InfoPanel: custom edit templates & null edit model fix

- Add InfoPanelEditTemplate to MgGridDataColumn for custom InfoPanel editors with refresh support
- Introduce MgGridInfoPanelEditContext for edit context/refresh
- Harden OnCustomizeEditModel to handle null edit models, preventing InfoPanel crashes and logging warnings
- Update docs: usage, editor resolution order, and new issue entry (ACBLAZOR-GRID-I-N7K2)
- Refactor grid templates to use new features and ensure consistent editor behavior
- Minor doc and formatting improvements

AyCode.Blazor.Components/Components/Grids/MgGridBase.cs

@@ -509,11 +509,7 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
     protected PropertyInfo? GetDataItemPropertyInfo(string propertyName)
         => typeof(TDataItem).GetProperty(propertyName);
 
-    protected virtual async Task OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
+    private void InitializeNewEditModel(TDataItem editModel)
-    {
-        var editModel = (e.EditModel as TDataItem)!;
-
-        if (e.IsNew)
     {
         if (!HasIdValue(editModel)) SetNewId(editModel);
 
@@ -522,7 +518,15 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
             KeyFieldPropertyInfoToParent ??= GetDataItemPropertyInfo(KeyFieldNameToParentId);
             KeyFieldPropertyInfoToParent!.SetValue(editModel, ParentDataItem.Id);
         }
+    }
 
+    protected virtual async Task OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
+    {
+        var editModel = e.EditModel as TDataItem;
+
+        if (e.IsNew && editModel != null)
+        {
+            InitializeNewEditModel(editModel);
             e.EditModel = editModel;
         }
 
@@ -531,8 +535,24 @@ public abstract class MgGridBase<TSignalRDataSource, TDataItem, TId, TLoggerClie
 
         await OnGridCustomizeEditModel.InvokeAsync(e);
 
+        // Re-read after the consumer callback — it may have created/replaced the edit model
+        // (the official DevExpress pattern for types without a parameterless constructor)
+        var preCallbackModel = editModel;
+        editModel = e.EditModel as TDataItem;
+
+        // Initialize any IsNew instance the pre-callback block has not seen (consumer-replaced or consumer-created)
+        if (e.IsNew && editModel != null && !ReferenceEquals(editModel, preCallbackModel))
+            InitializeNewEditModel(editModel);
+
         // Update InfoPanel to edit mode
+        if (editModel != null)
+        {
             InfoPanelInstance?.SetEditMode(this, editModel);
+        }
+        else
+        {
+            Logger.Warning($"[{GetType().Name}] CustomizeEditModel produced no edit model (EditModel is null or not {typeof(TDataItem).Name}); InfoPanel stays in view mode");
+        }
 
         await InvokeAsync(StateHasChanged);
     }

AyCode.Blazor.Components/Components/Grids/MgGridDataColumn.cs

@@ -7,6 +7,12 @@ using System.Text.RegularExpressions;
 
 namespace AyCode.Blazor.Components.Components.Grids;
 
+/// <summary>
+/// Context for <see cref="MgGridDataColumn.InfoPanelEditTemplate"/>: the edit model plus a Refresh action
+/// that re-renders the InfoPanel — call it after mutations other fields depend on (e.g. cascading lookups).
+/// </summary>
+public sealed record MgGridInfoPanelEditContext(object EditModel, Action Refresh);
+
 /// <summary>
 /// Extended DxGridDataColumn with additional parameters for InfoPanel support.
 /// </summary>
@@ -36,6 +42,14 @@ public partial class MgGridDataColumn : DxGridDataColumn
     [Parameter]
     public int InfoPanelOrder { get; set; } = int.MaxValue;
 
