function: 'uuid';
+            args: readonly [{ kind: 'literal'; value: 4 }, { kind: 'literal'; value: 'user_%s' }];
+        };
+        expectTypeOf<ExtractIdFormat<UuidCall>>().toEqualTypeOf<'user_%s'>();
+    });
+
+    it('extracts format from cuid call with format arg', () => {
+        type CuidCall = {
+            kind: 'call';
+            function: 'cuid';
+            args: readonly [{ kind: 'literal'; value: 2 }, { kind: 'literal'; value: 'post_%s' }];
+        };
+        expectTypeOf<ExtractIdFormat<CuidCall>>().toEqualTypeOf<'post_%s'>();
+    });
+
+    it('extracts format from nanoid call with format arg', () => {
+        type NanoidCall = {
+            kind: 'call';
+            function: 'nanoid';
+            args: readonly [{ kind: 'literal'; value: 21 }, { kind: 'literal'; value: 'nano_%s' }];
+        };
+        expectTypeOf<ExtractIdFormat<NanoidCall>>().toEqualTypeOf<'nano_%s'>();
+    });
+
+    it('extracts format from ulid call (format is first arg)', () => {
+        type UlidCall = {
+            kind: 'call';
+            function: 'ulid';
+            args: readonly [{ kind: 'literal'; value: 'ulid_%s' }];
+        };
+        expectTypeOf<ExtractIdFormat<UlidCall>>().toEqualTypeOf<'ulid_%s'>();
+    });
+
+    it('returns never for uuid call without format arg', () => {
+        type UuidNoFormat = {
+            kind: 'call';
+            function: 'uuid';
+            args: readonly [{ kind: 'literal'; value: 4 }];
+        };
+        expectTypeOf<ExtractIdFormat<UuidNoFormat>>().toEqualTypeOf<never>();
+    });
+
+    it('returns never for non-id-generator call', () => {
+        type OtherCall = {
+            kind: 'call';
+            function: 'now';
+            args: readonly [];
+        };
+        expectTypeOf<ExtractIdFormat<OtherCall>>().toEqualTypeOf<never>();
+    });
+
+    it('returns never for undefined', () => {
+        expectTypeOf<ExtractIdFormat<undefined>>().toEqualTypeOf<never>();
+    });
+});
+
+describe('MapStringWithFormat', () => {
+    it('returns template literal for uuid with format', () => {
+        type UuidCall = {
+            kind: 'call';
+            function: 'uuid';
+            args: readonly [{ kind: 'literal'; value: 4 }, { kind: 'literal'; value: 'user_%s' }];
+        };
+        expectTypeOf<MapStringWithFormat<UuidCall>>().toEqualTypeOf<`user_${string}`>();
+    });
+
+    it('returns plain string for uuid without format', () => {
+        type UuidNoFormat = {
+            kind: 'call';
+            function: 'uuid';
+            args: readonly [{ kind: 'literal'; value: 4 }];
+        };
+        expectTypeOf<MapStringWithFormat<UuidNoFormat>>().toEqualTypeOf<string>();
+    });
+
+    it('returns plain string for undefined default', () => {
+        expectTypeOf<MapStringWithFormat<undefined>>().toEqualTypeOf<string>();
+    });
+
+    it('returns plain string for non-call default', () => {
+        expectTypeOf<MapStringWithFormat<'static-value'>>().toEqualTypeOf<string>();
+    });
+
+    it('handles escaped format in uuid call', () => {
+        type UuidEscaped = {
+            kind: 'call';
+            function: 'uuid';
+            args: readonly [{ kind: 'literal'; value: 4 }, { kind: 'literal'; value: '\\%s_%s' }];
+        };
+        expectTypeOf<MapStringWithFormat<UuidEscaped>>().toEqualTypeOf<`%s_${string}`>();
+    });
+});
+
+describe('CreateInput with prefixed ID', () => {
+    // Mock schema with a User model that has a prefixed ID
+    type TestSchema = SchemaDef & {
+        provider: { type: 'sqlite' };
+        models: {
+            User: {
+                name: 'User';
+                fields: {
+                    id: {
+                        name: 'id';
+                        type: 'String';
+                        id: true;
+                        default: {
+                            kind: 'call';
+                            function: 'uuid';
+                            args: readonly [
+                                { kind: 'literal'; value: 4 },
+                                { kind: 'literal'; value: 'user_%s' },
+                            ];
+                        };
+                    };
+                    name: {
+                        name: 'name';
+                        type: 'String';
+                    };
+                };
+                uniqueFields: { id: { type: 'String' } };
+                idFields: readonly ['id'];
+            };
+        };
+        enums: {};
+        plugins: {};
+    };
+
+    it('enforces template literal type for prefixed ID in create input', () => {
+        type UserCreateInput = CreateInput<TestSchema, 'User'>;
+
+        // The id field should accept template literal type
