The Desktop venv-blocker scan (since #99724) defers ledger-verified
serve/dashboard holders to the CLI updater's stop+relaunch rungs, but the
scan output only carried an opaque deferred_backends count — nothing
explained WHICH holders the deferral consumed or why they vanished from
processes.
Add sanitized decision evidence (#98350): deferred_backend_evidence lists
structured ledger identity only (pid, purpose, recorded port) — never the
command line, which can carry tokens or private endpoints. Adds a desktop
parser contract fixture proving the consumer tolerates the diagnostics
while keeping blocked/processes authoritative.
Salvaged from PR #98350; the exemption half of that PR was independently
consolidated on main via #99724 (_is_updater_owned_backend).
liuhao1024
46ac31e84c