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

@@ -94,6 +94,58 @@ BACKFILL_CHUNK_SECONDS = 600
 _DEFAULT_GDL_TIMEOUT_SECONDS = 870
 
 
+# --- Discord naming ---------------------------------------------------------
+#
+# Derived from a REAL sidecar (operator's instance, 2026-09-13), not from memory
+# of gallery-dl's extractor. What gallery-dl's discord extractor actually emits
+# for an attachment: `channel` is a plain STRING (the channel's name), the
+# message is `message_id`, the attachment's position in it is `num`, and there
+# is NO `id` key at all.
+#
+# The previous patterns asked for `{channel[name]}` and `{id}`. Both render as
+# "None", so every Discord download since the platform was added landed in a
+# directory called `None` as `<date>_None_<original name>`. Worse, the sidecar was
+# named `{filename}.json` — the attachment's ORIGINAL name — which (a) `find_
+# sidecar` can never pair with `<date>_None_<name>.png`, so no Discord file ever
+# got a Post or a post date, and (b) collides: every `image.png` in a channel
+# overwrote the same `image.json`, so the one sidecar that survived described
+# whichever message happened to be written last.
+#
+# The fix names the sidecar EXACTLY like the media minus its extension, so
+# `find_sidecar`'s first candidate (`media.with_suffix(".json")`) is the match
+# and the name is unique per attachment. tests/test_gallery_dl_naming.py renders
+# these patterns against a sanitized copy of the real sidecar, so a key that
+# does not exist fails CI instead of silently becoming "None".
+DISCORD_FILENAME = "{date:%Y%m%d}_{message_id}_{num:>02}_{filename}.{extension}"
+DISCORD_DIRECTORY = ["{channel}"]
+
+
+def sidecar_name_for(media_pattern: str) -> str | None:
+    """The metadata filename pattern that names a sidecar exactly like its media.
+
+    Returns None for a pattern that does not end in `.{extension}`, since then
+    there is no media stem to mirror and the caller must fall back.
+    """
+    suffix = ".{extension}"
+    if not media_pattern.endswith(suffix):
+        return None
+    return media_pattern[: -len(suffix)] + ".json"
+
+
+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.
@@ -376,8 +428,11 @@ class GalleryDLService:
         },
         "discord": {
             "content_types": ["all"],
-            "directory": ["{channel[name]}"],
+            "directory": DISCORD_DIRECTORY,
-            "filename": "{date:%Y%m%d}_{id}_{filename}.{extension}",
+            "filename": DISCORD_FILENAME,
+            # Overrides the global `{filename}.json` sidecar for this extractor
+            # only — see the Discord naming note above.
+            "postprocessors": [metadata_postprocessor(sidecar_name_for(DISCORD_FILENAME))],
             "embeds": "all",
             "stickers": True,
             "reactions": False,
@@ -402,7 +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),
@@ -497,6 +552,17 @@ class GalleryDLService:
         if source_config.filename_pattern:
             platform_section["filename"] = source_config.filename_pattern
 
+        # A platform that names its sidecar after its media must keep doing so
+        # under a per-source filename override, or the pairing breaks exactly the
+        # way Discord's did. No metadata wanted means no platform postprocessor
+        # either — the global list was already dropped above.
+        if "postprocessors" in platform_section:
+            mirrored = sidecar_name_for(platform_section.get("filename") or "")
+            if not source_config.save_metadata or mirrored is None:
+                platform_section.pop("postprocessors")
+            else:
+                platform_section["postprocessors"] = [metadata_postprocessor(mirrored)]
+
         platform_section["metadata"] = source_config.save_metadata
 
         return config

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 {})
+        arm_backfill(source)
-        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
         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/posts/PostCard.vue

