feat(cms): dedicated grid columns for medium-specific row actions

Replace CmsAlbumBrowser's single RowActions slot with a SpecialColumns
list (header + per-row cell). Mix renders a Waveform column, Session a
Hero column, between Tracks and Actions; Edit/Delete stay rightmost.
Child-row colspan now computed from column count. Cut/ALL unchanged.

DeepDrftManager/Components/Pages/Tracks/CmsAlbumBrowser.razor

@@ -33,6 +33,10 @@ else
             <MudTh>Release Date</MudTh>
             <MudTh>Type</MudTh>
             <MudTh Style="width: 1%; white-space: nowrap;">Tracks</MudTh>
+            @foreach (var column in SpecialColumns)
+            {
+                <MudTh Style="width: 1%; white-space: nowrap;">@column.Header</MudTh>
+            }
             <MudTh Style="width: 1%; white-space: nowrap;">Actions</MudTh>
         </HeaderContent>
         <RowTemplate>
@@ -64,11 +68,14 @@ else
                 </MudChip>
             </MudTd>
             <MudTd DataLabel="Tracks">@context.TrackCount</MudTd>
+            @foreach (var column in SpecialColumns)
+            {
+                @* One dedicated cell per host-declared special-action column (Mix waveform, Session hero).
+                   The Cell fragment recovers its typed row state via the host's RowFor lookup. Sits between
+                   Tracks and Actions so the universal Edit/Delete stay rightmost. *@
+                <MudTd DataLabel="@column.Header">@column.Cell(context.Release)</MudTd>
+            }
             <MudTd DataLabel="Actions">
-                @* Medium-specific row action (Session hero, Mix waveform) when a host supplies one;
-                   the ALL tab supplies none. Rendered before the shared edit/delete so the medium
-                   affordance reads left-to-right ahead of the universal actions. *@
-                @RowActions?.Invoke(context.Release)
                 <MudTooltip Text="Batch Edit">
                     <MudIconButton Icon="@Icons.Material.Filled.Edit"
                                    Size="Size.Small"
@@ -88,7 +95,7 @@ else
             @if (context.IsExpanded)
             {
                 <MudTr>
-                    <MudTd colspan="9" Style="padding: 0;">
+                    <MudTd colspan="@ColumnCount" Style="padding: 0;">
                         @if (context.IsLoading)
                         {
                             <MudStack Row="true" AlignItems="AlignItems.Center" Class="pa-2">
@@ -126,12 +133,19 @@ else
     [Parameter] public bool IsLoading { get; set; }
     [Parameter] public EventCallback OnReleasesChanged { get; set; }
 
-    // Optional per-row, medium-specific action slot (Session hero upload, Mix waveform generate),
+    // Zero or more dedicated, header-labelled special-action columns (Session hero upload, Mix waveform
-    // rendered in the Actions cell ahead of the shared edit/delete buttons. The ALL tab leaves it
+    // generate), each rendered as its own header cell + per-row cell between the Tracks and Actions
-    // unset and renders the grid exactly as before. A per-medium host (CmsCut/Session/MixBrowser)
+    // columns. The ALL and Cut tabs leave this empty and render exactly as before — only the standard
-    // supplies it so the rich grid filtered to one medium keeps that medium's bespoke affordance —
+    // columns plus Edit/Delete. A per-medium host supplies its bespoke affordances here so the rich
-    // the rich expand/delete/Type-chip/edit logic stays here, single-sourced, rather than forked.
+    // expand/delete/Type-chip/edit logic stays single-sourced in this grid rather than forked.
-    [Parameter] public RenderFragment<ReleaseDto>? RowActions { get; set; }
+    [Parameter] public IReadOnlyList<SpecialActionColumn> SpecialColumns { get; set; } = Array.Empty<SpecialActionColumn>();
+
+    // Base columns: expand, Art, Album, Artist, Genre, Release Date, Type, Tracks, Actions = 9.
+    private const int BaseColumnCount = 9;
+
+    // Total rendered columns, driving the expanded child-row colspan so it always spans the full table
+    // regardless of how many special-action columns the host declared.
+    private int ColumnCount => BaseColumnCount + SpecialColumns.Count;
 
     private List<AlbumRow> _rows = new();
 

DeepDrftManager/Components/Pages/Tracks/CmsMixBrowser.razor

@@ -52,13 +52,22 @@ else
     protected override ReleaseDto ReleaseOf(MixRow row) => row.Release;
 
