[Ken Chau (kenotron-ms)]

Summary

Subagents could reset their delegation depth in a new host session, restart a closed pending handle, and continue executing after close_agent returned. Propagate the effective depth and limit, own one execution task per handle, wait for cancellation to settle, and report unfinished host results as unsuccessful.

The root-install CI fixture also overrode every module in this repository, displacing the public engine's same-named filesystem apply-patch dependency. Limit candidate overrides to the root distribution's five declared same-repository runtime dependencies; keep engine-owned dependencies and the mandatory public create_agent smoke intact.

The canonical coding-agent-loop specification §§7.2–7.3 defines termination, independent child sessions and configurable descendant depth together; these changes preserve that lifecycle contract without changing pipeline traversal or the existing deferred-start interface.

Verification

• Full loop-agent suite: 587 passed.
• Regressions cover propagated descendant limits, closed pending handles, concurrent waits without duplicate execution, active close settlement and incomplete/cancelled/failed helper results.
• An actual Goal verifier assembly exercised helper execution/result consumption, descendant refusal and native cancellation with controlled no-network provider responses. It requires a separate native Core cancellation repair; these runner unit tests alone do not establish that bridge behavior.
• Independent runtime source review and full-suite rerun completed without findings.
• CI correction independently reviewed. Original public-binding initialization failed after the overbroad override selected runner apply-patch 0.1.0; corrected installation retains engine-owned filesystem apply-patch 1.0.0 at d71bb95 and the unchanged public create_agent/close smoke passes. uv pip check passes for all 113 installed packages.
• Touched files formatted. Existing lint findings in the original files remain; no clean lint claim is made.

Checklist

• nlspec evidence: §§7.2–7.3 cited with surrounding lifecycle context
• Tests pass in the touched loop-agent module
• ruff check clean (existing file warnings retained)
• ruff format --check clean
• Diff scope matches description
• No contracts, ledger or extension changes