diff --git a/alembic/versions/0005_session_category.py b/alembic/versions/0005_session_category.py
index ac9b385..93c45e1 100644
--- a/alembic/versions/0005_session_category.py
+++ b/alembic/versions/0005_session_category.py
@@ -6,6 +6,7 @@ Create Date: 2026-05-06
 """
 import sqlalchemy as sa
 from alembic import op
+from sqlalchemy.dialects import postgresql
 
 revision = "0005"
 down_revision = "0004"
@@ -42,10 +43,10 @@ def upgrade():
     # ai_flags: anomalies/suggestions surfaced by the assistant
     op.create_table(
         "ai_flags",
-        sa.Column("id", sa.String(36), primary_key=True),
+        sa.Column("id", postgresql.UUID(as_uuid=False), primary_key=True),
         sa.Column(
             "user_id",
-            sa.String(36),
+            postgresql.UUID(as_uuid=False),
             sa.ForeignKey("users.id", ondelete="CASCADE"),
             nullable=False,
             index=True,
@@ -72,10 +73,10 @@ def upgrade():
     # assistant_messages: persisted chat history per user
     op.create_table(
         "assistant_messages",
-        sa.Column("id", sa.String(36), primary_key=True),
+        sa.Column("id", postgresql.UUID(as_uuid=False), primary_key=True),
         sa.Column(
             "user_id",
-            sa.String(36),
+            postgresql.UUID(as_uuid=False),
             sa.ForeignKey("users.id", ondelete="CASCADE"),
             nullable=False,
             index=True,