Stage 4 of the QoL arc, framing revision 4 (approved). Under
`truncate`, text past the right edge was UNREACHABLE; moving the cursor
now brings it into view. Automatic only — no commands, no bindings, no
new interaction island (Q#HS2).
THE CONTRACT. `view_left` is an unsnapped per-window display column
(Q#HS7(a)), and each line derives its own effective edge during the
walk it already performs from column 0. Starting at 0 is not laziness:
tab expansion depends on the absolute column from the line start, so a
walk beginning at the edge would put tab stops in the wrong place. The
walk stays line-absolute and only the emit translates.
Where the edge bisects a wide glyph on a given line (Q#HS7(c′)), its
trailing cell paints a styled BLANK rather than a `Continuation` — that
glyph means "the cell before me is a wide glyph's head", and here that
cell is off-screen, so emitting it would name a cell nobody painted.
The mapping designates that cell to the glyph's START byte, which keeps
`byte_at_place` total over visible cells and makes the character the
user scrolled toward clickable. Tabs keep FORWARD rounding (Q#HS7(c″))
— preserved, not chosen.
DECORATIONS TRAVEL WITH THE TEXT. The first version of this commit
translated the base glyph walk and nothing else, which split the frame
in half: at `view_left = 10` a glyph from source column 10 painted at
screen column 0 while its syntax style, diagnostic underline, search
wash and `BufferStyleOverlay` span painted at screen column 10 — or
vanished. Decorations drifting off the characters they describe,
silently, and only once a window had been scrolled.
Every such site carried the same two lines (`start_col.min(max_cols)`,
`end_col.min(max_cols)`), correct only while the left edge was pinned
at zero. `Viewport::visible_cols` is now the one rule all FIVE adopters
share — syntax/LSP styling, diagnostic underlines, search washes,
`BufferStyleOverlay`, and the selection painter — so a future decorator
inherits the translation instead of re-deriving it. It also subsumes
the old `end_col <= start_col` guard rather than sitting beside it.
`StyleSpanOverlay` and `VirtualCellOverlay` are deliberately untouched:
they are documented as viewport-relative, so translating them would be
the mirror defect.
The selection painter was nearly a sixth site with its own copy of the
rule, which I justified by a width it supposedly needed and the
viewport lacked. That was FALSE — the render viewport's
`cell_size.cols` is already `rect.size.cols - gutter_w` and its origin
already sits past the gutter. It now takes that same viewport and drops
its `rect`/`gutter_w` parameters entirely. A canonical rule with one
honest exception is not canonical.
The selection painter had the same defect with a worse failure mode: it
asked `pos_to_display` through the LIVE context, which returns `None`
for a position left of the edge, so a selection beginning off-screen
and reaching into view took `continue` and painted NOTHING. That is the
common shape, not an edge case — select rightward from column 0 past
the window width and the view scrolls with the cursor.
TWO THINGS THE TESTS FOUND, both in `pos_to_display`. My framing note
said a caret sits between characters so never lands inside a glyph;
true for the caret, false for the DESIGNATION direction — the glyph's
start byte must map to its visible trailing cell, so `screen_col` needs
the straddle rule and not a bare subtraction. And the `take == 0` early
return short-circuited the translation entirely, so byte 0 looked
visible at every offset.
`view_left` is inert under `wrap` BY CONSTRUCTION —
`LayoutCtx::effective_left` and `Viewport::left_edge` return 0 while
wrapping — rather than by every caller remembering.
Persisted per leaf at DESKTOP_VERSION 1 (Q#HS5) with both approval
conditions: `#[serde(default)]` and a literal v1 JSON fixture omitting
the field, hand-written because a generated one would gain the field
and prove nothing.
Also: `view_left: window.view_left` in the render viewport, not a
literal 0. My mechanical fill put 0 there and it is EXACTLY the
`aa3cd4d` defect — coordinates and the indicator following the scroll
while the painter stays pinned at column 0.
BITE, per clause. Forcing `bisected = false` fails the multi-line
straddle witness; dropping the backward designation fails the
round-trip witness; removing `#[serde(default)]` fails the v1 fixture;
pinning `visible_cols` to an absolute clamp fails all three decorator
witnesses; restoring the selection painter's live-context lookup fails
the off-screen-start selection witness. Each alone. And with selection
now reading the shared helper, pinning `visible_cols` to an absolute
clamp fails the selection witnesses TOO — which is the check that the
duplication is really gone rather than merely reworded.
