fix(assassin): preserve external potion effects

design/log.md

@@ -6,6 +6,12 @@ description: Chronological record of material decisions affecting the Spigot Tyr
 
 # Spigot Tyrant Design Log
 
+## 2026-08-18 — Preserve ordinary potion effects
+
+- Corrected Assassin effect maintenance so it refreshes active Tyrant abilities without removing invisibility, Speed, or Weakness supplied by potions, commands, or other plugins.
+- Expired or inapplicable Tyrant-managed effects stop refreshing and expire naturally within their short 30-tick maintenance duration, while double-jump flight cleanup remains immediate.
+- Reopened and completed US-005 with regression coverage; verified `./gradlew clean check jar`.
+
 ## 2026-08-14 — Opt-out proximity glow completed
 
 - Extended US-011 with a globally visible green outline for opted-out players in the Tyrant's world and configured range while the event is running.

design/user-stories/us-005-use-assassin-abilities.md

@@ -20,6 +20,13 @@ As the **Assassin**, I want stealth and burst mobility so that I can ambush oppo
 - [x] Grounding and supported movement reset jump availability only after the 60-second cooldown has elapsed.
 - [x] Ability cooldowns use unpaused elapsed time and survive death, logout, and restart.
 - [x] The player can inspect remaining cooldowns and receives clear feedback when an activation is unavailable.
+- [x] Tyrant removes only Assassin potion effects that Tyrant itself applied.
+- [x] Invisibility from potions, commands, or other plugins remains active for Assassins and non-Assassins.
+- [x] Tyrant-managed Assassin effects are still removed when abilities expire, roles change, games stop, or the plugin disables.
+
+## Validation
+
+Automated controller tests verify that inactive Tyrant state does not alter ordinary potion effects, active Assassin invisibility is refreshed, and refresh stops at expiry so the short managed effect expires naturally. The complete `./gradlew clean check jar` lifecycle passes.
 
 ## Related