Automated Outbound Engine Developer

We're an outbound/GTM agency running cold email for 9 brand workspaces. We already run a working outbound process end-to-end sourcing, enrichment, campaigns, reply handling today across scripts, an internal tool and vendor UIs. We want you to turn that process into a single automated outbound engine: software that runs it unattended instead of by hand. Concretely, a lead warehouse plus a real-time inbox ("unibox") that shows replies across all workspaces the moment they arrive, classifies them, and drafts answers a human approves before anything is sent. This is productizing a proven process, not inventing one we have a written PRD, a reference implementation to migrate from, and documented API quirks, so it's a well-specified build, not a blank page. This first job is the foundation and a functional v0, delivered within one week. We want the structure done right, because everything after it is built on top. If v0 is solid, we continue with you on the rest of the platform and pay per milestone, scoped and agreed before each one. There is real, ongoing work here for the right engineer.