Adding LLM Based Editing capability (#8677)

Co-authored-by: Xingyao Wang <xingyao@all-hands.dev>
Co-authored-by: Engel Nyst <enyst@users.noreply.github.com>
Co-authored-by: Engel Nyst <engel.nyst@gmail.com>

openhands/agenthub/codeact_agent/tools/llm_based_edit.py

@@ -2,10 +2,18 @@ from litellm import ChatCompletionToolParam, ChatCompletionToolParamFunctionChun
 
 _FILE_EDIT_DESCRIPTION = """Edit a file in plain-text format.
 * The assistant can edit files by specifying the file path and providing a draft of the new file content.
-* The draft content doesn't need to be exactly the same as the existing file; the assistant may skip unchanged lines using comments like `# unchanged` to indicate unchanged sections.
+* The draft content doesn't need to be exactly the same as the existing file; the assistant may skip unchanged lines using comments like `# ... existing code ...` to indicate unchanged sections.
 * IMPORTANT: For large files (e.g., > 300 lines), specify the range of lines to edit using `start` and `end` (1-indexed, inclusive). The range should be smaller than 300 lines.
+* -1 indicates the last line of the file when used as the `start` or `end` value.
+* Keep at least one unchanged line before the changed section and after the changed section wherever possible.
+* Make sure to set the `start` and `end` to include all the lines in the original file referred to in the draft of the new file content. Failure to do so will result in bad edits.
 * To append to a file, set both `start` and `end` to `-1`.
 * If the file doesn't exist, a new file will be created with the provided content.
+* IMPORTANT: Make sure you include all the required indentations for each line of code in the draft, otherwise the edited code will be incorrectly indented.
+* IMPORTANT: Make sure that the first line of the draft is also properly indented and has the required whitespaces.
+* IMPORTANT: NEVER include or make references to lines from outside the `start` and `end` range in the draft.
+* IMPORTANT: Start the content with a comment in the format: #EDIT: Reason for edit
+* IMPORTANT: If you are not appending to the file, avoid setting `start` and `end` to the same value.
 
 **Example 1: general edit for short files**
 For example, given an existing file `/path/to/file.py` that looks like this:
@@ -33,13 +41,12 @@ The assistant wants to edit the file to look like this:
 The assistant may produce an edit action like this:
 path="/path/to/file.txt" start=1 end=-1
 content=```
+#EDIT: I want to change the value of y to 2
 class MyClass:
     def __init__(self):
-        # no changes before
+        # ... existing code ...
         self.y = 2
-        # self.z is removed
 
-# MyClass().z is removed
 print(MyClass().y)
 ```
 
@@ -58,6 +65,7 @@ For example, given an existing file `/path/to/file.py` that looks like this:
 
 To append the following lines to the file:
 ```python
+#EDIT: I want to print the value of y
 print(MyClass().y)
 ```
 
@@ -93,9 +101,9 @@ The assistant wants to edit the file to look like this:
 (2000 more lines below)
 
 The assistant may produce an edit action like this:
-path="/path/to/file.txt" start=1001 end=1008
+path="/path/to/file.txt" start=1002 end=1008
 content=```
-class MyClass:
+#EDIT: I want to change the value of y to 2
     def __init__(self):
         # no changes before
         self.y = 2