Merge pull request #2942 from weijun-xia/fix/edit-fuzzy-preserve-whitespace

fix(edit): keep untouched lines intact on fuzzy match

agent/tools/utils/diff.py

@@ -111,20 +111,46 @@ def fuzzy_find_text(content: str, old_text: str) -> FuzzyMatchResult:
             content_for_replacement=content
         )
     
-    # Try fuzzy match
-    fuzzy_content = normalize_for_fuzzy_match(content)
-    fuzzy_old_text = normalize_for_fuzzy_match(old_text)
-    
-    index = fuzzy_content.find(fuzzy_old_text)
-    if index != -1:
-        # Fuzzy match successful, use normalized content for replacement
-        return FuzzyMatchResult(
-            found=True,
-            index=index,
-            match_length=len(fuzzy_old_text),
-            content_for_replacement=fuzzy_content
-        )
-    
+    # Fuzzy match: the exact substring was not found, most likely because the
+    # whitespace differs (indentation, spaces around operators, trailing
+    # spaces). Locate the region in the ORIGINAL content using a
+    # whitespace-flexible pattern and return offsets into that original
+    # content.
+    #
+    # This must NOT replace inside a whitespace-normalized copy of the file:
+    # doing so previously returned the normalized copy as
+    # content_for_replacement, which caused the whole file to be rewritten
+    # with collapsed indentation (every untouched line got reformatted).
+    stripped = old_text.strip('\n')
+    if stripped.strip():
+        source_lines = stripped.split('\n')
+        line_patterns = []
+        for i, line in enumerate(source_lines):
+            tokens = line.split()
+            if not tokens:
+                line_patterns.append(r'[ \t]*')
+                continue
+            # Tolerate any run of blanks between tokens.
+            core = r'[ \t]+'.join(re.escape(tok) for tok in tokens)
+            # First-line leading whitespace is folded into the match only when
+            # old_text itself was indented here; otherwise it stays OUTSIDE the
+            # match so a no-indent old_text preserves (does not swallow and drop)
+            # the file's existing indentation -- mirroring an exact substring
+            # match. Inner lines always tolerate indentation: it sits inside the
+            # matched region and is re-supplied by new_text.
+            if i > 0 or line[:1] in (' ', '\t'):
+                core = r'[ \t]*' + core
+            line_patterns.append(core + r'[ \t]*')
+        pattern = '\n'.join(line_patterns)
+        match = re.search(pattern, content)
+        if match:
+            return FuzzyMatchResult(
+                found=True,
+                index=match.start(),
+                match_length=match.end() - match.start(),
+                content_for_replacement=content
+            )
+
     # Not found
     return FuzzyMatchResult(found=False)