feat(progression): unlock stealth from potion invisibility

design/user-stories/us-001-accumulate-invisibility-and-unlock.md

@@ -2,7 +2,7 @@
 type: User Story
 title: "US-001: Accumulate invisibility time and unlock stealth"
 description: Reward sustained use of directly consumed invisibility potions with the stealth ability.
-status: backlog
+status: done
 ---
 
 # US-001: Accumulate invisibility time and unlock stealth
@@ -11,15 +11,19 @@ As a **player**, I want my qualifying invisibility time to accumulate so that su
 
 ## Acceptance criteria
 
-- [ ] Only time spent online under an invisibility effect produced by a potion the player directly drank contributes to progression.
-- [ ] Invisibility received from splash potions, lingering potions, tipped arrows, commands, plugins, or other sources does not contribute.
-- [ ] Qualifying time stops when the effect ends, is removed, is replaced by a non-qualifying source, the player disconnects, or the plugin disables.
-- [ ] Refreshed or overlapping qualifying effects never count elapsed time more than once.
-- [ ] Qualifying time accumulates across effects, sessions, and server restarts.
-- [ ] The ability unlocks when accumulated qualifying time reaches eight hours by default.
-- [ ] Reaching the threshold grants the unlock exactly once without discarding excess elapsed time.
-- [ ] When an online player unlocks stealth, they receive both a full-screen title and a chat message explaining the ability.
-- [ ] Progress and unlock ownership are associated with the player's UUID rather than their current name.
+- [x] Only time spent online under an invisibility effect produced by a potion the player directly drank contributes to progression.
+- [x] Invisibility received from splash potions, lingering potions, tipped arrows, commands, plugins, or other sources does not contribute.
+- [x] Qualifying time stops when the effect ends, is removed, is replaced by a non-qualifying source, the player disconnects, or the plugin disables.
+- [x] Refreshed or overlapping qualifying effects never count elapsed time more than once.
+- [x] Qualifying time accumulates across effects, sessions, and server restarts.
+- [x] The ability unlocks when accumulated qualifying time reaches eight hours by default.
+- [x] Reaching the threshold grants the unlock exactly once without discarding excess elapsed time.
+- [x] When an online player unlocks stealth, they receive both a full-screen title and a chat message explaining the ability.
+- [x] Progress and unlock ownership are associated with the player's UUID rather than their current name.
+
+## Validation
+
+Automated tests verify monotonic accumulation across intervals, refresh without duplicate time, exact-once threshold crossing with excess-time preservation, direct potion-drink cause filtering, non-qualifying replacement, UUID state, and online title and chat presentation. The complete `./gradlew clean check jar` lifecycle passes.
 
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