From 1cb5a1653b65d2f5bcd15da0df6d68b5029c8ca0 Mon Sep 17 00:00:00 2001
From: Waleed <walif6@gmail.com>
Date: Tue, 2 Jun 2026 18:54:53 -0700
Subject: [PATCH] fix(auth): show "account already exists" on duplicate email
 signup (#4855)

* fix(auth): show "account already exists" on duplicate email signup

* fix(auth): use exact path match for duplicate-email signup check
---
 apps/sim/lib/auth/auth.ts | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/apps/sim/lib/auth/auth.ts b/apps/sim/lib/auth/auth.ts
index 40037c938c..76465b45be 100644
--- a/apps/sim/lib/auth/auth.ts
+++ b/apps/sim/lib/auth/auth.ts
@@ -844,6 +844,22 @@ export const auth = betterAuth({
         }
       }
 
+      if (ctx.path === '/sign-up/email' && ctx.body?.email) {
+        const signupEmail = ctx.body.email.toLowerCase()
+        const [existingUser] = await db
+          .select({ id: schema.user.id })
+          .from(schema.user)
+          .where(eq(schema.user.email, signupEmail))
+          .limit(1)
+
+        if (existingUser) {
+          throw new APIError('UNPROCESSABLE_ENTITY', {
+            message: 'User already exists',
+            code: 'USER_ALREADY_EXISTS',
+          })
+        }
+      }
+
       return
     }),
   },