Writing to a pipe whose reader has already exited raises SIGPIPE, which
kills the whole process instead of throwing. MacNodeHostWorker already
guarded its stdin pipe with F_SETNOSIGPIPE; the codex App Server client
and the MLX TTS helper transport did not, so a child exiting mid-write
could take down the app. Suppressing the signal exposed that an
undelivered App Server request write was reported as appServerUnavailable
even though the frame was provably never sent, so it now requeues once
onto a fresh child instead of failing the caller.
Test-side pipe write ends whose readers are spawned children (or a
readability handler that can close the pipe mid-test) get the same
suppression so a racing reader exit fails the assertion instead of
killing swiftpm-testing-helper with signal 13, which is what caused the
macos-swift CI lane's intermittent unrelated-test crashes (e.g. PR
#126559, run 32341197738 job 96340683947).
* fix(macos): reap app-owned child process groups
macOS-owned SSH, Codex, and node-host descendants no longer survive terminal shutdown. Codex retains EOF-first graceful exit before bounded process-group termination and reaping.
* fix(macos): correct managed cleanup wake binding
* fix(macos): preserve Codex shutdown escalation
Keep the app-owned EOF grace window while allowing abortive requests to interrupt it before process-group TERM and KILL.
Peter Steinberger