Deployment scope: macOS 26 and macOS 27, Apple silicon / arm64 only. Intel / x86_64 and Rosetta behavior are outside this inquiry. Please distinguish applicability and limitations for each named macOS version; support for one version must not be assumed to establish support for the other.
We are evaluating a directly created child's lifecycle in a continuously living original parent, using documented posix_spawn, kill and wait interfaces. This is a support-contract clarification, not a report of a reproduced OS defect. We have not conducted a process experiment.
The proposed parent would serialize every action against every potentially consuming wait, exclude competing waiters, retain SIGCHLD status (no SA_NOCLDWAIT or explicit SIG_IGN), and permanently revoke further actions before permitting final reap. Parent loss or uncertain ownership causes refusal, with no adoption or respawn. We are not asking for private interfaces or implementation internals.
POSIX.1-2024 XBD 4.17 prohibits PID reuse before process lifetime ends. Its _exit description connects normal zombie lifetime to collection of status, with explicit automatic-disposal exceptions. We recognize that UNIX 03 certification is a different edition/profile and do not assume POSIX.1-2024 applicability to macOS.
For the specified deployment range, please identify the applicable supported documentation/standard profile and clarify:
- Under the stated exclusions, is a directly created child's positive PID reserved against reassignment through exit/zombie state until a defined consuming wait boundary? Which documented exceptions or ownership transitions defeat that premise?
- What is the supported consuming boundary for wait/waitpid, including WNOHANG, EINTR, stopped status and concurrent waiters? Does excluding all consuming waits during an action close the numeric-replacement risk, or is another supported condition required?
- Please identify the documented effects of explicit SIG_IGN versus SIG_DFL, SA_NOCLDWAIT, exec and parent death that are relevant to that exact reservation claim. We do not infer unchanged executable identity, permissions or successful termination from unchanged PID.
We are asking for version-applicable supported semantics, including any limits on the conclusion, rather than empirical plausibility or absence of a known counterexample. If this guarantee is not supported, please say so. We are not asking you to certify our implementation, cleanup of descendants, or full supervisor correctness.
Primary references: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap04.html https://pubs.opengroup.org/onlinepubs/9799919799/functions/_exit.html https://www.opengroup.org/openbrand/register/apple.htm