+    /// <summary>
+    /// Custom InfoPanel editor for this column (edit mode). Takes precedence over the EditSettings /
+    /// property-type based default editors. Use when the grid-side editor is a CellEditTemplate the
+    /// InfoPanel cannot reuse (e.g. cascading lookups).
+    /// </summary>
+    [Parameter]
+    public RenderFragment<MgGridInfoPanelEditContext>? InfoPanelEditTemplate { get; set; }
+
     /// <summary>
     /// URL template with {property} placeholders that will be replaced with row values.
     /// Example: https://shop.fruitbank.hu/Admin/Order/Edit/{Id}/{OrderId}

AyCode.Blazor.Components/Components/Grids/MgGridInfoPanel.razor

@@ -133,6 +133,14 @@
         return builder =>
         {
             var seq = 0;
+
+            // Column-provided editor template wins (e.g. cascading lookups the settings pipeline cannot express)
+            if (column is MgGridDataColumn { InfoPanelEditTemplate: not null } mgColumn)
+            {
+                builder.AddContent(seq++, mgColumn.InfoPanelEditTemplate(new MgGridInfoPanelEditContext(dataItem, () => InvokeAsync(StateHasChanged))));
+                return;
+            }
+
             var propertyInfo = dataItemType.GetProperty(column.FieldName);
 
             if (propertyInfo == null)

AyCode.Blazor.Components/docs/MGGRID/MGGRID_COLUMNS.md

@@ -11,8 +11,26 @@ Extended `DxGridDataColumn` with InfoPanel and URL link support.
 | `ShowInInfoPanel` | `bool` | `true` | Whether this column is visible in InfoPanel |
 | `InfoPanelDisplayFormat` | `string?` | `null` | Custom display format for InfoPanel |
 | `InfoPanelOrder` | `int` | `int.MaxValue` | Column order in InfoPanel (lower = earlier) |
+| `InfoPanelEditTemplate` | `RenderFragment<MgGridInfoPanelEditContext>?` | `null` | Custom InfoPanel editor (edit mode) — takes precedence over the `EditSettings` / property-type default editors |
 | `UrlLink` | `string?` | `null` | URL template with `{Property}` placeholders |
 
 **UrlLink example:** `https://admin.example.com/Entity/Edit/{Id}` — renders cell as `<a href="..." target="_blank">`.
 
+## InfoPanelEditTemplate
+
+Use when the grid-side editor is a `CellEditTemplate` the InfoPanel cannot reuse (it is bound to the grid-cell
+context) — without it, the panel falls back to the property-type default editor (e.g. `int` → number spinner).
+Context: `MgGridInfoPanelEditContext(object EditModel, Action Refresh)` — call `Refresh()` after mutations
+other fields depend on (cascading lookups), it re-renders the InfoPanel.
+
+```razor
+<MgGridDataColumn FieldName="CategoryId" Caption="Category">
+    <CellEditTemplate>@CategoryEditor((MyItem)context.EditModel)</CellEditTemplate>
+    <InfoPanelEditTemplate>@CategoryEditor((MyItem)context.EditModel, context.Refresh)</InfoPanelEditTemplate>
+</MgGridDataColumn>
+```
+
+Define the editor once as a shared fragment (`private RenderFragment CategoryEditor(MyItem item, Action? refresh = null) => @<DxComboBox ...>;`)
+so the grid cell and the InfoPanel render the same component — no duplicated markup.
+
 Uses compiled property accessors (`ConcurrentDictionary` cache) for performance.

