Approve complete runner prompt delivery after lifecycle checks

Changes: Accept the preserved S00-012 stdin correction and descendant regressions; record independent QA evidence. No source changes.
Validation: Reproduced the legacy 140000-byte delayed-reader timeout and reaped the child. All 28 automation tests and 72 make check tests passed, including complete UTF-8/EOF, submit/timeout descendant cleanup, fresh sessions, scope and snapshots. Reviewed executor message and cumulative patches; git diff --check passed. No Windows, live model or application readiness claim.