"""add users.last_login_at — when the account last signed in (E22 S1)

Revision ID: 0085_users_last_login_at
Revises: 0084_dl_job_error_detail
Create Date: 2026-09-16

Stamped by the one sign-in path (`routes/auth._establish_session`), which the Google callback and
password login share. No backfill is possible: the signal exists only at sign-in, so existing rows
read NULL until each account signs in again, and the admin UI says so rather than inventing a date.
"""

import sqlalchemy as sa
from alembic import op

revision: str = "0085_users_last_login_at"
down_revision: str | None = "0084_dl_job_error_detail"
branch_labels: str | None = None
depends_on: str | None = None


def upgrade() -> None:
    op.add_column("users", sa.Column("last_login_at", sa.DateTime(timezone=True), nullable=True))


def downgrade() -> None:
    op.drop_column("users", "last_login_at")