Picks up the "arrow keys do nothing in the GUI" investigation. Root
cause is the multi-buffer mismatch the manual investigation theorized,
now confirmed in code and tested:
- `build_fresh_frontend_view` binds an attaching frontend's window to
LOCAL's active buffer (a scratch the TUI never switched LOCAL away
from).
- `send_buffer_snapshots` ships a snapshot per buffer in registry
order; pmacs-gpu treats each as "switch visible buffer", so its
`current_buffer_id` (and what it displays) becomes the LAST one — the
file the TUI opened.
- So the GUI displays the file, but its daemon-side window edits the
scratch. Arrow keys → `dispatch_key` → move the scratch cursor →
`CursorByte { buffer_id: scratch }` → pmacs-gpu ignores it (its
`current_buffer_id` is the file). The caret never tracks.
Fix: the `Viewport` event already declares which buffer the frontend
is displaying. The daemon now calls `align_semantic_window_to_buffer`
on it — re-pointing the semantic frontend's window at the declared
buffer (rebuild the cheap `TextView` line index, reset cursor; a
semantic frontend has no grid overlays to migrate, it renders from the
wire). Input and the `CursorByte` it produces then target the buffer
the user is actually looking at. The guard makes it a no-op when the
buffer is unchanged (so per-edit Viewport re-declarations don't reset
the cursor).
Tests:
- `viewport_aligns_semantic_window_to_displayed_buffer` — window
starts on scratch, declares the file via align, a key then
self-inserts into the *file*.
- `semantic_frontend_key_event_reaches_the_core` (from the prior
commit) still green.
Also adds `PMACS_GPU_DEBUG_INPUT=1`: logs keys sent and each
`CursorByte` with `buf`/`current`/`match` so the displayed-vs-edited
buffer alignment is visible at a glance on retest.
Gates green: fmt; clippy --all-targets --workspace -D warnings
(default + crdt); pmacs lib 1334; crdt daemon tests 7; pmacs-gpu unit
18; m4_acceptance 88; m11_5_semantic_acceptance 2.
Still needs visual confirmation (arrow keys move the caret in a
running pmacs-gpu) before merge.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
4cd968bc0c