FabledCurator/tests/test_download_service.py

"""DownloadService orchestrator tests.

GalleryDLService is mocked to return a canned DownloadResult; tests
provide on-disk files for the importer to attach_in_place.
"""

from pathlib import Path
from types import SimpleNamespace
from unittest.mock import AsyncMock, MagicMock

import pytest
from sqlalchemy import select

from backend.app.models import Artist, DownloadEvent, ImportSettings, Source
from backend.app.services.credential_crypto import CredentialCrypto
from backend.app.services.credential_service import CredentialService
from backend.app.services.thumbnailer import Thumbnailer

pytestmark = pytest.mark.integration


@pytest.fixture
async def seed_artist_and_source(db, db_sync):
    artist = Artist(name="Alice", slug="alice")
    db.add(artist)
    await db.flush()
    source = Source(
        artist_id=artist.id, platform="patreon",
        url="https://patreon.com/alice", enabled=True,
        config_overrides={},
    )
    db.add(source)
    await db.commit()
    return artist, source


def _make_jpg(path: Path, split: str = "h"):
    """Write a structured JPEG so phash isn't degenerate.

    Solid-color images all phash-collapse (DCT of a flat image is zero).
    Use `split='h'` (top/bottom halves) or `split='v'` (left/right) to
    give each fixture file a distinct phash.
    """
    from PIL import Image
    path.parent.mkdir(parents=True, exist_ok=True)
    im = Image.new("RGB", (64, 64), (255, 255, 255))
    px = im.load()
    if split == "h":
        for y in range(32):
            for x in range(64):
                px[x, y] = (0, 0, 0)
    else:  # 'v'
        for y in range(64):
            for x in range(32):
                px[x, y] = (0, 0, 0)
    im.save(path, "JPEG")


def _make_fake_dl_result(
    *, success=True, written_paths=None, quarantined_paths=None,
    files_downloaded=0, error_type=None, error_message=None,
    stdout="", stderr="",
):
    return SimpleNamespace(
        success=success,
        url="https://patreon.com/alice",
        artist_slug="alice",
        platform="patreon",
        files_downloaded=files_downloaded,
        files_quarantined=len(quarantined_paths or []),
        quarantined_paths=quarantined_paths or [],
        written_paths=written_paths or [],
        stdout=stdout,
        stderr=stderr,
        return_code=0 if success else 1,
        error_type=error_type,
        error_message=error_message,
        duration_seconds=1.23,
        started_at="2026-05-20T14:00:00+00:00",
        completed_at="2026-05-20T14:01:00+00:00",
    )


def _fake_gdl_with_result(result):
    fake = MagicMock()
    fake.download = AsyncMock(return_value=result)
    fake._compute_run_stats = lambda *a, **k: {
        "exit_code": 0, "downloaded_count": len(result.written_paths),
        "skipped_count": 0, "per_item_failures": 0,
        "warning_count": 0, "tier_gated_count": 0,
    }
    fake._extract_errors_warnings = lambda *a, **k: ""
    fake._truncate_log = lambda x, **k: x
    return fake


@pytest.mark.asyncio
async def test_download_source_attaches_written_files(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source

    images_root = tmp_path / "images"
    f1 = images_root / "alice" / "patreon" / "post" / "a.jpg"
    f2 = images_root / "alice" / "patreon" / "post" / "b.jpg"
    # Structured h/v split → distinct sha256 AND distinct phash;
    # also pin phash_threshold=0 so even tiny perceptual similarity
    # between the two doesn't trigger duplicate_phash.
    _make_jpg(f1, split="h")
    _make_jpg(f2, split="v")

    fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
        success=True,
        written_paths=[str(f1), str(f2)],
        files_downloaded=2,
        stdout=f"{f1}\n{f2}\n",
    ))

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    sync_settings.phash_threshold = 0  # only exact phash collisions dedup

    importer = Importer(
        session=db_sync, images_root=images_root,
        import_root=images_root,
        thumbnailer=Thumbnailer(images_root=images_root),
        settings=sync_settings,
    )
    crypto = CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True)
    cred_service = CredentialService(db, crypto)

