diff --git a/package.json b/package.json
index ce90997d..f3076315 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "zenstack-v3",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack",
     "packageManager": "pnpm@10.23.0",
     "type": "module",
diff --git a/packages/auth-adapters/better-auth/package.json b/packages/auth-adapters/better-auth/package.json
index ed7c0294..bb7aafef 100644
--- a/packages/auth-adapters/better-auth/package.json
+++ b/packages/auth-adapters/better-auth/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/better-auth",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack Better Auth Adapter. This adapter is modified from better-auth's Prisma adapter.",
     "type": "module",
     "scripts": {
diff --git a/packages/cli/package.json b/packages/cli/package.json
index b00c0798..c2356c70 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -3,7 +3,7 @@
     "publisher": "zenstack",
     "displayName": "ZenStack CLI",
     "description": "FullStack database toolkit with built-in access control and automatic API generation.",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "type": "module",
     "author": {
         "name": "ZenStack Team"
diff --git a/packages/cli/src/actions/generate.ts b/packages/cli/src/actions/generate.ts
index bd11c622..2c29da5b 100644
--- a/packages/cli/src/actions/generate.ts
+++ b/packages/cli/src/actions/generate.ts
@@ -36,7 +36,7 @@ export async function run(options: Options) {
 
 \`\`\`ts
 import { ZenStackClient } from '@zenstackhq/orm';
-import { schema } from '${outputPath}/schema';
+import { schema } from '${path.relative('.', outputPath)}/schema';
 
 const client = new ZenStackClient(schema, {
     dialect: { ... }
diff --git a/packages/cli/src/actions/templates.ts b/packages/cli/src/actions/templates.ts
index 155e51db..4cd74660 100644
--- a/packages/cli/src/actions/templates.ts
+++ b/packages/cli/src/actions/templates.ts
@@ -21,7 +21,7 @@ model Post {
     title     String   @length(1, 256)
     content   String
     published Boolean  @default(false)
-    author    User     @relation(fields: [authorId], references: [id])
+    author    User     @relation(fields: [authorId], references: [id], onDelete: Cascade)
     authorId  String
 }
 `;
diff --git a/packages/clients/tanstack-query/package.json b/packages/clients/tanstack-query/package.json
index 4ed8c06f..401589cf 100644
--- a/packages/clients/tanstack-query/package.json
+++ b/packages/clients/tanstack-query/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/tanstack-query",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "TanStack Query Client for consuming ZenStack v3's CRUD service",
     "main": "index.js",
     "type": "module",
diff --git a/packages/common-helpers/package.json b/packages/common-helpers/package.json
index e7616d51..2b3aa8a3 100644
--- a/packages/common-helpers/package.json
+++ b/packages/common-helpers/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/common-helpers",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack Common Helpers",
     "type": "module",
     "scripts": {
diff --git a/packages/config/eslint-config/package.json b/packages/config/eslint-config/package.json
index b2eaf81d..43e47152 100644
--- a/packages/config/eslint-config/package.json
+++ b/packages/config/eslint-config/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/eslint-config",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "type": "module",
     "private": true,
     "license": "MIT"
diff --git a/packages/config/typescript-config/package.json b/packages/config/typescript-config/package.json
index 7898557b..a08b125f 100644
--- a/packages/config/typescript-config/package.json
+++ b/packages/config/typescript-config/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/typescript-config",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "license": "MIT"
 }
diff --git a/packages/config/vitest-config/package.json b/packages/config/vitest-config/package.json
index 78d8b455..c3f7ebb3 100644
--- a/packages/config/vitest-config/package.json
+++ b/packages/config/vitest-config/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@zenstackhq/vitest-config",
     "type": "module",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "license": "MIT",
