diff --git a/alembic/versions/0005_user_role_fk.py b/alembic/versions/0005_user_role_fk.py
new file mode 100644
index 0000000..0f8fff0
--- /dev/null
+++ b/alembic/versions/0005_user_role_fk.py
@@ -0,0 +1,37 @@
+"""T10: Add role_id FK column to users table (references roles.id).
+
+Revision ID: 0005_user_role_fk
+Revises: 0004_ai_workflows
+Create Date: 2026-07-03
+"""
+
+from __future__ import annotations
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+revision: str = "0005_user_role_fk"
+down_revision: Union[str, None] = "0004_ai_workflows"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "users",
+        sa.Column(
+            "role_id",
+            postgresql.UUID(as_uuid=True),
+            sa.ForeignKey("roles.id", ondelete="SET NULL"),
+            nullable=True,
+        ),
+    )
+    op.create_index("ix_users_role_id", "users", ["role_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_users_role_id", table_name="users")
+    op.drop_column("users", "role_id")