diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index 1df0c24d8..511bd9326 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -14,7 +14,7 @@ on:
         branches: ['dev', 'main', 'canary']
 
 jobs:
-    build:
+    build-test:
         runs-on: ubuntu-latest
 
         strategy:
@@ -35,11 +35,14 @@ jobs:
                   cache: 'pnpm'
             - run: pnpm install --frozen-lockfile
             - run: |
-                if [[ $GITHUB_REF == 'refs/heads/canary' ]]; then
-                    DEFAULT_NPM_TAG=canary pnpm run build
-                else
-                    DEFAULT_NPM_TAG=latest pnpm run build
-                fi
+                  if [[ $GITHUB_REF == 'refs/heads/canary' ]]; then
+                      DEFAULT_NPM_TAG=canary pnpm run build
+                  else
+                      DEFAULT_NPM_TAG=latest pnpm run build
+                  fi
+
+            - run: pnpm lint
+
             # install again for internal dependencies
             - run: pnpm install --frozen-lockfile
             - run: pnpm run test
diff --git a/README.md b/README.md
index 2104ff0eb..9205a8c44 100644
--- a/README.md
+++ b/README.md
@@ -89,6 +89,10 @@ const MyPosts = () => {
 };
 ```
 
+The following diagram gives a high-level overview of how it works.
+
+![Architecture](https://zenstack.dev/img/architecture-light.png)
+
 ## Links
 
 -   [Home](https://zenstack.dev)
diff --git a/package.json b/package.json
index b8864a499..7460dcb26 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "zenstack-monorepo",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "description": "",
     "scripts": {
         "build": "pnpm -r build",
diff --git a/packages/language/package.json b/packages/language/package.json
index 94dcb52da..f2b0565c0 100644
--- a/packages/language/package.json
+++ b/packages/language/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/language",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "displayName": "ZenStack modeling language compiler",
     "description": "ZenStack modeling language compiler",
     "homepage": "https://zenstack.dev",
diff --git a/packages/next/package.json b/packages/next/package.json
index 334de8570..d8bb8f774 100644
--- a/packages/next/package.json
+++ b/packages/next/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/next",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "displayName": "ZenStack Next.js integration",
     "description": "ZenStack Next.js integration",
     "homepage": "https://zenstack.dev",
diff --git a/packages/plugins/react/package.json b/packages/plugins/react/package.json
index bac8594ee..33d19d71d 100644
--- a/packages/plugins/react/package.json
+++ b/packages/plugins/react/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@zenstackhq/react",
     "displayName": "ZenStack plugin and runtime for ReactJS",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "description": "ZenStack plugin and runtime for ReactJS",
     "main": "index.js",
     "repository": {
diff --git a/packages/plugins/trpc/package.json b/packages/plugins/trpc/package.json
index 3ef3b3492..27dfb597b 100644
--- a/packages/plugins/trpc/package.json
+++ b/packages/plugins/trpc/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@zenstackhq/trpc",
     "displayName": "ZenStack plugin for tRPC",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "description": "ZenStack plugin for tRPC",
     "main": "index.js",
     "repository": {
diff --git a/packages/runtime/package.json b/packages/runtime/package.json
index b53331462..2f3772b1d 100644
--- a/packages/runtime/package.json
+++ b/packages/runtime/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@zenstackhq/runtime",
     "displayName": "ZenStack Runtime Library",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "description": "Runtime of ZenStack for both client-side and server-side environments.",
     "repository": {
         "type": "git",
diff --git a/packages/schema/package.json b/packages/schema/package.json
index 84f8be89c..7bdd76848 100644
--- a/packages/schema/package.json
+++ b/packages/schema/package.json
@@ -3,7 +3,7 @@
     "publisher": "zenstack",
     "displayName": "ZenStack Language Tools",
     "description": "A toolkit for building secure CRUD apps with Next.js + Typescript",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "author": {
         "name": "ZenStack Team"
     },
diff --git a/packages/schema/src/language-server/constants.ts b/packages/schema/src/language-server/constants.ts
index d6e7a27fd..e2bd60339 100644
--- a/packages/schema/src/language-server/constants.ts
+++ b/packages/schema/src/language-server/constants.ts
@@ -12,3 +12,7 @@ export const SCALAR_TYPES = ['String', 'Int', 'Float', 'Decimal', 'BigInt', 'Boo
  * Name of standard library module
  */
 export const STD_LIB_MODULE_NAME = 'stdlib.zmodel';
+
+export enum IssueCodes {
+    MissingOppositeRelation = 'miss-opposite-relation',
+}
