Answers review of revision 16. Still framing only; no code.
**"PER AXIS AND SURFACE" HAS TWO NOUNS AND 16 WITNESSED ONE.** The
background-to-cell crossing row proves a CATEGORY change and nothing
else, so an implementation could still share a residual between the two
axes, or between two panels, or between two terminals, and pass every
row written. Three discriminators added:
R1 cross-axis --- a sub-tick horizontal then a sub-tick vertical over
ONE surface must reach no tick on either axis.
Mutation: one residual per surface rather than per (surface,axis).
R2 panel A -> panel B replacement; motion over B starts from zero.
Mutation: key the residual by "the panel", not panel identity.
R3 terminal A -> terminal B, likewise.
R2 and R3 also pin discard-on-disappearance: a residual banked against
a surface that no longer exists must not be inherited by its successor.
Acceptance 49's epoch machinery is the existing precedent.
The end-to-end panel effect witness now runs BOTH AXES. "A wheel moves
the viewport" leaves the horizontal half untested exactly where the
emit-and-discard defect lived --- the axis with no handler at all.
**TWO MUTATION DEPENDENCIES WERE PREDICTIONS, NOT DERIVATIONS.**
Suppressing cursor-change release need not fail L8: clause 5 gives
wrap and buffer replacement their own explicit clear, which does not
run through the release path, so the latch is cleared and L8 passes.
Making the horizontal wheel write point need not fail L4: L4 asserts
the horizontal origin survives a VERTICAL wheel, and a spurious write
on the horizontal path does not change what the vertical path does.
Scoped to L3 and L5. Additional bites are now recorded only after a
mutation run shows them, with the run named.
**AND U10's CONCURRENCY CLAIM WAS FALSE.** I wrote that U10 ran U9's
comparison "in the opposite direction" --- red at low concurrency,
green at high. It did not. Cargo runs test binaries SEQUENTIALLY: the
sweep log shows strict `Running` -> `test result` -> `Running`
alternation across 119 binaries, the failing test is in the FIRST one,
and it is the same 1,940-test libtest executable `03-lib` ran with the
same default intra-binary threading. There was no concurrency
difference between the two steps to compare, so no experiment reversed
anything.
U9's candidate is withdrawn on that ground --- its premise was false,
which is a stronger and cheaper retirement than an experimental one,
and it never needed a run. What U10 establishes is what it always
established: another intermittent occurrence with an in-run control, on
a documentation-only diff. Synthetic load against the `--lib` binary
alone remains the useful experiment and remains unrun. Both rows
corrected in place, because the wrong version is what a later reader
would otherwise reconstruct from the two step names.
Gates: all nine green under `env -u TMPDIR`, log 20260814T084344Z.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
836f417313