feat(v3 library): genre field in the Fix-metadata popup Details tab

Adds Genre as a fifth Details field (edit / lock / revert / Yours-Pack
provenance), backed by the existing override store. To make it actually useful,
the genre FILTER and FACET now resolve the per-song override (effective genre =
override else scanned pack genre) — guarded so the common no-override case stays
on the plain indexed column — so a corrected/added genre is immediately
browsable. Genre stays a library-only overlay: it is NOT a write-to-file field
(split WRITE_FIELDS = the four file-safe fields from the five DETAIL_FIELDS), so
Write to file leaves the genre override in place and the copy says so. The
Match→Details bridge also carries a candidate's first genre.

Tests: effective-genre facet + filter, and that a value-less lock doesn't invent
an effective genre.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server.py

@@ -1277,6 +1277,27 @@ class MetadataDB:
             (filename,)).fetchone()
         return {k: ((row[i] or "") if row else "") for i, k in enumerate(keys)}
 
+    # 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)
+    # so a corrected genre is browsable — the correlated subquery is used ONLY
+    # when genre overrides actually exist; the common case stays on the plain
+    # indexed `genre` column. Genre stays a library-only overlay (it isn't a
+    # write-to-file field), so it never touches the pack.
+    _EFFECTIVE_GENRE_SQL = (
+        "COALESCE((SELECT o.value FROM song_field_override o "
+        "WHERE o.filename = songs.filename AND o.field = 'genre' "
+        "AND o.value IS NOT NULL AND o.value != ''), genre)"
+    )
+
+    def _has_genre_overrides(self) -> bool:
+        return self.conn.execute(
+            "SELECT 1 FROM song_field_override WHERE field = 'genre' "
+            "AND value IS NOT NULL AND value != '' LIMIT 1").fetchone() is not None
+
+    def _effective_genre_expr(self) -> str:
+        """`genre` normally; the override-aware COALESCE only when overrides exist."""
+        return self._EFFECTIVE_GENRE_SQL if self._has_genre_overrides() else "genre"
+
     def set_song_tags(self, filename: str, tags) -> list:
         """Replace ALL of a song's tags with the given set (each normalized;
         blanks + case-dupes dropped). Full-replace so the whole personal-meta
@@ -3464,7 +3485,7 @@ class MetadataDB:
         # list on scan). OR within the selected set.
         if genre:
             _gph = ",".join(["?"] * len(genre))
-            where += f" AND genre COLLATE NOCASE IN ({_gph})"
+            where += f" AND ({self._effective_genre_expr()}) COLLATE NOCASE IN ({_gph})"
             params += list(genre)
         # Mastery bands = best accuracy across a song's arrangements (song_stats,
         # a separate table -> correlated subquery). mastered >= 0.9, in_progress =
@@ -9118,9 +9139,10 @@ def library_genres(provider: str = "local"):
     if is_remote:
         return {"genres": []}
     with meta_db._lock:
+        g = meta_db._effective_genre_expr()
         rows = meta_db.conn.execute(
-            "SELECT DISTINCT genre FROM songs WHERE genre IS NOT NULL AND genre != '' "
-            "ORDER BY genre COLLATE NOCASE"
+            f"SELECT g FROM (SELECT DISTINCT ({g}) AS g FROM songs) "
+            "WHERE g IS NOT NULL AND g != '' ORDER BY g COLLATE NOCASE"
         ).fetchall()
     return {"genres": [r[0] for r in rows]}
 

static/v3/match-review.js

@@ -303,6 +303,7 @@
             '<span class="text-xs text-fb-textDim shrink-0">' + esc(pct) + '</span></span>' +
             '<span class="block text-xs text-fb-textDim truncate">' + esc(meta) + '</span>' +
             diffChips(song, c) +
+            (_single ? '<span class="block text-xs text-fb-primary pt-1">Use these values →</span>' : '') +
             '</button>';
     }
 
@@ -461,7 +462,11 @@
     // Each field sits on its pack value: editing above the pack makes it an
     // override ("Yours"); a lock pins it so an auto-match can't recanonicalize
     // it; revert (↺) drops back to the pack value.
-    const DETAIL_FIELDS = [['title', 'Title'], ['artist', 'Artist'], ['album', 'Album'], ['year', 'Year']];
+    const DETAIL_FIELDS = [['title', 'Title'], ['artist', 'Artist'], ['album', 'Album'], ['year', 'Year'], ['genre', 'Genre']];
+    // Only these four are written into the pack file; genre is a library-only
+    // overlay (drives the genre filter/facet + the auto-match lock), never baked
+    // to the file — so Write to file leaves genre's override in place.
+    const WRITE_FIELDS = ['title', 'artist', 'album', 'year'];
 