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    event_id = await svc.download_source(source.id)

    ev = (await db.execute(
        select(DownloadEvent).where(DownloadEvent.id == event_id)
    )).scalar_one()
    assert ev.status == "ok"
    assert ev.files_count == 2
    assert ev.metadata_["import_summary"]["attached"] == 2
    assert ev.metadata_["run_stats"]["downloaded_count"] == 2


@pytest.mark.asyncio
async def test_download_source_skipped_when_disabled(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source
    source.enabled = False
    await db.commit()

    fake_gdl = MagicMock()
    fake_gdl.download = AsyncMock()

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path,
        import_root=tmp_path,
        thumbnailer=Thumbnailer(images_root=tmp_path),
        settings=sync_settings,
    )
    cred_service = CredentialService(db, MagicMock())

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    event_id = await svc.download_source(source.id)

    ev = (await db.execute(
        select(DownloadEvent).where(DownloadEvent.id == event_id)
    )).scalar_one()
    assert ev.status == "skipped"
    assert ev.error == "source disabled"
    fake_gdl.download.assert_not_called()


@pytest.mark.asyncio
async def test_in_flight_idempotency_returns_existing_event(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    from backend.app.services.download_service import DownloadService

    _artist, source = seed_artist_and_source
    running = DownloadEvent(source_id=source.id, status="running")
    db.add(running)
    await db.commit()
    await db.refresh(running)

    fake_gdl = MagicMock()
    fake_gdl.download = AsyncMock()
    importer_stub = MagicMock()
    cred_service = CredentialService(db, MagicMock())

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer_stub, cred_service=cred_service,
    )
    event_id = await svc.download_source(source.id)
    assert event_id == running.id
    fake_gdl.download.assert_not_called()


@pytest.mark.asyncio
async def test_patreon_retry_caches_campaign_id(
    db, db_sync, tmp_path, seed_artist_and_source, monkeypatch,
):
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source

    failed = _make_fake_dl_result(
        success=False, written_paths=[], stdout="",
        stderr="[patreon][error] Failed to extract campaign ID for alice\n",
    )
    succeeded = _make_fake_dl_result(success=True, written_paths=[])

    download_calls = []

    async def fake_download(url, **k):
        download_calls.append(url)
        return failed if len(download_calls) == 1 else succeeded

    fake_gdl = MagicMock()
    fake_gdl.download = fake_download
    fake_gdl._compute_run_stats = lambda *a, **k: {
        "exit_code": 0, "downloaded_count": 0, "skipped_count": 0,
        "per_item_failures": 0, "warning_count": 0, "tier_gated_count": 0,
    }
    fake_gdl._extract_errors_warnings = lambda *a, **k: ""
    fake_gdl._truncate_log = lambda x, **k: x

    monkeypatch.setattr(
        "backend.app.services.download_service.resolve_campaign_id",
        AsyncMock(return_value="99"),
    )

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path,
        import_root=tmp_path,
        thumbnailer=Thumbnailer(images_root=tmp_path),
        settings=sync_settings,
    )
    cred_service = CredentialService(db, MagicMock())

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    assert len(download_calls) == 2
    assert "id:99" in download_calls[1]

    overrides = db_sync.execute(
        select(Source.config_overrides).where(Source.id == source.id)
    ).scalar_one()
    assert overrides.get("patreon_campaign_id") == "99"


# --- FC-3d: finalize hook updates Source health columns -------------------


async def _seed_source_with_health(db, *, failures=0, last_error=None, suffix="fz"):
    artist = Artist(name=f"alice-{suffix}", slug=f"alice-{suffix}")
    db.add(artist)
    await db.flush()
    source = Source(
        artist_id=artist.id, platform="patreon",
        url=f"https://patreon.com/alice-{suffix}", enabled=True,
        consecutive_failures=failures, last_error=last_error,
    )
    db.add(source)
    await db.flush()
    event = DownloadEvent(source_id=source.id, status="running")
    db.add(event)
    await db.commit()
    return source.id, event.id


