better prompt

aider/coders/udiff_simple_prompts.py

@@ -8,9 +8,18 @@ class UnifiedDiffSimplePrompts(UnifiedDiffPrompts):
     if a simpler wording is desired for this edit format.
     """
 
-    # For now, we inherit all prompts. Override specific ones below if needed.
+    example_messages = []
-    # For example, to override the main_system prompt:
+
-    # main_system = """
+    system_reminder = """# File editing rules:
-    # A simpler version of the main system prompt for udiff-simple.
+
-    # """
+Return edits similar to unified diffs that `diff -U0` would produce.
-    pass
+
+The user's patch tool needs CORRECT patches that apply cleanly against the current contents of the file!
+Think carefully and make sure you include and mark all lines that need to be removed or changed as `-` lines.
+Make sure you mark all new or modified lines with `+`.
+Don't leave out any lines or the diff patch won't apply correctly.
+
+To make a new file, show a diff from `--- /dev/null` to `+++ path/to/new/file.ext`.
+
+{lazy_prompt}
+"""