"""documents.created_at + created_at_manual: sourced document creation dates (phase 106)

Revision ID: 0020
Revises: 0019
Create Date: 2026-09-13

Phase 106 (document dates end to end: sourced at sync, displayed,
editable, recency-weighted in retrieval): every ``documents`` row carries
a NOT-NULL **creation date** — sourced at sync time (the git last-commit
date for git sources, the file mtime for local dirs and unpacked uploads
— D2) and normalized by ``app.rag.doc_dates.normalize_doc_date``
(undetermined or future → today; stored as UTC ``timestamptz`` at full
precision — D3). It is DISTINCT from ``indexed_at`` (the INDEX time,
untouched — the two concepts stay separate):

* ``documents.created_at`` — TIMESTAMP WITH TIME ZONE NOT NULL with
  server default ``now()``: pre-phase-106 rows backfill to the migration
  moment (≈ today — the owner's instruction, D1: "the timestamp can't be
  null so just set it to today's date during the migration") and the
  next sync replaces them with the real sourced date (the importer's
  unchanged path, phase 106 task 04 — a sync may move a date OLDER, D4).
* ``documents.created_at_manual`` — BOOLEAN NOT NULL with server default
  ``false``: ``true`` only while ``created_at`` is the OWNER'S
  correction (D1 — the ``folder_summaries.manually_edited`` phase-97
  precedent). Set ONLY by ``PATCH /api/documents/date`` (phase 106 task
  05); the sync-time importer SKIPS the refresh on a manual row (the
  correction survives syncs) and a content change RESETS both the date
  and the flag (a new version = a new date — D4).

One additive, fully reversible migration (A13); no other schema change.
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "0020"
down_revision = "0019"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.add_column(
        "documents",
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            server_default=sa.text("now()"),
            nullable=False,
        ),
    )
    op.add_column(
        "documents",
        sa.Column(
            "created_at_manual",
            sa.Boolean(),
            server_default=sa.text("false"),
            nullable=False,
        ),
    )


def downgrade() -> None:
    # Both columns are the only 0020 artefacts — dropping them leaves
    # 0019's schema byte-identical (A13, fully reversible).
    op.drop_column("documents", "created_at_manual")
    op.drop_column("documents", "created_at")