     "exports": {
diff --git a/packages/create-zenstack/package.json b/packages/create-zenstack/package.json
index a30ffadf..1bc4ac61 100644
--- a/packages/create-zenstack/package.json
+++ b/packages/create-zenstack/package.json
@@ -1,6 +1,6 @@
 {
     "name": "create-zenstack",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "Create a new ZenStack project",
     "type": "module",
     "scripts": {
diff --git a/packages/ide/vscode/package.json b/packages/ide/vscode/package.json
index bfaf079c..dee8389b 100644
--- a/packages/ide/vscode/package.json
+++ b/packages/ide/vscode/package.json
@@ -1,7 +1,7 @@
 {
     "name": "zenstack-v3",
     "publisher": "zenstack",
-    "version": "3.0.14",
+    "version": "3.0.15",
     "displayName": "ZenStack V3 Language Tools",
     "description": "VSCode extension for ZenStack (v3) ZModel language",
     "private": true,
diff --git a/packages/language/package.json b/packages/language/package.json
index a0a11793..3b62243c 100644
--- a/packages/language/package.json
+++ b/packages/language/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@zenstackhq/language",
     "description": "ZenStack ZModel language specification",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "license": "MIT",
     "author": "ZenStack Team",
     "files": [
diff --git a/packages/orm/package.json b/packages/orm/package.json
index 948f6f59..083018c1 100644
--- a/packages/orm/package.json
+++ b/packages/orm/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/orm",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack ORM",
     "type": "module",
     "scripts": {
diff --git a/packages/orm/src/client/crud-types.ts b/packages/orm/src/client/crud-types.ts
index 9704d173..1fefdc7d 100644
--- a/packages/orm/src/client/crud-types.ts
+++ b/packages/orm/src/client/crud-types.ts
@@ -139,50 +139,34 @@ type ModelSelectResult<
     Options extends QueryOptions<Schema>,
 > = {
     [Key in keyof Select as Select[Key] extends false | undefined
-        ? never
-        : Key extends keyof Omit
-          ? Omit[Key] extends true
-              ? never
-              : Key
-          : Key extends '_count'
-            ? Select[Key] extends SelectCount<Schema, Model>
-                ? Key
-                : never
+        ? // not selected
+          never
+        : Key extends '_count'
+          ? // select "_count"
+            Select[Key] extends SelectCount<Schema, Model>
+              ? Key
+              : never
+          : Key extends keyof Omit
+            ? Omit[Key] extends true
+                ? //   omit
+                  never
+                : Key
             : Key]: Key extends '_count'
-        ? SelectCountResult<Schema, Model, Select[Key]>
+        ? // select "_count" result
+          SelectCountResult<Schema, Model, Select[Key]>
         : Key extends NonRelationFields<Schema, Model>
-          ? MapModelFieldType<Schema, Model, Key>
+          ? // scalar field result
+            MapModelFieldType<Schema, Model, Key>
           : Key extends RelationFields<Schema, Model>
-            ? Select[Key] extends FindArgs<
+            ? // relation field result (recurse)
+              ModelResult<
                   Schema,
                   RelationFieldType<Schema, Model, Key>,
+                  Select[Key],
+                  Options,
+                  ModelFieldIsOptional<Schema, Model, Key>,
                   FieldIsArray<Schema, Model, Key>
               >
-                ? 'select' extends keyof Select[Key]
-                    ? ModelResult<
-                          Schema,
-                          RelationFieldType<Schema, Model, Key>,
-                          Pick<Select[Key], 'select'>,
-                          Options,
-                          ModelFieldIsOptional<Schema, Model, Key>,
-                          FieldIsArray<Schema, Model, Key>
-                      >
-                    : ModelResult<
-                          Schema,
-                          RelationFieldType<Schema, Model, Key>,
-                          Pick<Select[Key], 'include' | 'omit'>,
-                          Options,
-                          ModelFieldIsOptional<Schema, Model, Key>,
-                          FieldIsArray<Schema, Model, Key>
