v3 library: first-hour polish — zero-states, match progress, provenance, alias search (#730)

* v3 library: first-hour polish — zero-states, match progress, provenance, alias search

Six launch-eve fixes for a brand-new user's first hour with a fresh,
being-matched library. Each is small and reuses shipped idioms.

- Invitational repertoire meter: with no practice data yet, the home meter
  no longer reads "0 of N mastered" (debt framing) — it shows an empty bar
  with "grows as you master songs". A count of 0 read as failure on day one.
- "Start here" starter shelf: growth_edge_suggestions() distinguishes two
  empties — attempts exist but all mastered (honest empty shelf) vs nothing
  attempted yet (day one) → new starter_suggestions() returns up to 8
  approachable songs (90–480s, shortest first) flagged starter:true, and the
  client renders a "Start here" shelf instead of a blank home.
- Library-visible match progress: while the background pass runs, a quiet
  "Matching your library — X of Y" line sits by the review chip (5s poll,
  single guarded interval, cleared the moment the pass stops — no leak,
  no toast, silent completion).
- One-time transparency toast: the first time an install is seen matching a
  real library, one fbNotify names what's contacted (MusicBrainz / Cover Art
  Archive), that results are stored locally, that files aren't changed
  without you, and where the switch is. localStorage-gated, wrapped so a
  blocked notifier can't break the chip.
- Empty-library dead-end card: a genuinely empty local library (no songs, no
  query/filter) shows "Your library is empty" + drop-files hint + Open
  Settings, instead of a bare grid under dead dropdowns.
- Alias-aware search: searching a canonical name ("AC/DC") now also finds
  songs whose raw tag is a merged variant ("ACDC"), via the artist_alias
  table. Probe-guarded so a no-aliases library keeps the exact original
  3-term query; pure predicate, keyset-safe.
- Details-drawer provenance line: matched/manual rows show "Matched:
  <artist — title> (source) · Fix match" under the Identity fields — the
  wrong-match escape hatch at the point of the data, wired to the same
  fix-match flow the card menu uses. New read-only GET
  /api/enrichment/song/{filename} backs it.

Tests: tests/test_starter_suggestions.py (starter vs normal-shelf behaviour,
length window, attempts-exist path unchanged) + alias-search cases added to
tests/test_artist_alias.py. 34 targeted pass; node --check clean; no new
Tailwind classes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Nm7tHs1Yvjjtnnu4nzJgdN

* fix(v3 library): stop match-progress poll when leaving the library screen

The 5s enrichment poll (_pollTimer) was cleared on pass completion and on
fetch error, but not when the user navigated away from the library. Leaving
v3-songs mid-pass left the interval pinging /api/enrichment/status in the
background until the pass ended. Subscribe to the existing feedBack
'screen:changed' event: clear the poll when any non-v3-songs screen shows,
and refresh (re-arming if a pass is still running) on returning to v3-songs.

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

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: byrongamatos <xasiklas@gmail.com>

