feat: Settings can re-download the Discord images the None naming broke (3999)

The operator chose a clean re-download over relinking in place. The ~1,600 broken files can't be relinked reliably: their message ids are gone, and their sidecars collided.

Settings → Maintenance → "Repair Discord downloads" previews, then applies:
- Deletes every image whose path is `…/discord/None/<8 digits>_None_…`. Both the folder and the name are required, because that pair is only what the bug produced. It reuses cleanup_service.delete_images for the record and file deletes.
- Sweeps the leftover collided sidecars from those folders and removes the emptied folders.
- Only then clears gallery-dl's archive rows `discord%`, excluding `discordasset_%`. Upstream keys message attachments as `discord{message_id}_{num}`. Since the broken files lost their message ids, per-source forgetting is impossible. Every pre-fix Discord download is broken, and files fetched after the fix still exist on disk, so gallery-dl's `skip` won't re-fetch them.
- Arms a fresh backfill on every Discord source.

The apply defaults to preview at both the route and the task, runs on maintenance_long, and is never on a beat. The card uses the confirm-dialog pattern of AttachmentReclaimCard.

Supporting refactors, with no behaviour change:
- gallery_dl.archive_path() is the single definition of the archive location.
- source_service.arm_backfill() is the mutation start_backfill already did, now shared with the sync repair.

Tests (tests/test_discord_repair.py):
- The archive clear leaves other platforms and Discord assets alone, and counting mutates nothing.
- Case-twin artist folders are both found.
- The folder sweep works.
- An integration run shows only the broken image goes. A correctly named Discord file and a `None` folder under Patreon survive, and only Discord sources are re-armed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SHQB1YukL3VyvMK8rcbmV9

backend/app/api/admin.py

@@ -475,6 +475,20 @@ async def trigger_reclaim_attachments():
     return _queued(async_result)
 
 
+@admin_bp.route("/maintenance/repair-discord-downloads", methods=["POST"])
+async def trigger_repair_discord_downloads():
+    """Clean re-download of the Discord files broken by the `None` naming
+    (#3999). Body {"dry_run": bool}; dry_run is the DEFAULT, because the apply
+    deletes files and makes gallery-dl forget every Discord download. Returns the
+    Celery task id — poll /maintenance/task-result/<id> for the summary."""
+    from ..tasks.admin import repair_discord_downloads_task
+
+    body = await request.get_json(silent=True) or {}
+    dry_run = bool(body.get("dry_run", True))
+    async_result = repair_discord_downloads_task.delay(dry_run=dry_run)
+    return _queued(async_result)
+
+
 @admin_bp.route("/maintenance/dedup-videos", methods=["POST"])
 async def trigger_dedup_videos():
     """Tier-1 video dedup (#871). Body {"dry_run": bool}: dry_run=true previews