     async function renderDetailsTab(body, song) {
         body.innerHTML = '<div class="p-5"><p class="text-sm text-fb-textDim">Loading…</p></div>';
@@ -483,7 +488,40 @@
             };
         }
         song._detailsState = st;
+        // Match→Details bridge: a candidate picked with "Use these values" lands
+        // its fields here as the pending (unsaved) input values, shown pre-filled
+        // for review — the grid never adopts a match silently, so the user still
+        // Saves (or Writes to file).
+        const adopted = song._pendingDetails;
+        if (adopted) {
+            for (const [f] of DETAIL_FIELDS) {
+                if (f in adopted) st[f].value = String(adopted[f] || '');
+            }
+            song._pendingDetails = null;
+        }
         paintDetails(body, song);
+        if (adopted) {
+            const s = body.querySelector('[data-df-status]');
+            if (s) { s.className = 'text-xs leading-relaxed text-fb-textDim'; s.textContent = 'Filled from the match — review, then Save or Write to file.'; }
+        }
+    }
+
+    // Match→Details bridge: adopt a candidate's display fields into the Details
+    // tab (opt-in — never silent). Pin the match too so the art/canon follow,
+    // then land on Details pre-filled for review.
+    async function useTheseValues(song, cand) {
+        if (!cand) return;
+        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 || ''),
+        };
+        try {
+            await post('/api/enrichment/review/' + enc(song.filename) + '/pick', { candidate: cand });
+        } catch (_) { /* pin is best-effort; the values still populate Details */ }
+        try { window.feedBack?.emit('library:changed', { reason: 'match' }); } catch (_) { }
+        _tab = 'details';
+        renderTabbed();
     }
 
     function paintDetails(body, song) {
@@ -514,12 +552,13 @@
             '<div class="p-5 space-y-4 overflow-y-auto v3-scroll min-h-0">' +
             '<div class="flex items-start gap-3">' +
             '<img src="' + esc(artUrl(song)) + '" alt="" onerror="this.style.visibility=\'hidden\'" class="w-14 h-14 rounded-lg object-cover bg-fb-card shrink-0">' +
-            '<p class="text-xs text-fb-textDim pt-1">Your edits show in the library right away and are never written to the song files. Use <span class="text-fb-text">Match</span> to pull info from MusicBrainz, or lock a field to keep it.</p>' +
+            '<p class="text-xs text-fb-textDim pt-1"><span class="text-fb-text">Save</span> keeps edits as a reversible library overlay — the song files aren\'t touched. <span class="text-fb-text">Write to file</span> bakes the title, artist, album and year into the pack (genre stays a library-only tag). Lock a field to keep an auto-match from changing it.</p>' +
             '</div>' +
             DETAIL_FIELDS.map(row).join('') +
-            '<p data-df-status class="text-xs h-4"></p>' +
+            '<p data-df-status class="text-xs leading-relaxed"></p>' +
             '</div>' +
-            '<div class="flex items-center justify-end gap-2 p-5 pt-3 border-t border-fb-border/40 shrink-0">' +
+            '<div class="flex items-center justify-between gap-2 p-5 pt-3 border-t border-fb-border/40 shrink-0">' +
+            '<button data-df-write type="button" title="Write these values into the song file itself — permanent, survives a full rescan. The rest of the pack is untouched." class="text-sm text-fb-textDim hover:text-fb-text border border-fb-border/50 rounded-md px-3 py-2">Write to file</button>' +
             '<button data-df-save class="bg-fb-primary hover:bg-fb-primaryHi text-white px-4 py-2 rounded-md text-sm">Save</button>' +
             '</div>';
         body.querySelectorAll('[data-df-input]').forEach((inp) => {
@@ -532,6 +571,7 @@
             b.addEventListener('click', () => { const f = b.getAttribute('data-df-revert'); st[f].value = st[f].pack || ''; st[f].locked = false; paintDetails(body, song); });
         });
         body.querySelector('[data-df-save]')?.addEventListener('click', () => saveDetails(body, song));
+        body.querySelector('[data-df-write]')?.addEventListener('click', () => writeToFile(body, song));
     }
 
     async function saveDetails(body, song) {
@@ -572,6 +612,70 @@
         if (status) { status.className = 'text-xs h-4 text-fb-good'; status.textContent = 'Saved.'; }
     }
 
