Why: land U8, U9 and U11 across agent-native (cff6935), agent-squad
(9edb6ba) and modules/backend (race-repair tip) per the approved plan.
Evidence: per-unit SELF receipts under /tmp/agent-stack-b2 (all
exit=0); full make test re-run follows on this branch.
Impact: three component gitlinks.
Refs: docs/superpowers/plans/2026-10-21-agent-stack-audit-remediation-plan.md