Full-Stack Developer (Next.js/PostgreSQL) — Two-Party SaaS Workflow App — Fixed-Price MVP

I'm building a browser-based platform where two companies complete a structured contract workflow from a shared link. A fully working single-file HTML prototype and a detailed technical spec (data models, deterministic engine logic, 19 acceptance criteria, and a test-data generator) are ready and will be shared under NDA. Build: Next.js/React front end, Node + PostgreSQL back end, auth (email + OAuth), two-party sessions with strict server-side data isolation, a deterministic resolution module with a full unit-test suite, and DOCX/PDF document generation. Fixed price across four escrowed milestones; realistic timeline is 3–4 months; the posted budget is a placeholder — bid per the spec after reviewing it. Option to continue into later phases. In your proposal, describe similar multi-user apps you have shipped; final bids are expected only after the NDA and spec review, and should include your questions — the questions are part of the evaluation.