Prefer two-segment Codex session ids #146

Job	Run time
build-linux-host-simd	16m 17s
build (x86_64-apple-darwin, macos-latest)	7m 45s
build (aarch64-unknown-linux-gnu, ubuntu-latest)	8m 29s
build (x86_64-unknown-linux-gnu, ubuntu-latest)	6m 7s
build (aarch64-apple-darwin, macos-latest)	6m 59s
release	14s
	45m 51s

Provide feedback