     // The grid itself — identical in the embedded and standalone contexts. Defined once as a fragment so
-    // both branches above render the same markup without duplication. The waveform generate is the Mix's
+    // both branches above render the same markup without duplication. The Mix declares one dedicated
-    // medium-specific RowActions content; the grid hands it each release, and RowFor recovers the
+    // "Waveform" special-action column; the grid renders it between Tracks and Actions, handing the cell
-    // matching MixRow's generate state.
+    // each release, and RowFor recovers the matching MixRow's generate state.
     private RenderFragment GridContent => @<CmsAlbumBrowser Releases="Releases"
                                                            IsLoading="Loading"
-                                                           OnReleasesChanged="ReloadAsync">
+                                                           OnReleasesChanged="ReloadAsync"
-        <RowActions Context="release">
+                                                           SpecialColumns="_specialColumns" />;
+
+    private IReadOnlyList<SpecialActionColumn> _specialColumns => new[]
+    {
+        new SpecialActionColumn("Waveform", WaveformCell)
+    };
+
+    // Per-row cell for the dedicated "Waveform" column: status icon plus generate/regenerate button with
+    // progress. Recovers the typed MixRow via RowFor; skips rendering for a release not on the page.
+    private RenderFragment<ReleaseDto> WaveformCell => release =>@<text>
         @{ var row = RowFor(release); }
         @if (row is not null)
         {
@@ -90,8 +99,7 @@ else
                 }
             </MudButton>
         }
-        </RowActions>
+    </text>;
-    </CmsAlbumBrowser>;
 
     private async Task GenerateWaveformAsync(MixRow row)
     {

DeepDrftManager/Components/Pages/Tracks/CmsSessionBrowser.razor

@@ -53,13 +53,22 @@ else
     protected override ReleaseDto ReleaseOf(SessionRow row) => row.Release;
 
     // The grid itself — identical in the embedded and standalone contexts. Defined once as a fragment so
-    // both branches above render the same markup without duplication. The hero upload is the Session's
+    // both branches above render the same markup without duplication. The Session declares one dedicated
-    // medium-specific RowActions content; the grid hands it each release, and RowFor recovers the
+    // "Hero" special-action column; the grid renders it between Tracks and Actions, handing the cell each
-    // matching SessionRow's upload state.
+    // release, and RowFor recovers the matching SessionRow's upload state.
     private RenderFragment GridContent => @<CmsAlbumBrowser Releases="Releases"
                                                            IsLoading="Loading"
-                                                           OnReleasesChanged="ReloadAsync">
+                                                           OnReleasesChanged="ReloadAsync"
-        <RowActions Context="release">
+                                                           SpecialColumns="_specialColumns" />;
+
+    private IReadOnlyList<SpecialActionColumn> _specialColumns => new[]
+    {
+        new SpecialActionColumn("Hero", HeroCell)
+    };
+
+    // Per-row cell for the dedicated "Hero" column: thumbnail preview plus set/replace upload button with
+    // progress. Recovers the typed SessionRow via RowFor; skips rendering for a release not on the page.
+    private RenderFragment<ReleaseDto> HeroCell => release =>@<text>
         @{ var row = RowFor(release); }
         @if (row is not null)
         {
@@ -93,8 +102,7 @@ else
                 </ActivatorContent>
             </MudFileUpload>
         }
-        </RowActions>
+    </text>;
-    </CmsAlbumBrowser>;
 
     private async Task UploadHeroAsync(SessionRow row, IBrowserFile? file)
     {

DeepDrftManager/Components/Pages/Tracks/SpecialActionColumn.cs

@@ -0,0 +1,15 @@
+using DeepDrftModels.DTOs;
+using Microsoft.AspNetCore.Components;
+
+namespace DeepDrftManager.Components.Pages.Tracks;
+
+/// <summary>
+/// A dedicated, header-labelled grid column for a medium-specific row affordance (e.g. Mix waveform
+/// generate, Session hero upload) in <see cref="CmsAlbumBrowser"/>. A per-medium host declares zero or
+/// more of these; the grid renders one extra header cell and one extra per-row cell for each, positioned
+/// between the Tracks column and the universal Actions (Edit/Delete) column. The <see cref="Cell"/>
+/// fragment is handed each release; the host recovers its typed row state via its own RowFor lookup.
+/// </summary>
+/// <param name="Header">Column header label (e.g. "Waveform", "Hero").</param>
+/// <param name="Cell">Per-row cell content for a given release.</param>
+public sealed record SpecialActionColumn(string Header, RenderFragment<ReleaseDto> Cell);