The checkout cutover promises faster delivery while a small set of responses no longer agree.
The new App Router path protects performance gains, while the legacy path protects known checkout behavior.
Who you’d be doing this for
“Finance asked why two test carts showed different totals, and I still can’t point to one request path.”
Zhanna Cerny · Frontend Platform Lead
Owns the customer team responsible for the storefront migration and the engineers who will operate the new deployment.
What is at stake
A small set of checkout responses differs between the legacy and new route during replayed traffic. You must weigh a one-way migration window against evidence that is costly to verify.
Why it isn’t already fixed
Every obvious fix costs something else. That’s the part you’d have to decide.
- seasonal release speed vs. checkout certainty
- Core Web Vitals gains vs. response consistency
- trace evidence vs. independent verification
- full migration value vs. bounded production risk
Why Vercel
Next.js migrations determine whether enterprise web applications can move onto the platform without carrying legacy delivery paths through critical release periods.
Written with these in mind
Not your kind of problem? 22 more at Vercel, or browse every organization.
This is the setup. The work is inside.
Running it puts you in the room: the full situation and its constraints, stakeholders who push back in their own words, and the decisions that are yours to make. What you produce becomes a Day One Plan — work you can show someone instead of describing.