Let direct chat launchers open disappearing chats (#967)

app/MindWork AI Studio/Components/DirectChatLauncherForm.razor

@@ -10,7 +10,15 @@
     </MudSelect>
 }
 
-<MudTextField T="string" Text="@this.WorkspaceName" TextChanged="@this.SetWorkspaceName" Validation="@this.ValidateWorkspaceName" AdornmentIcon="@Icons.Material.Filled.CreateNewFolder" Adornment="Adornment.Start" IconSize="Size.Small" Label="@T("Workspace name")" HelperText="@T("Choose an existing workspace or enter a name that should be created when the launcher is opened.")" Variant="Variant.Outlined" Margin="Margin.Dense" Class="mb-3" UserAttributes="@USER_INPUT_ATTRIBUTES"/>
+<MudTextField T="string" Text="@this.WorkspaceName" TextChanged="@this.SetWorkspaceName" AdornmentIcon="@(this.OpensTemporaryChat ? Icons.Material.Filled.Timer : Icons.Material.Filled.CreateNewFolder)" Adornment="Adornment.Start" IconSize="Size.Small" Label="@T("Workspace name (Optional)")" HelperText="@T("Choose an existing workspace or enter a name that should be created when the launcher is opened.")" Variant="Variant.Outlined" Margin="Margin.Dense" Class="mb-1" UserAttributes="@USER_INPUT_ATTRIBUTES"/>
+
+@* The tile behaves differently with and without a workspace, so the form says which of the two is
+   chosen right now instead of only explaining that both are possible. *@
+<MudText Typo="Typo.body2" Class="mud-text-secondary mb-3">
+    @(this.OpensTemporaryChat
+        ? T("Without a workspace, the tile opens a disappearing chat: it belongs to no workspace and is deleted according to your workspace maintenance settings.")
+        : T("The tile opens its chat in this workspace and creates the workspace when it does not exist yet."))
+</MudText>
 <MudSelect T="string" Value="@this.ProviderId" ValueChanged="@this.SetProviderId" Label="@T("Chat provider")" Variant="Variant.Outlined" Margin="Margin.Dense" Class="mb-3 rounded-lg" Adornment="Adornment.Start" AdornmentIcon="@Icons.Material.Filled.SmartToy">
     <MudSelectItem T="string" Value="@string.Empty">@T("Use chat default")</MudSelectItem>
     @foreach (var provider in this.SettingsManager.GetConfidentProviders(Components.CHAT))

app/MindWork AI Studio/Components/DirectChatLauncherForm.razor.cs

@@ -3,8 +3,9 @@ using Microsoft.AspNetCore.Components;
 namespace AIStudio.Components;
 
 /// <summary>
-/// The selection a direct chat launcher needs: the workspace its chat is created in, and the
-/// provider, profile, chat template, and data sources that chat starts with.
+/// The selection a direct chat launcher needs: the workspace its chat is created in — or no
+/// workspace, for a disappearing chat — and the provider, profile, chat template, and data sources
+/// that chat starts with.
 /// </summary>
 /// <remarks>
 /// The Assistant Builder uses this form to describe a launcher it is about to generate, while the
@@ -15,7 +16,8 @@ public partial class DirectChatLauncherForm : MSGComponentBase
 {
     /// <summary>
     /// The name of the workspace the launcher opens its chat in. The workspace is created when it
-    /// does not exist yet, hence this is a free-text field and not a workspace ID.
+    /// does not exist yet, hence this is a free-text field and not a workspace ID. An empty name is
+    /// a choice of its own: the launcher then opens a disappearing chat.
     /// </summary>
     [Parameter]
     public string WorkspaceName { get; set; } = string.Empty;
@@ -75,11 +77,9 @@ public partial class DirectChatLauncherForm : MSGComponentBase
     public EventCallback<HashSet<string>> ToolIdsChanged { get; set; }
 
     /// <summary>
-    /// Validates the workspace name. The hosts differ here: the Builder requires a name only while
-    /// its launcher switch is on, whereas the settings dialog always requires one.
+    /// Whether the launcher currently describes a chat without a workspace.
     /// </summary>
-    [Parameter]
-    public Func<string, string?>? ValidateWorkspaceName { get; set; }
+    private bool OpensTemporaryChat => string.IsNullOrWhiteSpace(this.WorkspaceName);
 
     private IReadOnlyList<WorkspaceTreeWorkspace> availableWorkspaces = [];