diff --git a/packages/schema/src/language-server/validator/datamodel-validator.ts b/packages/schema/src/language-server/validator/datamodel-validator.ts
index 7c7742af9..828e40c26 100644
--- a/packages/schema/src/language-server/validator/datamodel-validator.ts
+++ b/packages/schema/src/language-server/validator/datamodel-validator.ts
@@ -15,7 +15,7 @@ import {
 import { ValidationAcceptor } from 'langium';
 import pluralize from 'pluralize';
 import { analyzePolicies } from '../../utils/ast-utils';
-import { SCALAR_TYPES } from '../constants';
+import { IssueCodes, SCALAR_TYPES } from '../constants';
 import { AstValidator } from '../types';
 import { assignableToAttributeParam, validateDuplicatedDeclarations } from './utils';
 
@@ -297,7 +297,7 @@ export default class DataModelValidator implements AstValidator<DataModel> {
             accept(
                 'error',
                 `The relation field "${field.name}" on model "${field.$container.name}" is missing an opposite relation field on model "${oppositeModel.name}"`,
-                { node: field }
+                { node: field, code: IssueCodes.MissingOppositeRelation }
             );
             return;
         } else if (oppositeFields.length > 1) {
diff --git a/packages/schema/src/language-server/validator/utils.ts b/packages/schema/src/language-server/validator/utils.ts
index b15de1e91..4dfaff554 100644
--- a/packages/schema/src/language-server/validator/utils.ts
+++ b/packages/schema/src/language-server/validator/utils.ts
@@ -7,9 +7,11 @@ import {
     ExpressionType,
     isArrayExpr,
     isDataModelField,
+    isEnum,
     isLiteralExpr,
     isReferenceExpr,
 } from '@zenstackhq/language/ast';
+import { resolved } from '@zenstackhq/sdk';
 import { AstNode, ValidationAcceptor } from 'langium';
 
 /**
@@ -99,7 +101,19 @@ export function assignableToAttributeParam(
     const dstIsArray = param.type.array;
     const dstRef = param.type.reference;
 
-    if (dstType) {
+    if (isEnum(argResolvedType.decl)) {
+        // enum type
+
+        let attrArgDeclType = dstRef?.ref;
+        if (dstType === 'ContextType' && isDataModelField(attr.$container) && attr.$container?.type?.reference) {
+            // attribute parameter type is ContextType, need to infer type from
+            // the attribute's container
+            attrArgDeclType = resolved(attr.$container?.type?.reference);
+        }
+        return attrArgDeclType === argResolvedType.decl && dstIsArray === argResolvedType.array;
+    } else if (dstType) {
+        // scalar type
+
         if (typeof argResolvedType?.decl !== 'string') {
             // destination type is not a reference, so argument type must be a plain expression
             return false;
@@ -115,6 +129,8 @@ export function assignableToAttributeParam(
                 return isReferenceExpr(arg.value) && isDataModelField(arg.value.target.ref);
             }
         } else if (dstType === 'ContextType') {
+            // attribute parameter type is ContextType, need to infer type from
+            // the attribute's container
             if (isDataModelField(attr.$container)) {
                 if (!attr.$container?.type?.type) {
                     return false;
@@ -129,6 +145,7 @@ export function assignableToAttributeParam(
             typeAssignable(dstType, argResolvedType.decl) && (dstType === 'Any' || dstIsArray === argResolvedType.array)
         );
     } else {
+        // reference type
         return dstRef?.ref === argResolvedType.decl && dstIsArray === argResolvedType.array;
     }
 }
diff --git a/packages/schema/src/language-server/zmodel-code-action.ts b/packages/schema/src/language-server/zmodel-code-action.ts
new file mode 100644
index 000000000..23a64ca62
--- /dev/null
+++ b/packages/schema/src/language-server/zmodel-code-action.ts
@@ -0,0 +1,133 @@
+import { DataModel, DataModelField, isDataModel } from '@zenstackhq/language/ast';
+import {
+    AstReflection,
+    CodeActionProvider,
+    findDeclarationNodeAtOffset,
+    getContainerOfType,
+    IndexManager,
+    LangiumDocument,
+    LangiumServices,
+    MaybePromise,
+} from 'langium';
+
+import { CodeAction, CodeActionKind, CodeActionParams, Command, Diagnostic } from 'vscode-languageserver';
+import { IssueCodes } from './constants';
+import { ZModelFormatter } from './zmodel-formatter';
+
+export class ZModelCodeActionProvider implements CodeActionProvider {
+    protected readonly reflection: AstReflection;
+    protected readonly indexManager: IndexManager;
+    protected readonly formatter: ZModelFormatter;
+
+    constructor(services: LangiumServices) {
+        this.reflection = services.shared.AstReflection;
+        this.indexManager = services.shared.workspace.IndexManager;
+        this.formatter = services.lsp.Formatter as ZModelFormatter;
+    }
+
+    getCodeActions(
+        document: LangiumDocument,
+        params: CodeActionParams
+    ): MaybePromise<Array<Command | CodeAction> | undefined> {
+        const result: CodeAction[] = [];
