Follow-up to #82179 addressing helix4u's review comment
(#82179 issuecomment-5229441571). Three parts:
1. Desktop teardown (salvaged from #77436, @4adwentures): the update
hand-off's releaseBackendLock() sent SIGTERM to the primary backend
BEFORE taskkill /T. If the launcher exits first, Windows can no longer
enumerate its descendants and they survive holding the venv — the
Electron path that creates the orphan #82179 then has to repair.
New stopBackendTreesForUpdate() tree-kills the live root first, with
the behavioral vitest from #77436. The scanner half of #77436 is
deliberately NOT taken (superseded by #82158's full-cmdline scan).
2. Tree-aware orphan classification: _orphaned_desktop_backend_pids()
previously refused the whole holder set when any holder had a live
parent. But the scanner legitimately returns an orphaned serve root
AND its descendants (the venv trampoline's uv-managed interpreter
worker — which carries the same backend argv — plus .hermes-runtime
children). Those have a live parent: the orphan root itself. Now
holders inside an accepted orphan root's tree fold into that root
(only roots are returned; taskkill /T reaps descendants), and
live-parent backends defer to the ancestry check instead of refusing
outright. Anything outside an orphan tree still refuses.
3. Tests for the mixed shapes: root+managed-runtime child,
grandchild depth, non-descendant stray alongside an orphan root
(still refuses), descendant exited mid-classify.
E2E on a real Windows box: spawned a detached backend-shaped orphan
that itself spawned children (3 python descendants); the scanner-shaped
mixed holder set classified to [root], taskkill /T reaped root and all
descendants. The live Desktop backend on the box still classified None
(refusal preserved). The first E2E attempt caught exactly the
trampoline/worker case the mocks missed — the live worker re-execs with
the same backend argv and a live parent — which is what part 2 fixes.
Co-Authored-By: 4adwentures <296413879+4adwentures@users.noreply.github.com>
