[elezar]

🏗️ build-from-issue-agent

Summary

Make sandbox child lifecycle ownership structural after the RFC 0012 rearchitecture. Canonical processes and boundary-exec processes now share one cross-platform managed-child API; Linux orphan-reaper registration remains internal to that owner.

Related Issue

Closes #3154

Changes

• Introduce a cross-platform ManagedChild<C> wrapper over the generation-safe Linux child registry.
• Centralize wait, try_wait, drop cleanup, and ECHILD diagnostics in the wrapper.
• Route the canonical Tokio process through ManagedChild<tokio::process::Child>.
• Route both piped and PTY BoundaryExec processes through ManagedChild<std::process::Child>; this is the execution path used by SSH after RFC 0012.
• Make raw registry mutation private so child-owning call sites cannot bypass the lifecycle owner.
• Preserve boundary terminal observation, signal ordering, process-group tracking, and cancellation cleanup.

Deviations from Plan

The original plan targeted child spawning in openshell-supervisor-process and its SSH implementation. RFC 0012 moved that responsibility into openshell-sandbox; Revision 3 of the issue plan updates the scope to the canonical process and BoundaryExec implementations there.

Testing

• mise run pre-commit passes
• cargo test -p openshell-sandbox passes (83 passed, 1 expected ignored)
• Existing managed-child and boundary-exec unit coverage retained
• E2E changes not required; no files under e2e/ changed

Tests added or updated:

• Unit: cross-platform standard/Tokio managed-child lifecycle, Linux registry/reaper interleavings, and existing piped/PTY boundary-exec lifecycle coverage.
• Integration: full openshell-sandbox crate test suite.
• E2E: N/A; the detached-fast-exit regression coverage from prerequisite PR fix(supervisor): serialize child registration with reaping #3142 is already on main.

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)

Documentation updated: None needed; this is an internal ownership refactor with no user-facing or configuration changes.

[github-actions]

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