diff --git a/AyCode.Blazor.Components/Components/Grids/MgGridBase.cs b/AyCode.Blazor.Components/Components/Grids/MgGridBase.cs
index 943e7d3..faf1036 100644
--- a/AyCode.Blazor.Components/Components/Grids/MgGridBase.cs
+++ b/AyCode.Blazor.Components/Components/Grids/MgGridBase.cs
@@ -101,6 +101,15 @@ public interface IMgGridBase : IGrid
     /// <paramref name="criteria"/> = null clears this field's filter. See ADR 0004.
     /// </summary>
     void SetFieldQuickFilter(string fieldName, CriteriaOperator? criteria);
+
+    /// <summary>Whether this grid has a quick-filter panel (i.e. <c>FilterPanel</c> is set).</summary>
+    bool HasFilterPanel { get; }
+
+    /// <summary>Whether the quick-filter panel is currently shown (toggled from the toolbar).</summary>
+    bool IsFilterPanelVisible { get; }
+
+    /// <summary>Shows/hides the quick-filter panel. No-op when the grid has no filter panel.</summary>
+    void ToggleFilterPanel();
 }
 
 public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClient> : DxGrid, IMgGridBase, IAsyncDisposable
@@ -251,7 +260,13 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
                 // Body
                 contentBuilder.OpenElement(12, "div");
                 contentBuilder.AddAttribute(13, "class", "mg-fullscreen-body");
-                if (FilterPanel != null) contentBuilder.AddContent(14, FilterPanel);
+                if (FilterPanel != null && IsFilterPanelVisible)
+                {
+                    contentBuilder.OpenElement(14, "div");
+                    contentBuilder.AddAttribute(15, "class", "mg-grid-filter-panel");
+                    contentBuilder.AddContent(16, FilterPanel);
+                    contentBuilder.CloseElement();
+                }
                 base.BuildRenderTree(contentBuilder);
                 contentBuilder.CloseElement(); // body div
 
@@ -263,7 +278,13 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
                 contentBuilder.OpenElement(0, "div");
                 contentBuilder.SetKey(_gridRenderKey);
                 contentBuilder.AddAttribute(1, "style", "display: contents;");
-                if (FilterPanel != null) contentBuilder.AddContent(2, FilterPanel);
+                if (FilterPanel != null && IsFilterPanelVisible)
+                {
+                    contentBuilder.OpenElement(2, "div");
+                    contentBuilder.AddAttribute(3, "class", "mg-grid-filter-panel");
+                    contentBuilder.AddContent(4, FilterPanel);
+                    contentBuilder.CloseElement();
+                }
                 base.BuildRenderTree(contentBuilder);
                 contentBuilder.CloseElement();
             }
@@ -294,12 +315,28 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
     [Parameter] public string Caption { get; set; } = typeof(TDataItem).Name;
 
     /// <summary>
-    /// Optional quick-filter panel rendered above the grid (typically a <c>GridFilterPanel</c> hosting
-    /// <see cref="MgTagBox{TData,TValue}"/> controls). Rendered within this grid's <see cref="IMgGridBase"/>
+    /// Optional quick-filter controls (typically <see cref="MgTagBox{TData,TValue}"/>) rendered above the grid
+    /// inside a styled <c>.mg-grid-filter-panel</c> container (the slot wraps the content). Within this grid's <see cref="IMgGridBase"/>
     /// cascade, so the controls can reach this grid and apply per-field filters. See ADR 0004.
     /// </summary>
     [Parameter] public RenderFragment? FilterPanel { get; set; }
 
+    /// <summary>Initial visibility of the <see cref="FilterPanel"/>; the toolbar toggle flips it at runtime. Default: shown.</summary>
+    [Parameter] public bool ShowFilterPanel { get; set; } = true;
+
+    /// <inheritdoc />
+    public bool HasFilterPanel => FilterPanel != null;
+
+    /// <inheritdoc />
+    public bool IsFilterPanelVisible { get; private set; } = true;
+
+    /// <inheritdoc />
+    public void ToggleFilterPanel()
+    {
+        IsFilterPanelVisible = !IsFilterPanelVisible;
+        InvokeAsync(StateHasChanged);
+    }
+
     /// <summary>
     /// Name for auto-saving/loading grid layout. If not set, defaults to "Grid{TDataItem.Name}"
     /// </summary>
@@ -406,6 +443,8 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
         if (Logger == null)
             throw new NullReferenceException($"[{GetType().Name}] Logger == null");
 
