- docs/dc-dc-deployment-workflow.md: new tooling-gap item 20 -- the durable
  host->isolated-site base leg had no owning tool; CLOSED for Office1 via
  scripts/site-baseleg.sh (installed+enabled 2026-07-17; boot-race unproven until
  a reboot). Documents the DC generalization so the gap does not reopen per-DC.
- SKILL.md: operating-model invariant extended -- durable host->site reach is
  standing per-SITE tooling (DCs included): at each DC standup MEASURE the reach
  and, if the DC net is ISOLATED, add a MEASURED site-baseleg.sh leg row + install
  as part of standup DoD (never an inferred DC IP; harness enforces it).

Doc-only follow-up to 1958063. Nothing merged to main (stage-close).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QMKdXCquMnh1jKH2sWXPMg