backend/app/services/discord_repair.py

@@ -0,0 +1,183 @@
+"""Repair the Discord downloads made before the naming fix (issue #3999).
+
+Until dc840fe, gallery-dl's Discord patterns asked for keys the extractor never
+emits, so every Discord download landed as
+`<artist>/discord/None/<date>_None_<original name>`, next to a sidecar named
+after the attachment's ORIGINAL name. That broke two things:
+
+* **No Post, no date.** `find_sidecar` can never pair those names, so these
+  files were imported as loose images with no Post, and a card shows the
+  download time.
+* **No trustworthy metadata to relink from.** Every `image.png` in a channel
+  wrote the same `image.json`, so the surviving sidecar describes whichever
+  message was written last. The message id is gone from the filename too.
+
+The operator chose a clean re-download (2026-09-13) over relinking in place:
+delete the broken files and their records, make gallery-dl forget it fetched
+them, and backfill every Discord source again under the fixed naming.
+
+## Why the archive is cleared for ALL of Discord
+
+gallery-dl records a download as `discord{message_id}_{num}` (upstream
+`DiscordExtractor.archive_fmt`, prefixed with the category). The broken files
+lost their message ids, so there is no way to forget one source's entries and
+not another's. Every Discord download made before the fix is broken, so
+forgetting all of them is exactly right. Anything downloaded AFTER the fix still
+exists on disk under its correct name, and gallery-dl's `skip` sees the file and
+does not fetch it again.
+
+## What it does not touch
+
+Discord posts FC grouped itself (#388 E2) are built from Posts, and these files
+never had one, so there is nothing grouped to unwind. Images outside a
+`discord/None/` directory are never selected: the path filter requires both the
+`None` directory and the `_None_` filename, the pair only the bug produced.
+
+Operator-triggered only (Settings, preview first). Never on a beat.
+"""
+
+from __future__ import annotations
+
+import logging
+import sqlite3
+from pathlib import Path
+
+from sqlalchemy import func, select
+from sqlalchemy.orm import Session
+
+from ..models import ImageRecord, Source
+from .cleanup_service import delete_images
+from .gallery_dl import archive_path
+from .source_service import arm_backfill
+
+log = logging.getLogger(__name__)
+
+# `%` and `_` are LIKE wildcards, so the literal underscores around None are
+# escaped. `________` is the eight-digit date prefix the old pattern wrote.
+_BROKEN_PATH_LIKE = r"%/discord/None/________\_None\_%"
+
+# Upstream keys asset downloads as `asset_{server_id}_{id}`. FC never fetches
+# server assets, but excluding them keeps this to exactly the message
+# attachments the bug mangled.
+_ARCHIVE_SQL_MATCH = r"entry LIKE 'discord%' AND entry NOT LIKE 'discordasset\_%' ESCAPE '\'"
+_COUNT_SQL = "SELECT COUNT(*) FROM archive WHERE " + _ARCHIVE_SQL_MATCH
+_DELETE_SQL = "DELETE FROM archive WHERE " + _ARCHIVE_SQL_MATCH
+
+
+def broken_directories(images_root: Path) -> list[Path]:
+    """Every `<artist>/discord/None` directory. Artist folders that differ only by
+    case (`Conto` and `conto`) are separate directories and both are found."""
+    return sorted(d for d in Path(images_root).glob("*/discord/None") if d.is_dir())
+
+
+def count_archive_entries(archive: Path) -> int:
+    return _archive(archive, delete=False)
+
+
+def forget_archive_entries(archive: Path) -> int:
+    return _archive(archive, delete=True)
+
+
