- Viewport: swallow the opening tap/scroll (justOpenedAt window) and
re-clamp ScrollOffset to [0,MaxScroll] in EditorLayout so a short file
never opens past its content (blank viewport).
- Chunked buffer: replace the fixed i*chunkSize slot model (which drifted
after length-changing edits and could re-read stale disk for shifted
tail chunks) with an ordered chunk slice + prefix-sum byte offsets.
In-range files now load fully on open (SetContent), so there is no lazy
load and no stale-disk re-read. Edits splice only the affected chunk(s).
- Size guard: files > MaxEditableFileSize (50 MB) show a 'too large to
edit' notice instead of loading; the browser still lists them. Edit
handlers (KeyDown/ReplaceRange) are no-ops for too-large files.
- Tests: rewrite chunked_buffer_test.go for prefix-sum correctness (insert/
delete across chunk boundaries, rune->byte after edit); fix the large-file
e2e expectation to the shift-correct ground truth.
Greg Pomerantz
3460ef3993