fix(core): preserve database option type inference (#11291)

Co-authored-by: Taesu <166604494+bytaesu@users.noreply.github.com>
Co-authored-by: Alexey Sokolov <alexvyber@gmail.com>

.changeset/quiet-d1-types.md

@@ -0,0 +1,5 @@
+---
+"@better-auth/core": patch
+---
+
+Restore database option type inference for projects that do not use Cloudflare Workers.

packages/core/package.json

@@ -178,15 +178,11 @@
     "@better-fetch/fetch": "catalog:",
     "@opentelemetry/api": "^1.9.0",
     "better-call": "catalog:",
-    "@cloudflare/workers-types": ">=4",
     "jose": "^6.1.0",
     "kysely": "catalog:peer",
     "nanostores": "^1.0.1"
   },
   "peerDependenciesMeta": {
-    "@cloudflare/workers-types": {
-      "optional": true
-    },
     "@opentelemetry/api": {
       "optional": true
     }

packages/core/src/types/database.test.ts

@@ -0,0 +1,9 @@
+import type { D1Database as CloudflareD1Database } from "@cloudflare/workers-types";
+import { describe, expectTypeOf, it } from "vitest";
+import type { D1Database } from "./database";
+
+describe("D1Database", () => {
+	it("accepts Cloudflare's D1 database type", () => {
+		expectTypeOf<CloudflareD1Database>().toExtend<D1Database>();
+	});
+});

packages/core/src/types/database.ts

@@ -0,0 +1,21 @@
+type D1Result<T> = {
+	results: T[];
+	meta: {
+		changes: number;
+		last_row_id: number;
+	};
+};
+
+interface D1PreparedStatement {
+	bind(...values: unknown[]): D1PreparedStatement;
+	all<T = Record<string, unknown>>(): Promise<D1Result<T>>;
+}
+
+/**
+ * A Cloudflare D1-compatible database.
+ */
+export interface D1Database {
+	prepare(query: string): D1PreparedStatement;
+	batch<T = unknown>(statements: D1PreparedStatement[]): Promise<D1Result<T>[]>;
+	exec(query: string): Promise<unknown>;
+}

packages/core/src/types/index.ts

@@ -12,6 +12,7 @@ export type {
 	BetterAuthCookie,
 	BetterAuthCookies,
 } from "./cookie";
+export type { D1Database } from "./database";
 export type * from "./helper";
 export type {
 	BaseURLConfig,

packages/core/src/types/init-options.ts

@@ -1,6 +1,5 @@
 import type { Database as BunDatabase } from "bun:sqlite";
 import type { DatabaseSync } from "node:sqlite";
-import type { D1Database } from "@cloudflare/workers-types";
 import type { CookieOptions } from "better-call";
 import type {
 	Dialect,
@@ -29,10 +28,12 @@ import type { BaseVerification } from "../db/schema/verification";
 import type { Logger } from "../env";
 import type { SocialProviderList, SocialProviders } from "../social-providers";
 import type { AuthContext, GenericEndpointContext } from "./context";
+import type { D1Database } from "./database";
 import type { Awaitable, LiteralString, LiteralUnion } from "./helper";
 import type { BetterAuthPlugin } from "./plugin";
 
 type KyselyDatabaseType = "postgres" | "mysql" | "sqlite" | "mssql";
+
 type Optional<T> = {
 	[P in keyof T]?: T[P] | undefined;
 };

packages/kysely-adapter/package.json

@@ -59,7 +59,6 @@
     }
   },
   "devDependencies": {
-    "@cloudflare/workers-types": "^4.20250121.0",
     "@better-auth/core": "workspace:*",
     "@better-auth/utils": "catalog:",
     "kysely": "catalog:",

packages/kysely-adapter/src/d1-sqlite-dialect.ts

@@ -1,4 +1,4 @@
-import type { D1Database } from "@cloudflare/workers-types";
+import type { D1Database } from "@better-auth/core";
 import type {
 	CompiledQuery,
 	DatabaseConnection,

pnpm-lock.yaml

@@ -1289,9 +1289,6 @@ importers:
       '@better-auth/utils':
         specifier: 'catalog:'
         version: 0.4.2
-      '@cloudflare/workers-types':
-        specifier: ^4.20250121.0
-        version: 4.20260226.1
       kysely:
         specifier: 'catalog:'
         version: 0.29.2