+        IsFilterPanelVisible = ShowFilterPanel;
+
         if (SignalRClient == null)
         {
             Logger.Error($"[{GetType().Name}] SignalRClient == null");
diff --git a/AyCode.Blazor.Components/Components/Grids/MgGridFilterPanelBase.cs b/AyCode.Blazor.Components/Components/Grids/MgGridFilterPanelBase.cs
deleted file mode 100644
index 5a87c80..0000000
--- a/AyCode.Blazor.Components/Components/Grids/MgGridFilterPanelBase.cs
+++ /dev/null
@@ -1,32 +0,0 @@
-using Microsoft.AspNetCore.Components;
-using Microsoft.AspNetCore.Components.Rendering;
-
-namespace AyCode.Blazor.Components.Components.Grids;
-
-/// <summary>
-/// Base for a grid quick-filter panel — a styled container placed in a grid's <c>FilterPanel</c> slot,
-/// hosting <see cref="MgTagBox{TData,TValue}"/> (or other) per-field quick-filter controls above the grid.
-/// <para>
-/// Framework base. Projects derive a (typically empty) <c>GridFilterPanel</c> per the Mg* seam policy
-/// (cf. <c>MgGridBase</c> → project grid). The grid reference reaches the child controls via the grid's own
-/// <see cref="IMgGridBase"/> cascade (<c>MgGridBase</c> provides it) — this panel is layout only, no wiring.
-/// </para>
-/// </summary>
-public class MgGridFilterPanelBase : ComponentBase
-{
-    /// <summary>The quick-filter controls (e.g. <see cref="MgTagBox{TData,TValue}"/>) to render in the panel.</summary>
-    [Parameter] public RenderFragment? ChildContent { get; set; }
-
-    /// <summary>Extra CSS classes appended to the panel container.</summary>
-    [Parameter] public string? CssClass { get; set; }
-
-    protected override void BuildRenderTree(RenderTreeBuilder builder)
-    {
-        builder.OpenElement(0, "div");
-        builder.AddAttribute(1, "class", string.IsNullOrWhiteSpace(CssClass)
-            ? "mg-grid-filter-panel"
-            : $"mg-grid-filter-panel {CssClass}");
-        builder.AddContent(2, ChildContent);
-        builder.CloseElement();
-    }
-}
diff --git a/AyCode.Blazor.Components/Components/Grids/MgGridToolbarTemplate.razor b/AyCode.Blazor.Components/Components/Grids/MgGridToolbarTemplate.razor
index 75885d3..0162ecb 100644
--- a/AyCode.Blazor.Components/Components/Grids/MgGridToolbarTemplate.razor
+++ b/AyCode.Blazor.Components/Components/Grids/MgGridToolbarTemplate.razor
@@ -30,6 +30,7 @@
 			</Items>
 		</DxToolbarItem>
 		<DxToolbarItem Text="@(ShowOnlyIcon ? "" : "Reload data")" BeginGroup="true" Click="ReloadData_Click" IconCssClass="grid-refresh" Enabled="@(!IsSyncing && !_isReloadInProgress && !IsEditing)" />
+		<DxToolbarItem Text="@(ShowOnlyIcon ? "" : FilterPanelButtonText)" Click="FilterPanel_Click" IconCssClass="grid-filter" Visible="@Grid.HasFilterPanel" Enabled="@(!IsEditing)" />
 		<DxToolbarItem Text="@(ShowOnlyIcon ? "" : FullscreenButtonText)" Click="Fullscreen_Click" IconCssClass="@FullscreenIconCssClass" Enabled="@(!IsEditing)" />
 		@ToolbarItemsExtended
 	}
@@ -82,6 +83,16 @@
 	/// </summary>
 	private string FullscreenIconCssClass => IsFullscreenMode ? "grid-fullscreen-exit" : "grid-fullscreen";
 
