feat(v3 library): searchable Cover Art Archive picker in Change-cover

The cover picker only offered CAA covers from a song's MATCHED release, so an
unmatched song (the city-pop pile) got nothing but Current/Pack/Upload/URL. Add
a search box: GET /api/song/{fn}/art/cover-search?q= searches MusicBrainz
release-groups and returns each album's CAA front-250 thumb; the picker renders
them as pickable tiles (same apply→/art/url path; covers with no CAA art
self-hide). Pre-filled from the song's artist + album/title (romaji fallback), so
a blank-artist pack pre-fills "Junko Yagami …". Reuses the throttled _mb_http_get.

server.py

@@ -1266,6 +1266,18 @@ class MetadataDB:
                 out.setdefault(fn, {})[field] = {"value": value, "locked": bool(locked)}
         return out
 
+    def _romaji_display(self, filename: str, artist: str, title: str):
+        """English-base display fallback. A blank-artist CDLC pack named
+        'Artist_Title_v1_p' has no readable name (artist blank; title = the raw
+        filename), and a match would fill it with the artist's NATIVE script
+        (kanji/kana). Surface the author's own romaji parsed from the filename
+        instead, so an English base reads 'Junko Yagami - BAY CITY'. Only kicks in
+        when the pack has no artist of its own — a real pack artist is untouched."""
+        if (artist or "").strip():
+            return artist, title
+        d = _artist_title_from_filename(filename)
+        return (d["artist"], d["title"]) if d else (artist, title)
+
     def pack_fields(self, filename: str) -> dict:
         """The stored (pack) values for the overridable catalog fields — the
         Fix-metadata popup shows these behind each override as the 'revert to
@@ -1275,7 +1287,11 @@ class MetadataDB:
         row = self.conn.execute(
             "SELECT title, artist, album, year, genre FROM songs WHERE filename = ?",
             (filename,)).fetchone()
-        return {k: ((row[i] or "") if row else "") for i, k in enumerate(keys)}
+        vals = {k: ((row[i] or "") if row else "") for i, k in enumerate(keys)}
+        # Baseline the author's romaji (from the filename) for a blank-artist pack,
+        # so the Details tab's Pack reference matches what the grid shows.
+        vals["artist"], vals["title"] = self._romaji_display(filename, vals["artist"], vals["title"])
+        return vals
 
     # Effective genre = a per-song genre OVERRIDE (Fix-metadata popup) else the
     # scanned pack genre. Applied at FILTER/FACET time (like the P4 artist alias)
@@ -4215,6 +4231,17 @@ class MetadataDB:
             s["unmatched"] = s["filename"] in um
             if amap:
                 s["artist"] = amap.get((s.get("artist") or "").lower(), s.get("artist"))
+            # English-base romaji fallback: a blank-artist CDLC pack shows nothing
+            # useful (artist blank; title = the raw filename). Surface the author's
+            # romaji from the "Artist_Title_v1_p" filename so the card reads
+            # "Junko Yagami — BAY CITY", never blank or native script. Display-only;
+            # a user override (below) still wins. Keyset-safe: stash the raw title
+            # for the cursor before replacing it.
+            if not (s.get("artist") or "").strip():
+                r_artist, r_title = self._romaji_display(s["filename"], s.get("artist"), s.get("title"))
+                if r_title != s.get("title") and "_sort_title" not in s:
+                    s["_sort_title"] = s["title"]
+                s["artist"], s["title"] = r_artist, r_title
             # Override wins over the pack AND the alias re-label — it's the user's
             # explicit per-song choice. Only a non-empty override VALUE replaces a
             # cell; a lock-only row (value None) leaves the displayed value alone.
@@ -4224,7 +4251,7 @@ class MetadataDB:
                     cell = ov.get(field)
                     val = cell.get("value") if cell else None
                     if val:
-                        if field == "title":
+                        if field == "title" and "_sort_title" not in s:
                             s["_sort_title"] = s["title"]   # raw title, for the keyset cursor
                         s[field] = val
         # Grouped rows carry the ⚑ N (chart_count) + the work_key from the
@@ -6520,6 +6547,36 @@ def _mb_search_recordings(artist, title, limit: int = 12) -> list[dict]:
     return cands
 