@@ -1,5 +1,8 @@
 <template>
-  <v-card class="fc-post-card" variant="outlined">
+  <v-card
+    ref="cardEl" class="fc-post-card" variant="outlined"
+    :class="{ 'fc-post-card--wide': wide }"
+  >
     <div class="fc-post-card__head">
       <!-- Posts with no live subscription have source=null (alembic 0030);
            show a "filesystem import" affordance instead of a platform chip. -->
@@ -58,7 +61,7 @@
         </button>
         <div
           v-if="rail.length || moreCount" class="fc-post-card__rail"
-          :style="{ '--fc-rail-cols': railCols }"
+          :style="{ '--fc-rail-cols': railCols, '--fc-grid-cols': Math.min(2, railCols) }"
         >
           <button
             v-for="t in rail" :key="t.image_id" type="button"
@@ -221,20 +224,33 @@ const synthesisTitle = computed(() => {
 })
 
 const hero = computed(() => images.value[0])
-// The thumbnail strip spans the hero's full width (CSS grid, equal columns),
+
-// rather than a fixed 3-cell cap. Show up to RAIL_MAX cells; when there are
+// Filmstrip layout (milestone #407, option A). On a very wide window a card
-// more images than fit, the last cell becomes a "+N" overflow tile so the
+// that just grew would give one post the whole screen, so a WIDE card instead
-// count stays accurate.
+// pins the hero to a fixed height and moves the extra images into a 2-column
-const RAIL_MAX = 5
+// grid BESIDE it. Measured on the card rather than the viewport because the
+// same card renders in the Latest feed, Browse, and the in-context view, each
+// at a different width.
+const WIDE_CARD_PX = 1100
+const cardEl = ref(null)
+const wide = ref(false)
+
+// The narrow layout's strip spans the hero's full width (CSS grid, equal
+// columns); the wide layout's grid is 2×2. Show up to that many cells; when
+// there are more images than fit, the last cell becomes a "+N" overflow tile so
+// the count stays accurate.
+const RAIL_MAX_NARROW = 5
+const RAIL_MAX_WIDE = 4
 const serverMore = computed(() => props.post.thumbnails_more || 0)
 const afterHero = computed(() => images.value.slice(1))
+const railMax = computed(() => (wide.value ? RAIL_MAX_WIDE : RAIL_MAX_NARROW))
 const hasOverflow = computed(
-  () => serverMore.value > 0 || afterHero.value.length > RAIL_MAX,
+  () => serverMore.value > 0 || afterHero.value.length > railMax.value,
 )
 const rail = computed(() =>
   hasOverflow.value
-    ? afterHero.value.slice(0, RAIL_MAX - 1)
+    ? afterHero.value.slice(0, railMax.value - 1)
-    : afterHero.value.slice(0, RAIL_MAX),
+    : afterHero.value.slice(0, railMax.value),
 )
 const visibleCount = computed(() => (images.value.length ? 1 + rail.value.length : 0))
 const moreCount = computed(() => {
@@ -349,8 +365,17 @@ function measureOverflow () {
 }
 
 let ro = null
+let cardRo = null
 onMounted(() => {
   nextTick(measureOverflow)
+  const root = cardEl.value?.$el
+  if (typeof ResizeObserver !== 'undefined' && root) {
+    cardRo = new ResizeObserver((entries) => {
+      const w = entries[0]?.contentRect?.width ?? 0
+      wide.value = w >= WIDE_CARD_PX
+    })
+    cardRo.observe(root)
+  }
   // Re-measure when the card resizes (the container-query clamp differs by
   // width). Guarded for happy-dom / older runtimes without ResizeObserver.
   if (typeof ResizeObserver !== 'undefined' && descEl.value) {
@@ -358,7 +383,10 @@ onMounted(() => {
     ro.observe(descEl.value)
   }
 })
-onBeforeUnmount(() => { if (ro) { ro.disconnect(); ro = null } })
+onBeforeUnmount(() => {
+  if (ro) { ro.disconnect(); ro = null }
+  if (cardRo) { cardRo.disconnect(); cardRo = null }
+})
 
 async function toggleDesc () {
   if (!descExpanded.value) {
@@ -495,6 +523,40 @@ function formatBytes (n) {
   color: rgb(var(--v-theme-accent));
 }
 