-                      >
-                : DefaultModelResult<
-                      Schema,
-                      RelationFieldType<Schema, Model, Key>,
-                      Omit,
-                      Options,
-                      ModelFieldIsOptional<Schema, Model, Key>,
-                      FieldIsArray<Schema, Model, Key>
-                  >
             : never;
 };
 
@@ -204,40 +188,29 @@ export type ModelResult<
     Array = false,
 > = WrapType<
     Args extends {
-        select: infer S;
-        omit?: infer O;
-    }
+        select: infer S extends object;
+        omit?: infer O extends object;
+    } & Record<string, unknown>
         ? ModelSelectResult<Schema, Model, S, O, Options>
         : Args extends {
-                include: infer I;
-                omit?: infer O;
-            }
-          ? DefaultModelResult<Schema, Model, O, Options, false, false> & {
+                include: infer I extends object;
+                omit?: infer O extends object;
+            } & Record<string, unknown>
+          ? // select all non-omitted scalar fields
+            DefaultModelResult<Schema, Model, O, Options, false, false> & {
+                // recurse for "include" relations
                 [Key in keyof I & RelationFields<Schema, Model> as I[Key] extends false | undefined
                     ? never
-                    : Key]: I[Key] extends FindArgs<
+                    : Key]: ModelResult<
                     Schema,
                     RelationFieldType<Schema, Model, Key>,
+                    I[Key],
+                    Options,
+                    ModelFieldIsOptional<Schema, Model, Key>,
                     FieldIsArray<Schema, Model, Key>
-                >
-                    ? ModelResult<
-                          Schema,
-                          RelationFieldType<Schema, Model, Key>,
-                          I[Key],
-                          Options,
-                          ModelFieldIsOptional<Schema, Model, Key>,
-                          FieldIsArray<Schema, Model, Key>
-                      >
-                    : DefaultModelResult<
-                          Schema,
-                          RelationFieldType<Schema, Model, Key>,
-                          undefined,
-                          Options,
-                          ModelFieldIsOptional<Schema, Model, Key>,
-                          FieldIsArray<Schema, Model, Key>
-                      >;
+                >;
             }
-          : Args extends { omit: infer O }
+          : Args extends { omit: infer O } & Record<string, unknown>
             ? DefaultModelResult<Schema, Model, O, Options, false, false>
             : DefaultModelResult<Schema, Model, undefined, Options, false, false>,
     Optional,
diff --git a/packages/orm/src/client/query-utils.ts b/packages/orm/src/client/query-utils.ts
index adeabd5d..51096722 100644
--- a/packages/orm/src/client/query-utils.ts
+++ b/packages/orm/src/client/query-utils.ts
@@ -232,18 +232,22 @@ export function getManyToManyRelation(schema: SchemaDef, model: string, field: s
     if (!fieldDef.array || !fieldDef.relation?.opposite) {
         return undefined;
     }
+
+    // in case the m2m relation field is inherited from a delegate base, get the base model
+    const realModel = fieldDef.originModel ?? model;
+
     const oppositeFieldDef = requireField(schema, fieldDef.type, fieldDef.relation.opposite);
     if (oppositeFieldDef.array) {
         // Prisma's convention for many-to-many relation:
         // - model are sorted alphabetically by name
         // - join table is named _<model1>To<model2>, unless an explicit name is provided by `@relation`
         // - foreign keys are named A and B (based on the order of the model)
-        const sortedModelNames = [model, fieldDef.type].sort();
+        const sortedModelNames = [realModel, fieldDef.type].sort();
 
         let orderedFK: [string, string];
-        if (model !== fieldDef.type) {
+        if (realModel !== fieldDef.type) {
             // not a self-relation, model name's sort order determines fk order
-            orderedFK = sortedModelNames[0] === model ? ['A', 'B'] : ['B', 'A'];
+            orderedFK = sortedModelNames[0] === realModel ? ['A', 'B'] : ['B', 'A'];
