Avoid batch S3 deletes in builder

agent_builder/tools.py

@@ -764,16 +764,15 @@ def _safe_supporting_skill_path(path: str) -> str:
 
 
 def _delete_workspace_objects(s3: Any, bucket: str, prefix: str) -> None:
+    # MinIO rejects boto3's batch DeleteObjects request in this environment
+    # when Content-MD5 is not present. Per-object deletes avoid that fragile
+    # API path and are fine for agent source workspaces.
     paginator = s3.get_paginator("list_objects_v2")
-    batch: list[dict[str, str]] = []
     for page in paginator.paginate(Bucket=bucket, Prefix=prefix):
         for obj in page.get("Contents") or ():
-            batch.append({"Key": obj["Key"]})
-            if len(batch) >= 1000:
-                s3.delete_objects(Bucket=bucket, Delete={"Objects": batch})
-                batch = []
-    if batch:
-        s3.delete_objects(Bucket=bucket, Delete={"Objects": batch})
+            key = obj.get("Key")
+            if key:
+                s3.delete_object(Bucket=bucket, Key=key)
 
 
 def _files_from_tarball(bundle: bytes) -> dict[str, bytes]: