feat: add soft-delete plugin

CLAUDE.md

@@ -58,7 +58,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 - **ORM**: Depends on Kysely, Zod, and various utility libraries
 - **CLI**: Depends on language package, Commander.js, and Prisma (for migrations)
 - **Language**: Uses Langium for grammar parsing and AST generation
-- **Database Support**: SQLite (better-sqlite3) and PostgreSQL (pg) only
+- **Database Support**: SQLite (better-sqlite3), PostgreSQL (pg), and MySQL
 
 ### Testing Strategy
 

packages/language/res/stdlib.zmodel

@@ -204,6 +204,12 @@ attribute @@@completionHint(_ values: String[])
  */
 attribute @@@once()
 
+/**
+ * Indicates that a field-level attribute can only be applied to a single field within a model
+ * (including fields inherited from base models and mixins).
+ */
+attribute @@@onceInModel()
+
 /**
  * Defines a single-field ID on the model.
  *

packages/language/src/validators/attribute-application-validator.ts

@@ -26,6 +26,7 @@ import {
 } from '../generated/ast';
 import {
     getAllAttributes,
+    getAllFields,
     getAttributeArg,
     getContainingDataModel,
     getDataSourceProvider,
@@ -81,6 +82,7 @@ export default class AttributeApplicationValidator implements AstValidator<Attri
 
         this.checkDeprecation(attr, accept);
         this.checkDuplicatedAttributes(attr, accept, contextDataModel);
+        this.checkOnceInModel(attr, accept);
 
         const filledParams = new Set<AttributeParam>();
 
@@ -163,6 +165,31 @@ export default class AttributeApplicationValidator implements AstValidator<Attri
         }
     }
 
+    private checkOnceInModel(attr: AttributeApplication, accept: ValidationAcceptor) {
+        const attrDecl = attr.decl.ref;
+        if (!attrDecl?.attributes.some((a) => a.decl.ref?.name === '@@@onceInModel')) {
+            return;
+        }
+
+        // only meaningful for field-level attributes within a data model
+        const field = attr.$container;
+        if (!isDataField(field)) {
+            return;
+        }
+        const dataModel = getContainingDataModel(attr);
+        if (!dataModel) {
+            return;
+        }
+
+        // count distinct fields (including inherited) carrying this attribute
+        const fieldsWithAttr = getAllFields(dataModel).filter((f) =>
+            f.attributes.some((a) => a.decl.ref === attrDecl),
+        );
+        if (fieldsWithAttr.length > 1) {
+            accept('error', `Attribute "${attrDecl.name}" can only be applied to one field per model`, { node: attr });
+        }
+    }
+
     // TODO: design a way to let plugin register validation
     @check('@@allow')
     @check('@@deny')

packages/language/test/attribute-application.test.ts

@@ -499,6 +499,67 @@ describe('Attribute application validation tests', () => {
         });
     });
 
+    describe('Field-level @@@onceInModel attribute', () => {
+        it('accepts a single field carrying the attribute', async () => {
+            await loadSchema(`
+                datasource db {
+                    provider = 'sqlite'
+                    url      = 'file:./dev.db'
+                }
+
+                attribute @softDelete() @@@targetField([DateTimeField]) @@@onceInModel
+
+                model Foo {
+                    id        Int       @id @default(autoincrement())
+                    deletedAt DateTime? @softDelete
+                }
+            `);
+        });
+
+        it('rejects two fields in the same model carrying the attribute', async () => {
+            await loadSchemaWithError(
+                `
+                datasource db {
+                    provider = 'sqlite'
+                    url      = 'file:./dev.db'
+                }
+
+                attribute @softDelete() @@@targetField([DateTimeField]) @@@onceInModel
+
+                model Foo {
+                    id        Int       @id @default(autoincrement())
+                    deletedAt DateTime? @softDelete
+                    removedAt DateTime? @softDelete
+                }
+                `,
+                /Attribute "@softDelete" can only be applied to one field per model/,
+            );
+        });
+
+        it('rejects when the attribute is inherited from a mixin and also declared locally', async () => {
+            await loadSchemaWithError(
+                `
+                datasource db {
+                    provider = 'sqlite'
+                    url      = 'file:./dev.db'
+                }
+
+                attribute @softDelete() @@@targetField([DateTimeField]) @@@onceInModel
+
+                type Base {
+                    deletedAt DateTime? @softDelete
+                }
+
+                model Foo with Base {
+                    id        Int       @id @default(autoincrement())
+                    removedAt DateTime? @softDelete
+                }
+                `,
+                /Attribute "@softDelete" can only be applied to one field per model/,
+            );
+        });
+    });
+
     it('requires relation and fk to have consistent optionality', async () => {
         await loadSchemaWithError(
             `