         } else {
             // for self-relations, since model names are identical, relation field name's
             // sort order determines fk order
@@ -251,7 +255,7 @@ export function getManyToManyRelation(schema: SchemaDef, model: string, field: s
             orderedFK = sortedFieldNames[0] === field ? ['A', 'B'] : ['B', 'A'];
         }
 
-        const modelIdFields = requireIdFields(schema, model);
+        const modelIdFields = requireIdFields(schema, realModel);
         invariant(modelIdFields.length === 1, 'Only single-field ID is supported for many-to-many relation');
         const otherIdFields = requireIdFields(schema, fieldDef.type);
         invariant(otherIdFields.length === 1, 'Only single-field ID is supported for many-to-many relation');
diff --git a/packages/plugins/policy/package.json b/packages/plugins/policy/package.json
index 8a2b76e1..a5c8c394 100644
--- a/packages/plugins/policy/package.json
+++ b/packages/plugins/policy/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/plugin-policy",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack Policy Plugin",
     "type": "module",
     "scripts": {
diff --git a/packages/schema/package.json b/packages/schema/package.json
index 55cd411b..2ab34409 100644
--- a/packages/schema/package.json
+++ b/packages/schema/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/schema",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack Runtime Schema",
     "type": "module",
     "scripts": {
diff --git a/packages/sdk/package.json b/packages/sdk/package.json
index a5ef69c4..7aaada5b 100644
--- a/packages/sdk/package.json
+++ b/packages/sdk/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/sdk",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack SDK",
     "type": "module",
     "scripts": {
diff --git a/packages/server/package.json b/packages/server/package.json
index ec3ce79a..068119de 100644
--- a/packages/server/package.json
+++ b/packages/server/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/server",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack automatic CRUD API handlers and server adapters",
     "type": "module",
     "scripts": {
diff --git a/packages/testtools/package.json b/packages/testtools/package.json
index 46cb5c85..45d443f3 100644
--- a/packages/testtools/package.json
+++ b/packages/testtools/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/testtools",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "ZenStack Test Tools",
     "type": "module",
     "scripts": {
diff --git a/packages/zod/package.json b/packages/zod/package.json
index 99c108da..187046dd 100644
--- a/packages/zod/package.json
+++ b/packages/zod/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/zod",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "",
     "type": "module",
     "main": "index.js",
diff --git a/samples/next.js/package.json b/samples/next.js/package.json
index de1d5dcd..71d496ec 100644
--- a/samples/next.js/package.json
+++ b/samples/next.js/package.json
@@ -1,6 +1,6 @@
 {
     "name": "next.js",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "scripts": {
         "generate": "zen generate --lite",
diff --git a/samples/orm/package.json b/samples/orm/package.json
index 01035a4b..1aae5022 100644
--- a/samples/orm/package.json
+++ b/samples/orm/package.json
@@ -1,6 +1,6 @@
 {
     "name": "sample-blog",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "description": "",
     "main": "index.js",
     "private": true,
diff --git a/tests/e2e/orm/schemas/typing/typecheck.ts b/tests/e2e/orm/schemas/typing/typecheck.ts
index 9c6860e3..976c04c8 100644
--- a/tests/e2e/orm/schemas/typing/typecheck.ts
+++ b/tests/e2e/orm/schemas/typing/typecheck.ts
@@ -167,6 +167,7 @@ async function find() {
             select: {
                 posts: {
                     where: { title: 'Foo' },
+                    take: 1,
                     select: {
                         author: {
                             select: {
diff --git a/tests/e2e/package.json b/tests/e2e/package.json
index 19a99f77..743bcd0c 100644
--- a/tests/e2e/package.json
+++ b/tests/e2e/package.json
@@ -1,6 +1,6 @@
 {
     "name": "e2e",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "type": "module",
