fix: preserve multiple edits targeting the same file

backend/app/main.py

@@ -214,7 +214,7 @@ def apply_edits(repo: Path, payload: dict[str, Any]) -> tuple[bool, str]:
     edits = payload.get("edits")
     if not isinstance(edits, list):
         return False, "Model response missing edits array"
-    staged: list[tuple[Path, str]] = []
+    staged: dict[Path, str] = {}
     for i, edit in enumerate(edits):
         if not isinstance(edit, dict):
             return False, f"Edit {i+1} is not an object"
@@ -234,17 +234,20 @@ def apply_edits(repo: Path, payload: dict[str, Any]) -> tuple[bool, str]:
             return False, f"Edit {i+1} requires string old/new values"
         if not path.exists() or not path.is_file():
             return False, f"File not found: {rel}"
-        try:
-            current = path.read_text(encoding="utf-8")
-        except UnicodeDecodeError:
-            return False, f"Binary/non-text file is not editable: {rel}"
+        if path in staged:
+            current = staged[path]
+        else:
+            try:
+                current = path.read_text(encoding="utf-8")
+            except UnicodeDecodeError:
+                return False, f"Binary/non-text file is not editable: {rel}"
         if current.count(old) != 1:
             return False, f"Expected exactly one match for old text in {rel}, found {current.count(old)}"
-        staged.append((path, current.replace(old, new, 1)))
+        staged[path] = current.replace(old, new, 1)
 
-    for path, content in staged:
+    for path, content in staged.items():
         path.write_text(content, encoding="utf-8")
-    return True, f"Applied {len(staged)} edit(s)"
+    return True, f"Applied {len(edits)} edit(s)"
 
 
 def build_patch(repo: Path) -> str:

backend/tests/test_main.py

@@ -60,6 +60,26 @@ def test_apply_edits_updates_exact_match(self) -> None:
             self.assertTrue(ok, message)
             self.assertEqual(target.read_text(encoding="utf-8"), "after\n")
 
+    def test_apply_edits_preserves_multiple_edits_to_same_file(self) -> None:
+        with tempfile.TemporaryDirectory() as temp_dir:
+            repo = Path(temp_dir)
+            target = repo / "example.txt"
+            target.write_text("alpha beta gamma", encoding="utf-8")
+
+            ok, message = apply_edits(
+                repo,
+                {
+                    "edits": [
+                        {"path": "example.txt", "old": "alpha", "new": "one"},
+                        {"path": "example.txt", "old": "gamma", "new": "three"},
+                    ]
+                },
+            )
+
+            self.assertTrue(ok, message)
+            self.assertEqual(target.read_text(encoding="utf-8"), "one beta three")
+            self.assertEqual(message, "Applied 2 edit(s)")
+
     def test_apply_edits_rejects_path_escape(self) -> None:
         with tempfile.TemporaryDirectory() as temp_dir:
             repo = Path(temp_dir)