Manual validation of 9.2 surfaced finding QB1: the CurrentLine wash
never appeared, and 9.1's Selection never actually rendered either.
Root cause: `Selection` and `CurrentLine` are the only two
per-WINDOW-state decorations; every other rendered family (StyleSpans,
diagnostics, inlay hints, minimap) is keyed to the shared BUFFER. The
producer emits both from the viewing frontend's own window
(`active_window_for(self.frontend_id)`). pmacs-gpu is a read-only
mirror with no input path — it never sends Key/cursor events, so its
own window's cursor stays pinned at 0 and its selection stays None.
Both decorations are therefore inert in pmacs-gpu: CurrentLine paints
a static line-0 wash (invisible at alpha 0.08) and Selection never
appears. What the user actually watches is the *editing* frontend's
(their TUI's) cursor — which is peer presence.
Fix is consumer-only — no producer or protocol change. The wire
already carries it: `InstanceMessage::PresenceUpdate { frontend_id,
buffer_id, cursor, selection }` is broadcast by the daemon to every
`multi_frontend` recipient, pmacs-gpu already negotiates
`multi_frontend: true`, and it was simply dropping the message at its
`_ => None` catch-all.
Q#5 (recorded in the framing doc): peer presence is the authoritative
cursor/selection source for a read-only mirror.
- New `peer_presences: HashMap<FrontendId, PeerPresence>` state,
cleared on BufferSnapshot (peer offsets are prior-buffer-relative).
- New `PresenceUpdate` arm stores per-peer (buffer_id, cursor,
selection) and requests a redraw.
- `peer_background_rects` replaces the old
`decoration_background_rects`: renders `CurrentLine` over the source
line holding each peer's cursor (`source_line_range`) and
`Selection` over each peer's selected range, both via the shared
`push_glyph_extent_rects` (the former inline glyph-overlap loop,
extracted). Own-window Selection/CurrentLine in `current_decorations`
are no longer drawn as backgrounds — they're inert for a read-only
mirror. Diagnostic (foreground) decorations are untouched.
- The producer keeps emitting own-window Selection/CurrentLine (9.1/
9.2) unchanged — correct and forward-looking for when pmacs-gpu
gains its own input in Phase B; simply unconsumed-for-backgrounds by
the mirror today.
Deferred within the stance (documented): per-peer stable colors (single
peer reuses the Selection/CurrentLine colors), peer caret glyph +
"user N" label, and own-vs-peer cursor merge once input lands.
New tests: `source_line_range_locates_enclosing_line` +
`source_line_range_handles_empty_and_leading_newline`. The peer
rect generation itself needs a laid-out buffer (font system) and is
covered by the manual probe.
Two pre-existing functions tipped past clippy's 100-line limit by the
additions (`State::new` 101, `apply_attach_message` 116, a per-variant
match dispatcher); both get `#[allow(clippy::too_many_lines)]`,
matching the precedent on `semantic_render::render_frame`.
Gates green:
- cargo fmt --all -- --check
- cargo clippy --all-targets --workspace -- -D warnings
- cargo clippy --all-targets --workspace --features crdt -- -D warnings
- pmacs lib 1329 + pmacs-protocol 11
- pmacs-gpu unit 15 (+2 source_line_range tests)
- m4_acceptance 88, m11_5_semantic_acceptance (--features crdt) 2
Manual probe: daemon + TUI attach + pmacs-gpu attach. Move the cursor
in the TUI — pmacs-gpu's CurrentLine wash should track the TUI's line.
Select text in the TUI — the Selection wash should mirror it. Both
should now actually appear and follow the editing frontend.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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