Hub tunables have no brain-side desired copy; re-assert covers demand only (targets, hysteresis, ladder waits live only in hub NVS)

Pass S2 landed 2026-09-07 (feat/dashboard-v2, uncommitted, firmware not flashed): brain/dsc_brain/hub_tunables.py (43 entities, adopt-on-first-run, validated set_desired, journal, sync states synced/pending/held/differs/failed/missing, reconcile from the ingest poll under the failover rules, never overwrites a hub-side change), stage_rail.py + firmware switch Brain Stage Targets gating apply_stage’s numeric writes, routes /settings/hub-tunables (+adopt/push), /settings/stage-rail (+reset/apply), /settings/root-steering-targets; SPA HubTunableRow / StageRailCard on Climate, Light, Root, Sensors, Network. 6 brain tests. Verify on the hotpatched Pi with the v4 firmware flashed: SYNCED within one poll, HELD while offline lands on reconnect, HUB DIFFERS after an ESPHome-web change, stage change stamps the edited preset, un-flashed hub shows ‘not in this firmware’.