+/* --- Filmstrip layout (wide cards, #407 A) ---------------------------------
+   The hero has a HEIGHT, not a width: a wide card must not turn into a
+   full-screen post, so its height stays roughly a third of the viewport
+   whatever the window's width. The extra images sit beside it as square cells
+   whose size derives from that same height, so the grid always ends flush with
+   the hero's bottom edge. */
+.fc-post-card--wide {
+  --fc-hero-h: clamp(260px, 34vh, 460px);
+  --fc-grid-gap: 8px;
+  --fc-cell: calc((var(--fc-hero-h) - var(--fc-grid-gap)) / 2);
+}
+.fc-post-card--wide .fc-post-card__body { flex-direction: row; gap: 24px; }
+.fc-post-card--wide .fc-post-card__media {
+  flex: 0 0 auto;
+  display: flex;
+  gap: var(--fc-grid-gap);
+}
+.fc-post-card--wide .fc-post-card__hero {
+  width: auto;
+  height: var(--fc-hero-h);
+}
+.fc-post-card--wide .fc-post-card__rail {
+  margin-top: 0;
+  gap: var(--fc-grid-gap);
+  grid-template-columns: repeat(var(--fc-grid-cols, 2), var(--fc-cell));
+  grid-auto-rows: var(--fc-cell);
+}
+.fc-post-card--wide .fc-post-card__rail-cell,
+.fc-post-card--wide .fc-post-card__rail-more { height: 100%; }
+.fc-post-card--wide .fc-post-card__text { flex: 1 1 0; min-width: 0; }
+/* Text is secondary here — long reads happen in the expanded view — so the
+   clamp keeps the text column no taller than the images beside it. */
+.fc-post-card--wide .fc-post-card__desc--clamped { -webkit-line-clamp: 4; }
+
 .fc-post-card__title {
   font-family: 'Fraunces', Georgia, serif;
   font-size: 18px; font-weight: 700;

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'

frontend/src/views/PostsView.vue

@@ -1,5 +1,8 @@
 <template>
-  <v-container class="pt-2 pb-6" max-width="900">
+  <!-- Width is set in CSS, not with `max-width` here: below 1600px it is
+       today's 900px column, and above it the feed widens and gains the rail
+       and day gutter (milestone #407). -->
+  <v-container fluid class="pt-2 pb-6 fc-posts">
     <!-- In-context view: deep-linked to one post, with bidirectional infinite
          scroll — newer posts load above, older posts below. -->
     <template v-if="postIdFilter != null">
@@ -48,15 +51,19 @@
     </template>
 
     <!-- Normal feed -->
-    <template v-else>
+    <div v-else class="fc-posts__layout">
-      <FeedStatusRibbon v-if="statusRibbon" />
+      <!-- On a wide window this is a sticky left rail (#407 E); below the
-
+           breakpoint it lays out exactly as the old inline header did. -->
+      <aside class="fc-posts__rail">
         <PostsFilterBar
           :artist-id="artistFilter"
           :platform="platformFilter"
           @update:filters="onFilters"
         />
+        <FeedStatusRibbon v-if="statusRibbon" />
+      </aside>
 
+      <div class="fc-posts__main">
       <v-alert v-if="store.error" type="error" variant="tonal" closable class="mb-3">
         {{ String(store.error) }}
       </v-alert>
@@ -74,14 +81,28 @@
       </div>
 
       <div v-else>
-        <PostCard v-for="p in store.items" :key="p.id" :post="p" />
+        <!-- Day groups (#407 D). The heading sits above its posts on a narrow
+             window and in a sticky left gutter on a wide one. -->
+        <section v-for="d in days" :key="d.key" class="fc-posts__day">
+          <header class="fc-posts__day-head">
+            <span class="fc-posts__day-label">{{ d.label }}</span>
+            <span class="fc-posts__day-count">
+              {{ d.posts.length }} post{{ d.posts.length === 1 ? '' : 's' }}
+              · {{ d.artistCount }} artist{{ d.artistCount === 1 ? '' : 's' }}
+            </span>
+          </header>
+          <div class="fc-posts__day-posts">
+            <PostCard v-for="p in d.posts" :key="p.id" :post="p" />
+          </div>
+        </section>
 