static/v3/match-review.js

@@ -35,9 +35,52 @@
     // ── Ambient chip + the Settings card's status line ───────────────────────
     // songs.js renders `#v3-songs-match-review` (hidden) in its toolbar and
     // calls window.__fbMatchReviewChip() after each toolbar build; review
-    // actions here re-call it. The same fetch feeds the Settings status line.
+    // actions here re-call it. The same fetch feeds the Settings status line
+    // and, while a pass is running, a quiet toolbar progress line (below).
     // Silent on failure — surfaces just stay as they are.
     let _chipBusy = false;
+    let _pollTimer = null;   // 5s status poll, alive ONLY while a pass runs
+
+    // Quiet library-visible progress (launch polish): a plain text line next
+    // to the review chip while the background pass is working through the
+    // queue — "Matching your library — X of Y". No toast, no sound; it simply
+    // disappears when the pass finishes (hearing-safe, design §11).
+    function _setProgressLine(running, states, total) {
+        let el = document.getElementById('v3-songs-match-progress');
+        const unscanned = states.unscanned || 0;
+        if (!running || unscanned <= 0 || total <= 0) {
+            if (el) el.remove();
+            return;
+        }
+        if (!el) {
+            const chip = document.getElementById('v3-songs-match-review');
+            if (!chip || !chip.parentElement) return;   // songs toolbar not on screen
+            el = document.createElement('span');
+            el.id = 'v3-songs-match-progress';
+            el.className = 'text-xs text-fb-textDim';
+            chip.insertAdjacentElement('afterend', el);
+        }
+        el.textContent = 'Matching your library — ' + Math.max(0, total - unscanned) + ' of ' + total;
+    }
+
+    // One-time transparency toast (launch polish): the first time this
+    // install is observed actually matching a real library, say plainly what
+    // is contacted, where results live, and where the switch is. Wrapped like
+    // app.js's fbNotify calls so a blocked localStorage / absent notifier can
+    // never break the chip.
+    function _announceOnce(running, total) {
+        try {
+            if (!running || total <= 0) return;
+            if (localStorage.getItem('fb_enrich_announce_v1')) return;
+            localStorage.setItem('fb_enrich_announce_v1', '1');
+            window.fbNotify?.show({
+                title: 'Library matching is on',
+                message: 'Song info and covers come from MusicBrainz and Cover Art Archive, stored locally. Your files are never changed unless you choose to write to them. Adjust in Settings → Library.',
+                icon: '📚',
+            });
+        } catch (_) { /* storage/notifier unavailable — skip quietly */ }
+    }
+
     async function refreshChip() {
         if (_chipBusy) return;
         _chipBusy = true;
@@ -62,7 +105,24 @@
                 if (st.unscanned) parts.push(st.unscanned + ' queued');
                 line.textContent = (body.running ? 'Matching… · ' : '') + parts.join(' · ');
             }
-        } catch (_) { /* offline — leave as-is */ } finally {
+            const running = !!body.running;
+            const total = body.total_songs || 0;
+            _setProgressLine(running, st, total);
+            _announceOnce(running, total);
+            // Poll only while a pass is actually running; a single guarded
+            // interval, cleared the moment the pass stops (no leaks).
+            if (running && !_pollTimer) {
+                _pollTimer = setInterval(refreshChip, 5000);
+            } else if (!running && _pollTimer) {
+                clearInterval(_pollTimer);
+                _pollTimer = null;
+            }
+        } catch (_) {
+            // Offline — leave surfaces as they are, but stop any poll so a
+            // dead server isn't pinged every 5s forever (the next toolbar
+            // build / settings open restarts it if a pass is still running).
+            if (_pollTimer) { clearInterval(_pollTimer); _pollTimer = null; }
+        } finally {
             _chipBusy = false;
         }
     }
@@ -455,10 +515,34 @@
         });
     }
 
+    // Stop the 5s poll when the library screen is left — the progress line and
+    // chip only live in the songs toolbar, so polling off-screen is pure waste
+    // (benign but tidy). Re-entering v3-songs re-arms it: songs.js re-calls
+    // window.__fbMatchReviewChip() on screen enter, and we also refresh here so
+    // this stays self-contained. Same single-guarded-interval invariant as
+    // refreshChip — no double-interval, cleared to null.
+    function wireScreenTeardown() {
+        const sm = window.feedBack;
+        if (!sm || typeof sm.on !== 'function') return;
+        sm.on('screen:changed', (e) => {
+            const id = e && e.detail && e.detail.id;
+            if (id === 'v3-songs') {
+                refreshChip();   // returning while a pass runs re-arms the poll
+            } else if (_pollTimer) {
+                clearInterval(_pollTimer);
+                _pollTimer = null;
+            }
+        });
+    }
+
     if (document.readyState === 'loading') {
-        document.addEventListener('DOMContentLoaded', wireSettingsCard, { once: true });
+        document.addEventListener('DOMContentLoaded', () => {
+            wireSettingsCard();
+            wireScreenTeardown();
+        }, { once: true });
     } else {
         wireSettingsCard();
+        wireScreenTeardown();
     }
 
     window.__fbMatchReviewChip = refreshChip;