diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 40bb33d65..9355a2d52 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -21,6 +21,7 @@ from pathlib import Path
 import git
 from rich.console import Console, Text
 from rich.markdown import Markdown
+from dataclasses import dataclass, fields
 
 from aider import __version__, models, prompts, urls, utils
 from aider.commands import Commands
@@ -49,6 +50,11 @@ def wrap_fence(name):
     return f"<{name}>", f"</{name}>"
 
 
+@dataclass
+class ChatChunks:
+    pass
+
+
 class Coder:
     abs_fnames = None
     abs_read_only_fnames = None
@@ -859,7 +865,7 @@ class Coder:
         )
         return prompt
 
-    def format_messages(self):
+    def format_chat_chunks(self):
         self.choose_fence()
         main_sys = self.fmt_system_prompt(self.gpt_prompts.main_system)
 
@@ -895,15 +901,17 @@ class Coder:
         if self.gpt_prompts.system_reminder:
             main_sys += "\n" + self.fmt_system_prompt(self.gpt_prompts.system_reminder)
 
-        messages = [
+        chunks = ChatChunks()
+
+        chunks.system = [
             dict(role="system", content=main_sys),
         ]
-        messages += example_messages
+        chunks.examples = example_messages
 
         self.summarize_end()
-        messages += self.done_messages
+        chunks.done = self.done_messages
 
-        messages += self.get_files_messages()
+        chunks.files = self.get_files_messages()
 
         if self.gpt_prompts.system_reminder:
             reminder_message = [
@@ -914,10 +922,13 @@ class Coder:
         else:
             reminder_message = []
 
+        chunks.cur = list(self.cur_messages)
+        chunks.reminder = []
+
         # TODO review impact of token count on image messages
-        messages_tokens = self.main_model.token_count(messages)
+        messages_tokens = 0 # self.main_model.token_count(messages)
         reminder_tokens = self.main_model.token_count(reminder_message)
-        cur_tokens = self.main_model.token_count(self.cur_messages)
+        cur_tokens = self.main_model.token_count(chunks.cur)
 
         if None not in (messages_tokens, reminder_tokens, cur_tokens):
             total_tokens = messages_tokens + reminder_tokens + cur_tokens
@@ -925,9 +936,7 @@ class Coder:
             # add the reminder anyway
             total_tokens = 0
 
-        messages += self.cur_messages
-
-        final = messages[-1]
+        final = chunks.cur[-1]
 
         max_input_tokens = self.main_model.info.get("max_input_tokens") or 0
         # Add the reminder prompt if we still have room to include it.
@@ -937,7 +946,7 @@ class Coder:
             and self.gpt_prompts.system_reminder
         ):
             if self.main_model.reminder_as_sys_msg:
-                messages += reminder_message
+                chunks.reminder = reminder_message
             elif final["role"] == "user":
                 # stuff it into the user message
                 new_content = (
@@ -945,9 +954,23 @@ class Coder:
                     + "\n\n"
                     + self.fmt_system_prompt(self.gpt_prompts.system_reminder)
                 )
-                messages[-1] = dict(role=final["role"], content=new_content)
+                chunks.cur[-1] = dict(role=final["role"], content=new_content)
 
-        return messages
+        return chunks
+
+    def format_messages(self):
+        chunks = self.format_chat_chunks()
+
+        msgs = (
+            chunks.system
+            + chunks.examples
+            + chunks.done
+            + chunks.files
+            + chunks.cur
+            + chunks.reminder
+        )
+
+        return msgs
 
     def send_message(self, inp):
         self.aider_edited_files = None