Thanks for digging into this, you were right on both counts.
The canvas numbers on the page were from my project settings, not from the browser. Fixed with measured values.
New Game: the click had to hit the lamp itself, and the label text sits just below it, so clicking the text missed by a few pixels. People click the glowing lamp; your agent clicked the text. New build accepts both, and Enter works on every screen now. ?seed=N and a read-only ?probe are in the release build too.
I'll play HELD OUT tonight.