"""retire the report_preference arm's rows (milestone 500 step 4)

Revision ID: 0121
Revises: 0120
Create Date: 2026-10-09

The fixed-question arm that searched for completion-report preferences when a
task closed is gone: the reply shapes and the preferences mounted beside them
now arrive on the moments (milestone 500 step 3). Its rows go with it (rule
22 — no legacy to preserve), because each one would otherwise mean something
different once the arm is no longer registered:

- `retrieval_logs` / `retrieval_judgments` — a source missing from the
  registry reads as `unregistered_source`, whose advice is "add it to the
  registry": the opposite of what happened.
- `rule_usage_events` — a source missing from `RANKED_SOURCES` reads as
  ambient, so its surfacings would silently move into the other column of
  every rule's pull-through.
- `retrieval_tuning_events` — the tuning history of a surface that no longer
  exists.
- `settings` — the arm's floor and budget keys, which nothing reads.

COST IS BOUNDED BY AN INDEX, NOT BY THE TABLE. A migration runs at boot
against the live tables, which CI never has (lesson #5221). `retrieval_logs`
and `retrieval_judgments` are indexed on `source`. `rule_usage_events` is not,
so its delete is also bounded by `created_at` (indexed): the arm shipped with
milestone 409 step 4, decided 2026-09-14, so no row of it predates
`ARM_BORN`, and the scan covers weeks rather than the table's whole history.

Not reversible: the arm is not coming back, so neither are its rows.
"""
from alembic import op

revision = "0121"
down_revision = "0120"
branch_labels = None
depends_on = None

SOURCE = "report_preference"
# A safe floor under the arm's first row (it shipped after 2026-09-14).
ARM_BORN = "2026-09-01"


def upgrade() -> None:
    op.execute(f"DELETE FROM retrieval_logs WHERE source = '{SOURCE}'")
    op.execute(f"DELETE FROM retrieval_judgments WHERE source = '{SOURCE}'")
    op.execute(
        f"DELETE FROM rule_usage_events WHERE created_at >= '{ARM_BORN}' "
        f"AND source = '{SOURCE}'"
    )
    op.execute(f"DELETE FROM retrieval_tuning_events WHERE surface = '{SOURCE}'")
    op.execute(
        "DELETE FROM settings WHERE key IN "
        "('kb_reportpref_threshold', 'kb_reportpref_top_k')"
    )


def downgrade() -> None:
    pass