privacy/security: add PM privacy levels and improve session visibility

alembic/versions/0023_privacy_pm_level.py

@@ -0,0 +1,38 @@
+"""add privacy private messages level
+
+Revision ID: 0023_privacy_pm_level
+Revises: 0022_user_access_revoked_before
+Create Date: 2026-03-09 00:40:00.000000
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = "0023_privacy_pm_level"
+down_revision: Union[str, Sequence[str], None] = "0022_user_access_revoked_before"
+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("privacy_private_messages", sa.String(length=16), nullable=False, server_default=sa.text("'everyone'")),
+    )
+    op.execute(
+        sa.text(
+            "UPDATE users "
+            "SET privacy_private_messages = CASE "
+            "WHEN allow_private_messages IS TRUE THEN 'everyone' "
+            "ELSE 'nobody' "
+            "END"
+        )
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("users", "privacy_private_messages")
+