/usr/bin/python3.12 CPython 3.12.3 (Ubuntu 3.12.3-1ubuntu0.17), Linux x86_64 ordinary GIL build; child interpreter sys.executable matches parent; signal.SIGKILL and returncode=-9 tested on this Linux only, other platforms NOT_RUN.
Hexo isolated: /opt/cloudcli/node/bin/node v22.16.0.
Connection: loopback 127.0.0.1, server read_timeout=10 s with drain_timeout=0 in forced cancellation scenario; separate normal request completes before close.
Database: temporary SQLite file created through SQLiteTaskGateway; child signals readiness after committed claim or from within an uncommitted run transaction. Parent forcibly kills child, reopens SQLite gateway and checks query/recover_running. Exclusive recovery assumes no active worker; not a distributed lease implementation.
Docs checked HTTP 200 on 2026-10-08: https://docs.python.org/3.12/library/asyncio-eventloop.html#asyncio.Server.wait_closed and https://docs.python.org/3.12/library/sqlite3.html#transaction-control.
External side-effect delivery/exactly-once, portable forced termination, persisted loopback service integration: NOT_RUN.
