Ensure user nick is present at the end of session buffer

Ensured that the user's nick is always present at the end of the session
buffer. Added checks and insertions to handle cases where the buffer
might not have the user's nick, especially for new sessions or empty
buffers. Adjusted the insertion points and conditions to maintain
consistency across different scenarios.

ellama.el

@@ -779,6 +779,16 @@ If EPHEMERAL non nil new session will not be associated with any file."
 	(save-buffer)
 	(goto-char (point-min))))
     (with-current-buffer buffer
+      ;; support sessions without user nick at the end of buffer
+      (when (not (save-excursion
+		   (save-match-data
+		     (goto-char (point-max))
+		     (and (search-backward (concat (ellama-get-nick-prefix-for-mode) " " ellama-user-nick ":\n") nil t)
+			  (search-forward (concat (ellama-get-nick-prefix-for-mode) " " ellama-user-nick ":\n") nil t)
+			  (equal (point) (point-max))))))
+	(goto-char (point-max))
+	(insert (ellama-get-nick-prefix-for-mode) " " ellama-user-nick ":\n")
+	(save-buffer))
       (let ((session (read session-buffer)))
 	(setq ellama--current-session
 	      (make-ellama-session
@@ -1566,7 +1576,7 @@ Extract profession from this message. Be short and concise."
 Will call `ellama-chat-done-callback' and ON-DONE on TEXT."
   (save-excursion
     (goto-char (point-max))
-    (insert "\n\n")
+    (insert "\n\n" (ellama-get-nick-prefix-for-mode) " " ellama-user-nick ":\n")
     (when ellama-session-auto-save
       (save-buffer)))
   (when ellama-chat-done-callback
@@ -1699,9 +1709,12 @@ the full response text when the request completes (with BUFFER current)."
       (with-current-buffer buffer
 	(save-excursion
 	  (goto-char (point-max))
-	  (insert (ellama-get-nick-prefix-for-mode) " " ellama-user-nick ":\n"
-		  (ellama--format-context session) (ellama--fill-long-lines prompt) "\n\n"
-		  (ellama-get-nick-prefix-for-mode) " " ellama-assistant-nick ":\n")
+	  (if (equal (point-min) (point-max)) ;; empty buffer
+	      (insert (ellama-get-nick-prefix-for-mode) " " ellama-user-nick ":\n"
+		      (ellama--format-context session) (ellama--fill-long-lines prompt) "\n\n"
+		      (ellama-get-nick-prefix-for-mode) " " ellama-assistant-nick ":\n")
+	    (insert (ellama--format-context session) (ellama--fill-long-lines prompt) "\n\n"
+		    (ellama-get-nick-prefix-for-mode) " " ellama-assistant-nick ":\n"))
 	  (ellama-stream prompt
 			 :session session
 			 :on-done (if donecb (list 'ellama-chat-done donecb)