The tests must write and read real temp files because `dismissFirstRunPrompts` calls `appendFile` directly with no injectable `logWriter` — add a `logWriter?` parameter to `first-run-preflight.ts` matching the pattern in `simulator-lifecycle.ts`, then replace `tempLogPath()` + `readFile` with an in-memory log writer.

The `child.stdin` stream has no `'error'` listener; if the spawned process closes its stdin end early (e.g. a crash or unexpected exit), Node.js emits an unhandled EPIPE error event on the writable stream, which terminates the process instead of rejecting the promise.

On the very first poll iteration, if `describe-ui` returns elements but none of the target labels are present (e.g. the app loaded its home screen before the first-run prompt appeared), `uiSeen` is set and then immediately checked on the same iteration, causing the loop to break with `promptsDismissed = true` without ever dismissing anything — silently skipping the preflight.

In `runCommand`, `child.on('error', reject)` only handles process-level errors; `child.stdin` has no error listener. If the child exits (or closes its side of the pipe) before `child.stdin.end(opts.stdin)` finishes flushing, Node.js emits an `'error'` event on the writable stdin stream. With no listener, this propagates as an uncaught exception and can crash the harness process. Add `child.stdin.on('error', () => {})` to suppress EPIPE silently, since a stdin write failure is non-fatal once the child has already errored.