@pytest.mark.asyncio
async def test_finalize_ok_resets_failures_and_clears_error(db):
    from backend.app.services.download_service import DownloadService

    source_id, event_id = await _seed_source_with_health(
        db, failures=3, last_error="prev", suffix="ok",
    )
    svc = DownloadService(
        async_session=db, sync_session=None,
        gdl=None, importer=None, cred_service=None,
    )
    await svc._finalize_event_and_source(
        event_id=event_id, source_id=source_id, status="ok",
        error_message=None,
    )

    row = (await db.execute(
        select(
            Source.consecutive_failures, Source.last_error, Source.last_checked_at,
        ).where(Source.id == source_id)
    )).one()
    assert row.consecutive_failures == 0
    assert row.last_error is None
    assert row.last_checked_at is not None


@pytest.mark.asyncio
async def test_finalize_error_increments_failures_and_sets_error(db):
    from backend.app.services.download_service import DownloadService

    source_id, event_id = await _seed_source_with_health(
        db, failures=2, last_error=None, suffix="err",
    )
    svc = DownloadService(
        async_session=db, sync_session=None,
        gdl=None, importer=None, cred_service=None,
    )
    await svc._finalize_event_and_source(
        event_id=event_id, source_id=source_id, status="error",
        error_message="boom",
    )

    row = (await db.execute(
        select(
            Source.consecutive_failures, Source.last_error, Source.last_checked_at,
        ).where(Source.id == source_id)
    )).one()
    assert row.consecutive_failures == 3
    assert row.last_error == "boom"
    assert row.last_checked_at is not None


@pytest.mark.asyncio
async def test_finalize_skipped_preserves_failures_clears_error(db):
    from backend.app.services.download_service import DownloadService

    source_id, event_id = await _seed_source_with_health(
        db, failures=4, last_error="stale", suffix="skip",
    )
    svc = DownloadService(
        async_session=db, sync_session=None,
        gdl=None, importer=None, cred_service=None,
    )
    await svc._finalize_event_and_source(
        event_id=event_id, source_id=source_id, status="skipped",
        error_message=None,
    )

    row = (await db.execute(
        select(
            Source.consecutive_failures, Source.last_error, Source.last_checked_at,
        ).where(Source.id == source_id)
    )).one()
    assert row.consecutive_failures == 4
    assert row.last_error is None
    assert row.last_checked_at is not None


# --- Plan #544: backfill lifecycle + PARTIAL → status=ok -------------------


@pytest.mark.asyncio
async def test_backfill_decrements_and_checkpoints_cursor(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """A backfill run that did NOT finish the walk (subprocess budget cut it
    short → success=False / rc!=0) decrements the run budget AND checkpoints
    gallery-dl's last-emitted cursor, so the next run resumes instead of
    re-walking from the top (plan #689, Anduo #40411)."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source
    source.backfill_runs_remaining = 3
    await db.commit()

    images_root = tmp_path / "images"
    fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
        success=False, written_paths=[], files_downloaded=0,
        stderr="[patreon][debug] Cursor: 03:PAGE2:xyz\n",
    ))

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=images_root, import_root=images_root,
        thumbnailer=Thumbnailer(images_root=images_root), settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))
    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    remaining, overrides = (await db.execute(
        select(Source.backfill_runs_remaining, Source.config_overrides)
        .where(Source.id == source.id)
    )).one()
    assert remaining == 2
    assert overrides.get("_backfill_cursor") == "03:PAGE2:xyz"


