feat(onboarding): welcome eligible new players

design/log.md

@@ -49,3 +49,10 @@
 - Ambiguous, cancelled, zero-damage, environmental, and self damage do not opt out a player.
 - Combat opt-out bypasses administrative locks, immediately reconciles effect and prefix state, persists once, and sends one explanatory message.
 - Verified attribution, victim safety, lock bypass, duplicate suppression, and the full build with `./gradlew clean check jar`.
+
+### US-004 onboarding completed
+
+- Join observation now sends the configurable welcome message on each login before the original first-join instant plus the configured calendar-day window.
+- The exact expiration boundary and globally disabled behavior suppress reminders without resetting first-join state.
+- The default message names all player commands and explains automatic combat opt-out.
+- Verified repeated joins, expiration, global suppression, first-join retention, and the full build with `./gradlew clean check jar`.

design/user-stories/us-004-introduce-new-players-to-leaf.md

@@ -2,7 +2,7 @@
 type: User Story
 title: "US-004: Introduce new players to Leaf"
 description: Remind players how to control Leaf during their first seven calendar days on the server.
-status: backlog
+status: done
 ---
 
 # US-004: Introduce new players to Leaf
@@ -11,14 +11,14 @@ As a **new player**, I want a brief explanation of Leaf when I join so that I kn
 
 ## Acceptance criteria
 
-- [ ] Leaf records the first observed join time for each player by UUID as an RFC 3339 UTC timestamp.
-- [ ] On every login before the first-join timestamp plus seven calendar days, the player receives a concise welcome message explaining Leaf protection.
-- [ ] The welcome message tells the player to use `/leaf on`, `/leaf off`, and `/leaf status`.
-- [ ] The message makes clear that attacking another player automatically opts the attacker out.
-- [ ] Players no longer receive the welcome message once their seven-day onboarding period expires.
-- [ ] Existing first-join timestamps are not reset by logout, restart, opt-in changes, or global disablement.
-- [ ] No onboarding reminders are shown while Leaf is globally disabled.
-- [ ] Re-enabling Leaf allows reminders to resume on subsequent logins only for players whose original seven-day period has not expired.
+- [x] Leaf records the first observed join time for each player by UUID as an RFC 3339 UTC timestamp.
+- [x] On every login before the first-join timestamp plus seven calendar days, the player receives a concise welcome message explaining Leaf protection.
+- [x] The welcome message tells the player to use `/leaf on`, `/leaf off`, and `/leaf status`.
+- [x] The message makes clear that attacking another player automatically opts the attacker out.
+- [x] Players no longer receive the welcome message once their seven-day onboarding period expires.
+- [x] Existing first-join timestamps are not reset by logout, restart, opt-in changes, or global disablement.
+- [x] No onboarding reminders are shown while Leaf is globally disabled.
+- [x] Re-enabling Leaf allows reminders to resume on subsequent logins only for players whose original seven-day period has not expired.
 
 ## Related