         <div ref="sentinel" class="fc-posts__sentinel">
           <v-progress-circular v-if="store.loading" indeterminate color="accent" size="24" />
           <span v-else-if="store.done" class="fc-posts__end">End of stream</span>
         </div>
       </div>
-    </template>
+      </div>
+    </div>
   </v-container>
 </template>
 
@@ -121,6 +142,48 @@ const hasActiveFilter = computed(() =>
   artistFilter.value != null || platformFilter.value != null || searchFilter.value != null
 )
 
+// --- day groups (#407 D) ---
+// CONSECUTIVE runs, not a bucket per date. The feed's sort key includes
+// `resurfaced_at` (a Discord grouping that grew moves back to the top), which
+// the payload does not carry, so a resurfaced post can sit above newer ones.
+// Bucketing by date would pull it out of order; a run gives it its own heading
+// where it actually appears. Counts cover what has LOADED, and grow as the
+// infinite scroll fetches more of the same day.
+function dayKey (iso) {
+  const d = new Date(iso)
+  return `${d.getFullYear()}-${d.getMonth()}-${d.getDate()}`
+}
+function dayLabel (iso) {
+  const d = new Date(iso)
+  const today = new Date()
+  const startOf = (x) => new Date(x.getFullYear(), x.getMonth(), x.getDate()).getTime()
+  const days = Math.round((startOf(today) - startOf(d)) / 86400000)
+  if (days === 0) return 'Today'
+  if (days === 1) return 'Yesterday'
+  if (days > 1 && days < 7) return d.toLocaleDateString(undefined, { weekday: 'long' })
+  const sameYear = d.getFullYear() === today.getFullYear()
+  return d.toLocaleDateString(undefined, {
+    month: 'short', day: 'numeric', ...(sameYear ? {} : { year: 'numeric' }),
+  })
+}
+const days = computed(() => {
+  const groups = []
+  for (const p of store.items) {
+    const iso = p.post_date || p.downloaded_at
+    const key = dayKey(iso)
+    let g = groups[groups.length - 1]
+    if (!g || g.dayKey !== key) {
+      // Suffix with the run index so a day that appears twice (see above)
+      // still has a unique v-for key.
+      g = { key: `${key}#${groups.length}`, dayKey: key, label: dayLabel(iso), posts: [], artists: new Set() }
+      groups.push(g)
+    }
+    g.posts.push(p)
+    if (p.artist?.id != null) g.artists.add(p.artist.id)
+  }
+  return groups.map((g) => ({ ...g, artistCount: g.artists.size }))
+})
+
 // Drop only `post_id` and stay where we are — keeps Browse's `tab=posts` (and
 // any active artist/platform scope) intact instead of resetting the surface.
 const allPostsTarget = computed(() => {
@@ -232,6 +295,80 @@ onUnmounted(() => { teardownFeed(); teardownAround() })
 </script>
 
