Step 3 previously proved that each completed fractional bank emitted one
panel event and moved the expected axis, but its positive assertions only
required the viewport origin to be greater than zero. A receiver applying
two steps therefore passed a witness whose contract says exactly one.
Assert the geometry declaration is accepted, require a completely empty
Step for each sub-threshold turn, require no frontend-local effect and one
correctly directed event for each completion, and pin both resulting
viewport origins to the frontend's one-notch constants.
Mutation checks: doubling the vertical receiver step fails at (6, 0),
doubling the horizontal receiver step fails at (3, 6), and adding a local
document scroll beside the panel event fails on the completion transcript.
Focused witness green outside the socket-restricted sandbox. Package-wide
all-target clippy with -D warnings, cargo fmt --check, and git diff --check
are clean.
Levi Neuwirth
9ec4ff1f33