     "scripts": {
diff --git a/tests/regression/package.json b/tests/regression/package.json
index d750958f..4b99fc7f 100644
--- a/tests/regression/package.json
+++ b/tests/regression/package.json
@@ -1,12 +1,12 @@
 {
     "name": "regression",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "type": "module",
     "scripts": {
-        "build": "pnpm run generate",
-        "generate": "tsx ../../scripts/test-generate.ts ./test",
-        "test": "pnpm generate && tsc && vitest run"
+        "build": "pnpm run test:generate",
+        "test:generate": "tsx ../../scripts/test-generate.ts ./test",
+        "test": "pnpm test:generate && tsc && vitest run"
     },
     "dependencies": {
         "@zenstackhq/testtools": "workspace:*",
diff --git a/tests/regression/test/issue-503/input.ts b/tests/regression/test/issue-503/input.ts
new file mode 100644
index 00000000..e1e5bb0d
--- /dev/null
+++ b/tests/regression/test/issue-503/input.ts
@@ -0,0 +1,70 @@
+//////////////////////////////////////////////////////////////////////////////////////////////
+// DO NOT MODIFY THIS FILE                                                                  //
+// This file is automatically generated by ZenStack CLI and should not be manually updated. //
+//////////////////////////////////////////////////////////////////////////////////////////////
+
+/* eslint-disable */
+
+import { type SchemaType as $Schema } from "./schema";
+import type { FindManyArgs as $FindManyArgs, FindUniqueArgs as $FindUniqueArgs, FindFirstArgs as $FindFirstArgs, CreateArgs as $CreateArgs, CreateManyArgs as $CreateManyArgs, CreateManyAndReturnArgs as $CreateManyAndReturnArgs, UpdateArgs as $UpdateArgs, UpdateManyArgs as $UpdateManyArgs, UpdateManyAndReturnArgs as $UpdateManyAndReturnArgs, UpsertArgs as $UpsertArgs, DeleteArgs as $DeleteArgs, DeleteManyArgs as $DeleteManyArgs, CountArgs as $CountArgs, AggregateArgs as $AggregateArgs, GroupByArgs as $GroupByArgs, WhereInput as $WhereInput, SelectInput as $SelectInput, IncludeInput as $IncludeInput, OmitInput as $OmitInput, QueryOptions as $QueryOptions } from "@zenstackhq/orm";
+import type { SimplifiedPlainResult as $Result, SelectIncludeOmit as $SelectIncludeOmit } from "@zenstackhq/orm";
+export type InternalChatFindManyArgs = $FindManyArgs<$Schema, "InternalChat">;
+export type InternalChatFindUniqueArgs = $FindUniqueArgs<$Schema, "InternalChat">;
+export type InternalChatFindFirstArgs = $FindFirstArgs<$Schema, "InternalChat">;
+export type InternalChatCreateArgs = $CreateArgs<$Schema, "InternalChat">;
+export type InternalChatCreateManyArgs = $CreateManyArgs<$Schema, "InternalChat">;
+export type InternalChatCreateManyAndReturnArgs = $CreateManyAndReturnArgs<$Schema, "InternalChat">;
+export type InternalChatUpdateArgs = $UpdateArgs<$Schema, "InternalChat">;
+export type InternalChatUpdateManyArgs = $UpdateManyArgs<$Schema, "InternalChat">;
+export type InternalChatUpdateManyAndReturnArgs = $UpdateManyAndReturnArgs<$Schema, "InternalChat">;
+export type InternalChatUpsertArgs = $UpsertArgs<$Schema, "InternalChat">;
+export type InternalChatDeleteArgs = $DeleteArgs<$Schema, "InternalChat">;
+export type InternalChatDeleteManyArgs = $DeleteManyArgs<$Schema, "InternalChat">;
+export type InternalChatCountArgs = $CountArgs<$Schema, "InternalChat">;
+export type InternalChatAggregateArgs = $AggregateArgs<$Schema, "InternalChat">;
+export type InternalChatGroupByArgs = $GroupByArgs<$Schema, "InternalChat">;
+export type InternalChatWhereInput = $WhereInput<$Schema, "InternalChat">;
+export type InternalChatSelect = $SelectInput<$Schema, "InternalChat">;
+export type InternalChatInclude = $IncludeInput<$Schema, "InternalChat">;
+export type InternalChatOmit = $OmitInput<$Schema, "InternalChat">;
+export type InternalChatGetPayload<Args extends $SelectIncludeOmit<$Schema, "InternalChat", true>, Options extends $QueryOptions<$Schema> = $QueryOptions<$Schema>> = $Result<$Schema, "InternalChat", Args, Options>;
+export type MessageFindManyArgs = $FindManyArgs<$Schema, "Message">;
+export type MessageFindUniqueArgs = $FindUniqueArgs<$Schema, "Message">;
+export type MessageFindFirstArgs = $FindFirstArgs<$Schema, "Message">;
+export type MessageCreateArgs = $CreateArgs<$Schema, "Message">;
