Codex flagged that parallel `start`s race on shared state: two cold
launches could both stop/build/boot the singleton on the same rootfs/PID,
concurrent builds share the infra VM's buildah store, the cleanup did
`buildah rm -a` (nuking a peer build's container), and the rootfs cache
was populated non-atomically.
- `infra_vm.ensure_running`: a host flock (`singleton.lock`) around the
cold stop/build/boot path, with a double-checked health re-test under
the lock so a second launcher adopts rather than re-boots. The healthy
fast-path stays lock-free.
- `image_builder.build_agent_rootfs_dir`: a host flock (`.build.lock`)
around cache-lookup + build + publish; build into `.building-<digest>`
and publish by atomic `os.rename`, so a partial build never appears as
`agent-<digest>`.
- scoped cleanup: per-build named working containers
(`<tag>-smoke`/`-export`) removed by name instead of `buildah rm -a`;
also cleared before the build to recover from a crashed prior run.
Verified: agent image builds via the locked/atomic path, infra VM stays
healthy, agent boots, `claude --version` = 2.1.172. Full unit suite +
pyright green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck
didericis
914f01fa8f