The self-hosted Linux runners ship no pwsh, and the pwshAvailable probes used spawnSync('where.exe'), which reports a missing binary as status null instead of throwing — the suites never skipped and failed with spawn pwsh ENOENT. Probe with resolvePwshPath() status instead, the same gate the coverage exemption uses. Exempt pwsh-sandbox src from coverage on pwsh-less hosts (its remaining helpers branch and the invariant companion ride the executor suites' real pwsh runs); pwsh-ful hosts keep the full 100% bar. Cover the windows-acl probe case and the runner-entry resolution in sandbox-local on Linux (chain-seam tests plus a windowsAclRunnerEntry seam) — the package's POSIX-only suites are Linux's only chance to cover the new lines. Static gate fixes: declare dsh-pwsh-sandbox in the base bundle, register the runner files entry in constraints, knip entries for the e2e suite and where.exe, regenerate the module graph. Verified in WSL (no-pwsh Linux): pwsh-sandbox 5 pass/13 skip with the exemption active, sandbox-local coverage 100%.
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