Teams can ditch rigid handoffs by pairing AI coding agents with every role in parallel. Early drafts turn ideas into working code instantly, shifting design and product feedback after proto­typing and moving reviews before pull requests to boost quality and speed.

• Three shifts (non-engineers can prompt working prototypes, coding got cheap enough that upfront specs slow things down more than building, and parallel AI agents make human review the bottleneck) are killing waterfall handoffs.
• The fix: build rough drafts first, let every role (PM, designer, QA) work directly with agents instead of routing through engineers, and move validation before the PR instead of after.
• Adoption should ramp through three stages—throwaway prototype repos, prototyping in the real codebase with live design systems, then AI agents wired directly into production repos.
• Humans still own final pull-request review even as AI handles the first draft and early iterations.