Clean release snapshot

tests/js/v3_songs_scroll.test.js

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+'use strict';
+const { test } = require('node:test');
+const assert = require('node:assert');
+
+// Mirror of static/v3/songs.js buildLibraryStateHash — keep in sync.
+function buildLibraryStateHash(st) {
+    const f = (st && st.filters) || {};
+    return JSON.stringify({
+        view: st.view || 'grid',
+        q: st.q || '',
+        sort: st.sort || 'artist',
+        provider: st.provider || 'local',
+        format: st.format || '',
+        artist: st.artist || '',
+        album: st.album || '',
+        filters: {
+            arr_has: [...(f.arr_has || [])].sort(),
+            arr_lacks: [...(f.arr_lacks || [])].sort(),
+            stem_has: [...(f.stem_has || [])].sort(),
+            stem_lacks: [...(f.stem_lacks || [])].sort(),
+            lyrics: f.lyrics || '',
+            tunings: [...(f.tunings || [])].sort(),
+        },
+    });
+}
+
+const SCROLL_STATE_KEY = 'v3:songs-scroll-state';
+
+function makeStore() {
+    const data = new Map();
+    return {
+        getItem(k) { return data.has(k) ? data.get(k) : null; },
+        setItem(k, v) { data.set(k, v); },
+        removeItem(k) { data.delete(k); },
+        clear() { data.clear(); },
+    };
+}
+
+function saveSnapshot(storage, state, scrollTop, page, loadedCount) {
+    const snap = {
+        hash: buildLibraryStateHash(state),
+        scrollTop,
+        view: state.view,
+        page,
+        loadedCount,
+    };
+    storage.setItem(SCROLL_STATE_KEY, JSON.stringify(snap));
+}
+
+function readSnapshot(storage) {
+    const raw = storage.getItem(SCROLL_STATE_KEY);
+    if (!raw) return null;
+    return JSON.parse(raw);
+}
+
+const baseState = {
+    view: 'grid',
+    q: '',
+    sort: 'artist',
+    provider: 'local',
+    format: '',
+    artist: '',
+    album: '',
+    filters: { arr_has: [], arr_lacks: [], stem_has: [], stem_lacks: [], lyrics: '', tunings: [] },
+};
+
+test('buildLibraryStateHash changes when sort changes', () => {
+    const a = buildLibraryStateHash(baseState);
+    const b = buildLibraryStateHash({ ...baseState, sort: 'title' });
+    assert.notStrictEqual(a, b);
+});
+
+test('buildLibraryStateHash changes when filter provider changes', () => {
+    const a = buildLibraryStateHash(baseState);
+    const b = buildLibraryStateHash({ ...baseState, provider: 'remote:x' });
+    assert.notStrictEqual(a, b);
+});
+
+test('buildLibraryStateHash is stable for equivalent filter arrays', () => {
+    const s1 = {
+        ...baseState,
+        filters: { ...baseState.filters, arr_has: ['Lead', 'Bass'], tunings: ['Drop D', 'E Standard'] },
+    };
+    const s2 = {
+        ...baseState,
+        filters: { ...baseState.filters, arr_has: ['Bass', 'Lead'], tunings: ['E Standard', 'Drop D'] },
+    };
+    assert.strictEqual(buildLibraryStateHash(s1), buildLibraryStateHash(s2));
+});
+
+test('snapshot stores scrollTop and page', () => {
+    const storage = makeStore();
+    saveSnapshot(storage, baseState, 1840, 3, 96);
+    const snap = readSnapshot(storage);
+    assert.strictEqual(snap.scrollTop, 1840);
+    assert.strictEqual(snap.page, 3);
+    assert.strictEqual(snap.loadedCount, 96);
+    assert.strictEqual(snap.hash, buildLibraryStateHash(baseState));
+});
+
+test('stale snapshot is detected when filters change', () => {
+    const storage = makeStore();
+    saveSnapshot(storage, baseState, 500, 1, 48);
+    const snap = readSnapshot(storage);
+    const changed = buildLibraryStateHash({ ...baseState, q: 'beatles' });
+    assert.notStrictEqual(snap.hash, changed);
+});
+
+test('state hash changes when artist or album changes', () => {
+    const a = buildLibraryStateHash(baseState);
+    const b = buildLibraryStateHash({ ...baseState, artist: 'A Band' });
+    const c = buildLibraryStateHash({ ...baseState, artist: 'A Band', album: 'A Band - LP' });
+    assert.notStrictEqual(a, b);
+    assert.notStrictEqual(b, c);
+});
+
+test('clearing artist should use different hash than album-only selection', () => {
+    const withArtist = buildLibraryStateHash({ ...baseState, artist: 'A Band', album: 'A Band - LP' });
+    const cleared = buildLibraryStateHash({ ...baseState, artist: '', album: '' });
+    assert.notStrictEqual(withArtist, cleared);
+});