 <style scoped>
+/* Below the breakpoint: today's layout exactly — a 900px column with the
+   filters and ribbon inline above the feed. */
+.fc-posts { max-width: 900px; }
+.fc-posts__day-head {
+  display: flex;
+  align-items: baseline;
+  gap: 10px;
+  padding: 4px 0 8px;
+  color: rgb(var(--v-theme-on-surface-variant));
+}
+.fc-posts__day-label {
+  font-family: 'Fraunces', Georgia, serif;
+  font-weight: 600;
+  font-size: 1rem;
+  color: rgb(var(--v-theme-accent));
+}
+.fc-posts__day-count { font-size: 0.78rem; }
+
+/* Wide window (#407 D + E). The rail holds filters and status; each day's
+   heading moves into a sticky gutter beside its posts; the column widens and
+   the cards switch to their filmstrip layout on their own (PostCard measures
+   itself). 1600px is where a 280px rail and a 150px gutter still leave a card
+   wide enough to be worth the change. */
+@media (min-width: 1600px) {
+  .fc-posts { max-width: 2360px; }
+  .fc-posts__layout {
+    display: grid;
+    grid-template-columns: 280px minmax(0, 1fr);
+    gap: 40px;
+    align-items: start;
+  }
+  .fc-posts__rail {
+    position: sticky;
+    top: calc(var(--fc-nav-h, 64px) + 16px);
+    display: flex;
+    flex-direction: column;
+    gap: 16px;
+  }
+  .fc-posts__rail :deep(.fc-posts-filters) {
+    flex-direction: column;
+    align-items: stretch;
+    padding-bottom: 0;
+  }
+  .fc-posts__rail :deep(.fc-posts-filters__artist),
+  .fc-posts__rail :deep(.fc-posts-filters__platform) {
+    flex: none;
+    width: 100%;
+    min-width: 0;
+    max-width: none;
+  }
+  .fc-posts__rail :deep(.fc-ribbon) {
+    flex-direction: column;
+    align-items: flex-start;
+    gap: 8px;
+  }
+  .fc-posts__main { max-width: 1900px; }
+  .fc-posts__day {
+    display: grid;
+    grid-template-columns: 150px minmax(0, 1fr);
+    gap: 0 24px;
+  }
+  .fc-posts__day-head {
+    position: sticky;
+    top: calc(var(--fc-nav-h, 64px) + 16px);
+    align-self: start;
+    flex-direction: column;
+    align-items: flex-end;
+    gap: 2px;
+    padding-top: 12px;
+    text-align: right;
+  }
+  .fc-posts__day-label { font-size: 1.1rem; }
+}
+
 .fc-posts__loading,
 .fc-posts__empty {
   display: flex;

tests/fixtures/discord_attachment_sidecar.json

@@ -0,0 +1,28 @@
+{
+  "author": "example-artist",
+  "author_files": [],
+  "author_id": "100000000000000001",
+  "category": "discord",
+  "channel": "nsfw-drops",
+  "channel_id": "200000000000000002",
+  "channel_topic": "",
+  "channel_type": 0,
+  "date": "2024-07-16 16:43:23",
+  "extension": "png",
+  "filename": "image",
+  "files": [],
+  "is_thread": false,
+  "message": "",
+  "message_id": "300000000000000003",
+  "num": 1,
+  "owner_id": "100000000000000001",
+  "parent": "",
+  "parent_id": "",
+  "parent_type": 0,
+  "server": "Example Server",
+  "server_files": [],
+  "server_id": "400000000000000004",
+  "subcategory": "channel",
+  "type": "attachment",
+  "url": "https://cdn.discordapp.com/attachments/200000000000000002/500000000000000005/image.png"
+}