@pytest.mark.asyncio
async def test_backfill_cursor_keeps_backfill_mode_after_budget_drained(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """A pending cursor with runs_remaining == 0 still runs in BACKFILL mode
    (skip:True + the resume cursor threaded to gallery-dl), so a large walk
    finishes across ticks without the operator re-triggering."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.gallery_dl import BACKFILL_SKIP_VALUE
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source
    source.backfill_runs_remaining = 0
    source.config_overrides = {"_backfill_cursor": "03:RESUME:here"}
    await db.commit()

    fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
        success=False, written_paths=[],
        stderr="[patreon][debug] Cursor: 03:RESUME2:next\n",
    ))
    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path / "images",
        import_root=tmp_path / "images",
        thumbnailer=Thumbnailer(images_root=tmp_path / "images"),
        settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))
    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    kwargs = fake_gdl.download.call_args.kwargs
    assert kwargs["skip_value"] is BACKFILL_SKIP_VALUE
    assert kwargs["source_config"].resume_cursor == "03:RESUME:here"

    overrides = (await db.execute(
        select(Source.config_overrides).where(Source.id == source.id)
    )).scalar_one()
    assert overrides.get("_backfill_cursor") == "03:RESUME2:next"


@pytest.mark.asyncio
async def test_backfill_completes_and_clears_cursor(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """A clean rc=0 finish means gallery-dl walked to the bottom — clear the
    checkpoint and drop back to tick mode, regardless of files this run."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source
    source.backfill_runs_remaining = 2
    source.config_overrides = {"_backfill_cursor": "03:NEAR:bottom"}
    await db.commit()

    fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
        success=True, written_paths=[], files_downloaded=0,
        stderr="[patreon][debug] Cursor: 03:LAST:page\n",
    ))
    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path / "images",
        import_root=tmp_path / "images",
        thumbnailer=Thumbnailer(images_root=tmp_path / "images"),
        settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))
    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    remaining, overrides = (await db.execute(
        select(Source.backfill_runs_remaining, Source.config_overrides)
        .where(Source.id == source.id)
    )).one()
    assert remaining == 0
    assert "_backfill_cursor" not in (overrides or {})


@pytest.mark.asyncio
async def test_backfill_cursor_stuck_guard_gives_up(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """If two consecutive non-completing runs fail to advance the cursor,
    drop the checkpoint + zero the budget so a wedged walk can't re-strand
    forever (cf. download soft-limit ladder)."""
    from unittest.mock import MagicMock

    from backend.app.services.download_service import DownloadService

    _artist, source = seed_artist_and_source
    source.backfill_runs_remaining = 0
    source.config_overrides = {"_backfill_cursor": "stuck"}
    await db.commit()

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=MagicMock(), importer=MagicMock(), cred_service=MagicMock(),
    )
    ctx = {
        "source_id": source.id, "platform": "patreon",
        "config_overrides": {"_backfill_cursor": "stuck"},
        "backfill_runs_remaining": 0,
    }
    stuck = _make_fake_dl_result(success=False, stderr="Cursor: stuck\n")

    # Run 1: cursor unchanged → 1 stall, checkpoint retained.
    await svc._apply_backfill_lifecycle(ctx, stuck)
    await db.commit()
    overrides = (await db.execute(
        select(Source.config_overrides).where(Source.id == source.id)
    )).scalar_one()
    assert overrides.get("_backfill_cursor") == "stuck"
    assert overrides.get("_backfill_cursor_stalls") == 1

    # Run 2: still stuck → give up.
    ctx["config_overrides"] = dict(overrides)
    await svc._apply_backfill_lifecycle(ctx, stuck)
    await db.commit()
    remaining, overrides2 = (await db.execute(
        select(Source.backfill_runs_remaining, Source.config_overrides)
        .where(Source.id == source.id)
    )).one()
    assert remaining == 0
    assert "_backfill_cursor" not in (overrides2 or {})


@pytest.mark.asyncio
async def test_backfill_auto_resets_on_clean_zero_files(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """A clean run (rc=0) that downloaded zero files means the backfill
    queue drained — reset to 0 immediately instead of wasting the rest of
    the N-run budget on no-op walks."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source
    source.backfill_runs_remaining = 3
    await db.commit()

    fake_result = _make_fake_dl_result(
        success=True, written_paths=[], files_downloaded=0,
    )
    fake_gdl = _fake_gdl_with_result(fake_result)