+def _archive(archive: Path, *, delete: bool) -> int:
+    if not archive.is_file():
+        return 0
+    # A download running at the same moment holds this file briefly. Waiting
+    # 30s for its lock beats failing the repair over a transient contention.
+    conn = sqlite3.connect(str(archive), timeout=30)
+    try:
+        has_table = conn.execute(
+            "SELECT 1 FROM sqlite_master WHERE type='table' AND name='archive'"
+        ).fetchone()
+        if not has_table:
+            return 0
+        if not delete:
+            return conn.execute(_COUNT_SQL).fetchone()[0]
+        cur = conn.execute(_DELETE_SQL)
+        conn.commit()
+        return cur.rowcount
+    finally:
+        conn.close()
+
+
+def _sweep_directory(directory: Path) -> tuple[int, bool]:
+    """Remove what the record deletes left behind: the collided sidecars, plus any
+    file that never became a record (a quarantined or rejected download). Then
+    the directory itself, if it is empty. Returns (files removed, dir removed)."""
+    removed = 0
+    for f in directory.iterdir():
+        if f.is_file():
+            try:
+                f.unlink()
+                removed += 1
+            except OSError as exc:
+                log.warning("discord repair: could not remove %s: %s", f, exc)
+    try:
+        directory.rmdir()
+        return removed, True
+    except OSError:
+        return removed, False
+
+
+def repair_discord_downloads(
+    session: Session, *, images_root: Path, dry_run: bool,
+) -> dict:
+    images_root = Path(images_root)
+    archive = archive_path(images_root)
+
+    broken = select(ImageRecord.id, ImageRecord.size_bytes).where(
+        ImageRecord.path.like(_BROKEN_PATH_LIKE, escape="\\")
+    )
+    rows = session.execute(broken).all()
+    image_ids = [r.id for r in rows]
+    directories = broken_directories(images_root)
+    sources = session.execute(
+        select(Source).where(Source.platform == "discord")
+    ).scalars().all()
+
+    summary = {
+        "images": len(image_ids),
+        "bytes": sum(r.size_bytes or 0 for r in rows),
+        "directories": len(directories),
+        "sources": len(sources),
+        "enabled_sources": sum(1 for s in sources if s.enabled),
+    }
+
+    if dry_run:
+        summary["archive_entries"] = count_archive_entries(archive)
+        return summary
+
+    deleted = delete_images(session, image_ids=image_ids, images_root=images_root)
+
+    swept = 0
+    directories_removed = 0
+    for d in directories:
+        n, gone = _sweep_directory(d)
+        swept += n
+        directories_removed += int(gone)
+
+    # Only after the files are gone. Forgetting first and failing half way would
+    # leave gallery-dl free to re-fetch into a directory still full of the old
+    # copies.
+    forgotten = forget_archive_entries(archive)
+
+    for source in sources:
+        arm_backfill(source)
+    session.commit()
+
+    remaining = session.execute(
+        select(func.count(ImageRecord.id)).where(
+            ImageRecord.path.like(_BROKEN_PATH_LIKE, escape="\\")
+        )
+    ).scalar_one()
+
+    summary.update(
+        images_deleted=deleted["images_deleted"],
+        files_failed=deleted["files_failed"],
+        leftover_files_removed=swept,
+        directories_removed=directories_removed,
+        archive_entries=forgotten,
+        backfills_started=len(sources),
+        remaining=remaining,
+    )
+    log.info("discord repair applied: %s", summary)
+    return summary

