diff --git a/init-scripts/init-script.sql b/init-scripts/init-script.sql
index db7586f..49f5c4b 100644
--- a/init-scripts/init-script.sql
+++ b/init-scripts/init-script.sql
@@ -88,7 +88,8 @@ CREATE TABLE users (
     n_first_name VARCHAR(50) NOT NULL,          -- vCard N.given
     n_last_name VARCHAR(50) NOT NULL,           -- vCard N.family
     fn VARCHAR(120) GENERATED ALWAYS AS (n_first_name || ' ' || n_last_name) STORED, -- vCard FN
-    email VARCHAR(255) UNIQUE,                 -- vCard EMAIL (nullable for social-only/guest)
+    email VARCHAR(255),                 -- vCard EMAIL (nullable for social-only/guest)
+                                       -- Uniqueness enforced only for non-guest users via partial index
     phone VARCHAR(20) NOT NULL,                         -- vCard TEL
     date_of_birth DATE NOT NULL,                        -- vCard BDAY
     profile_pic_url TEXT,                      -- vCard PHOTO
@@ -131,6 +132,10 @@ CREATE TABLE user_social_logins (
 CREATE INDEX idx_users_email_lower ON users (LOWER(email));
 CREATE INDEX idx_users_account_role ON users (account_role);
 
+-- Enforce unique email only for registered (non-guest) users
+-- Guest accounts can share emails; registered accounts cannot
+CREATE UNIQUE INDEX idx_users_email_registered ON users (email) WHERE account_role != 'guest';
+
 -- =======================================
 -- VERIFICATION CODES TABLE
 -- =======================================