A focused input's caret zombied to the bottom-left corner whenever an
unrelated repaint (spinner tick, log line, progress bar) committed
without re-declaring the cursor: the active cursor was gated on a
per-commit dirty/reference change, so an unrelated commit dropped it.
Real terminal programs that own an edit point re-place the caret there
every frame (vim emits an absolute CUP after each repaint, readline
re-lands the buffer offset on SIGWINCH, nano homes to its edit cell).
Match that: the runtime now re-emits the last-declared caret at the end
of every commit until the declaration changes or is cleared, so the
caret survives unrelated repaints in all component topologies. The
position is clamped to the visible region (D5) and a cleared
declaration emits no caret, so teardown still hands the cursor back.
This is a deliberate divergence FROM Ink, which re-asserts only when
the cursor's React component re-renders and so zombies the caret in
sibling/leaf topology too (run-verified). Aligning to Ink reduces bugs
only when Ink is correct; here matching Ink would preserve abnormal
behavior. Overrides the prior 2026-06-01 KEEP, whose rationale (avoid
diverging from Ink in the sibling direction) was overturned by running
real terminal apps. The {x,y} setCursorPosition API is unchanged (it
remains the IME primitive); the fix is an internal per-commit re-emit.
Red-first: a real-TTY PTY test with sibling-topology spinner state
asserts the spinner-only frame ends with the caret-restore suffix.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Yunfei He
86b94b9fa5