backend/app/services/gallery_dl.py

@@ -136,6 +136,16 @@ def metadata_postprocessor(filename: str) -> dict:
     return {"name": "metadata", "mode": "json", "directory": ".", "filename": filename}
 
 
+def archive_path(images_root: Path) -> Path:
+    """gallery-dl's download archive: the record of what it has already fetched.
+
+    One definition, because the Discord repair (services/discord_repair.py) has
+    to find the same file the downloader writes, without constructing a service
+    whose __init__ creates directories.
+    """
+    return Path(images_root) / ".gallery-dl" / "archive.sqlite3"
+
+
 @dataclass
 class SourceConfig:
     """Per-source overrides loaded from Source.config_overrides JSON.
@@ -447,7 +457,7 @@ class GalleryDLService:
         config = {
             "extractor": {
                 "base-directory": str(self.images_root),
-                "archive": str(self._config_dir / "archive.sqlite3"),
+                "archive": str(archive_path(self.images_root)),
                 "skip": True,
                 "sleep": self._rate_limit,
                 "sleep-request": max(0.5, self._rate_limit / 4),

backend/app/services/source_service.py

@@ -158,6 +158,19 @@ def _is_app_managed(key: str) -> bool:
 BACKFILL_MAX_CHUNKS = 200
 
 
+def arm_backfill(source: Source) -> None:
+    """Arm a fresh run-until-done backfill on `source` (plan #693). Mutation
+    only — the caller commits. Shared by `SourceService.start_backfill` and the
+    sync Discord repair, so both clear exactly the same resume state."""
+    co = dict(source.config_overrides or {})
+    co["_backfill_state"] = "running"
+    for k in ("_backfill_cursor", "_backfill_cursor_stalls", "_backfill_chunks",
+              "_backfill_posts"):
+        co.pop(k, None)
+    source.config_overrides = co
+    source.backfill_runs_remaining = BACKFILL_MAX_CHUNKS
+
+
 class SourceService:
     def __init__(self, session: AsyncSession):
         self.session = session
@@ -473,13 +486,7 @@ class SourceService:
         )).scalar_one_or_none()
         if source is None:
             raise LookupError(f"source id={source_id} not found")
-        co = dict(source.config_overrides or {})
-        co["_backfill_state"] = "running"
-        for k in ("_backfill_cursor", "_backfill_cursor_stalls", "_backfill_chunks",
-                  "_backfill_posts"):
-            co.pop(k, None)
-        source.config_overrides = co
-        source.backfill_runs_remaining = BACKFILL_MAX_CHUNKS
+        arm_backfill(source)
         await self.session.commit()
         return await self._row_to_record(source)
 

backend/app/tasks/admin.py

@@ -122,6 +122,28 @@ def prune_missing_file_records_task(self) -> dict:
     return {"checked": checked, "missing": len(missing_ids), "deleted": deleted}
 
 
+@celery.task(
+    name="backend.app.tasks.admin.repair_discord_downloads_task",
+    bind=True,
+    autoretry_for=(OperationalError, DBAPIError),
+    retry_backoff=15, retry_backoff_max=180, max_retries=1,
+    soft_time_limit=1800, time_limit=2400,  # 30 min / 40 min
+)
+def repair_discord_downloads_task(self, dry_run: bool = True) -> dict:
+    """Clean re-download of the Discord files broken by the `None` naming
+    (#3999). dry_run (the default) returns the projection; apply deletes the
+    broken images and their files, makes gallery-dl forget every Discord
+    download, and restarts every Discord source's backfill. Defaults to the SAFE
+    preview because the apply deletes files. Operator-triggered only."""
+    from ..services.discord_repair import repair_discord_downloads
+
+    SessionLocal = _sync_session_factory()
+    with SessionLocal() as session:
+        return repair_discord_downloads(
+            session, images_root=IMAGES_ROOT, dry_run=dry_run,
+        )
+
+
 @celery.task(
     name="backend.app.tasks.admin.dedup_videos_task",
     bind=True,

