From 6d32877dbbe718ebc09f63c72c030a19c3433a92 Mon Sep 17 00:00:00 2001
From: Tomas Sivicki <tomas.sivicki@gmail.com>
Date: Mon, 19 Jan 2026 23:38:32 +0100
Subject: [PATCH] fix(adapter): transforms output back to Date for better-auth
 compatibility

while this aligns with Convex stored _creationTime & numbers, this should still be transformed back
to a Date instance or better-auth handles the formatting wrong

fix #224
---
 src/client/adapter.ts        | 2 +-
 src/component/adapterTest.ts | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/client/adapter.ts b/src/client/adapter.ts
index 4194bc7..002d4fa 100644
--- a/src/client/adapter.ts
+++ b/src/client/adapter.ts
@@ -146,7 +146,7 @@ export const convexAdapter = <
       },
       customTransformOutput: ({ data, fieldAttributes }) => {
         if (data && fieldAttributes.type === "date") {
-          return new Date(data).getTime();
+          return new Date(data);
         }
         return data;
       },
diff --git a/src/component/adapterTest.ts b/src/component/adapterTest.ts
index 11b857c..1a9492b 100644
--- a/src/component/adapterTest.ts
+++ b/src/component/adapterTest.ts
@@ -499,5 +499,6 @@ function runCustomAdapterTests({
         where: [{ field: "createdAt", value: new Date().toISOString() }],
       })
     ).toEqual(user);
+    expect(user.createdAt).toBeInstanceOf(Date);
   });
 }