+export type MessageCreateManyArgs = $CreateManyArgs<$Schema, "Message">;
+export type MessageCreateManyAndReturnArgs = $CreateManyAndReturnArgs<$Schema, "Message">;
+export type MessageUpdateArgs = $UpdateArgs<$Schema, "Message">;
+export type MessageUpdateManyArgs = $UpdateManyArgs<$Schema, "Message">;
+export type MessageUpdateManyAndReturnArgs = $UpdateManyAndReturnArgs<$Schema, "Message">;
+export type MessageUpsertArgs = $UpsertArgs<$Schema, "Message">;
+export type MessageDeleteArgs = $DeleteArgs<$Schema, "Message">;
+export type MessageDeleteManyArgs = $DeleteManyArgs<$Schema, "Message">;
+export type MessageCountArgs = $CountArgs<$Schema, "Message">;
+export type MessageAggregateArgs = $AggregateArgs<$Schema, "Message">;
+export type MessageGroupByArgs = $GroupByArgs<$Schema, "Message">;
+export type MessageWhereInput = $WhereInput<$Schema, "Message">;
+export type MessageSelect = $SelectInput<$Schema, "Message">;
+export type MessageInclude = $IncludeInput<$Schema, "Message">;
+export type MessageOmit = $OmitInput<$Schema, "Message">;
+export type MessageGetPayload<Args extends $SelectIncludeOmit<$Schema, "Message", true>, Options extends $QueryOptions<$Schema> = $QueryOptions<$Schema>> = $Result<$Schema, "Message", Args, Options>;
+export type MediaFindManyArgs = $FindManyArgs<$Schema, "Media">;
+export type MediaFindUniqueArgs = $FindUniqueArgs<$Schema, "Media">;
+export type MediaFindFirstArgs = $FindFirstArgs<$Schema, "Media">;
+export type MediaCreateArgs = $CreateArgs<$Schema, "Media">;
+export type MediaCreateManyArgs = $CreateManyArgs<$Schema, "Media">;
+export type MediaCreateManyAndReturnArgs = $CreateManyAndReturnArgs<$Schema, "Media">;
+export type MediaUpdateArgs = $UpdateArgs<$Schema, "Media">;
+export type MediaUpdateManyArgs = $UpdateManyArgs<$Schema, "Media">;
+export type MediaUpdateManyAndReturnArgs = $UpdateManyAndReturnArgs<$Schema, "Media">;
+export type MediaUpsertArgs = $UpsertArgs<$Schema, "Media">;
+export type MediaDeleteArgs = $DeleteArgs<$Schema, "Media">;
+export type MediaDeleteManyArgs = $DeleteManyArgs<$Schema, "Media">;
+export type MediaCountArgs = $CountArgs<$Schema, "Media">;
+export type MediaAggregateArgs = $AggregateArgs<$Schema, "Media">;
+export type MediaGroupByArgs = $GroupByArgs<$Schema, "Media">;
+export type MediaWhereInput = $WhereInput<$Schema, "Media">;
+export type MediaSelect = $SelectInput<$Schema, "Media">;
+export type MediaInclude = $IncludeInput<$Schema, "Media">;
+export type MediaOmit = $OmitInput<$Schema, "Media">;
+export type MediaGetPayload<Args extends $SelectIncludeOmit<$Schema, "Media", true>, Options extends $QueryOptions<$Schema> = $QueryOptions<$Schema>> = $Result<$Schema, "Media", Args, Options>;
diff --git a/tests/regression/test/issue-503/models.ts b/tests/regression/test/issue-503/models.ts
new file mode 100644
index 00000000..e71f3a61
--- /dev/null
+++ b/tests/regression/test/issue-503/models.ts
@@ -0,0 +1,12 @@
+//////////////////////////////////////////////////////////////////////////////////////////////
+// DO NOT MODIFY THIS FILE                                                                  //
+// This file is automatically generated by ZenStack CLI and should not be manually updated. //
+//////////////////////////////////////////////////////////////////////////////////////////////
+
+/* eslint-disable */
+
+import { type SchemaType as $Schema } from "./schema";
+import { type ModelResult as $ModelResult } from "@zenstackhq/orm";
+export type InternalChat = $ModelResult<$Schema, "InternalChat">;
+export type Message = $ModelResult<$Schema, "Message">;
+export type Media = $ModelResult<$Schema, "Media">;
diff --git a/tests/regression/test/issue-503/regression.test.ts b/tests/regression/test/issue-503/regression.test.ts
new file mode 100644
index 00000000..c31864a7
--- /dev/null
+++ b/tests/regression/test/issue-503/regression.test.ts
@@ -0,0 +1,31 @@
+import { createTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+import { schema } from './schema';
+
+describe('Regression tests for issues #503', () => {
+    it('verifies the issue', async () => {
+        const db = await createTestClient(schema);
+        const r = await db.internalChat.create({
+            data: {
