Default lookahead 8s -> 4s: don't hang unsung lines through gaps

Field report ("Marks Of The Evil One", authored syllable-timed lyrics
with short lines around ~6s instrumental gaps): with an 8s lookahead the
banner no longer hid during those gaps — it sat there showing the next
dim lines while nothing was being sung, which reads as "the lyrics are
out of sync". The highlight clock was never wrong (invariant-tested);
the preview policy was.

4s keeps the full upcoming-context win during dense singing (next lines
start within a couple of seconds) while instrumental gaps go blank like
they used to. Still live-tunable via highway.setLyricsDisplay(). New
regression test pins the mid-gap hide + within-lookahead return.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: topkoa <topkoa@gmail.com>

plugins/highway_3d/screen.js

@@ -6965,7 +6965,7 @@
         // because this plugin deliberately does not import the shared
         // module. Both read localStorage['lyricsDisplay'], so
         // highway.setLyricsDisplay() tunes both at once.
-        const LYRICS_DISPLAY_DEFAULTS = { upcomingLines: 2, lookaheadSec: 8 };
+        const LYRICS_DISPLAY_DEFAULTS = { upcomingLines: 2, lookaheadSec: 4 };
         let _lyrCfgRaw, _lyrCfg = LYRICS_DISPLAY_DEFAULTS;
         function getLyricsDisplayCfg() {
             let raw = null;

static/js/highway-draw.js

@@ -929,7 +929,11 @@ export function drawChords(hwState, W, H) {
 // without a reload.
 //   upcomingLines — how many lines beyond the current one may be shown (0-4)
 //   lookaheadSec  — how far ahead a line may start and still be previewed (1-30)
-const LYRICS_DISPLAY_DEFAULTS = { upcomingLines: 2, lookaheadSec: 8 };
+// lookahead default is deliberately modest (4s): dense singing still gets
+// full upcoming context (next lines start within a couple of seconds), but
+// the banner goes away during instrumental gaps instead of hanging there
+// with unsung lines — which reads as "the lyrics are out of sync".
+const LYRICS_DISPLAY_DEFAULTS = { upcomingLines: 2, lookaheadSec: 4 };
 let _lyricsCfgRaw;
 let _lyricsCfg = LYRICS_DISPLAY_DEFAULTS;
 export function getLyricsDisplayCfg() {

tests/js/highway_lyrics_window.test.js

@@ -47,16 +47,16 @@ function makeStorage(initial) {
 test('cfg reader: defaults, clamping, corrupt JSON, live re-read', () => {
     const storage = makeStorage();
     const read = loadCfgReader(storage);
-    assert.deepEqual(read(), { upcomingLines: 2, lookaheadSec: 8 });
+    assert.deepEqual(read(), { upcomingLines: 2, lookaheadSec: 4 });
 
     storage.setItem('lyricsDisplay', JSON.stringify({ upcomingLines: 99, lookaheadSec: 0 }));
     assert.deepEqual(read(), { upcomingLines: 4, lookaheadSec: 1 }); // clamped
 
     storage.setItem('lyricsDisplay', '{not json');
-    assert.deepEqual(read(), { upcomingLines: 2, lookaheadSec: 8 }); // corrupt -> defaults
+    assert.deepEqual(read(), { upcomingLines: 2, lookaheadSec: 4 }); // corrupt -> defaults
 
     storage.setItem('lyricsDisplay', JSON.stringify({ upcomingLines: 1 }));
-    assert.deepEqual(read(), { upcomingLines: 1, lookaheadSec: 8 }); // partial merges over defaults
+    assert.deepEqual(read(), { upcomingLines: 1, lookaheadSec: 4 }); // partial merges over defaults
 });
 
 // ── drawLyrics harness ───────────────────────────────────────────────────
@@ -153,6 +153,22 @@ test('pre-song preview appears within lookahead, not before', () => {
     assert.deepEqual(near.calls.map(c => c.text), ['one']);
 });
 
+test('banner hides during an instrumental gap, returns within lookahead', () => {
+    // The "Marks Of The Evil One" report: short authored lines around a ~6s
+    // instrumental gap. Mid-gap the banner must hide (nothing is being
+    // sung), then return once the next line is inside the lookahead.
+    const lyrics = [syl(10, 'sung', true), syl(17, 'next', true)];
+    const draw = loadDrawLyrics({ upcomingLines: 2, lookaheadSec: 4 });
+
+    const midGap = makeCtx();
+    draw({ lyrics, ctx: midGap, currentTime: 12 }, 2000, H); // next is 5s out
+    assert.equal(midGap.calls.length, 0, 'mid-gap: no unsung lyrics on screen');
+
+    const nearNext = makeCtx();
+    draw({ lyrics, ctx: nearNext, currentTime: 13.5 }, 2000, H); // 3.5s out
+    assert.deepEqual(nearNext.calls.map(c => c.text), ['sung', 'next']);
+});
+
 test('banner hides after the last line ends with nothing upcoming', () => {
     const lyrics = [syl(10, 'one', true)];
     const draw = loadDrawLyrics({ upcomingLines: 2, lookaheadSec: 8 });