Fix tuner auto-open flash: opt-in + persist (issue E, stage 1/3) (#655)

The tuner self-closes on song:play; autoplay fires it right after a song
switch, so an auto-opened tuner flashed shut ~1s later. An arrangement
switch (which never arms autoplay) instead persisted — the opposite
tester reports, and not the mic.

- New opt-in setting autoOpenOnTuningChange (tuner Settings, default OFF)
- An auto-opened tuner persists: it ignores the autoplay song:play, stray
  outside-clicks, and same-screen re-emits, closing only via the new
  in-panel x / Skip buttons or leaving the song. A manual open keeps the
  classic click-away / play-to-close behaviour.
- Adds the panel's first in-box close (x + contextual Skip).
- All in the tuner plugin; no core app.js changes.

Default (opt-in vs opt-out) is teed up for Byron to flip one boolean.
Staged follow-ups: E1.5 = instrument-coverage smart prompting + badge
cue; E2 = holdAutoplay gate.

Tests: tests/js/tuner_auto_open.test.js (opt-in gate, persist mode,
play/click-proofing).


Claude-Session: https://claude.ai/code/session_01QbexxfTt8q2tAn436MqGWF

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/js/tuner_auto_open.test.js

@@ -26,7 +26,10 @@ function loadTuningHelpers() {
 
 const feedBackHelpers = loadTuningHelpers();
 
-function createTunerSandbox() {
+function createTunerSandbox(opts) {
+    // Auto-open is opt-in (default off in prod). The sandbox defaults it ON so the
+    // behaviour tests exercise the feature; pass { autoOpen: false } to gate it off.
+    const autoOpen = !opts || opts.autoOpen !== false;
     const enableCalls = [];
     let playerActive = true;
     let songInfo = null;
@@ -44,6 +47,7 @@ function createTunerSandbox() {
                         showFloatingButton: true,
                         visualizationMode: 'default',
                         audioInputMode: 'auto',
+                        autoOpenOnTuningChange: autoOpen,
                         lastInstrument: 'guitar-6',
                         lastTuning: 'Standard',
                         freeTune: false,
@@ -155,9 +159,9 @@ function createTunerSandbox() {
     vm.runInContext(fs.readFileSync(TUNER_SCREEN_JS, 'utf8'), sandbox);
 
     const realEnable = sandbox.window.tuner.enable.bind(sandbox.window.tuner);
-    sandbox.window.tuner.enable = async () => {
-        enableCalls.push(1);
-        return realEnable();
+    sandbox.window.tuner.enable = async (enableOpts) => {
+        enableCalls.push(enableOpts || {});
+        return realEnable(enableOpts);
     };
 
     return sandbox;
@@ -315,6 +319,37 @@ test('song:loading clears dismiss state for next load', async () => {
     assert.equal(sandbox.__enableCalls.length, 2);
 });
 
+test('auto-open is gated off when the setting is disabled (opt-in)', async () => {
+    const sandbox = createTunerSandbox({ autoOpen: false });
+    sandbox.window._tunerAutoOpen.resetState();
+    await ready(sandbox, CUSTOM_GUITAR);
+    await ready(sandbox, E_STANDARD);   // a real tuning change, but the setting is off
+    assert.equal(sandbox.__enableCalls.length, 0);
+});
+
+test('auto-open enables in persist mode (passes { auto: true })', async () => {
+    const sandbox = createTunerSandbox();
+    sandbox.window._tunerAutoOpen.resetState();
+    await ready(sandbox, CUSTOM_GUITAR);
+    await ready(sandbox, E_STANDARD);
+    assert.equal(sandbox.__enableCalls.length, 1);
+    assert.equal(sandbox.__enableCalls[0].auto, true);
+});
+
+test('persist: an auto-opened tuner is not torn down by autoplay / stray clicks', () => {
+    const screenSrc = fs.readFileSync(TUNER_SCREEN_JS, 'utf8');
+    const uiSrc = fs.readFileSync(
+        path.join(__dirname, '..', '..', 'plugins', 'tuner', 'utils', 'ui.js'), 'utf8');
+    // The gate is opt-in on the server config flag.
+    assert.match(screenSrc, /autoOpenOnTuningChange/);
+    // enable() records whether this was an auto-open …
+    assert.match(screenSrc, /_state\.autoOpened\s*=\s*auto/);
+    // … the outside-click dismiss is armed only for a manual open …
+    assert.match(screenSrc, /if \(!auto\)[\s\S]*?addEventListener\('click'/);
+    // … and the autoplay song:play closer ignores an auto-opened tuner (the flash fix).
+    assert.match(uiSrc, /state\.enabled && !state\.autoOpened/);
+});
+
 test('screen.js registers song:loading and song:ready auto-open listeners at boot', () => {
     const src = fs.readFileSync(TUNER_SCREEN_JS, 'utf8');
     assert.match(src, /function _installAutoOpenListeners/);