fix case-insensitive manifest merging

upload_to_s3.py

@@ -23,15 +23,20 @@ def compute_build_hash(files: list[dict]) -> str:
     return hashlib.sha256("\n".join(lines).encode("utf-8")).hexdigest()
 
 
+def normalized_path_key(path: str) -> str:
+    """Match client paths using Windows filesystem semantics."""
+    return path.replace("\\", "/").casefold()
+
+
 def merge_manifests(base_manifest: dict, staging_manifest: dict) -> dict:
     files_by_path = {
-        item["path"]: item
+        normalized_path_key(item["path"]): item
         for item in base_manifest.get("files", [])
     }
     for item in staging_manifest.get("files", []):
-        files_by_path[item["path"]] = item
+        files_by_path[normalized_path_key(item["path"])] = item
 
-    files = [files_by_path[path] for path in sorted(files_by_path)]
+    files = sorted(files_by_path.values(), key=lambda item: item["path"].casefold())
     return {
         "buildHash": compute_build_hash(files),
         "files": files,