+		/// <summary>
+		/// Whether the quick-filter panel is currently shown
+		/// </summary>
+		private bool IsFilterPanelVisible => Grid?.IsFilterPanelVisible ?? false;
+
+		/// <summary>
+		/// Button text for the filter-panel toggle
+		/// </summary>
+		private string FilterPanelButtonText => IsFilterPanelVisible ? "Hide Filters" : "Show Filters";
+
 	protected override async Task OnInitializedAsync()
 	{
 		_hasUserLayout = await Grid.HasUserLayoutAsync();
@@ -145,6 +156,11 @@
 		Grid.ToggleFullscreen();
 	}
 
+	void FilterPanel_Click()
+	{
+		Grid.ToggleFilterPanel();
+	}
+
 	async Task ExportXlsxItem_Click()
 	{
 		await Grid.ExportToXlsxAsync(ExportFileName);
diff --git a/AyCode.Blazor.Components/Components/Grids/README.md b/AyCode.Blazor.Components/Components/Grids/README.md
index eab2d31..4e3f772 100644
--- a/AyCode.Blazor.Components/Components/Grids/README.md
+++ b/AyCode.Blazor.Components/Components/Grids/README.md
@@ -4,10 +4,10 @@ Core grid system built on DevExpress `DxGrid`. For the full technical reference
 
 ## Key Files
 
-- **`MgGridBase.cs`** — `MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClient>`, the main abstract grid component. Extends `DxGrid` with SignalR CRUD, layout persistence, master-detail hierarchy, edit state tracking, fullscreen toggle.
+- **`MgGridBase.cs`** — `MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClient>`, the main abstract grid component. Extends `DxGrid` with SignalR CRUD, layout persistence, master-detail hierarchy, edit state tracking, fullscreen toggle, and a quick-filter `FilterPanel` slot (renders `MgTagBox` controls above the grid in a styled `.mg-grid-filter-panel` container; toolbar Show/Hide toggle).
 - **`MgGridWithInfoPanel.razor`** — `DxSplitter` wrapper: grid (left) + InfoPanel (right), fullscreen overlay, splitter size persistence.
 - **`MgGridToolbarBase.cs`** — Extends `DxToolbar` with `Grid`, `RefreshClick`, and `ShowOnlyIcon` parameters.
-- **`MgGridToolbarTemplate.razor`** — Full toolbar template: New/Edit/Delete/Save/Cancel, row navigation, layout menu (Load/Save/Reset), column chooser, export, reload, fullscreen. Extensible via `ToolbarItemsExtended`.
+- **`MgGridToolbarTemplate.razor`** — Full toolbar template: New/Edit/Delete/Save/Cancel, row navigation, layout menu (Load/Save/Reset), column chooser, export, reload, filter-panel toggle (visible only when the grid has a `FilterPanel`), fullscreen. Extensible via `ToolbarItemsExtended`.
 - **`MgGridDataColumn.cs`** — Extends `DxGridDataColumn` with InfoPanel parameters (`ShowInInfoPanel`, `InfoPanelOrder`, `InfoPanelDisplayFormat`) and `UrlLink` template with `{Property}` placeholder substitution via compiled accessors.
 - **`MgGridInfoPanel.razor`** / **`.razor.cs`** — `MgGridInfoPanel` implementing `IInfoPanelBase`. Responsive column layout (1-4 columns with breakpoints), edit/view mode with typed editors, template system, sticky positioning via JS interop.
 - **`MgGridSignalRDataSource.cs`** — `GridCustomDataSource` wrapping `AcSignalRDataSource`. Local cache for seen filter criteria, background refresh.
diff --git a/AyCode.Blazor.Components/Components/MgTagBox.cs b/AyCode.Blazor.Components/Components/MgTagBox.cs
index aea3e5a..85d7692 100644
--- a/AyCode.Blazor.Components/Components/MgTagBox.cs
+++ b/AyCode.Blazor.Components/Components/MgTagBox.cs
@@ -34,32 +34,31 @@ public class MgTagBox<TData, TValue> : DxTagBox<TData, TValue>
     /// </summary>
     [CascadingParameter] public IMgGridBase? Grid { get; set; }
 