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] == {}

tests/test_gallery_dl_naming.py

@@ -0,0 +1,117 @@
+"""gallery-dl naming patterns, rendered against the metadata gallery-dl really emits.
+
+gallery-dl does not fail on a format field that names a key the extractor never
+sets. It renders "None" and carries on. That is how every Discord download
+landed in a `None/` directory as `<date>_None_<name>`: the patterns asked for
+`{channel[name]}` and `{id}`, and the real metadata has a string `channel` and
+`message_id`, with no `id` at all. The mismatch also broke sidecar pairing, so
+no Discord file ever got a Post or a post date.
+
+The fixture keeps the key set and value TYPES of a real attachment sidecar from
+the operator's instance (2026-09-13), with every value invented. Rendering
+through Python's own formatter raises on a missing key or a subscript into a
+string, which is the loud failure gallery-dl does not give.
+"""
+
+import json
+import string
+from datetime import datetime
+from pathlib import Path
+
+import pytest
+
+from backend.app.services.gallery_dl import (
+    DISCORD_DIRECTORY,
+    DISCORD_FILENAME,
+    GalleryDLService,
+    SourceConfig,
+    sidecar_name_for,
+)
+from backend.app.utils.sidecar import find_sidecar
+
+_FIXTURE = Path(__file__).parent / "fixtures" / "discord_attachment_sidecar.json"
+
+
+@pytest.fixture
+def kwdict():
+    data = json.loads(_FIXTURE.read_text())
+    # gallery-dl hands the formatter a datetime; the JSON sidecar stores it as text.
+    data["date"] = datetime.strptime(data["date"], "%Y-%m-%d %H:%M:%S")
+    return data
+
+
+def _render(pattern, kwdict):
+    return string.Formatter().vformat(pattern, (), kwdict)
+
+
+def test_the_discord_filename_renders_from_real_keys(kwdict):
+    name = _render(DISCORD_FILENAME, kwdict)
+    assert "None" not in name
+    assert name == "20240716_300000000000000003_01_image.png"
+
+
+def test_the_discord_directory_renders_from_real_keys(kwdict):
+    assert [_render(p, kwdict) for p in DISCORD_DIRECTORY] == ["nsfw-drops"]
+
+
+@pytest.mark.parametrize(
+    "broken", ["{channel[name]}", "{date:%Y%m%d}_{id}_{filename}.{extension}"],
+)
+def test_the_patterns_that_shipped_would_have_failed_here(kwdict, broken):
+    """Positive control: the two patterns that produced `None/..._None_...`
+    must fail this renderer, or the tests above prove nothing."""
+    with pytest.raises((KeyError, TypeError)):
+        _render(broken, kwdict)
+
+
+def test_the_sidecar_is_named_exactly_like_its_media(kwdict, tmp_path):
+    """So `find_sidecar` pairs them on its first candidate, and two attachments
+    that share an original name (`image.png`) can never share a sidecar."""
+    media = tmp_path / _render(DISCORD_FILENAME, kwdict)
+    sidecar = tmp_path / _render(sidecar_name_for(DISCORD_FILENAME), kwdict)
+    media.write_bytes(b"x")
+    sidecar.write_text("{}")
+    assert find_sidecar(media) == sidecar
+
+
+def test_two_attachments_with_the_same_original_name_get_distinct_sidecars(kwdict):
+    other = {**kwdict, "message_id": "300000000000000099"}
+    pattern = sidecar_name_for(DISCORD_FILENAME)
+    assert _render(pattern, kwdict) != _render(pattern, other)
+
+
+def test_sidecar_name_for_needs_an_extension_suffix():
+    assert sidecar_name_for("{a}_{b}.{extension}") == "{a}_{b}.json"
+    assert sidecar_name_for("{a}_{b}") is None
+
+
+# --- the config gallery-dl is actually given -----------------------------------
+
+
+@pytest.fixture
+def gdl(tmp_path):
+    return GalleryDLService(images_root=tmp_path / "images", validate_files=False)
+
+
+def _discord_section(gdl, **overrides):
+    cfg = gdl._build_config_for_source(
+        platform="discord", source_config=SourceConfig(**overrides), artist_slug="a",
+    )
+    return cfg["extractor"]["discord"]
+
+
+def test_discord_config_carries_the_mirrored_sidecar(gdl):
+    section = _discord_section(gdl)
+    assert section["filename"] == DISCORD_FILENAME
+    assert section["directory"] == DISCORD_DIRECTORY
+    assert section["postprocessors"][0]["filename"] == sidecar_name_for(DISCORD_FILENAME)
+
+
+def test_a_filename_override_keeps_the_sidecar_mirrored(gdl):
+    section = _discord_section(gdl, filename_pattern="{message_id}_{num}.{extension}")
+    assert section["postprocessors"][0]["filename"] == "{message_id}_{num}.json"
+
+
+def test_no_metadata_means_no_discord_postprocessor(gdl):
+    section = _discord_section(gdl, save_metadata=False)
+    assert "postprocessors" not in section