fix(vm): harden guest sandbox startup

[alangou]

Summary

Harden VM guest startup so the packaged sandbox keeps its expected executable identity during initialization.

Related Issue

Tracked in the maintainer workflow.

Changes

• Simplify the VM guest sandbox startup path
• Add regression coverage for the expected launch contract

Testing

• Checks appropriate to the affected code and behavior pass
• Unit tests added/updated
• E2E tests added/updated (the local run reached VM launch, then host access to /dev/kvm was denied)

Validation performed:

• cargo fmt --all -- --check
• cargo clippy -p openshell-driver-vm --all-targets -- -D warnings
• cargo test -p openshell-driver-vm
• VM bundle build and integrity checks

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (not applicable)

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[github-actions]

Label test:e2e applied, but pull-request/4539 does not exist yet. A maintainer needs to comment /ok to test cda251026bd4f05b2367d59e09d33fcfdd367383 to mirror this PR. Once the mirror exists, re-apply the label or re-run Branch E2E Checks from the Actions tab.

[alangou]

/ok to test d5c483d

[alangou]

gator-agent

PR Review Status

The independent code review found no blocking findings. Directly executing the packaged, statically linked guest sandbox preserves its executable identity; the bundle build already rejects a sandbox that requires an ELF interpreter.

Thanks @elezar for asking about the script-content tests and the sandbox-versus-supervisor startup path. I checked the new packaging-boundary explanation, the bundle's static-link checks, and both guest launch modes: the guest starts openshell-sandbox for capability-free launch or qualification, while the host supervisor is packaged separately. The bootstrap-variable nit is non-blocking.

Blocking findings: None.
Carried findings: None.

The current head has been mirrored with /ok to test. Branch Checks and Branch E2E Checks are queued, Helm Lint is running, and Trivy Changes passed. Gator will inspect their results next cycle; maintainer approval remains outstanding.

Gator metadata

• Validation: Focused VM startup bug fix and regression coverage; author has verified repository admin authority.
• Docs: Not needed for this internal executable-identity fix; no new user commands, configuration, or workflow.
• Checks: DCO and Trivy Changes passed; Branch Checks and Helm Lint queued/running on the current head.
• E2E: test:e2e retained; Branch E2E Checks queued on the current-head mirror.
• Head SHA: d5c483d1f8fb014d671f595d01684df9cdd4e9c1
• Base SHA: 6e69360d0e1536d891f4abfbb60c1d90e50188c9
• Merge base SHA: 6e69360d0e1536d891f4abfbb60c1d90e50188c9
• Patch ID: 27fb69fc8c31fdeb184ba0dbffd1f6e06f0d38f0
• Gator payload: 12
• Review mode: initial
• Previous reviewed SHA: none
• Review budget exhausted: no
• Maintainer decision required: no
• Next state: gator:watch-pipeline

[alangou]

/ok to test cfc81e5

[alangou]

gator-agent

PR Review Status

The independent follow-up review found no blocking findings in the startup delta. Thanks @alangou for explaining that both guest paths launched the sandbox and that the bootstrap runtime is always available. I checked the removed fallback against bootstrap staging and mount preparation, and confirmed the extra variable was removed as @elezar suggested.

The latest head is now mirrored with /ok to test. Branch Checks, Helm Lint, and Branch E2E Checks are running; Gator will inspect their results next cycle. Maintainer approval remains outstanding.

Blocking findings: None.
Carried findings: None.

Gator metadata

• Validation: Focused VM startup fix; author has verified repository admin authority.
• Docs: Not needed for this internal startup change; no new user command, configuration, or workflow.
• Checks: DCO and Trivy Changes passed; current-head Branch Checks and Helm Lint running.
• E2E: test:e2e retained; current-head Branch E2E Checks running.
• Head SHA: cfc81e567f8303cd8b5e62596190ba9c4bbd6e13
• Base SHA: 6e69360d0e1536d891f4abfbb60c1d90e50188c9
• Merge base SHA: 6e69360d0e1536d891f4abfbb60c1d90e50188c9
• Patch ID: 82ba256adf13c5e4f15cb79653143f05af18179a
• Gator payload: 12
• Review mode: follow_up
• Previous reviewed SHA: d5c483d1f8fb014d671f595d01684df9cdd4e9c1
• Review budget exhausted: no
• Maintainer decision required: no
• Next state: gator:watch-pipeline

[alangou]

gator-agent

Monitoring Complete

Monitoring is complete because this PR has merged. The last Gator state was gator:merge-ready, and maintainer approval was present.

I removed the active gator:* label because there is nothing left for Gator to monitor on this PR.

Gator metadata

• Head SHA: cfc81e567f8303cd8b5e62596190ba9c4bbd6e13
• Gator payload: 12