-    private bool _initialized;
-    private IEnumerable<TValue>? _selected;
-
     protected override void OnParametersSet()
     {
         base.OnParametersSet();
 
-        // Own the selection internally so the consumer needs no @bind-Values.
-        // COMPILE-VERIFY (DevExpress version specific): Blazor re-applies base.Values / base.ValuesChanged from the
-        // consumer markup on every parameter set, so we re-assert ours here each time. First set adopts any initial Values.
-        if (!_initialized)
-        {
-            _selected = Values;
-            _initialized = true;
-        }
-
-        base.Values = _selected;
+        // Route the tag box's selection through our handler so a change applies the grid filter.
+        // (The consumer does not bind Values; the selection is owned internally — see OnSelectionChanged.)
         base.ValuesChanged = EventCallback.Factory.Create<IEnumerable<TValue>>(this, OnSelectionChanged);
     }
 
     private void OnSelectionChanged(IEnumerable<TValue>? values)
     {
-        _selected = values;
-        base.Values = values;   // reflect the new selection in the editor
+        // DevExpress tracks its parameters; setting Values imperatively (outside markup, e.g. from this event
+        // callback) must be wrapped in BeginUpdate/EndUpdate — otherwise DevExpress throws
+        // "A parameter value is specified outside a component's markup."
+        BeginUpdate();
+        try
+        {
+            Values = values;
+        }
+        finally
+        {
+            EndUpdate();
+        }
+
         ApplyQuickFilter(values);
-        StateHasChanged();
     }
 
     private void ApplyQuickFilter(IEnumerable<TValue>? values)
@@ -68,8 +67,7 @@ public class MgTagBox<TData, TValue> : DxTagBox<TData, TValue>
 
         var selected = values?.Where(v => v is not null).Cast<object>().ToArray() ?? [];
 
-        // COMPILE-VERIFY: confirm the InOperator(string, IEnumerable / params object[]) overload on your
-        // DevExpress.Data version. Empty selection => null => clears this field's filter.
+        // Empty selection => null => clears this field's filter. Otherwise IN(FieldName, selected...).
         CriteriaOperator? criteria = selected.Length > 0 ? new InOperator(FieldName, selected) : null;
 
         Grid.SetFieldQuickFilter(FieldName, criteria);
diff --git a/AyCode.Blazor.Components/Components/README.md b/AyCode.Blazor.Components/Components/README.md
index 008a925..97467a9 100644
--- a/AyCode.Blazor.Components/Components/README.md
+++ b/AyCode.Blazor.Components/Components/README.md
@@ -1,6 +1,6 @@
 # Components
 
-DevExpress component wrappers and grid infrastructure for the AyCode Blazor component library. Each `Ac*` class extends a DevExpress Blazor control to allow project-wide customization from a single point.
+DevExpress component wrappers and grid infrastructure for the AyCode Blazor component library. Each wrapper class extends a DevExpress Blazor control to allow project-wide customization from a single point (`Mg*` = current prefix; `Ac*` = legacy prefix, kept as-is).
 
 ## Key Files
 
@@ -13,6 +13,7 @@ DevExpress component wrappers and grid infrastructure for the AyCode Blazor comp
 - **`AcMaskedInput.cs`** -- Generic wrapper for `DxMaskedInput<T>`.
 - **`AcMemo.cs`** -- Extends `DxMemo`.
 - **`AcSpinEdit.cs`** -- Generic wrapper for `DxSpinEdit<T>`.
+- **`MgTagBox.cs`** -- Generic wrapper for `DxTagBox<TData, TValue>` with grid quick-filter support: a `FieldName` parameter + the grid cascade let a selection apply a per-field `IN` filter via `IMgGridBase.SetFieldQuickFilter` (see `Grids/` and `docs/MGGRID/MGGRID_PARAMETERS.md` → Quick-Filter Panel).
 - **`MgComponentsHelper.cs`** -- Placeholder helper class (currently empty).
 
