"""kb_overview: single-row, lite-generated knowledge-base outline

Revision ID: 0005
Revises: 0004
Create Date: 2026-08-25

Phase 31 (kb-overview-prompt story, A13 — one additive, reversible table,
no other schema change):

* ``kb_overview`` — a **single-row** table (``id INTEGER PK DEFAULT 1``)
  holding a plain-text outline of the knowledge base's basic categories,
  generated by the aipi ``lite`` model (phase 30's ``LLMClient.chat``)
  whenever an import changes the KB. Chat turns only *read* the row (one
  indexed PK lookup) and inject it into the system prompt as the
  ``<knowledge_base>`` section, so the agent knows roughly what the KB
  contains before retrieval returns documents. ``content`` defaults to the
  empty string — no row / empty row means the prompts are byte-identical
  to the pre-phase text (phase 15 convention); ``updated_at`` is stamped
  server-side on every upsert.
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "0005"
down_revision = "0004"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_table(
        "kb_overview",
        sa.Column("id", sa.Integer(), primary_key=True, server_default=sa.text("1")),
        sa.Column("content", sa.Text(), nullable=False, server_default=sa.text("''")),
        sa.Column(
            "updated_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.func.now(),
        ),
    )


def downgrade() -> None:
    op.drop_table("kb_overview")