feat: auto-add new session to active user view on creation

When a session is created via the + button while a user view is active,
auto-add the new session's key to that view's sessions list.

- In createNewSession(), after the successful POST call, check _activeView
- Skip auto-add for reserved views ('all', 'hidden')
- Build sessionKey correctly using device_id or remoteId
- PATCH /api/settings with updated views, catch errors gracefully
- Update local _serverSettings.views cache immediately

Test: test_create_new_session_references_active_view

muxplex/frontend/app.js

@@ -2133,6 +2133,30 @@ async function createNewSession(name, remoteId) {
     const res = await api('POST', endpoint, { name });
     const data = await res.json();
     const sessionName = data.name || name;
+
+    // Auto-add to active user view (not 'all' or 'hidden')
+    if (_activeView !== 'all' && _activeView !== 'hidden') {
+      var views = (_serverSettings && _serverSettings.views) || [];
+      var viewIdx = -1;
+      for (var vi = 0; vi < views.length; vi++) {
+        if (views[vi].name === _activeView) { viewIdx = vi; break; }
+      }
+      if (viewIdx >= 0) {
+        var newSessionKey = remoteId ? (remoteId + ':' + sessionName) : sessionName;
+        if (!remoteId && _serverSettings && _serverSettings.device_id) {
+          newSessionKey = _serverSettings.device_id + ':' + sessionName;
+        }
+        var updatedViews = JSON.parse(JSON.stringify(views));
+        if (!updatedViews[viewIdx].sessions.includes(newSessionKey)) {
+          updatedViews[viewIdx].sessions.push(newSessionKey);
+          api('PATCH', '/api/settings', { views: updatedViews }).catch(function(err) {
+            console.warn('[createNewSession] auto-add to view failed:', err);
+          });
+          if (_serverSettings) _serverSettings.views = updatedViews;
+        }
+      }
+    }
+
     showToast('Creating session \'' + sessionName + '\'…');
 
     // Inject a loading placeholder tile so the user sees feedback immediately

muxplex/tests/test_frontend_js.py

@@ -3093,3 +3093,22 @@ def test_set_active_view_helper_exported() -> None:
     assert "_setActiveView" in exports, (
         "module.exports must export _setActiveView test helper"
     )
+
+
+# ---------------------------------------------------------------------------
+# Auto-add session to active user view on creation (task-3-auto-add-to-view)
+# ---------------------------------------------------------------------------
+
+
+def test_create_new_session_references_active_view() -> None:
+    """createNewSession must reference _activeView to auto-add the new session to the active user view."""
+    match = re.search(
+        r"async function createNewSession\s*\([\w,\s]+\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "createNewSession function not found"
+    body = match.group(1)
+    assert "_activeView" in body, (
+        "createNewSession must reference _activeView to auto-add new session to the active user view"
+    )