 ## Subfolders
diff --git a/AyCode.Blazor.Components/docs/MGGRID/MGGRID_PARAMETERS.md b/AyCode.Blazor.Components/docs/MGGRID/MGGRID_PARAMETERS.md
index 3dd5a05..0773e74 100644
--- a/AyCode.Blazor.Components/docs/MGGRID/MGGRID_PARAMETERS.md
+++ b/AyCode.Blazor.Components/docs/MGGRID/MGGRID_PARAMETERS.md
@@ -41,6 +41,26 @@ These are bundled into a `SignalRCrudTags` during `OnInitializedAsync`. See `AyC
 | `AutoSaveLayoutName` | `string?` | `"Grid{TDataItem.Name}"` | Base name for layout storage keys |
 | `EnableServerLayouts` | `bool` | `true` | Roams the UserSave layout tier via the SignalR server endpoint (see `MGGRID_LAYOUT.md` → Server Roaming). Server calls happen only on the Save/Load layout buttons. |
 
+## Quick-Filter Panel
+
+| Parameter | Type | Default | Description |
+|---|---|---|---|
+| `FilterPanel` | `RenderFragment?` | `null` | Quick-filter controls rendered above the grid; the slot wraps them in a styled `.mg-grid-filter-panel` container. When set, the toolbar shows a Show/Hide Filters toggle (`MGGRID_TOOLBAR.md`). |
+| `ShowFilterPanel` | `bool` | `true` | Initial visibility of the filter panel; the toolbar toggle flips it at runtime (`IsFilterPanelVisible` / `ToggleFilterPanel`). |
+
+Place `MgTagBox` controls (from `Components/`) in the slot. Each control applies a per-field `IN(FieldName, selected...)` criteria via `IMgGridBase.SetFieldQuickFilter` → DevExpress `SetFieldFilterCriteria`; DevExpress AND-combines the per-field criteria with each other and with the user's filter row automatically (no clobber). Empty selection clears that field's filter.
+
+```razor
+<FilterPanel>
+    <MgTagBox TData="string" TValue="string" FieldName="Status"
+              Data="@_statusOptions" NullText="All statuses" />
+</FilterPanel>
+```
+
+Implementation note: imperative `Values` writes inside DevExpress editors must be wrapped in `BeginUpdate()`/`EndUpdate()` (the parameter tracker throws otherwise) — `MgTagBox` handles this internally.
+
+Design + the server-side forward path (`FilterMode.Server`): AyCode.Core repo `docs/adr/0004-signalr-datasource-server-side-filtering.md`.
+
 ## Event Callbacks
 
 All grid events are re-exposed with `OnGrid` prefix to avoid collisions with `DxGrid` base events:
diff --git a/AyCode.Blazor.Components/docs/MGGRID/MGGRID_TOOLBAR.md b/AyCode.Blazor.Components/docs/MGGRID/MGGRID_TOOLBAR.md
index 2885202..3a25848 100644
--- a/AyCode.Blazor.Components/docs/MGGRID/MGGRID_TOOLBAR.md
+++ b/AyCode.Blazor.Components/docs/MGGRID/MGGRID_TOOLBAR.md
@@ -15,6 +15,7 @@ The standard toolbar rendered inside grid's `ToolbarTemplate`. Provides all stan
 | **Navigation** | Prev Row, Next Row | When NOT editing |
 | **Layout** | Column Chooser, Layout (Load/Save/Reset) | When `OnlyGridEditTools=false` |
 | **Actions** | Export (CSV/XLSX/XLS/PDF), Reload Data, Fullscreen | When `OnlyGridEditTools=false` |
+| **Quick-filter** | Show Filters / Hide Filters (toggles the `FilterPanel`) | When `OnlyGridEditTools=false` AND `Grid.HasFilterPanel` |
 
