feat(notification): announce earned tree unlocks

src/main/java/games/dmg/treefeller/CompositeProgressObserver.java

@@ -0,0 +1,18 @@
+package games.dmg.treefeller;
+
+import java.util.List;
+import org.bukkit.entity.Player;
+
+/** Delivers one persisted progress update to each presentation observer in order. */
+public final class CompositeProgressObserver implements ProgressObserver {
+    private final List<ProgressObserver> observers;
+
+    public CompositeProgressObserver(ProgressObserver... observers) {
+        this.observers = List.of(observers);
+    }
+
+    @Override
+    public void onProgress(Player player, ProgressUpdate update) {
+        observers.forEach(observer -> observer.onProgress(player, update));
+    }
+}

src/main/java/games/dmg/treefeller/TreeFellerPlugin.java

@@ -42,7 +42,9 @@ public final class TreeFellerPlugin extends JavaPlugin {
                     playerStateRepository,
                     species -> settingsService.current().threshold(species),
                     automaticBreakRegistry,
-                    progressBossBarObserver,
+                    new CompositeProgressObserver(
+                            progressBossBarObserver,
+                            new TreeUnlockAnnouncement(settingsService::current)),
                     exception -> getLogger().log(
                             Level.SEVERE, "Unable to persist Tree Feller progress", exception));
             getServer().getPluginManager().registerEvents(progressListener, this);

src/main/java/games/dmg/treefeller/TreeUnlockAnnouncement.java

@@ -0,0 +1,36 @@
+package games.dmg.treefeller;
+
+import java.util.function.Supplier;
+import org.bukkit.entity.Player;
+
+/** Presents the one-time earned unlock title and safety guidance. */
+public final class TreeUnlockAnnouncement implements ProgressObserver {
+    private final Supplier<TreeFellerSettings> settings;
+
+    public TreeUnlockAnnouncement(Supplier<TreeFellerSettings> settings) {
+        this.settings = settings;
+    }
+
+    @Override
+    public void onProgress(Player player, ProgressUpdate update) {
+        if (!update.newlyUnlocked()) {
+            return;
+        }
+        TreeFellerSettings current = settings.get();
+        player.sendTitle(
+                format(current.titleText(), update),
+                format(current.subtitleText(), update),
+                current.titleFadeInTicks(),
+                current.titleStayTicks(),
+                current.titleFadeOutTicks());
+        player.sendMessage(format(current.message("unlock-guidance"), update));
+    }
+
+    private String format(String template, ProgressUpdate update) {
+        return template
+                .replace("{species}", update.species().displayName())
+                .replace("{progress}", Long.toString(update.progress()))
+                .replace("{threshold}", Integer.toString(update.threshold()))
+                .replace('&', '\u00a7');
+    }
+}