fix(venue): fly in once per set, not before every song (#978)

Tester, mid-gig: "the second song in the gig started when the first one ended.
But it showed the flyover intro again."

The flyover is arriving at the venue, and you arrive once. #968 stopped it
replaying on an arrangement SWITCH (same filename), but a gig's song 2 is a
genuinely different file, so it took the full-teardown path and played the
arrival flyover again — the camera flew in from the back of the room before
every track of the set.

The play queue now answers isContinuation(): false for the first song of a set
(or a standalone play — an arrival), true for song 2..N. onSongLoaded carries
the room over to the new song's loop on a continuation, and only a real arrival
plays the intro.

Verified on the built AppImage: isContinuation goes false (song 1) -> true
(song 2) across an advance, and song 2 no longer flies in.

Also confirmed NOT a bug, same session: "didn't show the author for the second
song." The credits card shows on a queue advance whenever the song carries
authors — reproduced with a song that has them as the advanced-to track. The
tester's song 2 simply had no `authors:` metadata (most auto-converted feedpaks
don't). No code change.

Tests: isContinuation across start/advance/clear, and that onSongLoaded gates the
flyover on the continuation check. Both fail on pre-fix source. JS 1214/1214.

static/app.js

@@ -1384,6 +1384,11 @@ window.feedBack.playQueue = (function () {
     }
     return {
         start: start, advance: advance, hasNext: hasNext, active: active, clear: clear,
+        // True when the current song is a queue ADVANCE (song 2..N of a set),
+        // false for its first song or a standalone play. The venue uses this to
+        // fly in once on arrival at the set, then continue the room between
+        // songs instead of replaying the arrival flyover every track.
+        isContinuation: function () { return active() && idx > 0; },
         // One-shot: true iff _play just kicked off this playSong. Consumed on
         // read so a later MANUAL play still clears the queue. playSong calls this
         // instead of trusting options.fromQueue to survive the wrapper chain.

static/v3/venue-crowd.js

@@ -529,7 +529,27 @@
         _loadingLoop = null;
         _fadingLoop = null;
         if (_venueActive && _manifest) {
-            if (!playIntro()) showLoop(machine.current, FADE_MS);
+            // The flyover is ARRIVING at the venue, and you arrive once. Songs
+            // 2..N of a set (a gig / album / playlist) are a NEW song but the
+            // SAME arrival — the camera should not fly in from the back of the
+            // room before every track (tester: "it showed the flyover intro
+            // again" on a gig's second song). Continue the room to the new song's
+            // loop; only a first-song / standalone arrival flies in.
+            if (_isSetContinuation()) showLoop(machine.current, FADE_MS);
+            else if (!playIntro()) showLoop(machine.current, FADE_MS);
+        }
+    }
+
+    // Is this song load a continuation of a play queue (a set already in
+    // progress), rather than an arrival? True for song 2..N of a gig/album/
+    // playlist. The queue owns the answer; treat any error / absent queue as
+    // "not a continuation" so a standalone play still flies in.
+    function _isSetContinuation() {
+        try {
+            const q = window.feedBack && window.feedBack.playQueue;
+            return !!(q && typeof q.isContinuation === 'function' && q.isContinuation());
+        } catch (_) {
+            return false;
         }
     }
 

tests/js/play_queue_peek.test.js

@@ -109,3 +109,20 @@ test('fromQueue in options still works on its own (in-band path)', () => {
     clearGuard(win, { fromQueue: true });
     assert.strictEqual(q.active(), true, 'options.fromQueue alone must still keep the queue');
 });
+
+// isContinuation(): true for song 2..N of a set, false for the first song / a
+// standalone play. The venue uses it to fly in once on arrival, then carry the
+// room between songs instead of replaying the arrival flyover every track
+// (tester: "it showed the flyover intro again" on a gig's second song).
+test('isContinuation is false on the first song, true after advancing', () => {
+    const { q } = makeQueue();
+    assert.strictEqual(q.isContinuation(), false, 'idle queue is not a continuation');
+    q.start(['a.sloppak', 'b.sloppak', 'c.sloppak'], { source: 'gig' });
+    assert.strictEqual(q.isContinuation(), false, 'the FIRST song of a set is an arrival, not a continuation');
+    q.advance();
+    assert.strictEqual(q.isContinuation(), true, 'song 2 is a continuation — no re-flyover');
+    q.advance();
+    assert.strictEqual(q.isContinuation(), true, 'song 3 too');
+    q.clear();
+    assert.strictEqual(q.isContinuation(), false, 'a cleared queue is not a continuation');
+});

tests/js/venue_scope.test.js

@@ -117,3 +117,22 @@ test('a throwing document does not take the venue down with it', () => {
         global.document = prev;
     }
 });
+
+// The arrival flyover must NOT replay for songs 2..N of a set. onSongLoaded
+// consults the play queue: a continuation (gig/album/playlist song 2+) carries
+// the room over with a loop crossfade, only an arrival plays the intro.
+test('a set continuation carries the room over instead of re-flying-in', () => {
+    const fs = require('node:fs');
+    const path = require('node:path');
+    const src = fs.readFileSync(path.join(__dirname, '..', '..', 'static', 'v3', 'venue-crowd.js'), 'utf8');
+    const start = src.indexOf('function onSongLoaded(');
+    const open = src.indexOf('{', src.indexOf(')', start));
+    let depth = 1, i = open + 1;
+    while (i < src.length && depth > 0) { const ch = src[i]; if (ch === '{') depth++; else if (ch === '}') depth--; i++; }
+    const fn = src.slice(start, i);
+    const contIdx = fn.search(/_isSetContinuation\s*\(\s*\)/);
+    const introIdx = fn.search(/playIntro\s*\(/);
+    assert.ok(contIdx !== -1, 'onSongLoaded must consult the set-continuation signal');
+    assert.ok(introIdx !== -1, 'the intro must still exist for a real arrival');
+    assert.ok(contIdx < introIdx, 'the continuation check must gate the flyover — a set song 2+ must not fly in');
+});