Extends the previous commit's fix rather than changing it. `waitUntil` now
settles, but the same window is open wherever a key is written without having
just polled: `press()` reaches its `stdin.write` on a turn that may still have
React's passive-effect flush queued (straight after a plain `tick`, or after an
earlier key committed a render), and `mount()`'s absorbing keypress lands one
tick after the mount commit. Both now `await settleInputHandlers()` before
writing, so "frame visible" implies "input handlers armed" at every dispatch
point, not only after a frame wait.
Adds a `test helpers` case that pins the contract: a `setImmediate` sentinel
stands in for the pending effect flush and must have run by the time
`waitUntil` resolves. Verified it fails when the yield is removed, so a future
regression surfaces here instead of as a differently-named flaky OAuth test
under coverage instrumentation.
Signed-off-by: cliffhall <cliff@futurescale.com>
ae0e9d53a3