 ### Parameters
 
@@ -37,3 +38,4 @@ The standard toolbar rendered inside grid's `ToolbarTemplate`. Provides all stan
 | `IsSyncing` | `Grid.IsSyncing` |
 | `HasFocusedRow` | `Grid.GetFocusedRowIndex() >= 0` |
 | `IsFullscreenMode` | `Grid.IsFullscreen` |
+| `IsFilterPanelVisible` | `Grid.IsFilterPanelVisible` |
diff --git a/AyCode.Blazor.Components/docs/MGGRID/README.md b/AyCode.Blazor.Components/docs/MGGRID/README.md
index adafe30..ffbd8fb 100644
--- a/AyCode.Blazor.Components/docs/MGGRID/README.md
+++ b/AyCode.Blazor.Components/docs/MGGRID/README.md
@@ -14,12 +14,13 @@
 - **InfoPanel integration** — side panel shows focused row details, supports edit mode
 - **Fullscreen mode** — standalone overlay or via `MgGridWithInfoPanel` wrapper
 - **Change tracking** — client-side tracking with server sync via `SaveChangesAsync`
+- **Quick-filter panel** — `FilterPanel` slot above the grid hosting `MgTagBox` controls; per-field criteria AND-combined by DevExpress with the user's filter row; toolbar Show/Hide toggle (see `MGGRID_PARAMETERS.md` → Quick-Filter Panel; design: AyCode.Core repo `docs/adr/0004-signalr-datasource-server-side-filtering.md`)
 
 ## Detailed Documentation
 
 | File | Topics |
 |---|---|
-| `MGGRID_PARAMETERS.md` | Component parameters (required, CRUD tags, data & context, display), event callbacks, default grid settings |
+| `MGGRID_PARAMETERS.md` | Component parameters (required, CRUD tags, data & context, display), quick-filter panel (`FilterPanel` slot + `MgTagBox`), event callbacks, default grid settings |
 | `MGGRID_CRUD.md` | Lifecycle, CRUD operations, ID generation, edit flow, disposal |
 | `MGGRID_LAYOUT.md` | Layout persistence (storage keys, three tiers, operations, persisted state) |
 | `MGGRID_DETAIL.md` | Master-detail hierarchy |
@@ -96,6 +97,10 @@ The public contract exposed to companion components (toolbar, InfoPanel, wrapper
 | `IsFullscreen` | `bool` | Current fullscreen state |
 | `AutomaticLayoutStorageKey` | `string` | Current auto-save storage key |
 | `ToggleFullscreen()` | `void` | Toggle fullscreen mode |
+| `SetFieldQuickFilter(fieldName, criteria)` | `void` | Apply/clear a per-field quick-filter (delegates to DevExpress `SetFieldFilterCriteria`; `null` criteria clears the field) |
+| `HasFilterPanel` | `bool` | Whether the grid has a `FilterPanel` (drives toolbar-toggle visibility) |
+| `IsFilterPanelVisible` | `bool` | Current quick-filter panel visibility |
+| `ToggleFilterPanel()` | `void` | Show/hide the quick-filter panel |
 | `SaveUserLayoutAsync()` | `Task` | Save layout manually |
 | `LoadUserLayoutAsync()` | `Task` | Load manually saved layout |
 | `ResetLayoutAsync()` | `Task` | Reset to default layout |
diff --git a/AyCode.Blazor.Components/wwwroot/css/mg-grid-info-panel.css b/AyCode.Blazor.Components/wwwroot/css/mg-grid-info-panel.css
index 9fde37d..9701eed 100644
--- a/AyCode.Blazor.Components/wwwroot/css/mg-grid-info-panel.css
+++ b/AyCode.Blazor.Components/wwwroot/css/mg-grid-info-panel.css
@@ -5,6 +5,18 @@
    These are defined on .dxbl-theme-fluent class and inherited by child elements.
 */
 
+/* Grid quick-filter panel (rendered above the grid; hosts MgTagBox quick-filter controls) */
+.mg-grid-filter-panel {
+	display: flex;
+	flex-wrap: wrap;
+	align-items: center;
+	gap: var(--DS-sizing-80, 0.5rem);
+	padding: var(--DS-sizing-80, 0.5rem) var(--DS-sizing-160, 1rem);
+	background-color: var(--DS-color-surface-neutral-subdued-rest, #f8f9fa);
+	border: 1px solid var(--DS-color-border-neutral-default-rest, #dee2e6);
+	border-bottom: none;
+}
+
 /* Main panel - uses DevExpress Design System variables */
 .mg-grid-info-panel {
 	background-color: var(--DS-color-surface-neutral-subdued-rest, #f8f9fa);