AyCode.Blazor.Components/docs/MGGRID/MGGRID_INFOPANEL.md

@@ -52,6 +52,10 @@ Edit starts       → InfoPanelInstance.SetEditMode(grid, editModel)
 Edit ends/cancel  → InfoPanelInstance.ClearEditMode()
 ```
 
+When the grid produces no edit model (`CustomizeEditModel` fires with a null `EditModel` — e.g. stale
+focused row after a datasource reload), `SetEditMode` is skipped with a `Logger.Warning` and the panel
+stays in view mode (see `MGGRID_ISSUES.md#acblazor-grid-i-n7k2`).
+
 `InfoPanelInstance` resolution: own `GridWrapper.InfoPanelInstance` → root grid's `GridWrapper.InfoPanelInstance` → `null`.
 
 ### Responsive Column Layout
@@ -77,10 +81,20 @@ Edit ends/cancel  → InfoPanelInstance.ClearEditMode()
 
 `InfoPanelContext` = `record(object? DataItem, bool IsEditMode)`.
 
-### Edit Mode Editors (by property type)
+### Edit Mode Editors
+
+Edit mode reads/writes properties via reflection and **assumes non-throwing accessors** — computed
+properties (e.g. GenericAttribute-backed getters that fail on edit-model copies, or deliberately
+throwing setters) MUST be declared `ReadOnly` on the column, otherwise rendering the editor crashes.
+This is by design (fail-fast): the missing `ReadOnly` declaration is a consumer bug that should surface
+in development, not be masked by silent fallbacks.
+
+Editor resolution order: **column `InfoPanelEditTemplate` first** (`MgGridDataColumn` — see `MGGRID_COLUMNS.md`),
+then `EditSettings` (`DxComboBoxSettings`, `Memo`), then property type:
 
 | Type | Editor Component |
 |---|---|
+| Column `InfoPanelEditTemplate` (`MgGridDataColumn`) | the provided template — wins over everything below |
 | `bool` | `DxCheckBox<bool>` |
 | `DateTime` / `DateTime?` | `DxDateEdit<DateTime>` / `DxDateEdit<DateTime?>` |
 | `DateOnly` / `DateOnly?` | `DxDateEdit<DateOnly>` / `DxDateEdit<DateOnly?>` |
@@ -94,5 +108,5 @@ Edit ends/cancel  → InfoPanelInstance.ClearEditMode()
 ### Additional Features
 
 - **Sticky positioning** via JS interop (`MgGridInfoPanel.initSticky`)
-- **Built-in toolbar** with `MgGridToolbarTemplate` (`OnlyGridEditTools=true`)
+- **Built-in toolbar** with `MgGridToolbarTemplate` (`OnlyGridEditTools=true`) — its edit tools are currently not configurable per grid (hardcoded `EnableNew`/`EnableEdit` defaults; see `MGGRID_ISSUES.md#acblazor-grid-i-k5r3`)
 - **OnDataItemChanged** callback when focused row changes

AyCode.Blazor.Components/docs/MGGRID/MGGRID_ISSUES.md

@@ -1,10 +1,65 @@
 # MGGRID — Known Issues
 
-For planned/actionable work see `MGGRID_TODO.md`.
+For planned/actionable work see `MGGRID_TODO.md`. In-code TODOs are recorded as TODO entries (`ACBLAZOR-GRID-T-*`) there, since they describe unfinished work rather than confirmed broken behaviour.
 
-No formally-tracked issues yet. In-code TODOs are recorded as TODO entries (`ACBLAZOR-GRID-T-*`) in `MGGRID_TODO.md`, since they describe unfinished work rather than confirmed broken behaviour.
+## ACBLAZOR-GRID-I-N7K2: InfoPanel.SetEditMode crashes the WASM renderer when DxGrid produces no edit model
 
-Add the first `## ACBLAZOR-GRID-I-XXXX: ...` entry below when a concrete issue is observed.
+**Severity:** Major (unhandled exception killed the renderer) · **Status:** Closed (2026-07-12) · **Area:** `Components/Grids/MgGridBase.cs` → `OnCustomizeEditModel`
+
+### Description
+Clicking the toolbar Edit button could crash the entire WebAssembly renderer with
+`System.ArgumentNullException: editModel` thrown by `MgGridInfoPanel.SetEditMode`. Observed on a
+`ProductDto` grid right after a datasource reload (`OnDataSourceLoaded` → immediate Edit click):
