Design interactive prototypes

I need an interactive prototype of the checkout flow for the mobile app so we can test whether users complete purchase steps without help. Build the flow from the current screens in the project file named Mobile Checkout v3, include tap states for Continue and Back, an animated transition from Shipping to Payment, and a working address-autocomplete mock. Share a single link I can open on my phone by Friday so UX research can run five moderated sessions.

Before I hand this prototype to research, make it quick to test: surface the conversion-critical steps up front, label which taps are mocked versus functioning, make the cart total persist across screens so researchers can validate pricing, and flag any microcopy that might confuse users. Highlight anything that will make a reviewer hesitate during a live session.

The team pushed the new Payment screen and when I opened the prototype on my phone the transition stutters and the address-autocomplete mock doesn't populate. Engineers say it looks fine on desktop. I need to know whether this is a prototype performance issue I can fix here, a file setup problem, or a device-specific limitation. Should I strip the animation and test again, reduce image sizes, or ask the engineers to re-run the web build? What’s the fastest test that will tell me which it is?

Across projects I keep losing time because prototypes look polished on desktop but break in moderated sessions on phones: animations stutter, mocked inputs don't behave, and researchers waste session minutes explaining fakes. Where should I change my habit so prototypes work reliably in research? Recommend a checklist or three rules I can follow during handoff that stop these failures from happening.