Add more real Git-style diffs in command feedback

aider/tools/delete_block.py

@@ -8,6 +8,7 @@ from .tool_utils import (
     apply_change,
     handle_tool_error,
     format_tool_result,
+    generate_unified_diff_snippet,
 )
 
 def _execute_delete_block(coder, file_path, start_pattern, end_pattern=None, line_count=None, near_context=None, occurrence=1, change_id=None, dry_run=False):
@@ -50,7 +51,7 @@ def _execute_delete_block(coder, file_path, start_pattern, end_pattern=None, lin
             return f"Warning: No changes made (deletion would not change file)"
 
         # 5. Generate diff for feedback
-        diff_snippet = coder._generate_diff_snippet_delete(original_content, start_line, end_line)
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
         num_deleted = end_line - start_line + 1
         num_occurrences = len(start_pattern_indices)
         occurrence_str = f"occurrence {occurrence} of " if num_occurrences > 1 else ""

aider/tools/delete_line.py

@@ -1,5 +1,6 @@
 import os
 import traceback
+from .tool_utils import generate_unified_diff_snippet
 
 def _execute_delete_line(coder, file_path, line_number, change_id=None, dry_run=False):
     """
@@ -62,7 +63,7 @@ def _execute_delete_line(coder, file_path, line_number, change_id=None, dry_run=
             return f"Warning: No changes made (deleting line {line_num_int} would not change file)"
 
         # Generate diff snippet (using the existing delete block helper for simplicity)
-        diff_snippet = coder._generate_diff_snippet_delete(original_content, line_idx, line_idx)
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
 
         # Handle dry run
         if dry_run:

aider/tools/delete_lines.py

@@ -1,5 +1,6 @@
 import os
 import traceback
+from .tool_utils import generate_unified_diff_snippet
 
 def _execute_delete_lines(coder, file_path, start_line, end_line, change_id=None, dry_run=False):
     """
@@ -71,7 +72,7 @@ def _execute_delete_lines(coder, file_path, start_line, end_line, change_id=None
             return f"Warning: No changes made (deleting lines {start_line_int}-{end_line_int} would not change file)"
 
         # Generate diff snippet
-        diff_snippet = coder._generate_diff_snippet_delete(original_content, start_idx, end_idx)
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
 
         # Handle dry run
         if dry_run:

aider/tools/extract_lines.py

@@ -1,5 +1,6 @@
 import os
 import traceback
+from .tool_utils import generate_unified_diff_snippet
 
 def _execute_extract_lines(coder, source_file_path, target_file_path, start_pattern, end_pattern=None, line_count=None, near_context=None, occurrence=1, dry_run=False):
     """
@@ -145,9 +146,9 @@ def _execute_extract_lines(coder, source_file_path, target_file_path, start_patt
         new_target_content = target_content + extracted_block
 
         # --- Generate Diffs ---
-        source_diff_snippet = coder._generate_diff_snippet_delete(original_source_content, start_line, end_line)
+        source_diff_snippet = generate_unified_diff_snippet(original_source_content, new_source_content, rel_source_path)
         target_insertion_line = len(target_content.splitlines()) if target_content else 0
-        target_diff_snippet = coder._generate_diff_snippet_insert(original_target_content, target_insertion_line, extracted_lines)
+        target_diff_snippet = generate_unified_diff_snippet(original_target_content, new_target_content, rel_target_path)
 
         # --- Handle Dry Run ---
         if dry_run:

aider/tools/indent_lines.py

@@ -9,6 +9,7 @@ from .tool_utils import (
     apply_change,
     handle_tool_error,
     format_tool_result,
+    generate_unified_diff_snippet,
 )
 
 def _execute_indent_lines(coder, file_path, start_pattern, end_pattern=None, line_count=None, indent_levels=1, near_context=None, occurrence=1, change_id=None, dry_run=False):
@@ -81,7 +82,7 @@ def _execute_indent_lines(coder, file_path, start_pattern, end_pattern=None, lin
             return f"Warning: No changes made (indentation would not change file)"
 
         # 5. Generate diff for feedback
-        diff_snippet = coder._generate_diff_snippet_indent(original_content, new_content, start_line, end_line)
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
         num_occurrences = len(start_pattern_indices)
         occurrence_str = f"occurrence {occurrence} of " if num_occurrences > 1 else ""
         action = "indent" if indent_levels > 0 else "unindent"

aider/tools/insert_block.py

@@ -8,6 +8,7 @@ from .tool_utils import (
     apply_change,
     handle_tool_error,
     format_tool_result,
+    generate_unified_diff_snippet,
 )
 
 def _execute_insert_block(coder, file_path, content, after_pattern=None, before_pattern=None, near_context=None, occurrence=1, change_id=None, dry_run=False):
@@ -51,7 +52,7 @@ def _execute_insert_block(coder, file_path, content, after_pattern=None, before_
             return f"Warning: No changes made (insertion would not change file)"
 
