fix(cms): gate Session hero input to upload path; warn (not error) on missing hero

Edit forms (BatchEdit/TrackEdit/TrackNew) show the guidance alert instead of an
inert picker, via an AllowHeroUpload flag. Missing-hero nudge is Severity.Warning;
null-ReleaseId hero drop is now logged.

DeepDrftManager/Components/Pages/Tracks/AlbumHeaderFields.razor

@@ -68,6 +68,7 @@
                   @bind-ReleaseType="ReleaseTypeBinding"
                   HeroImageFile="HeroImageFile"
                   HeroImageFileChanged="HeroImageFileChanged"
+                  AllowHeroUpload="AllowHeroUpload"
                   Disabled="Disabled" />
 </MudPaper>
 
@@ -92,6 +93,10 @@
     [Parameter] public IBrowserFile? HeroImageFile { get; set; }
     [Parameter] public EventCallback<IBrowserFile?> HeroImageFileChanged { get; set; }
 
+    // Gates the hero file picker in SessionFields (threaded to MediumFields → SessionFields).
+    // Set true only on the BatchUpload create path; leave false/absent on all edit paths.
+    [Parameter] public bool AllowHeroUpload { get; set; }
+
     // BatchEdit only: when set (and no new file picked), preview the release's current cover.
     // The parent nulls this to drop the preview when the admin clears the existing cover.
     [Parameter] public string? ExistingImagePath { get; set; }

DeepDrftManager/Components/Pages/Tracks/BatchUpload.razor

@@ -27,6 +27,7 @@
                        MediumChanged="OnMediumChanged"
                        @bind-SelectedImageFile="_selectedImageFile"
                        @bind-HeroImageFile="_heroImageFile"
+                       AllowHeroUpload="true"
                        Disabled="_uploading" />
 
     @if (_medium == ReleaseMedium.Cut)
@@ -72,6 +73,11 @@
         <MudAlert Severity="Severity.Error" Class="mt-4">@_errorMessage</MudAlert>
     }
 
+    @if (!string.IsNullOrEmpty(_warningMessage))
+    {
+        <MudAlert Severity="Severity.Warning" Class="mt-4">@_warningMessage</MudAlert>
+    }
+
     <MudStack Row="true" Justify="Justify.FlexEnd" Spacing="2" Class="mt-4">
         <MudButton Variant="Variant.Text"
                    OnClick="@(() => Navigation.NavigateTo("/tracks"))"
@@ -105,6 +111,8 @@
     private bool _uploading;
     private int _uploadedCount;
     private string? _errorMessage;
+    // Separate from _errorMessage: a soft non-blocking nudge (Severity.Warning), not a hard failure.
+    private string? _warningMessage;
 
     private IBrowserFile? _selectedImageFile;
     private string? _imagePath;
@@ -205,6 +213,7 @@
     private async Task SubmitAsync()
     {
         _errorMessage = null;
+        _warningMessage = null;
 
         if (string.IsNullOrWhiteSpace(_albumName))
         {
@@ -258,7 +267,7 @@
         if (_medium == ReleaseMedium.Session && _heroImageFile is null && !_heroWarningAcknowledged)
         {
             _heroWarningAcknowledged = true;
-            _errorMessage = "No hero image selected. A Session usually needs one — you can add it now, "
+            _warningMessage = "No hero image selected. A Session usually needs one — you can add it now, "
                 + "or submit again to create the Session without it (set the hero later from the Sessions browser).";
             return;
         }
@@ -382,6 +391,15 @@
                                 Snackbar.Add("Session uploaded, but the hero image failed. Set it from the Sessions browser.", Severity.Warning);
                             }
                         }
+                        else if (_medium == ReleaseMedium.Session && _heroImageFile is not null)
+                        {
+                            // ReleaseId was null on a Session track result — internal inconsistency.
+                            // Hero file is held but cannot be uploaded without a release id; log and
+                            // surface so the admin can set it from the Sessions browser.
+                            Logger.LogWarning("Batch upload: Session track '{TrackName}' (id={Id}) has no ReleaseId — hero image dropped",
+                                row.TrackName, result.Value.Id);
+                            Snackbar.Add("Session uploaded, but the hero image could not be linked (no release id). Set it from the Sessions browser.", Severity.Warning);
+                        }
 
                         // Mix uploads fire the server-side high-res waveform trigger (§3.4). The CMS
                         // computes nothing — the API derives the datum from the audio it just stored.

