diff --git a/internal/store/postgres.go b/internal/store/postgres.go
index e556852..197e3fc 100644
--- a/internal/store/postgres.go
+++ b/internal/store/postgres.go
@@ -1324,13 +1324,13 @@ func (s *postgresStore) DeleteStaleAgents(ctx context.Context, staleThreshold ti
 }
 
 func (s *postgresStore) CreateSession(ctx context.Context, token, userID string, expiresAt time.Time) error {
-	const query = "INSERT INTO sessions (token, user_id, expires_at) VALUES ($1, $2, $3) ON CONFLICT (token) DO UPDATE SET user_id = EXCLUDED.user_id, expires_at = EXCLUDED.expires_at"
+	const query = "INSERT INTO sessions (token, user_uuid, expires_at) VALUES ($1, $2, $3) ON CONFLICT (token) DO UPDATE SET user_uuid = EXCLUDED.user_uuid, expires_at = EXCLUDED.expires_at"
 	_, err := s.db.ExecContext(ctx, query, token, userID, expiresAt.UTC())
 	return err
 }
 
 func (s *postgresStore) GetSession(ctx context.Context, token string) (string, time.Time, error) {
-	const query = "SELECT user_id, expires_at FROM sessions WHERE token = $1"
+	const query = "SELECT user_uuid, expires_at FROM sessions WHERE token = $1"
 	var userID string
 	var expiresAt time.Time
 	err := s.db.QueryRowContext(ctx, query, token).Scan(&userID, &expiresAt)
diff --git a/sql/20260205_sessions_token_unique.sql b/sql/20260205_sessions_token_unique.sql
new file mode 100644
index 0000000..e57fc3b
--- /dev/null
+++ b/sql/20260205_sessions_token_unique.sql
@@ -0,0 +1,6 @@
+-- Migration: Add unique constraint on sessions.token
+-- Date: 2026-02-05
+-- Description: Adds a unique index on the sessions.token column to support
+--              the ON CONFLICT clause in session upsert operations.
+
+CREATE UNIQUE INDEX IF NOT EXISTS sessions_token_uk ON public.sessions (token);
diff --git a/sql/schema.sql b/sql/schema.sql
index d4b67fd..96e21a7 100644
--- a/sql/schema.sql
+++ b/sql/schema.sql
@@ -191,6 +191,7 @@ CREATE UNIQUE INDEX users_email_lower_uk ON public.users (lower(email)) WHERE em
 CREATE UNIQUE INDEX users_single_root_role_uk ON public.users ((lower(role))) WHERE lower(role) = 'root';
 CREATE INDEX idx_identities_user_uuid ON public.identities (user_uuid);
 CREATE INDEX idx_sessions_user_uuid ON public.sessions (user_uuid);
+CREATE UNIQUE INDEX sessions_token_uk ON public.sessions (token);
 CREATE INDEX idx_admin_settings_version ON public.admin_settings (version);
 CREATE INDEX idx_subscriptions_user_uuid ON public.subscriptions (user_uuid);
 CREATE INDEX idx_subscriptions_status ON public.subscriptions (status);