         # 5. Generate diff for feedback
-        diff_snippet = coder._generate_diff_snippet_insert(original_content, insertion_line_idx, content_lines)
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
         num_occurrences = len(pattern_line_indices)
         occurrence_str = f"occurrence {occurrence} of " if num_occurrences > 1 else ""
 

aider/tools/replace_lines.py

@@ -1,5 +1,7 @@
 import os
 import traceback
+from .tool_utils import generate_unified_diff_snippet
+from .tool_utils import generate_unified_diff_snippet
 
 def _execute_replace_lines(coder, file_path, start_line, end_line, new_content, change_id=None, dry_run=False):
     """
@@ -7,7 +9,6 @@ def _execute_replace_lines(coder, file_path, start_line, end_line, new_content,
     Useful for fixing errors identified by error messages or linters.
     
     Parameters:
-    - coder: The Coder instance
     - file_path: Path to the file to modify
     - start_line: The first line number to replace (1-based)
     - end_line: The last line number to replace (1-based)
@@ -86,6 +87,7 @@ def _execute_replace_lines(coder, file_path, start_line, end_line, new_content,
         if original_content == new_content_full:
             coder.io.tool_warning("No changes made: new content is identical to original")
             return f"Warning: No changes made (new content identical to original)"
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content_full, rel_path)
          
         # Create a readable diff for the lines replacement
         diff = f"Lines {start_line}-{end_line}:\n"
@@ -101,7 +103,7 @@ def _execute_replace_lines(coder, file_path, start_line, end_line, new_content,
         # Handle dry run
         if dry_run:
             coder.io.tool_output(f"Dry run: Would replace lines {start_line}-{end_line} in {file_path}")
-            return f"Dry run: Would replace lines {start_line}-{end_line}. Diff:\n{diff}"
+            return f"Dry run: Would replace lines {start_line}-{end_line}. Diff snippet:\n{diff_snippet}"
 
         # --- Apply Change (Not dry run) ---
         coder.io.write_text(abs_path, new_content_full)

aider/tools/replace_text.py

@@ -5,6 +5,7 @@ from .tool_utils import (
     apply_change,
     handle_tool_error,
     format_tool_result,
+    generate_unified_diff_snippet,
 )
 
 def _execute_replace_text(coder, file_path, find_text, replace_text, near_context=None, occurrence=1, change_id=None, dry_run=False):
@@ -57,7 +58,7 @@ def _execute_replace_text(coder, file_path, find_text, replace_text, near_contex
 
         # 5. Generate diff for feedback
         # Note: _generate_diff_snippet is currently on the Coder class
-        diff_snippet = coder._generate_diff_snippet(original_content, start_index, len(find_text), replace_text)
+        diff_snippet = generate_unified_diff_snippet(original_content, new_content, rel_path)
         occurrence_str = f"occurrence {occurrence}" if num_occurrences > 1 else "text"
 
         # 6. Handle dry run

aider/tools/tool_utils.py

@@ -1,3 +1,4 @@
+import difflib
 import os
 import traceback
 
@@ -170,6 +171,42 @@ def determine_line_range(
     return start_line, end_line
 
 
+def generate_unified_diff_snippet(original_content, new_content, file_path, context_lines=3):
+    """
+    Generates a unified diff snippet between original and new content.
+
+    Args:
+        original_content (str): The original file content.
+        new_content (str): The modified file content.
+        file_path (str): The relative path to the file (for display in diff header).
+        context_lines (int): Number of context lines to show around changes.
+
+    Returns:
+        str: A formatted unified diff snippet, or an empty string if no changes.
+    """
+    if original_content == new_content:
+        return ""
+
+    original_lines = original_content.splitlines(keepends=True)
+    new_lines = new_content.splitlines(keepends=True)
+
+    diff = difflib.unified_diff(
+        original_lines,
+        new_lines,
+        fromfile=f"a/{file_path}",
+        tofile=f"b/{file_path}",
+        n=context_lines, # Number of context lines
+    )
+
+    # Join the diff lines, potentially skipping the header if desired,
+    # but let's keep it for standard format.
+    diff_snippet = "".join(diff)
+
+    # Ensure snippet ends with a newline for cleaner formatting in results
+    if diff_snippet and not diff_snippet.endswith('\n'):
+        diff_snippet += '\n'
+
+    return diff_snippet
 def apply_change(coder, abs_path, rel_path, original_content, new_content, change_type, metadata, change_id=None):
     """
     Writes the new content, tracks the change, and updates coder state.