+    // "Write to file" — bake the shown title/artist/album/year INTO the pack
+    // itself (the one action here that touches the file), via the existing
+    // POST /api/song/{fn}/meta (writes the manifest, re-stats, coalesces a
+    // rescan). On a real file write the display overrides for those fields are
+    // now redundant, so clear their VALUES (keeping any locks) and re-render —
+    // the field then reads from the file as "Pack". Loose-folder / unwritable
+    // packs fall back to a DB-only update: we say so and keep the overlay.
+    async function writeToFile(body, song) {
+        const st = song._detailsState;
+        const fields = {};
+        for (const f of WRITE_FIELDS) fields[f] = String(st[f].value || '').trim();
+        const status = body.querySelector('[data-df-status]');
+        const writeBtn = body.querySelector('[data-df-write]');
+        const saveBtn = body.querySelector('[data-df-save]');
+        if (writeBtn) writeBtn.disabled = true;
+        if (saveBtn) saveBtn.disabled = true;
+        if (status) { status.className = 'text-xs leading-relaxed text-fb-textDim'; status.textContent = 'Writing to the song file…'; }
+        let ok = false, persisted = false;
+        try {
+            const r = await fetch('/api/song/' + enc(song.filename) + '/meta', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify(fields),
+            });
+            ok = r.ok;
+            const j = await r.json().catch(() => ({}));
+            persisted = !!(j && j.persisted);
+        } catch (_) { ok = false; }
+        if (writeBtn) writeBtn.disabled = false;
+        if (saveBtn) saveBtn.disabled = false;
+        if (!ok) {
+            if (status) { status.className = 'text-xs leading-relaxed text-fb-accent'; status.textContent = 'Could not write to the file — try again.'; }
+            return;
+        }
+        // Keep the in-memory song + grid in step with what was *persisted*, not
+        // the raw input: the server coerces a non-numeric/empty year to "" (see
+        // update_song_meta), so mirror that here or the grid card flashes the
+        // typed text (e.g. "abcd") until the next natural refresh corrects it.
+        const applied = { ...fields };
+        if ('year' in applied) {
+            const yr = /^[+-]?\d+$/.test(applied.year) ? parseInt(applied.year, 10) : 0;
+            applied.year = yr ? String(yr) : '';
+        }
+        for (const f of WRITE_FIELDS) song[f] = applied[f];
+        try { window.feedBack?.emit('library:changed', { reason: 'write' }); } catch (_) { }
+        if (persisted) {
+            const clear = {};
+            for (const f of WRITE_FIELDS) clear[f] = { value: null, locked: !!st[f].locked };
+            try {
+                await fetch('/api/song/' + enc(song.filename) + '/overrides', {
+                    method: 'PUT',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({ overrides: clear }),
+                });
+            } catch (_) { /* the file write still succeeded; the overlay just lingers */ }
+            await renderDetailsTab(body, song);   // re-fetch: pack now = written values, overrides cleared
+            const s2 = body.querySelector('[data-df-status]');
+            if (s2) { s2.className = 'text-xs leading-relaxed text-fb-good'; s2.textContent = 'Written to the song file.'; }
+        } else if (status) {
+            status.className = 'text-xs leading-relaxed text-fb-textDim';
+            status.textContent = 'Saved to the library — this pack’s file couldn’t be written, so it may revert on a full rescan.';
+        }
+    }
+
     // Cover-art tab: the current art + a button that hands off to the shared
     // cover picker (image-picker.js, its own z-[200] modal). A pick there
     // refreshes every <img> for this song's art — including this thumbnail — so
@@ -639,6 +743,7 @@
             btn.addEventListener('click', async () => {
                 const cand = cands[Number(btn.getAttribute('data-mr-cand'))];
                 if (!cand) return;
+                if (_single) { useTheseValues(song, cand); return; }   // popup → adopt into Details
                 await post('/api/enrichment/review/' + enc(song.filename) + '/pick',
                     { candidate: cand });
                 settle(song);
@@ -691,6 +796,7 @@
             btn.addEventListener('click', async () => {
                 const cand = cands[Number(btn.getAttribute('data-mr-cand'))];
                 if (!cand) return;
+                if (_single) { useTheseValues(song, cand); return; }   // popup → adopt into Details
                 await post('/api/enrichment/review/' + enc(song.filename) + '/pick',
                     { candidate: cand });
                 settle(song);

tests/test_field_overrides.py

@@ -209,6 +209,30 @@ def test_route_strips_private_sort_title(client, server):
     assert "_sort_title" not in row              # private keyset stash never leaks to the client
 
 
+def test_genre_override_drives_facet_and_filter(client, server):
+    # a.archive: pack genre "Rock"; b.archive: blank genre, overridden to "City Pop".
+    _put(server, "a.archive", title="A", genre="Rock")
+    _put(server, "b.archive", title="B", genre="")
+    server.meta_db.set_song_override("b.archive", "genre", value="City Pop")
+    # Facet lists the EFFECTIVE genres (override surfaces; empty raw doesn't).
+    genres = client.get("/api/library/genres").json()["genres"]
+    assert "City Pop" in genres and "Rock" in genres
+    # Filtering by the override genre returns the overridden song…
+    fns = [s["filename"] for s in client.get("/api/library?genre=City%20Pop").json()["songs"]]
+    assert fns == ["b.archive"]
+    # …and its raw (blank) genre no longer matches a stale query for it.
+    rock = [s["filename"] for s in client.get("/api/library?genre=Rock").json()["songs"]]
+    assert rock == ["a.archive"]
+
+
+def test_lock_only_genre_does_not_change_facet(server):
+    # A pure lock (no value) must not invent an effective genre.
+    _put(server, "a.archive", title="A", genre="Metal")
+    server.meta_db.set_song_override("a.archive", "genre", locked=True)
+    assert server.meta_db._has_genre_overrides() is False   # value-less rows don't count
+    assert server.meta_db._effective_genre_expr() == "genre"
+
+
 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")