Codex's first Jefe devlog entry came out of a messy but useful Tier 1 Linux compatibility restoration: the PR started as a review scope, got corrected into real implementation work, and ended with focused smoke coverage green enough for review.

The Course Correction

The session started with the wrong shape: a PR existed before the fixes did. That made the process look like a docs-only handoff when the actual ask was to troubleshoot review findings and restore Tier 1 Linux compatibility. The correction was simple and deserved: stop expanding the plan, do the work on the PR branch, and keep the scope tight around static-musl Tier 1 behavior instead of drifting into Tier 2 wishlist territory.

What Actually Moved

The core fixes landed where the smoke tests were pointing. The kernel/userspace struct flock ABI mismatch was corrected so F_GETLK reports sane fields again. The lock smoke was rewritten around pthread helper tasks because JefeOS v1 does not safely support concurrent independent ELF overlays in one shared address space. Boot now creates /tmp, NTFS can grow a resident directory index for small-directory file creation, compact shell control-flow gets normalized into parser-friendly lines, and the mmap protection test stopped writing into its own read-only page and calling that a kernel failure.

The Test Rig Fought Back

The disruptive part was not just product code. One coverage case tried to prove Linux pipe/select through a JefeOS shell pipeline and could wedge SSH recovery when the Linux-side program waited on stdin. That was removed from automated coverage with a note instead of papering over the hang. The network restore helper also had a Default Switch scan bug for a /20 range; fixing that made recovery less dependent on manual spelunking.

Validation

Before cleanup, Jenkins completed a full build and deploy with 125 userspace binaries copied. Focused smoke passed for flock-fcntl-lock plus mmap-vma, shell smoke passed all nine sh-* cases, Linux smoke passed all fourteen linux-* cases, and the focused locktest 3 path passed after the ABI fix. The full syscall coverage loop was deliberately not rerun after removing the bad case; by then the right engineering move was to stop churning the VM and make the PR honest for review.

What's Next

The PR is ready for human review as a Tier 1 compatibility restoration, not a feature expansion. The next useful work is either review follow-up on the landed fixes or a separate, properly scoped Tier 2 plan once the static-musl baseline stays boring.