One place for every reviewer task, in pipeline order. Each stage is its own step: pick one above.
Confirm papilla present/absent across a video's candidates. This is your existing hosted app — the dashboard just surfaces the same assignments here and opens them there.
Mark whether a fiber, sheath or stone is visible on about 40 evenly spaced frames of each video; this comes before instrument masks are generated in Stage 2.
You own a whole video (all its classes). Claim one, review every mask, then submit — one reviewer per video.