improve replies, formatting and system prompt handling

src/commands/gemini-chat.ts

@@ -44,7 +44,10 @@ export class GeminiChat extends ChatCommand {
             };
         });
         chatMessages.reverse();
-        chatMessages.unshift({role: "system", content: Environment.SYSTEM_PROMPT});
+
+        if (Environment.SYSTEM_PROMPT) {
+            chatMessages.unshift({role: "system", content: Environment.SYSTEM_PROMPT});
+        }
 
         let chatContent = "";
         for (const part of chatMessages) {

src/commands/mistral-chat.ts

@@ -58,7 +58,10 @@ export class MistralChat extends ChatCommand {
             };
         });
         chatMessages.reverse();
-        chatMessages.unshift({role: "system", content: [{type: "text", text: Environment.SYSTEM_PROMPT}]});
+
+        if (Environment.SYSTEM_PROMPT) {
+            chatMessages.unshift({role: "system", content: [{type: "text", text: Environment.SYSTEM_PROMPT}]});
+        }
 
         let waitMessage: Message;
 
@@ -116,7 +119,7 @@ export class MistralChat extends ChatCommand {
                             chat_id: chatId,
                             message_id: waitMessage.message_id,
                             text: escapeMarkdownV2Text(text),
-                            parse_mode: "Markdown"
+                            parse_mode: "MarkdownV2"
                         }
                     ).catch(logError);
 

src/commands/ollama-chat.ts

@@ -44,7 +44,10 @@ export class OllamaChat extends ChatCommand {
             };
         });
         chatMessages.reverse();
-        chatMessages.unshift({role: "system", content: Environment.SYSTEM_PROMPT, images: []});
+
+        if (Environment.SYSTEM_PROMPT) {
+            chatMessages.unshift({role: "system", content: Environment.SYSTEM_PROMPT, images: []});
+        }
 
         let waitMessage: Message;
 

src/commands/openai-chat.ts

@@ -58,11 +58,14 @@ export class OpenAIChat extends ChatCommand {
             };
         });
         chatMessages.reverse();
-        chatMessages.unshift({
-            role: "system",
-            content: [{type: "input_text", text: Environment.SYSTEM_PROMPT}],
-            type: "message"
-        });
+
+        if (Environment.SYSTEM_PROMPT) {
+            chatMessages.unshift({
+                role: "system",
+                content: [{type: "input_text", text: Environment.SYSTEM_PROMPT}],
+                type: "message"
+            });
+        }
 
         let waitMessage: Message;