fix: use s.remoteId == null check instead of !s.remoteId in getVisibleSessions()

Fixes falsy-0 bug where sessions with remoteId=0 (first remote instance) were
incorrectly hidden because !s.remoteId treats 0 as falsy. The null check
s.remoteId == null correctly handles:
- remoteId=0 (first remote instance) → truthy, not hidden
- remoteId=null or undefined (local sessions) → falsy, hidden if in hidden list

Changes:
- muxplex/frontend/app.js: Line 533 condition in getVisibleSessions()
- muxplex/frontend/tests/test_app.mjs: Added 2 tests for remoteId=0 behavior
- muxplex/tests/test_frontend_js.py: Added pattern test verifying source code

All 330 JS tests pass, all 200 Python tests pass.

Generated with Amplifier (https://github.com/microsoft/amplifier)

Co-Authored-By: Amplifier <240397093+microsoft-amplifier@users.noreply.github.com>

muxplex/frontend/app.js

@@ -530,7 +530,7 @@ function buildStatusTileHTML(deviceName, statusText, statusClass) {
 function getVisibleSessions(sessions) {
   var hidden = (_serverSettings && _serverSettings.hidden_sessions) || [];
   return (sessions || []).filter(function(s) {
-    if (hidden.length > 0 && !s.remoteId && hidden.includes(s.name)) {
+    if (hidden.length > 0 && s.remoteId == null && hidden.includes(s.name)) {
       return false;
     }
     return true;

muxplex/frontend/tests/test_app.mjs

@@ -4619,3 +4619,25 @@ test('getDisplaySettings reads display keys from _serverSettings with DISPLAY_DE
   assert.ok(!('unknownKey' in ds), 'getDisplaySettings must not include keys not in DISPLAY_DEFAULTS');
   app._setServerSettings(null);
 });
+
+// --- getVisibleSessions: remoteId=0 falsy-zero bug fix ---
+
+test('getVisibleSessions does NOT hide sessions with remoteId 0 whose name is in hidden_sessions', () => {
+  app._setServerSettings({ hidden_sessions: ['work'] });
+  const sessions = [{ name: 'work', remoteId: 0 }];
+  const visible = app.getVisibleSessions(sessions);
+  assert.strictEqual(visible.length, 1, 'session with remoteId=0 must NOT be hidden even if name is in hidden_sessions');
+  app._setServerSettings(null);
+});
+
+test('getVisibleSessions hides local session (remoteId null) but keeps remote session (remoteId 0) with same name', () => {
+  app._setServerSettings({ hidden_sessions: ['work'] });
+  const sessions = [
+    { name: 'work', remoteId: null },
+    { name: 'work', remoteId: 0 },
+  ];
+  const visible = app.getVisibleSessions(sessions);
+  assert.strictEqual(visible.length, 1, 'only the remote session (remoteId=0) should be visible');
+  assert.strictEqual(visible[0].remoteId, 0, 'the visible session must be the remote one with remoteId=0');
+  app._setServerSettings(null);
+});

muxplex/tests/test_frontend_js.py

@@ -2710,3 +2710,26 @@ def test_bind_sidebar_click_away_calls_patch_server_setting() -> None:
     assert "patchServerSetting" in body, (
         "bindSidebarClickAway must call patchServerSetting to persist collapsed state"
     )
+
+
+# ─── task-1: getVisibleSessions falsy-0 bug fix ────────────────────────────
+
+
+def test_get_visible_sessions_uses_null_check_not_falsy() -> None:
+    """getVisibleSessions must use s.remoteId == null (not !s.remoteId) to avoid
+    treating remoteId=0 (first remote instance) as falsy and incorrectly hiding it."""
+    match = re.search(
+        r"function getVisibleSessions\s*\(\w+\)\s*\{(.*?)(?=\n(?:function|//|window\.))",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "getVisibleSessions function not found in app.js"
+    body = match.group(1)
+    assert "!s.remoteId" not in body, (
+        "getVisibleSessions must NOT use '!s.remoteId' — this treats remoteId=0 as falsy, "
+        "hiding the first remote instance. Use 's.remoteId == null' instead."
+    )
+    assert "s.remoteId == null" in body or "s.remoteId === null" in body, (
+        "getVisibleSessions must use 's.remoteId == null' (or '=== null') to correctly treat "
+        "remoteId=0 as a real remote while matching null/undefined as local sessions."
+    )