 
+def _mb_search_release_groups(query: str, limit: int = 8) -> list[dict]:
+    """Text search /release-group for the Change-cover picker: albums matching a
+    free query, each mapped to its Cover Art Archive front thumb. One request;
+    tiles whose CAA art is missing self-hide client-side (front-250 404s). Lets a
+    cover be found even for a song with no metadata match (the city-pop pile)."""
+    q = (query or "").strip()
+    if not q:
+        return []
+    body = _mb_http_get("release-group", {"query": q, "limit": limit})
+    out: list[dict] = []
+    for rg in ((body or {}).get("release-groups") or []):
+        rid = rg.get("id")
+        if not rid:
+            continue
+        # artist-credit is a list of {name, joinphrase, artist} (joinphrase glues
+        # collaborations) — reconstruct the credited name.
+        artist = "".join(
+            (c.get("name", "") + c.get("joinphrase", "")) if isinstance(c, dict) else str(c)
+            for c in (rg.get("artist-credit") or [])
+        ).strip()
+        title = rg.get("title") or ""
+        year = (rg.get("first-release-date") or "")[:4]
+        out.append({
+            "id": rid,
+            "label": " · ".join(x for x in (title, artist, year) if x) or title or "Cover",
+            "thumb_url": f"https://coverartarchive.org/release-group/{rid}/front-250",
+        })
+    return out
+
+
 # ── AcoustID audio fingerprinting (content-based identification) ──────────────
 # Optional path: requires the Chromaprint `fpcalc` binary AND an AcoustID API
 # key ($ACOUSTID_API_KEY). Both absent ⇒ graceful no-op; the text matcher runs.
@@ -12222,6 +12279,26 @@ async def get_song_art(filename: str, request: Request = None, source: str = "")
 _ART_PICKER_MAX_CAA = 12
 
 
+@app.get("/api/song/{filename:path}/art/cover-search")
+def api_art_cover_search(filename: str, q: str = ""):
+    """Search Cover Art Archive (via MusicBrainz release-groups) for album covers
+    — powers the Change-cover picker's search box, so a cover can be found even
+    for a song with no metadata match (the unmatched city-pop pile, where
+    /art/candidates is empty). `q` defaults to the song's own artist + album/
+    title (romaji fallback applied). Read-only; the picker renders the thumbs and
+    applies a pick through the existing /art/url route."""
+    query = (q or "").strip()
+    if not query:
+        pack = meta_db.pack_fields(meta_db._canonical_song_filename(filename))
+        query = " ".join(x for x in (pack.get("artist"), pack.get("album") or pack.get("title")) if x).strip()
+    if not query:
+        return {"query": "", "covers": []}
+    try:
+        return {"query": query, "covers": _mb_search_release_groups(query, limit=8)}
+    except EnrichTransportError:
+        return {"query": query, "covers": [], "error": "unavailable"}
+
+
 @app.get("/api/song/{filename:path}/art/candidates")
 def get_song_art_candidates(filename: str):
     """Everything the cover picker can offer for one song, without fetching a

