Better auth type errors

.changeset/better-auth-type-errors.md

@@ -0,0 +1,6 @@
+---
+"@proofkit/better-auth": patch
+---
+
+Fix TypeScript build errors by making adapter/migration types resilient to upstream Better Auth changes.
+

packages/better-auth/src/adapter.ts

@@ -1,6 +1,6 @@
 /** biome-ignore-all lint/suspicious/noExplicitAny: library code */
 import { logger } from "better-auth";
-import { type AdapterDebugLogs, type CleanedWhere, createAdapter } from "better-auth/adapters";
+import { type CleanedWhere, createAdapter } from "better-auth/adapters";
 import buildQuery from "odata-query";
 import { prettifyError, z } from "zod/v4";
 import { createRawFetch, type FmOdataConfig } from "./odata";
@@ -19,7 +19,7 @@ interface FileMakerAdapterConfig {
   /**
    * Helps you debug issues with the adapter.
    */
-  debugLogs?: AdapterDebugLogs;
+  debugLogs?: boolean | { isRunningAdapterTests?: boolean };
   /**
    * If the table names in the schema are plural.
    */

packages/better-auth/src/cli/index.ts

@@ -11,6 +11,33 @@ import { executeMigration, planMigration, prettyPrintMigrationPlan } from "../mi
 import { createRawFetch } from "../odata";
 import "dotenv/config";
 
+function getFileMakerAdapterConfigFromAdapterOptions(
+  options: unknown,
+): AdapterOptions["config"] {
+  if (!options || typeof options !== "object") {
+    throw new Error("FileMaker adapter options were missing.");
+  }
+
+  const opts = options as Record<string, unknown>;
+
+  // Our adapter returns: { options: { config: FileMakerAdapterConfig } }
+  if (opts.config && typeof opts.config === "object") {
+    return opts.config as AdapterOptions["config"];
+  }
+
+  // Some Better Auth versions wrap adapter options under `adapterConfig`.
+  if (opts.adapterConfig && typeof opts.adapterConfig === "object") {
+    const adapterConfig = opts.adapterConfig as Record<string, unknown>;
+    if (adapterConfig.config && typeof adapterConfig.config === "object") {
+      return adapterConfig.config as AdapterOptions["config"];
+    }
+  }
+
+  throw new Error(
+    "Could not locate FileMaker adapter configuration from Better Auth adapter options.",
+  );
+}
+
 async function main() {
   const program = new Command();
 
@@ -52,7 +79,9 @@ async function main() {
 
       const betterAuthSchema = getAuthTables(config);
 
-      const adapterConfig = (adapter.options as AdapterOptions).config;
+      const adapterConfig = getFileMakerAdapterConfigFromAdapterOptions(
+        adapter.options,
+      );
       const { fetch } = createRawFetch({
         ...adapterConfig.odata,
         auth:

packages/better-auth/src/migrate.ts

@@ -1,9 +1,27 @@
-import type { BetterAuthDbSchema } from "better-auth/db";
 import chalk from "chalk";
 import type { Metadata } from "fm-odata-client";
 import z from "zod/v4";
 import type { createRawFetch } from "./odata";
 
+type BetterAuthTableField = {
+  fieldName?: string;
+  type: unknown;
+};
+
+type BetterAuthTableDef = {
+  modelName: string;
+  fields: Record<string, BetterAuthTableField>;
+  order?: number;
+};
+
+export type BetterAuthAuthTables = Record<string, BetterAuthTableDef>;
+
+function normalizeBetterAuthFieldType(fieldType: unknown): string {
+  if (typeof fieldType === "string") return fieldType;
+  if (Array.isArray(fieldType)) return fieldType.map(String).join("|");
+  return String(fieldType);
+}
+
 export async function getMetadata(fetch: ReturnType<typeof createRawFetch>["fetch"], databaseName: string) {
   console.log("getting metadata...");
   const result = await fetch("/$metadata", {
@@ -28,7 +46,7 @@ export async function getMetadata(fetch: ReturnType<typeof createRawFetch>["fetc
 
 export async function planMigration(
   fetch: ReturnType<typeof createRawFetch>["fetch"],
-  betterAuthSchema: BetterAuthDbSchema,
+  betterAuthSchema: BetterAuthAuthTables,
   databaseName: string,
 ): Promise<MigrationPlan> {
   const metadata = await getMetadata(fetch, databaseName);
@@ -93,12 +111,11 @@ export async function planMigration(
 
   for (const baTable of baTables) {
     const fields: FmField[] = Object.entries(baTable.fields).map(([key, field]) => {
-      let type: "varchar" | "numeric" | "timestamp" = "varchar";
-      if (field.type === "boolean" || field.type.includes("number")) {
-        type = "numeric";
-      } else if (field.type === "date") {
-        type = "timestamp";
-      }
+      // Better Auth's FieldType can be a string literal union or arrays.
+      // Normalize it to a string so our FM mapping logic remains stable.
+      const t = normalizeBetterAuthFieldType(field.type);
+      const type: "varchar" | "numeric" | "timestamp" =
+        t === "boolean" || t.includes("number") ? "numeric" : t === "date" ? "timestamp" : "varchar";
       return {
         name: field.fieldName ?? key,
         type,