frontend/src/components/settings/DiscordRepairCard.vue

@@ -0,0 +1,118 @@
+<template>
+  <!-- #3999: Discord downloads made before the naming fix landed in a `None`
+       folder with no post and a download-time date. This re-downloads them
+       cleanly. Preview first; the apply deletes files. -->
+  <MaintenanceTile
+    icon="mdi-download-off-outline"
+    title="Repair Discord downloads"
+    blurb="Re-download Discord images that were saved with no post and the wrong date."
+    destructive
+    :open="applying || previewing"
+  >
+    <p class="text-body-2 mb-3">
+      Before the naming fix, every Discord download was saved into a folder
+      called <code>None</code>. Those images never got a post, so they show the
+      time Curator downloaded them rather than when they were posted.
+      <strong>Apply</strong> deletes those images, clears Discord from the
+      download history, and starts a fresh backfill of every Discord source so
+      they come back with their posts and dates. Tags you added by hand to those
+      images are lost. Nothing outside a Discord <code>None</code> folder is
+      touched.
+    </p>
+
+    <div class="d-flex align-center flex-wrap" style="gap: 12px;">
+      <v-btn
+        color="primary" variant="tonal" rounded="pill"
+        :loading="previewing" :disabled="applying" @click="preview"
+      >
+        <v-icon start>mdi-magnify</v-icon> Preview
+      </v-btn>
+      <v-btn
+        color="error" rounded="pill"
+        :loading="applying"
+        :disabled="previewing || !canApply"
+        @click="confirmOpen = true"
+      >
+        <v-icon start>mdi-download-off-outline</v-icon> Apply
+      </v-btn>
+    </div>
+
+    <v-alert
+      v-if="summary" :type="summaryType" variant="tonal" class="mt-4"
+      density="comfortable"
+    >
+      <span v-if="applied">
+        Deleted {{ summary.images_deleted }} image(s) and cleared
+        {{ summary.archive_entries }} Discord download record(s). Backfills
+        started on {{ summary.backfills_started }} Discord source(s).
+      </span>
+      <span v-else-if="hasWork">
+        {{ summary.images }} broken image(s) ({{ humanBytes(summary.bytes) }})
+        across {{ summary.directories }} folder(s), and
+        {{ summary.archive_entries }} Discord download record(s) to clear.
+        {{ summary.sources }} Discord source(s) will backfill again.
+      </span>
+      <span v-else>Nothing to repair — no broken Discord downloads found.</span>
+
+      <div v-if="applied && summary.files_failed" class="mt-1 text-caption">
+        {{ summary.files_failed }} file(s) could not be removed — see the worker log.
+      </div>
+      <div v-if="applied && summary.remaining" class="mt-1 text-caption">
+        {{ summary.remaining }} broken image(s) are still present. Run it again.
+      </div>
+    </v-alert>
+
+    <QueueStatusBar queue="maintenance_long" queue-label="Maintenance" />
+
+    <v-dialog v-model="confirmOpen" max-width="440">
+      <v-card>
+        <v-card-title>Repair Discord downloads?</v-card-title>
+        <v-card-text class="text-body-2">
+          This permanently deletes <strong>{{ summary?.images ?? 0 }}</strong>
+          Discord image(s) ({{ humanBytes(summary?.bytes) }}) and re-downloads
+          them from Discord with their posts and dates. Any tags you added to
+          those images by hand will not come back.
+        </v-card-text>
+        <v-card-actions>
+          <v-spacer />
+          <v-btn variant="text" @click="confirmOpen = false">Cancel</v-btn>
+          <v-btn color="error" @click="apply">Repair</v-btn>
+        </v-card-actions>
+      </v-card>
+    </v-dialog>
+  </MaintenanceTile>
+</template>
+
+<script setup>
+import { computed, ref } from 'vue'
+
+import { useMaintenanceTask } from '../../composables/useMaintenanceTask.js'
+import { humanBytes } from '../../utils/bytes.js'
+import MaintenanceTile from '../common/MaintenanceTile.vue'
+import QueueStatusBar from './QueueStatusBar.vue'
+
+const confirmOpen = ref(false)
+
+const { previewing, applying, summary, applied, preview, apply: applyTask } = useMaintenanceTask({
+  endpoint: '/api/admin/maintenance/repair-discord-downloads',
+  storageKey: 'fc.maint.repairDiscordDownloads',
+  appliedToast: 'Discord downloads cleared — backfills started',
+})
+
+// The archive count matters too: files could already be gone while gallery-dl
+// still believes it has them, which would stop the backfill re-fetching.
+const hasWork = computed(
+  () => !!summary.value && (summary.value.images > 0 || summary.value.archive_entries > 0),
+)
+const canApply = computed(() => hasWork.value && !applied.value)
+const summaryType = computed(() => {
+  if (applied.value) return 'success'
+  return hasWork.value ? 'info' : 'success'
+})
+
+// The confirm dialog gates the destructive apply; close it, then run.
+function apply () {
+  confirmOpen.value = false
+  applyTask()
+}
+</script>

frontend/src/components/settings/MaintenancePanel.vue

@@ -15,6 +15,7 @@
         <ImportFiltersForm />
         <TranslationCard />
         <DiscordGroupingCard />
+        <DiscordRepairCard />
         <PostAssociationsCard />
         <MembershipRosterCard />
         <MembershipSuggestionsCard />
@@ -85,6 +86,7 @@ import VideoEmbeddingCard from './VideoEmbeddingCard.vue'
 import CropProposersCard from './CropProposersCard.vue'
 import HeadsCard from './HeadsCard.vue'
 import DiscordGroupingCard from './DiscordGroupingCard.vue'
+import DiscordRepairCard from './DiscordRepairCard.vue'
 import MembershipRosterCard from './MembershipRosterCard.vue'
 import MembershipSuggestionsCard from './MembershipSuggestionsCard.vue'
 import PostAssociationsCard from './PostAssociationsCard.vue'

