Move activeDisplay lifecycle to shared (one path, not duplicated in App):
- activateDisplay({campaignId, encounterId})
- clearDisplay()
- toggleHidePlayerHp(current)
All 6 App sites wired (start/end/2×delete-encounter/delete-campaign/hp-toggle).
Existing {patch,log} return shape preserved. No interface changes.
Combat.scenario.test.js rewritten to call shared directly, no React:
- Same actions as old UI version (roster chars, monsters, addAll, hp-toggle×2,
start, 100 rounds of damage/heal/conditions/toggle/edit/deathsave/pause/
resume/add/remove, end). Same funcs, same order, same data.
- Models two firestore docs (encounter + activeDisplay) via shared patches.
- Run time: 72s -> 4ms.
Both suites green: shared 91/91, App 77/77.
david raistrick
e650cd2710