"""task_claims — a task can say a session is working it (milestone 381 step 2)

Revision ID: 0110
Revises: 0109
Create Date: 2026-09-23

`status` is durable and nothing clears it, so `in_progress` cannot also mean
"someone is on this now". The claim is that second meaning, stored as WHO and
WHEN rather than as a flag, so it can be read as dead without anything having
cleared it (`services/task_claims.py` has the semantics).

Four nullable columns, no backfill: no existing row has ever been claimed, and
inventing a claim for one would assert attention nobody observed. No CHECK
enum is touched.
"""
import sqlalchemy as sa
from alembic import op

revision = "0110"
down_revision = "0109"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.add_column("notes", sa.Column(
        "claimed_by", sa.Integer(), sa.ForeignKey("users.id", ondelete="SET NULL"), nullable=True,
    ))
    op.add_column("notes", sa.Column("claimed_at", sa.DateTime(timezone=True), nullable=True))
    op.add_column("notes", sa.Column("claim_touched_at", sa.DateTime(timezone=True), nullable=True))
    op.add_column("notes", sa.Column("claim_session", sa.Text(), nullable=True))


def downgrade() -> None:
    op.drop_column("notes", "claim_session")
    op.drop_column("notes", "claim_touched_at")
    op.drop_column("notes", "claimed_at")
    op.drop_column("notes", "claimed_by")