+        expectTypeOf<UserCreateInput['id']>().toEqualTypeOf<`user_${string}` | undefined>();
+    });
+
+    it('allows plain string for non-prefixed ID fields', () => {
+        // Schema with plain uuid (no format)
+        type PlainIdSchema = SchemaDef & {
+            provider: { type: 'sqlite' };
+            models: {
+                Post: {
+                    name: 'Post';
+                    fields: {
+                        id: {
+                            name: 'id';
+                            type: 'String';
+                            id: true;
+                            default: {
+                                kind: 'call';
+                                function: 'uuid';
+                                args: readonly [{ kind: 'literal'; value: 4 }];
+                            };
+                        };
+                        title: {
+                            name: 'title';
+                            type: 'String';
+                        };
+                    };
+                    uniqueFields: { id: { type: 'String' } };
+                    idFields: readonly ['id'];
+                };
+            };
+            enums: {};
+            plugins: {};
+        };
+
+        type PostCreateInput = CreateInput<PlainIdSchema, 'Post'>;
+
+        // The id field should accept plain string
+        expectTypeOf<PostCreateInput['id']>().toEqualTypeOf<string | undefined>();
+    });
+
+    it('enforces template literal for cuid with format', () => {
+        type CuidSchema = SchemaDef & {
+            provider: { type: 'sqlite' };
+            models: {
+                Comment: {
+                    name: 'Comment';
+                    fields: {
+                        id: {
+                            name: 'id';
+                            type: 'String';
+                            id: true;
+                            default: {
+                                kind: 'call';
+                                function: 'cuid';
+                                args: readonly [
+                                    { kind: 'literal'; value: 2 },
+                                    { kind: 'literal'; value: 'cmt_%s' },
+                                ];
+                            };
+                        };
+                    };
+                    uniqueFields: { id: { type: 'String' } };
+                    idFields: readonly ['id'];
+                };
+            };
+            enums: {};
+            plugins: {};
+        };
+
+        type CommentCreateInput = CreateInput<CuidSchema, 'Comment'>;
+        expectTypeOf<CommentCreateInput['id']>().toEqualTypeOf<`cmt_${string}` | undefined>();
+    });
+
+    it('enforces template literal for ulid with format (format is first arg)', () => {
+        type UlidSchema = SchemaDef & {
+            provider: { type: 'sqlite' };
+            models: {
+                Order: {
+                    name: 'Order';
+                    fields: {
+                        id: {
+                            name: 'id';
+                            type: 'String';
+                            id: true;
+                            default: {
+                                kind: 'call';
+                                function: 'ulid';
+                                args: readonly [{ kind: 'literal'; value: 'ord_%s' }];
+                            };
+                        };
+                    };
+                    uniqueFields: { id: { type: 'String' } };
+                    idFields: readonly ['id'];
+                };
+            };
+            enums: {};
+            plugins: {};
+        };
+
+        type OrderCreateInput = CreateInput<UlidSchema, 'Order'>;
+        expectTypeOf<OrderCreateInput['id']>().toEqualTypeOf<`ord_${string}` | undefined>();
+    });
+});
diff --git a/packages/schema/src/index.ts b/packages/schema/src/index.ts
index 6a171e59..0140ef01 100644
--- a/packages/schema/src/index.ts
+++ b/packages/schema/src/index.ts
@@ -1,3 +1,3 @@
 export type * from './expression';
 export * from './expression-utils';
-export type * from './schema';
+export * from './schema';
diff --git a/packages/schema/src/schema.ts b/packages/schema/src/schema.ts
index 40f7d8bd..cc0cdcb8 100644
--- a/packages/schema/src/schema.ts
+++ b/packages/schema/src/schema.ts
@@ -315,3 +315,13 @@ export type FieldIsDelegateDiscriminator<
 > = GetModelField<Schema, Model, Field>['isDiscriminator'] extends true ? true : false;
 
 //#endregion
+
+//#region Field defaults
+
+/**
+ * ID generator functions that support format strings (e.g., uuid(4, "user_%s"))
+ */
+export const ID_GENERATOR_FUNCTIONS = ['uuid', 'cuid', 'nanoid', 'ulid'] as const;
+export type IdGeneratorFunction = (typeof ID_GENERATOR_FUNCTIONS)[number];
+
+//#endregion