packages/plugins/soft-delete/eslint.config.js

@@ -0,0 +1,4 @@
+import config from '@zenstackhq/eslint-config/base.js';
+
+/** @type {import("eslint").Linter.Config} */
+export default config;

packages/plugins/soft-delete/package.json

@@ -0,0 +1,68 @@
+{
+    "name": "@zenstackhq/plugin-soft-delete",
+    "displayName": "ZenStack Soft Delete Plugin",
+    "description": "ZenStack plugin that implements soft-delete by intercepting Kysely queries",
+    "version": "3.7.2",
+    "type": "module",
+    "author": {
+        "name": "ZenStack Team",
+        "email": "contact@zenstack.dev"
+    },
+    "homepage": "https://zenstack.dev",
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/zenstackhq/zenstack"
+    },
+    "license": "MIT",
+    "scripts": {
+        "build": "tsc --noEmit && tsdown",
+        "watch": "tsdown --watch",
+        "lint": "eslint src --ext ts",
+        "test": "vitest run",
+        "pack": "pnpm pack"
+    },
+    "keywords": [],
+    "files": [
+        "dist",
+        "plugin.zmodel"
+    ],
+    "exports": {
+        ".": {
+            "import": {
+                "types": "./dist/index.d.mts",
+                "default": "./dist/index.mjs"
+            },
+            "require": {
+                "types": "./dist/index.d.cts",
+                "default": "./dist/index.cjs"
+            }
+        },
+        "./plugin.zmodel": {
+            "import": "./plugin.zmodel",
+            "require": "./plugin.zmodel"
+        },
+        "./package.json": {
+            "import": "./package.json",
+            "require": "./package.json"
+        }
+    },
+    "dependencies": {
+        "@zenstackhq/common-helpers": "workspace:*",
+        "@zenstackhq/orm": "workspace:*",
+        "ts-pattern": "catalog:"
+    },
+    "peerDependencies": {
+        "kysely": "catalog:"
+    },
+    "devDependencies": {
+        "@types/better-sqlite3": "catalog:",
+        "@types/node": "catalog:",
+        "@zenstackhq/eslint-config": "workspace:*",
+        "@zenstackhq/testtools": "workspace:*",
+        "@zenstackhq/tsdown-config": "workspace:*",
+        "@zenstackhq/typescript-config": "workspace:*",
+        "@zenstackhq/vitest-config": "workspace:*",
+        "better-sqlite3": "catalog:"
+    },
+    "funding": "https://github.com/sponsors/zenstackhq"
+}

packages/plugins/soft-delete/plugin.zmodel

@@ -0,0 +1,10 @@
+/**
+ * Marks a `DateTime` field as the soft-delete indicator for its owning model.
+ *
+ * When the soft-delete plugin is installed, reads against the model are automatically filtered
+ * to exclude rows whose marked field is non-null, and delete operations are rewritten to set
+ * the marked field to the current timestamp instead of physically removing the row.
+ *
+ * A model can have at most one `@deletedAt` field.
+ */
+attribute @deletedAt() @@@targetField([DateTimeField]) @@@once @@@onceInModel

packages/plugins/soft-delete/src/index.ts

@@ -0,0 +1 @@
+export * from './plugin';