tests/test_discord_repair.py

@@ -0,0 +1,170 @@
+"""The Discord repair (#3999): forget the broken downloads, delete them, backfill again.
+
+The danger in a repair like this is reach. It deletes files and clears
+gallery-dl's memory of what it fetched, so most of these tests pin what it must
+NOT touch: other platforms' archive entries, Discord server assets, images
+outside a `discord/None/` folder, and a correctly named Discord file that
+happens to share a folder name.
+"""
+
+import sqlite3
+
+import pytest
+from sqlalchemy import func, select
+
+from backend.app.models import Artist, ImageRecord, Source
+from backend.app.services import discord_repair
+from backend.app.services.gallery_dl import archive_path
+from backend.app.services.source_service import BACKFILL_MAX_CHUNKS
+
+
+def _archive(tmp_path, entries):
+    path = archive_path(tmp_path)
+    path.parent.mkdir(parents=True, exist_ok=True)
+    conn = sqlite3.connect(path)
+    # The table gallery-dl itself creates (gallery_dl/archive.py).
+    conn.execute("CREATE TABLE archive (entry TEXT PRIMARY KEY) WITHOUT ROWID")
+    conn.executemany("INSERT INTO archive (entry) VALUES (?)", [(e,) for e in entries])
+    conn.commit()
+    conn.close()
+    return path
+
+
+def _entries(path):
+    conn = sqlite3.connect(path)
+    try:
+        return sorted(r[0] for r in conn.execute("SELECT entry FROM archive"))
+    finally:
+        conn.close()
+
+
+# --- the archive ------------------------------------------------------------
+
+
+def test_only_discord_message_entries_are_forgotten(tmp_path):
+    path = _archive(tmp_path, [
+        "discord300000000000000003_1",
+        "discord300000000000000004_2",
+        "discordasset_400000000000000004_9",
+        "hentaifoundry12345",
+    ])
+    assert discord_repair.count_archive_entries(path) == 2
+    assert discord_repair.forget_archive_entries(path) == 2
+    assert _entries(path) == ["discordasset_400000000000000004_9", "hentaifoundry12345"]
+
+
+def test_counting_changes_nothing(tmp_path):
+    path = _archive(tmp_path, ["discord1_1", "discord2_1"])
+    discord_repair.count_archive_entries(path)
+    assert _entries(path) == ["discord1_1", "discord2_1"]
+
+
+def test_a_missing_archive_or_table_is_zero_not_an_error(tmp_path):
+    assert discord_repair.count_archive_entries(tmp_path / "nope.sqlite3") == 0
+    empty = tmp_path / "empty.sqlite3"
+    sqlite3.connect(empty).close()
+    assert discord_repair.forget_archive_entries(empty) == 0
+
+
+# --- the folders ------------------------------------------------------------
+
+
+def test_broken_directories_finds_every_artist_folder_including_case_twins(tmp_path):
+    for artist in ("Conto", "conto", "knuxy"):
+        (tmp_path / artist / "discord" / "None").mkdir(parents=True)
+    (tmp_path / "conto" / "discord" / "general").mkdir(parents=True)
+    (tmp_path / "conto" / "patreon" / "None").mkdir(parents=True)
+    found = [
+        p.relative_to(tmp_path).as_posix()
+        for p in discord_repair.broken_directories(tmp_path)
+    ]
+    assert found == ["Conto/discord/None", "conto/discord/None", "knuxy/discord/None"]
+
+
+def test_sweep_removes_leftover_sidecars_and_the_empty_folder(tmp_path):
+    d = tmp_path / "conto" / "discord" / "None"
+    d.mkdir(parents=True)
