From 414d0693030cd1fa71c3f5ea216b364f1296ff28 Mon Sep 17 00:00:00 2001
From: Gautam Manchandani <manchandanigautam@gmail.com>
Date: Wed, 5 Nov 2025 22:32:29 +0530
Subject: [PATCH] fix: `string[]` inference for additionalFields  (#5778)

Signed-off-by: GautamBytes <manchandanigautam@gmail.com>
---
 packages/better-auth/src/db/field.ts | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/packages/better-auth/src/db/field.ts b/packages/better-auth/src/db/field.ts
index 6d0c0bb1ac..7dfc992e8d 100644
--- a/packages/better-auth/src/db/field.ts
+++ b/packages/better-auth/src/db/field.ts
@@ -26,13 +26,15 @@ export type InferValueType<T extends DBFieldType> = T extends "string"
 			? boolean
 			: T extends "date"
 				? Date
-				: T extends `${infer T}[]`
-					? T extends "string"
-						? string[]
-						: number[]
-					: T extends Array<any>
-						? T[number]
-						: never;
+				: T extends "json"
+					? Record<string, any>
+					: T extends `${infer U}[]`
+						? U extends "string"
+							? string[]
+							: number[]
+						: T extends Array<any>
+							? T[number]
+							: never;
 
 export type InferFieldsOutput<Field> = Field extends Record<
 	infer Key,