Corner correction
Also said as Corner nudge, Ledge snap
When your head clips the very corner of a block during a jump, the game slides you sideways around it rather than stopping you dead.
A jump that dies because of two pixels feels like a bug even when it is geometrically correct. Players never see the correction, only that the game is fair.
Say it
“Add corner correction: if a rising player overlaps a ceiling by 8 px or less horizontally, push them clear and keep their upward speed.”
Where you’ve seen it
Celeste does this for jumps: if you bonk a corner, it wiggles you around it.
Not to be confused with hitbox
A smaller hitbox makes every contact more lenient. Corner correction changes only what happens when you clip an edge.