+        const acceptor = (ca: CodeAction | undefined) => ca && result.push(ca);
+        for (const diagnostic of params.context.diagnostics) {
+            this.createCodeActions(diagnostic, document, acceptor);
+        }
+        return result;
+    }
+
+    private createCodeActions(
+        diagnostic: Diagnostic,
+        document: LangiumDocument,
+        accept: (ca: CodeAction | undefined) => void
+    ) {
+        switch (diagnostic.code) {
+            case IssueCodes.MissingOppositeRelation:
+                accept(this.fixMissingOppositeRelation(diagnostic, document));
+        }
+
+        return undefined;
+    }
+
+    private fixMissingOppositeRelation(diagnostic: Diagnostic, document: LangiumDocument): CodeAction | undefined {
+        const offset = document.textDocument.offsetAt(diagnostic.range.start);
+        const rootCst = document.parseResult.value.$cstNode;
+
+        if (rootCst) {
+            const cstNode = findDeclarationNodeAtOffset(rootCst, offset);
+
+            const astNode = cstNode?.element as DataModelField;
+
+            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+            const oppositeModel = astNode.type.reference!.ref! as DataModel;
+
+            const lastField = oppositeModel.fields[oppositeModel.fields.length - 1];
+
+            const container = getContainerOfType(cstNode?.element, isDataModel) as DataModel;
+
+            const idField = container.fields.find((f) =>
+                f.attributes.find((attr) => attr.decl.ref?.name === '@id')
+            ) as DataModelField;
+
+            if (container && container.$cstNode && idField) {
+                // indent
+                let indent = '\t';
+                const formatOptions = this.formatter.getFormatOptions();
+                if (formatOptions?.insertSpaces) {
+                    indent = ' '.repeat(formatOptions.tabSize);
+                }
+                indent = indent.repeat(this.formatter.getIndent());
+
+                const typeName = container.name;
+                const fieldName = this.lowerCaseFirstLetter(typeName);
+
+                // might already exist
+                let referenceField = '';
+
+                const idFieldName = idField.name;
+                const referenceIdFieldName = fieldName + this.upperCaseFirstLetter(idFieldName);
+
+                if (!oppositeModel.fields.find((f) => f.name === referenceIdFieldName)) {
+                    referenceField = '\n' + indent + `${referenceIdFieldName} ${idField.type.type}`;
+                }
+
+                return {
+                    title: `Add opposite relation fields on ${oppositeModel.name}`,
+                    kind: CodeActionKind.QuickFix,
+                    diagnostics: [diagnostic],
+                    isPreferred: false,
+                    edit: {
+                        changes: {
+                            [document.textDocument.uri]: [
+                                {
+                                    range: {
+                                        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+                                        start: lastField.$cstNode!.range.end,
+                                        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+                                        end: lastField.$cstNode!.range.end,
+                                    },
+                                    newText:
+                                        '\n' +
+                                        indent +
+                                        `${fieldName} ${typeName} @relation(fields: [${referenceIdFieldName}], references: [${idFieldName}])` +
+                                        referenceField,
+                                },
+                            ],
+                        },
+                    },
+                };
+            }
+        }
+
+        return undefined;
+    }
+
+    private lowerCaseFirstLetter(str: string) {
+        return str.charAt(0).toLowerCase() + str.slice(1);
+    }
+
+    private upperCaseFirstLetter(str: string) {
+        return str.charAt(0).toUpperCase() + str.slice(1);
+    }
+}
diff --git a/packages/schema/src/language-server/zmodel-formatter.ts b/packages/schema/src/language-server/zmodel-formatter.ts
index bf14e7268..c9300fa7a 100644
--- a/packages/schema/src/language-server/zmodel-formatter.ts
+++ b/packages/schema/src/language-server/zmodel-formatter.ts
@@ -1,13 +1,31 @@
-import { AbstractFormatter, AstNode, Formatting } from 'langium';
+import { AbstractFormatter, AstNode, Formatting, LangiumDocument } from 'langium';
 
 import * as ast from '@zenstackhq/language/ast';
+import { FormattingOptions, Range, TextEdit } from 'vscode-languageserver';
 
 export class ZModelFormatter extends AbstractFormatter {
+    private formatOptions?: FormattingOptions;
     protected format(node: AstNode): void {
         const formatter = this.getNodeFormatter(node);
