post
https://api.mercury.com/api/v1/transaction//attachments
Upload a file attachment to a transaction. The file is uploaded via multipart/form-data. Supported file types include PDF, images (PNG, JPG, GIF), and common document formats.
200Successfully uploaded attachment. Returns attachmentId and downloadUrl.
400Bad request. Either no file was uploaded or the filename exceeds the 299 character limit.
404Transaction not found
413File too large. Maximum file size is 32MB.
415Unsupported file type. Potentially dangerous file extensions (e.g., .exe, .bat) are not allowed.