+DevExpress `StartEditRowAsync` raised `CustomizeEditModel` with `e.EditModel == null` (stale
+`FocusedRowVisibleIndex` → null data item), and `OnCustomizeEditModel` passed the null straight to
+`SetEditMode`, whose `ArgumentNullException.ThrowIfNull` escalated to an unhandled rendering exception.
+
+### Root cause
+`MgGridBase.OnCustomizeEditModel` captured `(e.EditModel as TDataItem)!` (null-forgiving cast) with no
+null check, and on the Edit path (`IsNew == false`) nothing validated it before
+`InfoPanelInstance.SetEditMode`. The local was also captured BEFORE the `OnGridCustomizeEditModel`
+consumer callback — so a consumer-created edit model (the official DevExpress pattern for types without
+a parameterless constructor) never reached the InfoPanel either.
+
+### Resolution (2026-07-12)
+`OnCustomizeEditModel` hardened: null-tolerant cast, guarded `IsNew` branch, the edit model is re-read
+AFTER the consumer callback, and when it is still null the InfoPanel stays in view mode with a
+`Logger.Warning` (`[GridName] CustomizeEditModel produced no edit model...`) instead of crashing.
+
+### Known workaround
+None needed after the fix.
+
+### Related TODO
+None.
+
+## ACBLAZOR-GRID-I-K5R3: InfoPanel built-in toolbar edit tools are not configurable
+
+**Severity:** Minor (UX / consistency gap; can re-open a crash path on listing-only grids) · **Status:** Open · **Area:** `Components/Grids/MgGridInfoPanel.razor` (built-in toolbar) + `MgGridToolbarTemplate`
+
+### Description
+`MgGridInfoPanel` renders its built-in toolbar with hardcoded defaults
+(`MgGridInfoPanel.razor:20`: `<MgGridToolbarTemplate Grid="_currentGrid" OnlyGridEditTools="true" ShowOnlyIcon="true" />`),
+so `EnableNew` / `EnableEdit` are always `true` there. When a consumer disables New/Edit on its own
+master toolbar (e.g. a listing-only grid such as a product grid whose data is managed in an external
+admin and has no Add/Update SignalR tags), the InfoPanel toolbar still offers **+** and **edit** —
+the edit flow can be started through a side door the consumer cannot close.
+
+### Root cause
+The panel's toolbar instance is not parameterizable from the outside, and there is no grid-level
+edit-enable flag the toolbar could consult — the `Enable*` flags live only on individual
+`MgGridToolbarTemplate` instances.
+
+### Known workaround
+None from the consumer side (the panel toolbar cannot be reached). Master-toolbar `EnableNew="false"
+EnableEdit="false"` covers the primary path only.
+
+### Proposed fix
+Grid-level `EditItemsEnabled` parameter on `MgGridBase` / `IMgGridBase` (default `true`);
+`MgGridToolbarTemplate` computes effective enablement as `own Enable* && Grid.EditItemsEnabled`,
+so both the master and the built-in InfoPanel toolbar respect a single consumer declaration.
+
+### Related TODO
+None yet — becomes a TODO when scheduled.
 
 ## Issue entry template
 

AyCode.Blazor.Components/docs/MGGRID/README.md

@@ -28,7 +28,7 @@
 | `MGGRID_TOOLBAR.md` | MgGridToolbarTemplate (buttons, parameters, state) |
 | `MGGRID_COLUMNS.md` | MgGridDataColumn (InfoPanel params, UrlLink) |
 | `MGGRID_DATASOURCE.md` | MgGridSignalRDataSource (server-side data, local cache, background refresh) |
-| `MGGRID_ISSUES.md` | Known issues (`ACBLAZOR-GRID-I-*`, `ACBLAZOR-GRID-B-*`) — currently none formally tracked |
+| `MGGRID_ISSUES.md` | Known issues (`ACBLAZOR-GRID-I-*`, `ACBLAZOR-GRID-B-*`) |
 | `MGGRID_TODO.md` | Planned work (`ACBLAZOR-GRID-T-*`) — refactors, missing features, optimizations |
 
 ## Component Hierarchy