Introduce should_include_change

bin/mechanicaldiff.py

@@ -3,7 +3,30 @@
 import sys
 
 
+def should_include_change(change_lines: list[str], search: str, replace: str) -> bool:
+    return True
+
+
 def should_include_hunk(hunk_text: str, search: str, replace: str) -> bool:
+    lines = hunk_text.splitlines()
+    if not lines:
+        return True
+
+    change = []
+    for line in lines[1:]:
+        if line.startswith(("+", "-")):
+            change.append(line)
+            continue
+
+        if change:
+            if not should_include_change(change, search, replace):
+                return False
+            change = []
+
+    if change:
+        if not should_include_change(change, search, replace):
+            return False
+
     return True