Two retrospective design-review findings:
- design.md's System Flows sequence diagram showed the controller-layer
resval check as an independently-launched client session, implying no
dependency on the injecting worker staying connected. As-built (bug-1579),
host-attrs resources reset to baseline the instant the worker disconnects,
so the check actually runs nested inside the still-open worker session via
xce_test's `!` shell-escape. Updated the diagram and prose to show this,
and documented the still-open residual risk for custom host-attrs
resource names in Error Handling.
- Added explicit "do not change this format" warning comments at both
trace-log call sites (core_events.c's RESVALS_DELTA case, apiserver's
OnResourceLocationUpdated) that xce-test-resources' log-grep depends on --
an unrelated logging cleanup at either site would otherwise silently turn
every future verification run into a false UNREACHABLE/timeout.
No behavior change in either source file -- comments only.