[earakely-scale]

What changes

launcher_test.py's three tests fail now and then in the slow tier with KeyError: 'image': on main at eac7660 and at #580's merge (d1fcdf8), and on #666. The shared desktop's amd64 disk had failed its probe, so the computer had no disk image:

docker run ... --mount type=image,source=localhost:5000/agentenv-computers:832369…@sha256:9ee29… ...
docker: Error response from daemon: No such image: localhost:5000/agentenv-computers:832369…@sha256:9ee29…

Why. A slow shard runs two pytest workers, and both compose the shared desktop. When its disk's key is new, as on the first run after the computer images change, neither finds it stored, so both build it. Each build tags localhost:5000/agentenv-computers:<key> and pushes it, and the two builds' bytes differ. So the second build moves the tag off the image the first had pinned by digest. The first's probe then mounts name:tag@digest with --mount type=image, which Docker doesn't pull for, and the image under that name is gone. A run that copies the disk from the computer image mirror builds nothing, which is why later main runs pass.

I checked Docker's side on a Docker 28 daemon on the containerd image store, the store CI uses. docker image inspect and --mount type=image agree on a pinned name every time. Once the tag moves to a rebuilt image, the first image's pinned name is gone for both, and an explicit pull brings it back.

The fix. The Linux disk is now looked up, made and pushed holding a lock of its key (linux-disk:<key>), as Windows and Omarchy disks already are. A second compose of the same disk on the machine waits, finds the first's push, and reuses it: one build, and no tag moves.

Testing

• A new unit test, test_a_disk_is_looked_up_made_and_pushed_holding_a_lock_of_its_key_so_composes_of_it_take_turns: each arch's disk is looked up, made and pushed while its key's lock is held. It fails without the change.
• tst/unit/env/envs/test_computer_disk.py: 43 passed.

🤖 Generated with Claude Code

Confidence Score: 5/5

The PR appears safe to merge; no actionable new issue was found.

Summary

The PR keeps Linux disk lookup, build, and push under one lock per disk key.

• Linux disk composes now reuse the first image built for a key.
• Integration workers now share locks for the machine resources they use.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Compute disk key] --> B[Acquire shared lock]
  B --> C{Disk already stored?}
  C -->|Yes| D[Reuse pinned image]
  C -->|No| E[Build and push disk]
  E --> F[Pin image digest]
  D --> G[Release lock]
  F --> G
  G --> H[Probe disk]

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_{Reviews (2) · Last reviewed commit: "test: the integration tier's workers sha..." · Reviewed by Greptile}

[earakely-scale]

Folded into #666 (commits 9f14ba4 and 3a8f4b4 there): #666 changes the disk, so its slow shard 3 hit this race on every run; one PR keeps the release fix and what lets its CI pass together.