DeepDrftManager/Components/Pages/Tracks/MediumFields.razor

@@ -29,6 +29,7 @@
         case ReleaseMedium.Session:
             <SessionFields HeroImageFile="HeroImageFile"
                            HeroImageFileChanged="HeroImageFileChanged"
+                           AllowHeroUpload="AllowHeroUpload"
                            Disabled="Disabled" />
             break;
         case ReleaseMedium.Mix:
@@ -49,5 +50,9 @@
     [Parameter] public IBrowserFile? HeroImageFile { get; set; }
     [Parameter] public EventCallback<IBrowserFile?> HeroImageFileChanged { get; set; }
 
+    // Gates the hero file picker in SessionFields. True on the BatchUpload create path;
+    // false/absent on all edit paths so SessionFields falls back to the guidance alert.
+    [Parameter] public bool AllowHeroUpload { get; set; }
+
     [Parameter] public bool Disabled { get; set; }
 }

DeepDrftManager/Components/Pages/Tracks/SessionFields.razor

@@ -1,11 +1,13 @@
 @using Microsoft.AspNetCore.Components.Forms
 
-@* Session-medium fields. The hero image is resource-addressed (POST api/release/{id}/session/hero-image)
+@* Session-medium fields. When AllowHeroUpload is true (BatchUpload create path), the hero image
-   and therefore cannot be uploaded until the release exists. The file is selected here, held by the
+   file picker is shown — the file is held by the parent and POSTed after the release is created.
-   parent form, and uploaded after the create call returns a release id — the same deferred-upload
+   When false (edit paths: BatchEdit, TrackEdit, TrackNew), the original guidance alert is rendered
-   pattern AlbumHeaderFields uses for cover art ("Will upload on submit"). The hero is optional; the
+   instead, directing the admin to the Sessions browser per-row replace action. This gate prevents
-   parent warns (does not block) when a Session is submitted without one. *@
+   a dead/inert control on edit forms that do not wire the hero callbacks. *@
-<MudItem xs="12">
+@if (AllowHeroUpload)
+{
+    <MudItem xs="12">
         <MudField Label="Hero Image" Variant="Variant.Outlined" InnerPadding="false">
             <MudStack Spacing="3">
                 <MudText Typo="Typo.body2" Color="Color.Default">
@@ -36,13 +38,28 @@
                 }
             </MudStack>
         </MudField>
-</MudItem>
+    </MudItem>
+}
+else
+{
+    <MudItem xs="12">
+        <MudAlert Severity="Severity.Info" Dense="true" Variant="Variant.Outlined">
+            Sessions are single-track live releases. After upload, set the hero image from the
+            <strong>Release Archive → Sessions</strong> browser.
+        </MudAlert>
+    </MudItem>
+}
 
 @code {
     [Parameter] public IBrowserFile? HeroImageFile { get; set; }
     [Parameter] public EventCallback<IBrowserFile?> HeroImageFileChanged { get; set; }
     [Parameter] public bool Disabled { get; set; }
 
+    // When true (BatchUpload create path), render the hero file picker.
+    // When false/absent (edit paths), render the guidance alert directing the admin to the
+    // Sessions browser — no dead control where callbacks are unwired.
+    [Parameter] public bool AllowHeroUpload { get; set; }
+
     private Task HandleHeroFileSelected(InputFileChangeEventArgs e) =>
         HeroImageFileChanged.InvokeAsync(e.File);