Making Vault Uploads Faster and More Reliable | Harvey

This post details the migration of Vault's file upload architecture from server-proxied uploads to a presigned URL model. This involved splitting the control plane (backend) from the data plane (storage). The frontend was re-architected into a three-stage concurrent pipeline to manage uploads directly to Azure Blob Storage. The backend's role shifted to authorization, validation, and finalization, with optimizations for batched operations to maintain scalability. Production safety was enhanced by controlling browser/network concurrency and preserving backend correctness through tight transaction boundaries and idempotent operations.