refactor(llc/adapters): share pid-probe + SIGTERM/SIGKILL terminate primitives (ProcessAdapter dups subprocess_base) #9839

Consolidation: share pid-probe + terminate primitives between ProcessAdapter and SubprocessLifecycleAdapter

#9834 (PR #9835) extracted SubprocessLifecycleAdapter for the two CLI adapters. But process_adapter.py (the generic GH#8226 process adapter) still hand-rolls the same two primitives:

• PID probe — process_adapter.status (lines 58-71) is byte-identical to SubprocessLifecycleAdapter._probe_pid: os.kill(pid, 0) → RUNNING / ProcessLookupError→COMPLETED / PermissionError→RUNNING / OSError→FAILED.
• Terminate loop — process_adapter.cancel (lines 72-92) is the same SIGTERM → grace-poll → SIGKILL pattern as SubprocessLifecycleAdapter._cancel (only the grace constant differs: 5s vs 10s).

ProcessAdapter can't inherit the full lifecycle base (it has no state file — run_id is a bare PID), but the two pure primitives are genuinely shareable.

Proposed fix

Extract into subprocess_support.py:

• probe_pid(pid: int) -> AdapterRunStatus
• async terminate_pid(pid: int, grace_seconds: int, log_name: str) -> None

Then have both SubprocessLifecycleAdapter and ProcessAdapter call them (ProcessAdapter passes grace_seconds=5; the lifecycle base passes 10). Removes the last copy of these primitives.

References

Discovered auditing the merged/under-review #9834 (PR #9835). CodexSubscriptionAdapter is a NotImplementedError stub — correctly excluded (no subprocess). autobot_agent_adapter is in-process and http_adapter is HTTP — neither applies.

Labels: enhancement · backend · agents · priority: low