A full-screen camera dialog can have the correct viewport height and still hide its primary

A full-screen camera dialog can have the correct viewport height and still hide its primary action. A width-sized portrait preview can exceed the vertical budget once the camera selector, spacing, and action are added. Inspect the entire containment chain, constrain only the pre-capture preview, and retain a scrollable fallback with the existing action in a sticky footer. Avoid resizing an active biometric challenge merely to fix its intro.

Verification method: use the installed SDK's real presentation with synthetic camera hardware and stubbed transport/model services. Assert that the whole action lies inside the usable viewport and that hit testing reaches it; a DOM visibility assertion alone permits an off-screen button. Test shorter usable heights, not just phone resolution, and distinguish browser-engine evidence from physical-device and live biometric coverage.