Round 6 widened dialog focus ownership to count focus inside ANY `aria-modal` subtree as ours, so a
dialog and the dialog stacked on it closing together would still hand the focus back. That clause has
no way to tell a layer closing WITH us from one that stays open, so a dialog closing on its own — an
in-flight mutation's `onSuccess`, not a click, since a scrim covers it — under a modal raised above it
pulled the focus onto its own pre-open trigger, behind that scrim, where Enter still activated it.
Three verifiers confirmed the mechanism and two corrected the severity down: it self-heals on the
next Tab, which is why this is a containment violation rather than a broken end state.
`lib/layerStack` cannot refine it. Measured against the real hook: at the instant the lower dialog's
focus cleanup runs, the both-closing case and the sibling-stays-open case give identical readings —
`anyLayerAbove` true, the upper layer topmost — because passive cleanups run parent-first and
`useDialogChrome` is declared before the effect that calls `removeLayer`. Gating on the stack turns
round 6's own test red. What separates them is the DOM: React detaches a deleted subtree before
passive cleanups, so a layer closing with us is already disconnected while one that stays open is
not. Both tests are green, and each was mutation-checked against the other.
Verified in Chrome on localdev: opening the cheat sheet from a sidebar button and closing it restores
that button; with the command palette stacked over the cheat sheet, closing the top one leaves the
focus neither on the background trigger nor on <body>, and closing both returns it to the trigger.
Welcome's Lightbox got the trap and the restore in round 6 but not the layer membership the other
shells have, so its Escape and Tab fired from a raw window listener whatever was on top — the shape
the wizard's comment records being bitten by, unreachable today only by a mount ordering nothing
enforces. It joins the stack. Its comment also read as though the four-shell sweep were finished:
`PlayerModal` is still an `aria-modal` surface with no name, no trap and no restore, which is on
ROADMAP.md now rather than implied to be done.
peter
c7a377396b