Senior Full-Stack / Platform Engineer for AI SaaS Platform

We are building a confidential AI SaaS platform and need a hands-on senior technical operator who can learn quickly, hit the ground running, and help us move faster without breaking production quality. This is not a junior role, not an agency role, and not a theory-only architecture role. We need someone who can open a complex repo, understand what matters, identify risk, fix real issues, improve tests, and help ship safely. You will work directly with the founder on a fast-moving AI SaaS product with active frontend, backend, infrastructure, security, integration, and release-quality workstreams. The ideal candidate has a strong track record of joining complex products, learning quickly, and becoming useful within days, not months. The first engagement will likely involve reviewing active PRs, resolving CI failures, fixing security/dependency issues, improving frontend/backend reliability, reducing Dev/Prod risk, and helping stabilise release quality. You must be evidence-driven. Every change needs clear proof: what changed, what was tested, what risk remains, and whether the work is safe to merge. NDA required before detailed access is provided.