Answers review of revision 13. Still framing only; no code.
**Q#S1-11 IS RULED (B), VIEWPORT ONLY.** (A) is not viable in 1b and
the vertical precedent does not reach it. `scroll_window` can carry
point because it is TUI-side, where the editor owns the cursor.
`OwnCursor` is "pmacs-gpu's own cursor position, MIRRORED from
`CursorByte`" --- a read-only reflection --- and the only wire operation
that positions it, `dispatch_pointer`, sets `active_frontend`, calls
`break_command_chain`, and by its own comment moves point or changes
selection on every kind. Carrying point from a wheel therefore needs a
NEW wire operation, which contradicts 1b's non-protocol scope. (A)
would not even be self-consistent: GPU vertical scrolling already does
not carry point.
**And "do not carry" alone is not a ruling** --- it leaves the origin's
lifetime undefined, which is the part that decides whether the feature
works. Five clauses, all of them the ruling: viewport only; an
EFFECTIVE move arms authority; repaint, same-cursor follow, resize and
vertical wheel preserve it while geometry and content changes CLAMP
rather than release; a genuine cursor-position change releases it; wrap
and buffer replacement clear it and pin zero.
**THE HAZARD LANDS ON THE NEXT PAINT, NOT THE NEXT CARET EVENT.**
Revision 13 said caret event and understated the exposure:
`horizontal_follow` is the FIRST act of `prepare_window_cursor_visible`,
which `paint_frame` runs every frame. The origin is overwritten by a
redraw with no input at all. Witnesses must therefore drive real call
sites on both frontends --- a helper unit test cannot see a follow that
runs inside `paint_frame` --- and a TUI cross-axis row is required
because vertical wheel DOES carry point there. Both mutations named:
follow ignores authority, and authority never releases.
**B1'S "SURFACE" IS NOW ENUMERATED.** Two facts made the gap real:
quantization and the zero return happen at `:3074`, BEFORE the panel
(`:3090`) and terminal (`:3112`) branches, so a sub-tick delta is
discarded before anything knows where it was going; and
`PointerSurface::Elsewhere` conflates document, terminal, minimap and
chrome, so the existing classifier cannot name what B1 needs. Six
targets are tabulated with a residual owner and a horizontal answer
each. The horizontal gap is NOT a wire gap --- `MouseKind::ScrollLeft`
and `ScrollRight` already exist and round-trip --- it is a missing
handler, so each target must be ruled emit-and-handle or explicitly
inert. Without the table, one global accumulator passes every
per-surface row that tests one surface.
Recorded while measuring: a wheel over the panel divider or the band's
background scrolls the DOCUMENT today, though the enum says the band
owns the pixel.
**B3 TAKES B7'S EXACT BOUND.** "Content bounds" was vaguer than B7's
saturated widest-line-minus-viewport rule, for the same bound on the
same rule, and B7 is exact precisely because the loose version blanks
the viewport. Stated in the GPU's column grid, since
`horizontal_follow` already reckons there and re-multiplies to snap the
offset --- a pixel clamp would break the snap the shared rule depends
on. Narrow-buffer and final-column-visible rows added; a clamp at full
content width must fail.
Ledger: the minimal 1b recovery/checkpoint entry, plus three lane
headers that were lying --- #240 and #239 were still marked OPEN, and
the arc header still said 1a was next. The #239/#240 absorption stays
deferred and is a separate lane.
Gates: all nine green under `env -u TMPDIR`, log 20260813T211645Z.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
e94ce85be1