static/v3/image-picker.js

@@ -138,6 +138,17 @@
             '<div class="flex flex-wrap gap-3">' + SKELETON_TILE + SKELETON_TILE + SKELETON_TILE + '</div>' +
             '<div class="text-xs text-fb-textDim pt-2">Fetching covers… the source is rate-limited.</div>' +
             '</div>' +
+            // Search Cover Art Archive — find an album cover even when the song has
+            // no match (the auto candidates above are empty then). Pre-filled from
+            // the song's artist + album/title; the source is rate-limited.
+            '<div class="space-y-2 pt-1">' +
+            '<div class="text-xs font-semibold uppercase tracking-wider text-fb-textDim">Search covers</div>' +
+            '<div class="flex gap-2">' +
+            '<input data-ip-search-input type="text" value="' + esc(_cur.query || '') + '" placeholder="artist album" class="flex-1 bg-gray-800/50 border border-gray-700 rounded-md px-2 py-1 text-sm text-fb-text outline-none focus:border-fb-primary">' +
+            '<button data-ip-search-go class="text-sm text-fb-primary hover:text-fb-primaryHi border border-fb-primary/40 rounded-md px-3">Search</button>' +
+            '</div>' +
+            '<div data-ip-search-results class="flex flex-wrap gap-3"></div>' +
+            '</div>' +
             '<div data-ip-status class="hidden text-xs text-fb-accent"></div>' +
             '</div></div>' +
             '<input type="file" accept="image/*" data-ip-file class="hidden">';
@@ -185,9 +196,47 @@
                 }
             });
         });
+        const searchInput = panel.querySelector('[data-ip-search-input]');
+        const runSearch = () => coverSearch(panel, (searchInput && searchInput.value) || '');
+        panel.querySelector('[data-ip-search-go]')?.addEventListener('click', runSearch);
+        searchInput?.addEventListener('keydown', (e) => { if (e.key === 'Enter') { e.preventDefault(); runSearch(); } });
         panel.querySelector('[data-ip-close]')?.focus();
     }
 
+    // Search Cover Art Archive (via the song-scoped cover-search endpoint) and
+    // render the album covers as pickable tiles — the same apply('url') path as
+    // the auto candidates. Covers with no CAA art self-hide (img onerror).
+    async function coverSearch(panel, query) {
+        const out = panel.querySelector('[data-ip-search-results]');
+        const fn = _cur && _cur.filename;
+        if (!out || !fn) return;
+        out.innerHTML = '<div class="flex flex-wrap gap-3">' + SKELETON_TILE + SKELETON_TILE + '</div>';
+        let body = null;
+        try {
+            const r = await fetch('/api/song/' + enc(fn) + '/art/cover-search?q=' + enc(String(query).trim()));
+            if (r.ok) body = await r.json();
+        } catch (_) { /* falls through to the empty state */ }
+        if (!_cur || _cur.filename !== fn) return;   // closed / changed song while searching
+        const covers = (body && body.covers) || [];
+        if (!covers.length) {
+            out.innerHTML = '<div class="text-xs text-fb-textDim">' +
+                ((body && body.error) ? 'Cover search is unavailable right now.' : 'No covers found — try a different search.') +
+                '</div>';
+            return;
+        }
+        out.innerHTML = covers.map((c, i) =>
+            tileHtml('data-ip-cover="' + i + '"', imgFace(c.thumb_url), c.label || 'Cover')).join('');
+        out.querySelectorAll('[data-ip-cover]').forEach((btn) => {
+            const img = btn.querySelector('img');
+            if (img) img.onerror = () => btn.classList.add('hidden');   // no CAA art for this album → hide
+            btn.addEventListener('click', () => {
+                if (_busy) return;
+                const c = covers[Number(btn.getAttribute('data-ip-cover'))];
+                if (c) apply('url', c.thumb_url);
+            });
+        });
+    }
+
     // The one candidates fetch, cancelled if the modal closes first. Failure
     // (offline, demo mode, aborted) is silent: the skeletons just clear and
     // the instant tiles remain — never an error wall.
@@ -281,7 +330,13 @@
         const filename = opts && opts.filename;
         if (!filename) return;
         _lastFocus = document.activeElement;
-        _cur = { filename: filename, title: (opts && opts.title) || filename };
+        const title = (opts && opts.title) || filename;
+        const artist = (opts && opts.artist) || '';
+        const album = (opts && opts.album) || '';
+        // Pre-fill the cover search: "artist album" when the album is known, else
+        // just the artist, else the title — the server default backs it up.
+        const query = [artist, album].filter(Boolean).join(' ').trim() || title;
+        _cur = { filename: filename, title: title, query: query };
         _busy = false;
         const m = ensureModal();
         const panel = document.getElementById('v3-imgpick-panel');