+    (d / "image.json").write_text("{}")
+    (d / "20240716_None_rejected.png").write_bytes(b"x")
+    removed, gone = discord_repair._sweep_directory(d)
+    assert (removed, gone) == (2, True)
+    assert not d.exists()
+
+
+# --- the whole repair, against the database -----------------------------------
+
+
+def _image(db_sync, artist, path, sha):
+    img = ImageRecord(
+        artist_id=artist.id, path=str(path), sha256=sha * 64, size_bytes=100,
+        mime="image/png", origin="downloaded",
+    )
+    db_sync.add(img)
+    return img
+
+
+@pytest.mark.integration
+def test_repair_deletes_only_broken_discord_images_and_rearms_discord_backfills(
+    db_sync, tmp_path,
+):
+    artist = Artist(name="Conto", slug="conto")
+    db_sync.add(artist)
+    db_sync.flush()
+    discord = Source(
+        artist_id=artist.id, platform="discord", url="https://discord.com/channels/1/2",
+        enabled=True, config_overrides={"_backfill_state": "complete", "_backfill_cursor": "x"},
+    )
+    patreon = Source(
+        artist_id=artist.id, platform="patreon", url="https://www.patreon.com/conto",
+        enabled=True, config_overrides={},
+    )
+    db_sync.add_all([discord, patreon])
+
+    broken_dir = tmp_path / "conto" / "discord" / "None"
+    good_dir = tmp_path / "conto" / "discord" / "general"
+    patreon_dir = tmp_path / "conto" / "patreon" / "None"
+    for d in (broken_dir, good_dir, patreon_dir):
+        d.mkdir(parents=True)
+    broken = broken_dir / "20240716_None_image.png"
+    good = good_dir / "20240716_300000000000000003_01_image.png"
+    # A `None` folder under another platform, and a `_None_` name outside one.
+    # Neither is the bug's pair, so neither may be touched.
+    elsewhere = patreon_dir / "20240716_None_image.png"
+    for f in (broken, good, elsewhere):
+        f.write_bytes(b"x")
+    (broken_dir / "image.json").write_text("{}")
+    _image(db_sync, artist, broken, "a")
+    _image(db_sync, artist, good, "b")
+    _image(db_sync, artist, elsewhere, "c")
+    db_sync.commit()
+    _archive(tmp_path, ["discord300000000000000003_1", "hentaifoundry1"])
+
+    preview = discord_repair.repair_discord_downloads(db_sync, images_root=tmp_path, dry_run=True)
+    assert preview["images"] == 1
+    assert preview["archive_entries"] == 1
+    assert broken.exists()
+
+    result = discord_repair.repair_discord_downloads(db_sync, images_root=tmp_path, dry_run=False)
+    assert result["images_deleted"] == 1
+    assert result["remaining"] == 0
+    assert result["backfills_started"] == 1
+
+    assert not broken.exists() and not broken_dir.exists()
+    assert good.exists() and elsewhere.exists()
+    assert _entries(archive_path(tmp_path)) == ["hentaifoundry1"]
+
+    kept = db_sync.execute(select(func.count(ImageRecord.id))).scalar_one()
+    assert kept == 2
+
+    rows = {
+        platform: (runs, overrides)
+        for platform, runs, overrides in db_sync.execute(
+            select(Source.platform, Source.backfill_runs_remaining, Source.config_overrides)
+        ).all()
+    }
+    runs, overrides = rows["discord"]
+    assert runs == BACKFILL_MAX_CHUNKS
+    assert overrides["_backfill_state"] == "running"
+    assert "_backfill_cursor" not in overrides
+    # Only Discord sources are re-armed.
+    assert rows["patreon"][1] == {}