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path / "images",
        import_root=tmp_path / "images",
        thumbnailer=Thumbnailer(images_root=tmp_path / "images"),
        settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))
    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    remaining = (await db.execute(
        select(Source.backfill_runs_remaining).where(Source.id == source.id)
    )).scalar_one()
    assert remaining == 0


@pytest.mark.asyncio
async def test_tick_mode_does_not_touch_backfill_counter(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """When backfill_runs_remaining is already 0, downloads don't go
    negative or otherwise mutate the counter."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source
    assert source.backfill_runs_remaining == 0

    fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
        success=True, written_paths=[], files_downloaded=0,
    ))

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path / "images",
        import_root=tmp_path / "images",
        thumbnailer=Thumbnailer(images_root=tmp_path / "images"),
        settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))
    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    remaining = (await db.execute(
        select(Source.backfill_runs_remaining).where(Source.id == source.id)
    )).scalar_one()
    assert remaining == 0


@pytest.mark.asyncio
async def test_partial_error_type_maps_to_ok_status(
    db, db_sync, tmp_path, seed_artist_and_source,
):
    """A non-zero gallery-dl exit accompanied by PARTIAL error_type
    (real files were downloaded before the run was cut short) is treated
    as status=ok by the orchestrator — next tick continues."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.gallery_dl import ErrorType
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source

    images_root = tmp_path / "images"
    f1 = images_root / "alice" / "patreon" / "post" / "a.jpg"
    _make_jpg(f1, split="h")

    fake_result = _make_fake_dl_result(
        success=False, written_paths=[str(f1)], files_downloaded=1,
        error_type=ErrorType.PARTIAL,
        error_message="Downloaded 1 file; run did not complete in budget",
        stdout=f"{f1}\n",
    )
    fake_gdl = _fake_gdl_with_result(fake_result)

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=images_root, import_root=images_root,
        thumbnailer=Thumbnailer(images_root=images_root), settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))
    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    event_id = await svc.download_source(source.id)

    ev = (await db.execute(
        select(DownloadEvent).where(DownloadEvent.id == event_id)
    )).scalar_one()
    assert ev.status == "ok"
    assert ev.error is None
    # And the source's failure counter isn't bumped — PARTIAL isn't a failure.
    src_after = (await db.execute(
        select(Source.consecutive_failures).where(Source.id == source.id)
    )).scalar_one()
    assert src_after == 0


@pytest.mark.asyncio
async def test_download_enqueues_thumbnail_and_ml_per_attached_image(
    db, db_sync, tmp_path, seed_artist_and_source, monkeypatch,
):
    """Operator-flagged 2026-06-01: downloaded images stayed at
    thumbnail_path=NULL until periodic backfill swept them up, surfacing
    as broken-thumbnail tiles in the gallery. Importer.attach_in_place
    deliberately skips inline generation; the calling code MUST enqueue
    the thumbnail + ML tasks per attached image (matching the pattern in
    tasks/import_file.py)."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source

    images_root = tmp_path / "images"
    f1 = images_root / "alice" / "patreon" / "post" / "a.jpg"
    f2 = images_root / "alice" / "patreon" / "post" / "b.jpg"
    _make_jpg(f1, split="h")
    _make_jpg(f2, split="v")

    fake_gdl = _fake_gdl_with_result(_make_fake_dl_result(
        success=True, written_paths=[str(f1), str(f2)],
        files_downloaded=2, stdout=f"{f1}\n{f2}\n",
    ))

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    sync_settings.phash_threshold = 0
    importer = Importer(
        session=db_sync, images_root=images_root, import_root=images_root,
        thumbnailer=Thumbnailer(images_root=images_root), settings=sync_settings,
    )
    cred_service = CredentialService(db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True))

