Implementation Plan: Define Owned Process-Group Cleanup and Evidence Contract

[Trecek]

Summary

Implement one execution-layer OwnedProcessGroup lifecycle object for subprocesses that AutoSkillit directly creates as fresh POSIX process-group leaders. Managed runners and PTY cook create a new session; direct-TTY cook deliberately creates only a new process group so it can remain in the parent's terminal session. Ownership is a live capability in both cases: it exists only while the spawning controller retains the waitable, unreaped direct child and verifies pgid == pid; a stored PID/PGID or a previously checked process identity never authorizes killpg().

Requirements

REQ-OWN-001: The system must positively establish that a process group is owned before sending group-wide signals.

REQ-OWN-002: The ownership mechanism must prevent stale or reused process-group identities from authorizing cleanup.

REQ-EVD-001: Cleanup evidence must distinguish expected process disappearance from permission failures.

REQ-EVD-002: Cleanup results must not identify an inaccessible PID as a group member without evidence establishing membership.

REQ-EVD-003: ProcessCleanupResult.complete and access_denied_pids must have documented, tested semantics for incomplete or inaccessible observations.

REQ-CLN-001: The implementation must define whether cleanup guarantees termination of the verified owned group or reports only observed process termination.

REQ-TST-001: Tests must cover exited roots, partial enumeration, permission failures, stale or reused group identities, and group-wide signaling safeguards.

Closes #4550

Implementation Plan

Plan file: /home/talon/projects/generic_automation_mcp/.autoskillit/temp/make-plan/define_owned_process_group_cleanup_plan_2026-08-12_101818.md

🤖 Generated with Claude Code via AutoSkillit

[Trecek]

Audit reconciliation: REQ-SCOPE-001 is a stale-base false positive

I investigated the sole blocking finding and did not revert the package
version, because doing so would create a real out-of-scope version change in
this PR. The audit used stale local develop at cb2f3cef7; the fetched PR
base and merge-base are 02327064e, which already contains 0.10.965.

Reproducible evidence:

• Before remediation, local develop was cb2f3cef7, while
  origin/develop was 02327064e.
• git merge-base HEAD origin/develop is 02327064e.
• git merge-base --is-ancestor 02327064e origin/develop exits 0.
• git log origin/develop..HEAD contains exactly the 10 feature commits and
  does not contain 02327064e.
• git diff origin/develop...HEAD -- pyproject.toml src/autoskillit/.claude-plugin/plugin.json is empty.
• GitHub reports PR Implementation Plan: Define Owned Process-Group Cleanup and Evidence Contract #4569 as 52 files, +2,028/-1,057; neither version file is
  in its changed-file list, and 02327064e is not in its PR commit list.
• Both origin/develop and HEAD contain version = "0.10.965" in
  pyproject.toml and "version": "0.10.965" in plugin.json.

The audit's reported 62 files, +4,365/-1,522 are exactly reproduced by the
incorrect git diff develop...HEAD while local develop was stale. I
fast-forwarded the clean local develop checkout to 02327064e. The same
comparison now reports the correct 52-file, +2,028/-1,057 PR diff, with no
version-file changes.

Independent verification by a separate worker reached the same disposition:
02327064e belongs to origin/develop, not PR #4569, and REQ-SCOPE-001 should
be COVERED when audited against the PR base.

Verification after correcting the audit base:

• git rebase origin/develop: already up to date
• pre-commit run --all-files: PASS (including version consistency and
  uv lock --check)
• task test-check: PASS — 36,545 passed, 586 skipped, 27 xfailed in 442.97s

Disposition: no branch rewrite or source commit is warranted. Please re-run
/audit-impl against origin/develop, the PR base, or merge-base 02327064e.