+                messages: {
+                    create: {
+                        media: {
+                            create: {
+                                type: 'Image',
+                            },
+                        },
+                    },
+                },
+            },
+            select: {
+                messages: {
+                    take: 1,
+                    include: {
+                        media: true,
+                    },
+                },
+            },
+        });
+        expect(r.messages[0]?.media).toMatchObject({ type: 'Image' });
+    });
+});
diff --git a/tests/regression/test/issue-503/schema.ts b/tests/regression/test/issue-503/schema.ts
new file mode 100644
index 00000000..0c857314
--- /dev/null
+++ b/tests/regression/test/issue-503/schema.ts
@@ -0,0 +1,109 @@
+//////////////////////////////////////////////////////////////////////////////////////////////
+// DO NOT MODIFY THIS FILE                                                                  //
+// This file is automatically generated by ZenStack CLI and should not be manually updated. //
+//////////////////////////////////////////////////////////////////////////////////////////////
+
+/* eslint-disable */
+
+import { type SchemaDef, ExpressionUtils } from "@zenstackhq/orm/schema";
+export class SchemaType implements SchemaDef {
+    provider = {
+        type: "sqlite"
+    } as const;
+    models = {
+        InternalChat: {
+            name: "InternalChat",
+            fields: {
+                id: {
+                    name: "id",
+                    type: "Int",
+                    id: true,
+                    attributes: [{ name: "@id" }, { name: "@default", args: [{ name: "value", value: ExpressionUtils.call("autoincrement") }] }],
+                    default: ExpressionUtils.call("autoincrement")
+                },
+                messages: {
+                    name: "messages",
+                    type: "Message",
+                    array: true,
+                    relation: { opposite: "chat" }
+                }
+            },
+            idFields: ["id"],
+            uniqueFields: {
+                id: { type: "Int" }
+            }
+        },
+        Message: {
+            name: "Message",
+            fields: {
+                id: {
+                    name: "id",
+                    type: "Int",
+                    id: true,
+                    attributes: [{ name: "@id" }, { name: "@default", args: [{ name: "value", value: ExpressionUtils.call("autoincrement") }] }],
+                    default: ExpressionUtils.call("autoincrement")
+                },
+                chat: {
+                    name: "chat",
+                    type: "InternalChat",
+                    attributes: [{ name: "@relation", args: [{ name: "fields", value: ExpressionUtils.array([ExpressionUtils.field("chatId")]) }, { name: "references", value: ExpressionUtils.array([ExpressionUtils.field("id")]) }] }],
+                    relation: { opposite: "messages", fields: ["chatId"], references: ["id"] }
+                },
+                chatId: {
+                    name: "chatId",
+                    type: "Int",
+                    foreignKeyFor: [
+                        "chat"
+                    ]
+                },
+                media: {
+                    name: "media",
+                    type: "Media",
+                    optional: true,
+                    attributes: [{ name: "@relation", args: [{ name: "fields", value: ExpressionUtils.array([ExpressionUtils.field("mediaId")]) }, { name: "references", value: ExpressionUtils.array([ExpressionUtils.field("id")]) }] }],
+                    relation: { opposite: "messages", fields: ["mediaId"], references: ["id"] }
+                },
+                mediaId: {
+                    name: "mediaId",
+                    type: "Int",
+                    optional: true,
+                    foreignKeyFor: [
+                        "media"
+                    ]
+                }
+            },
+            idFields: ["id"],
+            uniqueFields: {
+                id: { type: "Int" }
+            }
+        },
+        Media: {
+            name: "Media",
+            fields: {
