"""source_labels: per-source name, label and tags (phase 191, task 01)

Revision ID: 0030
Revises: 0029
Create Date: 2026-10-18

``TODO.md`` L4: "Sources need a name, a label, tag(s) so you can focus
the model when prompting if you have a project name or a standard name
you reference things by." This revision carries the storage half
(phase 191 D1) — the matching rule (D2), the boost (D3), the API (D5)
and the UI (D6) are the later tasks.

* ``source_labels`` — one row per SOURCE the owner has named:

  * ``source`` — VARCHAR(120) NOT NULL, PRIMARY KEY. The source name
    EXACTLY as ``documents.source`` carries it (the derived basename —
    the clone dir / local dir / upload file stem): the join key to the
    documents and to the ``git_sources`` row. The PK is the uniqueness
    guard (one label row per source — the ``app_settings`` 0028
    reasoning). **An ALIAS key only (D1):** a label row never renames a
    document, a ``source/path`` locator, a citation or the KB tree.
  * ``display_name`` — TEXT nullable (the owner's name for the source,
    "the git server"). Plain TEXT: the ≤ 120-char trimmed limit is
    enforced at the API boundary (the phase-121 ``git_sources.branch``
    pattern — plain column, boundary validation). NULL = no name.
  * ``label`` — TEXT nullable (the short one-line description /
    category, ≤ 200 trimmed, same boundary rule). NULL = no label.
  * ``tags`` — JSONB NOT NULL with server default ``'[]'`` (the
    phase-89 ``git_sources.ignore_paths`` shape): the focus tokens,
    each ≤ 32 chars, ≤ 10 entries, guarded at the API boundary
    (``app.rag.source_labels.normalize_tags``).
  * ``updated_at`` — TIMESTAMPTZ NOT NULL, ``now()`` server default
    (the ``app_settings`` / ``folder_summaries`` house style).

NO backfill (D1): the table is created EMPTY — a source without a row
has no name/label/tags and behaves exactly as pre-phase, so "no label
row → every surface byte-identical" holds without a data step. No index
beyond the PK: every read is a PK lookup or a whole-table walk of a
handful of rows (the ``app_settings`` "never a query surface" note).

One additive, fully reversible migration (A13).
"""
from __future__ import annotations

import sqlalchemy as sa
from sqlalchemy.dialects import postgresql

from alembic import op

revision = "0030"
down_revision = "0029"
branch_labels = None
depends_on = None


def upgrade() -> None:
    # No index beyond the PK (every read is a PK lookup or the whole
    # handful-row table), no backfill (an empty table = every source
    # keeps its pre-phase "no row" behavior).
    op.create_table(
        "source_labels",
        sa.Column("source", sa.String(length=120), primary_key=True),
        sa.Column("display_name", sa.Text(), nullable=True),
        sa.Column("label", sa.Text(), nullable=True),
        sa.Column(
            "tags",
            postgresql.JSONB(astext_type=sa.Text()),
            server_default=sa.text("'[]'"),
            nullable=False,
        ),
        sa.Column(
            "updated_at",
            sa.DateTime(timezone=True),
            server_default=sa.func.now(),
            nullable=False,
        ),
    )


def downgrade() -> None:
    # The table is the only 0030 artefact — dropping it leaves 0029's
    # schema byte-identical (A13, fully reversible). No owner data is
    # trapped: the names/labels/tags are re-enterable from the Sources
    # page (task 03), and nothing else was mutated by 0030.
    op.drop_table("source_labels")