static/v3/match-review.js

@@ -511,10 +511,17 @@
     // then land on Details pre-filled for review.
     async function useTheseValues(song, cand) {
         if (!cand) return;
+        // Smart adopt for an English base: KEEP the readable name + title the card
+        // already shows (the author's romaji, e.g. "Junko Yagami / BAY CITY") — the
+        // match is often native script (kanji/kana). Take only what the pack lacks
+        // — album / year / genre — from the match; the pin below still brings the
+        // correct art + identity. The user can still edit any field.
         song._pendingDetails = {
-            title: String(cand.title || ''), artist: String(cand.artist || ''),
-            album: String(cand.album || ''), year: String(cand.year || ''),
-            genre: (Array.isArray(cand.genres) && cand.genres[0]) ? String(cand.genres[0]) : String(cand.genre || ''),
+            artist: String(song.artist || cand.artist || ''),
+            title:  String(song.title  || cand.title  || ''),
+            album:  String(cand.album  || song.album  || ''),
+            year:   String(cand.year   || song.year   || ''),
+            genre:  String((Array.isArray(cand.genres) && cand.genres[0]) || cand.genre || ''),
         };
         try {
             await post('/api/enrichment/review/' + enc(song.filename) + '/pick', { candidate: cand });
@@ -689,7 +696,7 @@
             '</div>';
         body.querySelector('[data-cover-open]')?.addEventListener('click', () => {
             if (window.__fbOpenImagePicker) {
-                window.__fbOpenImagePicker({ filename: song.filename, title: song.title || song.filename });
+                window.__fbOpenImagePicker({ filename: song.filename, title: song.title || song.filename, artist: song.artist, album: song.album });
             }
         });
     }

static/v3/songs.js

@@ -515,15 +515,22 @@
             done:     ['bg-fb-good/90 text-black', '✓ Updated', ''],
             nochange: ['bg-black/60 text-fb-textDim', '— No match', ''],
             // Resting indicator: subtle, so a mostly-unmatched library isn't a
-            // wall of loud badges; points at the manual fix.
-            nomatch:  ['bg-black/60 text-fb-textDim', 'No match', 'No metadata match found — right-click to fix it by hand'],
+            // wall of loud badges. Clickable — a one-click handoff into the
+            // Fix-metadata popup for this song (see the [data-meta-fix] wiring).
+            nomatch:  ['bg-black/60 text-fb-textDim', 'No match', 'Click to fix the metadata by hand'],
         };
         const conf = M[st] || M.queued;
+        const fixable = st === 'nomatch';   // resting badge → opens Fix-metadata
         // top-10 clears the tuning chip (top-2) in both normal and select mode;
-        // z-20 sits it above the art. Non-interactive so it never eats a click.
-        return '<span class="v3-meta-tile absolute top-10 left-2 z-20 ' + conf[0] +
-            ' text-[0.5625rem] font-bold px-1.5 py-0.5 rounded-sm leading-tight pointer-events-none"' +
-            (conf[2] ? ' title="' + conf[2] + '"' : '') + '>' + conf[1] + '</span>';
+        // z-20 sits it above the art. Batch states are non-interactive; the
+        // resting "no match" badge is the handoff into the popup.
+        const cls = 'v3-meta-tile absolute top-10 left-2 z-20 ' + conf[0] +
+            ' text-[0.5625rem] font-bold px-1.5 py-0.5 rounded-sm leading-tight ' +
+            (fixable ? 'pointer-events-auto cursor-pointer hover:bg-fb-primary hover:text-white transition-colors' : 'pointer-events-none');
+        return '<span class="' + cls + '"' +
+            (fixable ? ' data-meta-fix="1"' : '') +
+            (conf[2] ? ' title="' + conf[2] + '"' : '') +
+            '>' + conf[1] + '</span>';
     }
 