+                id: {
+                    name: "id",
+                    type: "Int",
+                    id: true,
+                    attributes: [{ name: "@id" }, { name: "@default", args: [{ name: "value", value: ExpressionUtils.call("autoincrement") }] }],
+                    default: ExpressionUtils.call("autoincrement")
+                },
+                type: {
+                    name: "type",
+                    type: "String"
+                },
+                messages: {
+                    name: "messages",
+                    type: "Message",
+                    array: true,
+                    relation: { opposite: "media" }
+                }
+            },
+            idFields: ["id"],
+            uniqueFields: {
+                id: { type: "Int" }
+            }
+        }
+    } as const;
+    plugins = {};
+}
+export const schema = new SchemaType();
diff --git a/tests/regression/test/issue-503/schema.zmodel b/tests/regression/test/issue-503/schema.zmodel
new file mode 100644
index 00000000..7cbe035d
--- /dev/null
+++ b/tests/regression/test/issue-503/schema.zmodel
@@ -0,0 +1,23 @@
+datasource db {
+    provider = "sqlite"
+    url      = "file:./dev.db"
+}
+
+model InternalChat {
+    id       Int       @id @default(autoincrement())
+    messages Message[]
+}
+
+model Message {
+    id      Int          @id @default(autoincrement())
+    chat    InternalChat @relation(fields: [chatId], references: [id])
+    chatId  Int
+    media   Media?       @relation(fields: [mediaId], references: [id])
+    mediaId Int?
+}
+
+model Media {
+    id       Int       @id @default(autoincrement())
+    type     String
+    messages Message[]
+}
diff --git a/tests/regression/test/issue-505.test.ts b/tests/regression/test/issue-505.test.ts
new file mode 100644
index 00000000..da848285
--- /dev/null
+++ b/tests/regression/test/issue-505.test.ts
@@ -0,0 +1,69 @@
+import { createTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+
+describe('Regression tests for issues 505', () => {
+    it('verifies the issue', async () => {
+        const db = await createTestClient(
+            `
+model Media {
+  id        String   @id @default(cuid())
+  type      String
+  @@delegate(type)
+
+  messages   Message[]
+}
+
+model TelegramPhoto extends Media {
+  tgFileId String @unique
+  width          Int
+  height         Int
+}
+
+model Message {
+  id        String      @id @default(cuid())
+  media     Media[]
+  type String
+  @@delegate(type)
+}
+
+model TelegramMessage extends Message {
+  tgId BigInt @unique
+}
+`,
+            { usePrismaPush: true },
+        );
+
+        const photo = await db.telegramPhoto.create({
+            data: {
+                tgFileId: 'file123',
+                width: 800,
+                height: 600,
+            },
+        });
+
+        const message = await db.telegramMessage.create({
+            data: {
+                tgId: BigInt(1),
+                media: {
+                    connect: {
+                        id: photo.id,
+                    },
+                },
+            },
+            include: {
+                media: true,
+            },
+        });
+
+        expect(message).toMatchObject({
+            media: [photo],
+        });
+
+        const media = await db.media.findFirst({
+            include: { messages: true },
+        });
+        expect(media).toMatchObject({
+            messages: [expect.objectContaining({ tgId: BigInt(1), type: 'TelegramMessage' })],
+        });
+    });
+});
diff --git a/tests/runtimes/bun/package.json b/tests/runtimes/bun/package.json
index dc9c1ed6..ded75caf 100644
--- a/tests/runtimes/bun/package.json
+++ b/tests/runtimes/bun/package.json
@@ -1,6 +1,6 @@
 {
     "name": "bun-e2e",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "type": "module",
     "scripts": {
diff --git a/tests/runtimes/edge-runtime/package.json b/tests/runtimes/edge-runtime/package.json
index 3b46fddc..6a3004a4 100644
--- a/tests/runtimes/edge-runtime/package.json
+++ b/tests/runtimes/edge-runtime/package.json
@@ -1,6 +1,6 @@
 {
     "name": "edge-runtime-e2e",
-    "version": "3.0.0-beta.31",
+    "version": "3.0.0-beta.32",
     "private": true,
     "type": "module",
     "scripts": {