-        if (ast.isAbstractDeclaration(node)) {
+        if (ast.isDataModelField(node)) {
+            formatter.property('type').prepend(Formatting.oneSpace());
+            if (node.attributes.length > 0) {
+                formatter.properties('attributes').prepend(Formatting.oneSpace());
+            }
+        } else if (ast.isDataModelFieldAttribute(node)) {
+            formatter.keyword('(').surround(Formatting.noSpace());
+            formatter.keyword(')').prepend(Formatting.noSpace());
+            formatter.keyword(',').append(Formatting.oneSpace());
+            if (node.args.length > 1) {
+                formatter.nodes(...node.args.slice(1)).prepend(Formatting.oneSpace());
+            }
+        } else if (ast.isAttributeArg(node)) {
+            formatter.keyword(':').prepend(Formatting.noSpace());
+            formatter.keyword(':').append(Formatting.oneSpace());
+        } else if (ast.isAbstractDeclaration(node)) {
             const bracesOpen = formatter.keyword('{');
             const bracesClose = formatter.keyword('}');
+            // this line decide the indent count return by this.getIndent()
             formatter.interior(bracesOpen, bracesClose).prepend(Formatting.indent());
             bracesOpen.prepend(Formatting.oneSpace());
             bracesClose.prepend(Formatting.newLine());
@@ -17,4 +35,21 @@ export class ZModelFormatter extends AbstractFormatter {
             nodes.prepend(Formatting.noIndent());
         }
     }
+
+    protected override doDocumentFormat(
+        document: LangiumDocument<AstNode>,
+        options: FormattingOptions,
+        range?: Range | undefined
+    ): TextEdit[] {
+        this.formatOptions = options;
+        return super.doDocumentFormat(document, options, range);
+    }
+
+    public getFormatOptions(): FormattingOptions | undefined {
+        return this.formatOptions;
+    }
+
+    public getIndent() {
+        return 1;
+    }
 }
diff --git a/packages/schema/src/language-server/zmodel-module.ts b/packages/schema/src/language-server/zmodel-module.ts
index 5a3507789..077675ed5 100644
--- a/packages/schema/src/language-server/zmodel-module.ts
+++ b/packages/schema/src/language-server/zmodel-module.ts
@@ -20,6 +20,7 @@ import {
 import { TextDocuments } from 'vscode-languageserver';
 import { TextDocument } from 'vscode-languageserver-textdocument';
 import { ZModelValidationRegistry, ZModelValidator } from './validator/zmodel-validator';
+import { ZModelCodeActionProvider } from './zmodel-code-action';
 import { ZModelFormatter } from './zmodel-formatter';
 import { ZModelLinker } from './zmodel-linker';
 import { ZModelScopeComputation } from './zmodel-scope';
@@ -56,6 +57,7 @@ export const ZModelModule: Module<ZModelServices, PartialLangiumServices & ZMode
     },
     lsp: {
         Formatter: () => new ZModelFormatter(),
+        CodeActionProvider: (services) => new ZModelCodeActionProvider(services),
     },
 };
 
diff --git a/packages/schema/tests/schema/validation/attribute-validation.test.ts b/packages/schema/tests/schema/validation/attribute-validation.test.ts
index e713a43ae..0d49e050f 100644
--- a/packages/schema/tests/schema/validation/attribute-validation.test.ts
+++ b/packages/schema/tests/schema/validation/attribute-validation.test.ts
@@ -314,4 +314,19 @@ describe('Attribute tests', () => {
         `)
         ).toContain('attribute "@length" cannot be used on this type of field');
     });
+
+    it('enum as default', async () => {
+        await loadModel(`
+            ${prelude}
+
+            enum E {
+                E1
+                E2
+            }
+
+            model M {
+                e E @default(E1)
+            }
+        `);
+    });
 });
diff --git a/packages/sdk/package.json b/packages/sdk/package.json
index 018906cba..bff8cc0ba 100644
--- a/packages/sdk/package.json
+++ b/packages/sdk/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@zenstackhq/sdk",
-    "version": "1.0.0-alpha.31",
+    "version": "1.0.0-alpha.33",
     "description": "ZenStack plugin development SDK",
     "main": "index.js",
     "scripts": {
diff --git a/tests/integration/test-run/package-lock.json b/tests/integration/test-run/package-lock.json
index 43ae64eac..ee995b27a 100644
--- a/tests/integration/test-run/package-lock.json
+++ b/tests/integration/test-run/package-lock.json
@@ -126,7 +126,7 @@
         },
         "../../../packages/runtime/dist": {
             "name": "@zenstackhq/runtime",
-            "version": "1.0.0-alpha.31",
+            "version": "1.0.0-alpha.33",
             "license": "MIT",
             "dependencies": {
                 "@types/bcryptjs": "^2.4.2",
@@ -160,7 +160,7 @@
         },
         "../../../packages/schema/dist": {
             "name": "zenstack",
-            "version": "1.0.0-alpha.31",
+            "version": "1.0.0-alpha.33",
             "hasInstallScript": true,
             "license": "MIT",
             "dependencies": {