CI flake: livestore wa-sqlite preflight fails in cachix.package eval with invalid /nix/store path

Problem

A Livestore PR CI job (wa-sqlite-test) failed during preflight bootstrap before running wa-sqlite build/tests.

Failure signature:

• Failed to convert config.cachix to JSON
• Evaluation error: Failed to get attribute 'package'
• ... while evaluating the option \cachix.package``
• error: path '/nix/store/xrkag36scyx65im0m582hm09xnaa9zcc-setup.sh' is not valid

Where

• Livestore PR: https://github.com/livestorejs/livestore/pull/1035
• Failed run: https://github.com/livestorejs/livestore/actions/runs/22064735021
• Failed job: https://github.com/livestorejs/livestore/actions/runs/22064735021/job/63753512497?pr=1035

Notes

• The failure occurs in Preflight workspace bootstrap (devenv tasks run pnpm:install genie:run ts:build --mode before --verbose) and the wa-sqlite build/test steps are skipped.
• This job runs on GitHub-hosted ubuntu-24.04 (not Namespace runner labels), while many other Livestore jobs in the same workflow use Namespace labels.

Potentially related

• overengineeringstudio/effect-utils#201 (same signature family on another repo/workflow context)
• namespacelabs/nscloud-setup#8 (invalid Nix store path flake discussion; environment differs)
• Historical InvalidPath reports in cachix-action: https://github.com/cachix/cachix-action/issues/106

Ask

Track this as a CI flake class around Nix store/cachix/devenv evaluation integrity and collect additional occurrences from GitHub-hosted Linux jobs.

Footnote: Created by an automated coding agent on behalf of the repository owner.

Start with the linked GitHub Actions run, job, and Livestore PR, focusing on the Preflight workspace bootstrap command and its cachix.package evaluation failure. Compare this ubuntu-24.04 job with workflow jobs using Namespace labels and review the related invalid-path reports. Done means documenting whether this is a reproducible CI flake and collecting confirmed occurrences or a clear failure boundary.