One unrelated red, logged as R7 in ci-red-signatures.md — the first
this session with a COMPLETE signature, so a matchable row rather than
a U note. `pmacs-gpu`'s managed-retry attach hit a BrokenPipe once
under full-sweep load and did not reproduce (6 isolated runs plus a
clean 113-target sweep). Per the rerun rule that is intermittence only,
and the row explicitly does not claim harmlessness. Not attributed to
this lane: Stage 4 touches no `pmacs-gpu` file and adds no wire
surface.
Gates: fmt; clippy --workspace --all-targets -D warnings, both
configurations; `cargo test --workspace --no-fail-fast -- --skip
basedpyright` 113 targets exit 0, and the same with --features crdt,
113 targets exit 0; git diff --check. No protocol change, so no version
bump and no protocol-bump matrix.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Closes Stage 3's remaining obligations.
THE PTY TEST. Every other test in this lane checks a mechanism.
tests/long_line_readable_acceptance.rs checks the complaint: the
shipped binary, a real 80x24 PTY, one source line 200 columns wide,
and an assertion that its tail marker reaches the host. It bites —
`scripts/bite HEAD~2 src/editor.rs --test long_line_readable_acceptance`
against the pre-aa3cd4d editor never paints TAILZQX in 20s.
Its truncate control (an isolated init.lua pinning the mode) is what
makes that marker discriminating, and it is also the honest statement
of what truncate costs today: those bytes are not off-screen, they are
unreachable until Stage 4.
What it does not prove: the workspace has no screen model and no
vt100/termwiz/vte, so this shows the tail was WRITTEN to the terminal,
not which row a human would point at. That is nonetheless the whole of
the report — under truncation the bytes are never emitted at all.
§1.1 WAS WRONG, FOR NINETEEN REVISIONS. `editing.fill-column` is not
an orphaned registry setting "of the exact shape Stage 1 just fixed".
Both cited occurrences are inside `#[cfg(test)] mod tests` — fixture
names in round-trip tests covering one setting per ConfigKind. Two of
those five names are real; three, including this one, are defined
nowhere else in the tree. There is no shipped setting, so the Q#LL4
deliverable "sharpen its description" had no object.
The mechanism is worth more than the correction. A grep hit at a src/
path, a genuine `r.define(...)` call that is real API usage rather
than a mock, and `#[cfg(test)]` about fifty lines above the citation.
Every later revision inherited the conclusion instead of the evidence,
and three review rounds reasoned about the consequences of an orphaned
setting rather than re-checking that it existed. A file:line citation
is not a substitute for reading the scope it sits in.
Had it gone unchecked into implementation, Stage 3 would have shipped
an edit to a unit-test fixture believing it was rewording a
user-visible setting — a no-op with a misleading commit message.
§1.1 is withdrawn in place, keeping the original text and the
reasoning that produced it; §6's answer is unchanged (a setting that
does not exist is a stronger reason not to adopt it) and its premise
corrected. Both fixture sites now say they are fixtures. The approval
is not reopened: nothing else in the document rested on §1.1, which
argued for a display setting separate from fill-column — which is what
shipped.
AND ONE UNCLASSIFIABLE RED, logged as U1 in ci-red-signatures.md. A
`-p pmacs-gpu` run went 227/1 once; every run since is 228/0. The
failing test name was NOT captured, because I piped that command
through `tail -3` and discarded the failure block above the summary.
36 later runs are clean, 6 under deliberate concurrent load — which
per the rerun rule establishes intermittence only, and without a
selector not even that. Deliberately NOT matched against A1 despite
A1 also being GPU-headless-under-load: matching requires an exact
selector and every required fragment, and calling a shapeless red
"probably the known one" is the reputation-by-adjacency that file
exists to deny.
Gates: fmt; clippy --workspace --all-targets -D warnings; --lib
1917/0; --lib --features crdt 2102/0; line_wrap 6/0;
long_line_readable 2/0; folding 21/0; folding_stage2 48/0;
full_grid_resync 1/0; config_registry 16/0; m4 150/0;
PMACS_REQUIRE_GPU=1 -p pmacs-gpu 228/0 (see U1); git diff --check.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth