Viewr

Viewr is a video client whose interesting half is the server. Rather than one ranked list reused everywhere, it runs the same two-stage funnel separately per surface, each with its own objective.

Stage one is candidate generation: a two-tower model with approximate nearest-neighbour retrieval, cutting the catalogue down to hundreds. Stage two ranks those hundreds with a multitask model weighting engagement against satisfaction signals, tuned per surface.

The architecture is modelled on how large video platforms actually structure this, with one shared item store rather than a separate database per surface. The Flutter client renders whatever the surface returns.