Fixed and improved the system prompt of chats started from assistants (#1172)

app/MindWork AI Studio/Assistants/EMail/AssistantEMail.razor.cs

@@ -14,12 +14,32 @@ public partial class AssistantEMail : AssistantBaseCore<SettingsDialogWritingEMa
     
     protected override string Description => T("Provide a list of bullet points and some basic information for an e-mail. The assistant will generate an e-mail based on that input.");
     
+    // The prompt of this assistant describes an automated system which only writes the email, so the chat gets a prompt of its own, which keeps the settings of the email:
+    protected override ChatSystemPromptChoice ChatSystemPrompt => ChatSystemPromptChoice.Custom(this.CreateChatSystemPrompt);
+
     protected override string SystemPrompt => 
         $"""
         You are an automated system that writes emails. {this.SystemPromptHistory()} The user provides you with bullet points on what
         he want to address in the response. Regarding the writing style of the email: {this.selectedWritingStyle.Prompt}
         {this.SystemPromptGreeting()} {this.SystemPromptName()} You write the email in the following language: {this.SystemPromptLanguage()}.
         """;
+
+    /// <summary>
+    /// Creates the system prompt of a chat which continues an email, for follow-up questions about it.
+    /// </summary>
+    private string CreateChatSystemPrompt() =>
+        $"""
+        You are an expert in writing emails. The user had an email written: the conversation so far holds the bullet
+        points of the user, the previous conversation when the user gave one, and the email. Now you answer the user's
+        follow-up questions about the email, e.g., why it is worded a certain way, and you revise it when the user asks
+        for it. A revised version is always the complete email.
+
+        The user chose these settings for the email, which a revised version keeps unless the user asks otherwise:
+        Regarding the writing style of the email: {this.selectedWritingStyle.Prompt}
+        {this.SystemPromptGreeting()} {this.SystemPromptName()} You write the email in the following language: {this.SystemPromptLanguage()}.
+
+        Answer questions in the language the user writes in.
+        """;
     
     protected override IReadOnlyList<IButtonData> FooterButtons => [];