    # Capture the IDs that the orchestrator hands off to each Celery task.
    # The .delay() shim runs inside DownloadService._phase3_persist (lazy
    # imports under ..tasks.thumbnail / ..tasks.ml), so monkeypatch the
    # symbols on those modules.
    thumb_calls: list[int] = []
    ml_calls: list[int] = []
    from backend.app.tasks import ml as ml_mod
    from backend.app.tasks import thumbnail as thumb_mod
    monkeypatch.setattr(
        thumb_mod.generate_thumbnail, "delay",
        lambda image_id: thumb_calls.append(image_id),
    )
    monkeypatch.setattr(
        ml_mod.tag_and_embed, "delay",
        lambda image_id: ml_calls.append(image_id),
    )

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    await svc.download_source(source.id)

    # Two files attached → two thumbnail enqueues + two ML enqueues, IDs
    # match the actually-imported records (not ad-hoc — drawn from the
    # importer's returned image_id so future supersede paths stay covered).
    assert len(thumb_calls) == 2
    assert len(ml_calls) == 2
    assert sorted(thumb_calls) == sorted(ml_calls)


@pytest.mark.asyncio
async def test_releases_db_connections_before_subprocess(
    db, db_sync, tmp_path, seed_artist_and_source, monkeypatch,
):
    """Phase 1's DB connections must be released BEFORE the (up to ~19.5-min
    in backfill) gallery-dl subprocess, so they don't idle-die and strand
    phase 3 with ConnectionDoesNotExistError (Anduo #40014). Spy on the
    async session close and assert it happened before gdl.download runs;
    phase 3 must still finalize the event."""
    from backend.app.services.download_service import DownloadService
    from backend.app.services.importer import Importer

    _artist, source = seed_artist_and_source

    closed = {"async": False}
    orig_close = db.close

    async def spy_close():
        closed["async"] = True
        await orig_close()

    monkeypatch.setattr(db, "close", spy_close)

    seen = {}

    async def fake_download(url, **k):
        seen["closed_before_download"] = closed["async"]
        return _make_fake_dl_result(success=True, written_paths=[], stdout="")

    fake_gdl = MagicMock()
    fake_gdl.download = fake_download
    fake_gdl._compute_run_stats = lambda *a, **k: {
        "exit_code": 0, "downloaded_count": 0, "skipped_count": 0,
        "per_item_failures": 0, "warning_count": 0, "tier_gated_count": 0,
    }
    fake_gdl._extract_errors_warnings = lambda *a, **k: ""
    fake_gdl._truncate_log = lambda x, **k: x

    sync_settings = db_sync.execute(
        select(ImportSettings).where(ImportSettings.id == 1)
    ).scalar_one()
    importer = Importer(
        session=db_sync, images_root=tmp_path, import_root=tmp_path,
        thumbnailer=Thumbnailer(images_root=tmp_path), settings=sync_settings,
    )
    cred_service = CredentialService(
        db, CredentialCrypto(tmp_path / "key.b64", bootstrap_ok=True)
    )

    svc = DownloadService(
        async_session=db, sync_session=db_sync,
        gdl=fake_gdl, importer=importer, cred_service=cred_service,
    )
    event_id = await svc.download_source(source.id)

    assert seen["closed_before_download"] is True
    ev = (await db.execute(
        select(DownloadEvent).where(DownloadEvent.id == event_id)
    )).scalar_one()
    assert ev.status == "ok"


@pytest.mark.asyncio
async def test_async_task_engine_uses_nullpool():
    """The per-task async engine must use NullPool so phase 3 re-acquires a
    fresh connection instead of a pooled one the server reaped during the
    long subprocess (Anduo #40014)."""
    from sqlalchemy.pool import NullPool

    from backend.app.tasks._async_session import async_session_factory

    _factory, engine = async_session_factory()
    try:
        assert isinstance(engine.sync_engine.pool, NullPool)
    finally:
        await engine.dispose()