"""Add parental_leave_fetch.transferable_days_reported.

Tracks provenance of `transferable_days_left`: True when it is FK's own
reported figure (parsed from the "Dagar ni kan föra över" panel on the
`min-foraldrapenning` e-service page, or a detailed manual entry that
supplied it directly); False when `app.services.leave_snapshot.build_snapshot`
derived it via the transferable-first fallback (manual entry with no split
known, or a failed parse of that panel).

Existing rows default to false, which is accurate — every snapshot persisted
before this migration was derived via the fallback, never FK-reported.

A plain `ADD COLUMN` suffices here (like 003's `take_pl_on_red_days`, unlike
002's CHECK-constraint change which needed a full table rebuild) since
SQLite supports adding a NOT NULL column with a constant DEFAULT directly.

Must stay byte-for-byte equivalent to the `parental_leave_fetch` table in
`app/db/connection.py`'s `_FULL_SCHEMA` —
`tests/integration/test_schema_parity.py` asserts exactly that.

Revision ID: 006
Revises: 005
Create Date: 2026-09-20
"""

from __future__ import annotations

from alembic import op

revision: str = "006"
down_revision: str | None = "005"
branch_labels: str | None = None
depends_on: str | None = None


def upgrade() -> None:
    op.execute(
        "ALTER TABLE parental_leave_fetch "
        "ADD COLUMN transferable_days_reported INTEGER NOT NULL DEFAULT 0"
    )


def downgrade() -> None:
    op.execute("ALTER TABLE parental_leave_fetch DROP COLUMN transferable_days_reported")