[demrom]

When two children in one session return different exit codes, waiting for the second and then the first reports the second child's code twice. waitpid and ios_full_waitpid read the shared session status, so a completed child's result can be overwritten before its caller waits.

Store the exit code with the synthetic PID and read that slot when waiting. Normal command returns, ios_exit and commands that finish without starting a thread record their result before the PID is released. Commands that end without recording a result retain status 130, the code already used for cancellation before dispatch. The slot is reset when the existing allocator reuses the PID.

tests/child-wait-status.m starts a child that returns 7 and another that waits for it before calling ios_exit(23). The parent waits in reverse order. The same executable reports 23/23 and exits 1 against master, then reports 7/23 and exits 0 with this change. It also checks a missing command returns 127 and empty and NULL commands return 0. Both frameworks were built with Xcode 27.1, arm64 Release, Simulator SDK 27.1 and an iOS 15 deployment target; the patched build uses the command in tests/README.md. The root README's all-targets iPhoneOS build also passes after resolving the declared Swift package dependencies and setting IPHONEOS_DEPLOYMENT_TARGET=15.0 for Xcode 27.

On an iPhone running iOS 27.0.1, the fixture run as an a-Shell command reports 7/23, missing 127 and empty/NULL 0. File copying, pipelines and exit code checks pass, and an ordinary command after the test writes the expected file.