FN-8606 declared the window shell as a component inside PlanningModeModal and
SettingsModal render. A component declared in render is a new element type on
every render, so React remounted the whole subtree on each keystroke, destroying
the focused input: Planning Mode dropped everything after the first character and
Settings text fields did the same.
Replace ModalShell with a plain renderModalShell(children) call so the returned
element types stay stable, and add a Planning regression test that types
per-character across both the modal and embedded surfaces (fireEvent.change
cannot observe this class of bug, which is why it shipped).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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