fix(db): recognize postgres int8 as a number type in migration diffs (#10719)

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

.changeset/postgres-int8-migration-diff.md

@@ -0,0 +1,5 @@
+---
+"better-auth": patch
+---
+
+Recognize PostgreSQL `int8` as a valid number type in migration diffs. Kysely's introspector reports `pg_type.typname`, so Better Auth's own `bigint` columns (such as the database-backed rate limiter's `lastRequest`) came back as `int8` and were reported as a type mismatch on every run.

packages/better-auth/src/db/get-migration-schema.test.ts

@@ -12,7 +12,7 @@ import {
 	it,
 } from "vitest";
 import { betterAuth } from "../auth/full";
-import { getMigrations } from "./get-migration";
+import { getMigrations, matchType } from "./get-migration";
 
 const CONNECTION_STRING = "postgres://user:password@localhost:5433/better_auth";
 // Check if PostgreSQL is available
@@ -928,3 +928,61 @@ describe.runIf(isPostgresAvailable)("PostgreSQL configured schema name", () => {
 		expect(await compileMigrations()).toEqual(";");
 	});
 });
+
+describe("matchType", () => {
+	/**
+	 * @see https://github.com/better-auth/better-auth/issues/10718
+	 *
+	 * Kysely's PostgreSQL introspector reports `pg_type.typname`, so a
+	 * `bigint` column comes back as `int8` — the name the acceptable-types
+	 * map has to carry for the diff to recognize Better Auth's own
+	 * `rateLimit.lastRequest` column.
+	 */
+	it("should accept the pg_type name Kysely reports for a bigint column", () => {
+		expect(matchType("int8", "number", "postgres")).toBe(true);
+	});
+
+	it("should still accept the spelled-out bigint name", () => {
+		expect(matchType("bigint", "number", "postgres")).toBe(true);
+	});
+});
+
+/**
+ * @see https://github.com/better-auth/better-auth/issues/10718
+ */
+describe.runIf(isPostgresAvailable)("PostgreSQL rate limit schema diff", () => {
+	const pool = new Pool({ connectionString: CONNECTION_STRING });
+	const dropTables = `DROP TABLE IF EXISTS public."rateLimit" CASCADE; DROP TABLE IF EXISTS public.session CASCADE; DROP TABLE IF EXISTS public.account CASCADE; DROP TABLE IF EXISTS public.verification CASCADE; DROP TABLE IF EXISTS public."user" CASCADE;`;
+
+	beforeAll(async () => {
+		await pool.query(dropTables);
+	});
+
+	afterAll(async () => {
+		await pool.query(dropTables);
+		await pool.end();
+	});
+
+	it("should not warn about its own bigint lastRequest column on a subsequent run", async () => {
+		const warnings: string[] = [];
+		const config: BetterAuthOptions = {
+			database: pool,
+			rateLimit: {
+				storage: "database",
+			},
+			logger: {
+				log: (level, message) => {
+					if (level === "warn") warnings.push(message);
+				},
+			},
+		};
+
+		const initial = await getMigrations(config);
+		await initial.runMigrations();
+
+		const second = await getMigrations(config);
+		expect(second.toBeCreated.length).toBe(0);
+		expect(second.toBeAdded.length).toBe(0);
+		expect(warnings.filter((w) => w.includes("lastRequest"))).toEqual([]);
+	});
+});

packages/better-auth/src/db/get-migration.ts

@@ -44,6 +44,7 @@ const postgresMap = {
 	string: ["character varying", "varchar", "text", "uuid"],
 	number: [
 		"int4",
+		"int8",
 		"integer",
 		"bigint",
 		"smallint",