Deep-review round 5, over round 4's own fixes.
- Round 4 gave `ui/Modal` a persistent portal host so a fullscreen transition would stop tearing
the dialog down. The host was attached in a `useLayoutEffect` — one commit phase AFTER React
runs `autoFocus` in `commitMount`, and `focus()` on a disconnected node is a no-op. Every
autoFocus in every dialog was dead: Mod+K opened the command palette with the focus on the ✕,
so typing searched nothing and Enter closed it; the same for the download rename field and
every non-danger confirm. The host is attached in a `useInsertionEffect` now, a whole phase
earlier, and the whole re-parent — including the focus save/restore across the move, which
`appendChild` needs because it is remove-then-insert — lives in one `useFullscreenPortalHost`.
`ui/AnchoredPopover` had a second copy of that re-parent WITHOUT the focus restore, and a
comment claiming focus survived it; both now come from the hook.
- `ui/Toaster` classified a toast raised in the SAME commit as a host takeover among the ones it
inherits, because it read the store live at the takeover render. A dialog that notifies and
closes in one handler (UploadDialog) therefore put its toast up with no role, into a region
still `aria-live="off"` — announced by neither path. "Inherited" is now what the outgoing host
last had on screen, and a toast that is NOT inherited is announced even inside the unarmed
window.
- The onboarding wizard renders its own shell, and Escape ordering was all of the dialog contract
it had: no role, no label, no initial focus, no trap, no restore. A keyboard user tabbed out of
the first-login wizard into the app behind the scrim. The focus half of the contract is now one
shared `ui/dialogFocus` that both `ui/Modal` and the wizard use.
Every fix has a regression test, each mutation-checked (6 mutations, all red on the assertion
they are named after).
peter
41b652f8fd