feat: remove 'filtered' gridViewMode, keep only flat and grouped

- renderGrid: remove all _gridViewMode === 'filtered' branches (device
  filter application and filter bar rendering); filter bar is now always
  cleared for flat/grouped modes
- loadGridViewMode: add 'filtered' → 'flat' fallback so existing users
  who had the setting stored don't get a broken state
- _setGridViewMode (test helper): same guard so tests can't accidentally
  set the removed mode
- test_frontend_js.py: three new static-analysis tests assert the guards
  are present and the renderGrid filtered checks are gone

muxplex/frontend/app.js

@@ -762,11 +762,6 @@ function renderGrid(sessions) {
 
   var visible = getVisibleSessions(sessions);
 
-  // In filtered mode, apply device filter
-  if (_gridViewMode === 'filtered' && _activeFilterDevice !== 'all') {
-    visible = visible.filter(function(s) { return s.deviceName === _activeFilterDevice; });
-  }
-
   if (visible.length === 0) {
     // Build status tiles for auth_failed/unreachable sessions even when no regular sessions exist
     var statusTilesHtml = '';
@@ -781,14 +776,7 @@ function renderGrid(sessions) {
       if (statusTilesHtml) emptyState.classList.add('hidden');
       else emptyState.classList.remove('hidden');
     }
-    // Show filter bar even when filtered to empty (so user can switch back)
+    if (filterBar) filterBar.innerHTML = '';
-    if (filterBar) {
-      if (_gridViewMode === 'filtered') {
-        renderFilterBar(filterBar, sessions);
-      } else {
-        filterBar.innerHTML = '';
-      }
-    }
     return;
   }
 
@@ -821,14 +809,8 @@ function renderGrid(sessions) {
   });
   if (grid) grid.innerHTML = html + statusTilesHtml;
 
-  // Render filter bar
+  // Clear filter bar (filtered mode removed; bar is a no-op for flat/grouped)
-  if (filterBar) {
+  if (filterBar) filterBar.innerHTML = '';
-    if (_gridViewMode === 'filtered') {
-      renderFilterBar(filterBar, sessions);
-    } else {
-      filterBar.innerHTML = '';
-    }
-  }
 
   // Bind interaction handlers on each tile
   document.querySelectorAll('.session-tile').forEach(function(tile) {
@@ -1551,7 +1533,10 @@ function applyDisplaySettings(ds) {
  */
 function loadGridViewMode() {
   var ds = getDisplaySettings();
-  return ds.gridViewMode || 'flat';
+  var mode = ds.gridViewMode || 'flat';
+  // 'filtered' was removed in the Views feature — fall back to 'flat'
+  if (mode === 'filtered') mode = 'flat';
+  return mode;
 }
 
 /**
@@ -2482,6 +2467,8 @@ function _getGridViewMode() {
 
 /** Test-only: set _gridViewMode directly. */
 function _setGridViewMode(mode) {
+  // 'filtered' was removed in the Views feature — fall back to 'flat'
+  if (mode === 'filtered') mode = 'flat';
   _gridViewMode = mode;
 }
 

muxplex/tests/test_frontend_js.py

@@ -2872,3 +2872,60 @@ def test_create_new_session_uses_device_id_variable_internally() -> None:
         "createNewSession must declare 'var deviceId' internally (assigned from the remoteId parameter) "
         "to reflect that the value is now a device_id string used in federation API URLs"
     )
+
+
+# ─── Task 12: Remove 'filtered' from gridViewMode options ─────────────────────
+
+
+def test_load_grid_view_mode_guards_filtered_value() -> None:
+    """loadGridViewMode must remap 'filtered' to 'flat' for users who had it set."""
+    match = re.search(
+        r"function loadGridViewMode\s*\(\s*\)\s*\{(.*?)(?=\nfunction |\n// |\n/\*\*)",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "loadGridViewMode function not found"
+    body = match.group(1)
+    assert "filtered" in body, (
+        "loadGridViewMode must guard against 'filtered': "
+        "if (mode === 'filtered') mode = 'flat';  — graceful fallback for existing users"
+    )
+    assert "flat" in body, (
+        "loadGridViewMode must fall back to 'flat' when mode is 'filtered'"
+    )
+
+
+def test_set_grid_view_mode_guards_filtered_value() -> None:
+    """_setGridViewMode (test helper) must remap 'filtered' to 'flat'."""
+    match = re.search(
+        r"function _setGridViewMode\s*\(\w+\)\s*\{(.*?)(?=\n\})",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "_setGridViewMode function not found"
+    body = match.group(1)
+    assert "filtered" in body, (
+        "_setGridViewMode must guard against 'filtered': "
+        "if (mode === 'filtered') mode = 'flat';"
+    )
+    assert "flat" in body, "_setGridViewMode must remap 'filtered' to 'flat'"
+
+
+def test_render_grid_no_filtered_mode_check() -> None:
+    """renderGrid must not contain any _gridViewMode === 'filtered' check.
+
+    The 'filtered' gridViewMode has been removed.  All references in renderGrid
+    that branch on _gridViewMode === 'filtered' must be deleted so the filter bar
+    is never rendered and the device-filter logic is never applied.
+    """
+    match = re.search(
+        r"function renderGrid\s*\(\w+\)\s*\{(.*?)(?=\n(?:function|//|window\.))",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "renderGrid function not found in app.js"
+    body = match.group(1)
+    assert "'filtered'" not in body and '"filtered"' not in body, (
+        "renderGrid must not check _gridViewMode === 'filtered' — "
+        "the 'filtered' mode has been removed; only 'flat' and 'grouped' remain"
+    )