     // After a song is scored, the badge for that card is stale until the next
@@ -1000,7 +1007,7 @@
             // the group's work_key/chart_count and pre-ticks the shown chart.)
             if (id === '__fixmatch') { if (window.__fbFixMatch) window.__fbFixMatch(playTarget); return; }
             if (id === '__cover') {
-                if (window.__fbOpenImagePicker) window.__fbOpenImagePicker({ filename: playTarget.filename, title: playTarget.title || playTarget.filename });
+                if (window.__fbOpenImagePicker) window.__fbOpenImagePicker({ filename: playTarget.filename, title: playTarget.title || playTarget.filename, artist: playTarget.artist, album: playTarget.album });
                 return;
             }
             if (id === '__refreshmeta') {
@@ -1467,6 +1474,13 @@
                 e.stopPropagation();
                 openChartsDrawer(e.currentTarget.getAttribute('data-charts'), song);
             });
+            // "No match" badge → straight into the Fix-metadata popup for this
+            // song (the batch → fix handoff). stopPropagation so it doesn't also
+            // trigger the card's play. Follows the displayed chart, like the menu.
+            el.querySelector('[data-meta-fix]')?.addEventListener('click', (e) => {
+                e.stopPropagation();
+                if (window.__fbFixMatch) window.__fbFixMatch(playTarget);
+            });
             // Artist line → the artist page (PR-B). In select mode the grid's
             // capture-phase toggle intercepts first, so selection still wins.
             el.querySelector('[data-v3-artist]')?.addEventListener('click', (e) => {
@@ -3112,7 +3126,7 @@
             // when image-picker.js isn't loaded.
             artWrap.addEventListener('click', () => {
                 if (window.__fbOpenImagePicker) {
-                    window.__fbOpenImagePicker({ filename: song.filename, title: song.title || song.filename });
+                    window.__fbOpenImagePicker({ filename: song.filename, title: song.title || song.filename, artist: song.artist, album: song.album });
                 } else {
                     artFile.click();
                 }

tests/test_field_overrides.py

@@ -233,6 +233,24 @@ def test_lock_only_genre_does_not_change_facet(server):
     assert server.meta_db._effective_genre_expr() == "genre"
 
 
+def test_romaji_fallback_for_blank_artist_pack(server):
+    fn = "CDLC/0 - City Pop/Junko-Yagami_BAY-CITY_v1_p.feedpak"
+    _put(server, fn, title="Junko-Yagami_BAY-CITY_v1_p", artist="")   # scanner fell back to the filename
+    s = {x["filename"]: x for x in server.meta_db.query_page()[0]}[fn]
+    # the grid shows the author's romaji, not blank / the raw filename / kanji
+    assert s["artist"] == "Junko Yagami"
+    assert s["title"] == "BAY CITY"
+    # the Details baseline (pack_fields) matches, so the popup agrees with the grid
+    pack = server.meta_db.pack_fields(fn)
+    assert pack["artist"] == "Junko Yagami" and pack["title"] == "BAY CITY"
+
+
+def test_romaji_fallback_left_alone_when_pack_has_artist(server):
+    _put(server, "a.archive", title="Real Title", artist="Real Artist")
+    s = {x["filename"]: x for x in server.meta_db.query_page()[0]}["a.archive"]
+    assert s["artist"] == "Real Artist" and s["title"] == "Real Title"
+
+
 def test_title_keyset_paging_is_complete_with_overrides(client, server):
     # Raw titles A/B/C → title-sort order is A, B, C on the RAW column.
     _put(server, "b.archive", title="B")