A pending clarify card binds Enter / 1-9 / A-Z / arrows on `window`, and
inactive tabs stay MOUNTED, so every parked clarify keeps a live listener.
Nothing in the handler asked whether the card was on screen: the first
listener registered won, called preventDefault(), and the rest bailed on
defaultPrevented. Registration order is mount order, not visibility.
With two chats waiting on a question, answering the one in front of you
sent `clarify.respond` for a background session's request instead —
silently answering a question the user never saw and resuming that turn.
The invariant is already stated one file over, in composer-focus-keys.ts:
"a clarify card waiting in a background thread must not take the
foreground composer's letter keys". `clarifyCardOwnsKey` honours it via
queryVisible(); the card's own listener did not. That asymmetry is the
bug — the key-ownership resolver and the key handler disagreed about
which card is live.
Export that lookup as `visibleClarifyCard()` and have both sides use it,
so they cannot drift apart again. The card bails unless it IS the visible
card, which also leaves the keystroke unprevented for the composer when
the only pending card is hidden.
Scoped by visible-card identity rather than `usePaneVisible()`: split
zones each render their own active pane, so two cards can be visible at
once and a per-pane visible flag would not disambiguate them.
briandevans
a3662bb32c