feat(vigilante): add arena boss succession

design/concepts/game-state-machine.md

@@ -16,20 +16,23 @@ Pausing freezes gameplay progression, role inactivity checks, pending-selection
 
 When a player directly kills the Tyrant, that killer becomes the new Tyrant. When no player is credited with the death, an eligible opted-in player active during the preceding 24 hours is selected randomly. The former Tyrant is excluded when another candidate exists.
 
-Every Tyrant death ends the reign, clears all role-side assignments, resets the former Tyrant's reign progression, and requires a new Vigilante. The new Tyrant receives one starting unlock choice.
+Every Tyrant death ends the reign, clears all role-side assignments, resets the former Tyrant's reign progression, and leaves the Vigilante role open for the arena challenge. The new Tyrant receives one starting unlock choice.
 
 ## Vigilante succession
 
-Every Vigilante death ends that assignment regardless of cause. A replacement is selected randomly from eligible opted-in players active during the preceding 24 hours. The Tyrant is never eligible. The previous Vigilante is excluded when another eligible non-Tyrant exists and may be selected again only as a fallback. Followers are cleared rather than transferred.
+Every Vigilante death ends that assignment regardless of cause. Vigilante inactivity and relinquishment also end the assignment, and every new Tyrant reign clears the previous assignment. Followers are cleared rather than transferred.
 
-A Tyrant earns progression from the death only when the Tyrant personally killed the Vigilante.
+While the game is running with an active Tyrant and no Vigilante, an administrator-configured arena opens. One eligible opted-in non-Tyrant player at a time may challenge the arena boss. Defeating it assigns that player as Vigilante. Leaving, disconnecting, or dying resets the fight without preventing an immediate retry. Without an active Tyrant or configured arena, the role remains vacant and no boss exists.
+
+A Tyrant earns progression from a Vigilante death only when the Tyrant personally killed the Vigilante.
 
 ## Pending selections
 
-An offline random selectee has 24 hours of unpaused time to log in and confirm the assignment. Failure causes another selection. When no eligible candidate exists, the position remains vacant and selection retries periodically without assigning the Tyrant to both roles.
+An offline randomly selected Tyrant has 24 hours of unpaused time to log in and confirm the assignment. Failure causes another Tyrant selection. When no eligible Tyrant candidate exists, the position remains vacant and selection retries periodically. Vigilante vacancies use the arena rather than pending random selection.
 
 ## Related stories
 
 - [Start, pause, and administer the game](../user-stories/us-001-start-pause-and-administer.md)
 - [Transfer and reset the Tyrant role](../user-stories/us-002-transfer-and-reset-tyrant.md)
 - [Handle inactivity and pending selections](../user-stories/us-010-handle-inactivity-and-selection.md)
+- [Claim the Vigilante role in the arena](../user-stories/us-019-claim-vigilante-in-arena.md)

design/concepts/persistence-model.md

@@ -6,7 +6,7 @@ description: Defines the durable state and timekeeping needed to restore a Tyran
 
 # Persistence Model
 
-State is keyed by player UUID while retaining the latest known player name for display. Durable global state includes lifecycle status, current and pending role holders, selection deadlines, paused durations, and the current Tyrant reign.
+State is keyed by player UUID while retaining the latest known player name for display. Durable global state includes lifecycle status, current and pending role holders, selection deadlines, paused durations, the current Tyrant reign, and the administrator-configured Vigilante arena center. Active boss and challenger entities are transient and are reconstructed or reset from authoritative role and arena state after restart.
 
 Durable player state includes participation status, opt-out deadline, login history, role or class, Tyrant level, purchased unlocks, unspent choices, Follower relationship, ability cooldowns, daily intelligence use, bound-item delivery state, and captured mobs.
 
@@ -17,3 +17,4 @@ Elapsed-time rules use UTC instants. Paused time is excluded from timers. Saves
 - [Inform players and manage participation](../user-stories/us-011-inform-and-manage-participation.md)
 - [Configure and persist game state](../user-stories/us-012-configure-and-persist-state.md)
 - [Use class ability items](../user-stories/us-014-use-class-ability-items.md)
+- [Claim the Vigilante role in the arena](../user-stories/us-019-claim-vigilante-in-arena.md)

design/concepts/role-and-class-model.md

@@ -8,7 +8,7 @@ description: Defines Tyrant-side classes, Vigilante-side membership, progression
 
 ## Roles and affiliations
 
-A running game has one Tyrant and, when an eligible player is available, one Vigilante. The Vigilante may recruit Followers through invitations that require acceptance. The Tyrant may assign the Assassin, Fixer, and Tamer classes after unlocking them.
+A running game has one active or pending Tyrant. It has at most one Vigilante, and a vacant Vigilante role remains open until an eligible player wins the configured arena challenge. The Vigilante may recruit Followers through invitations that require acceptance. The Tyrant may assign the Assassin, Fixer, and Tamer classes after unlocking them.
 
 Role alignment and Tyrant-side class are independent. A Vigilante or Follower may simultaneously hold one Tyrant-side class, allowing divided loyalties. A player cannot simultaneously be the Tyrant, Vigilante, and/or a Follower, and cannot hold more than one Tyrant-side class. Each Tyrant-side class may be assigned to only one player at a time. Opted-out players are ineligible for every assignment.
 
@@ -36,3 +36,4 @@ Vigilante Follower scaling is capped by default at Strength V and Resistance IV,
 - [Progress and purchase Tyrant unlocks](../user-stories/us-003-progress-and-purchase-unlocks.md)
 - [Assign unlocked classes](../user-stories/us-004-assign-unlocked-classes.md)
 - [Support the Vigilante and Followers](../user-stories/us-008-support-vigilante-and-followers.md)
+- [Claim the Vigilante role in the arena](../user-stories/us-019-claim-vigilante-in-arena.md)