feat(ability): add Shield Bash

src/main/java/games/dmg/fantasystick/FantasyStickPlugin.java

@@ -59,6 +59,8 @@ public final class FantasyStickPlugin extends JavaPlugin {
     private games.dmg.fantasystick.persistence.SecondWindSettings secondWindSettings;
     private games.dmg.fantasystick.ability.CombatMitigation combatMitigation;
     private games.dmg.fantasystick.ability.StoneSkin stoneSkin;
+    private games.dmg.fantasystick.ability.ShieldBash shieldBash;
+    private games.dmg.fantasystick.persistence.ShieldBashSettings shieldBashSettings;
     private games.dmg.fantasystick.persistence.StoneSkinSettings stoneSkinSettings;
     private games.dmg.fantasystick.ability.GreatSword greatSword;
     private games.dmg.fantasystick.ability.Revive revive;
@@ -101,6 +103,8 @@ public final class FantasyStickPlugin extends JavaPlugin {
             var secondWindInitial = games.dmg.fantasystick.persistence.SecondWindSettings.parse(secondWindConfiguration);
             var stoneSkinConfiguration = stoneSkinConfiguration();
             var stoneSkinInitial = games.dmg.fantasystick.persistence.StoneSkinSettings.parse(stoneSkinConfiguration);
+            var shieldBashConfiguration = shieldBashConfiguration();
+            var shieldBashInitial = games.dmg.fantasystick.persistence.ShieldBashSettings.parse(shieldBashConfiguration);
             var factory = new CharacterFactory();
             characters = new CharacterStorage(new YamlCharacterRepository(getDataFolder().toPath()), Clock.systemUTC());
             crafting = new ManualCraftingController(characters, () -> factory.create(rules),
@@ -159,6 +163,11 @@ public final class FantasyStickPlugin extends JavaPlugin {
                 getDataFolder().toPath(), stoneSkinConfiguration);
             combatMitigation = new games.dmg.fantasystick.ability.CombatMitigation();
             stoneSkin = new games.dmg.fantasystick.ability.StoneSkin(stoneSkinInitial, combatMitigation);
+            shieldBashSettings = new games.dmg.fantasystick.persistence.ShieldBashSettings(
+                getDataFolder().toPath(), shieldBashConfiguration);
+            shieldBash = new games.dmg.fantasystick.ability.ShieldBash(
+                shieldBashInitial,
+                event -> getServer().getPluginManager().callEvent(event));
             greatSword = new games.dmg.fantasystick.ability.GreatSword(greatSwordSettings);
             revivals = new games.dmg.fantasystick.persistence.RevivalStore(getDataFolder().toPath());
             revive = new games.dmg.fantasystick.ability.Revive(characters, revivals, Clock.systemUTC(), nextTick,
@@ -170,6 +179,7 @@ public final class FantasyStickPlugin extends JavaPlugin {
             abilityRegistry.register(quickstep.definition());
             abilityRegistry.register(secondWind.definition());
             abilityRegistry.register(stoneSkin.definition());
+            abilityRegistry.register(shieldBash.definition());
             abilityRegistry.register(greatSword.definition());
             abilityRegistry.register(revive.definition());
             sessions.attachAbilityRegistry(abilityRegistry);
@@ -215,7 +225,7 @@ public final class FantasyStickPlugin extends JavaPlugin {
                     + " for player " + problem.player(), problem.cause()), adventureSettings,
                 frostShardSettings, frostShard, longbowSettings, longbow,
                 quickstepSettings, quickstep, secondWindSettings, secondWind,
-                stoneSkinSettings, stoneSkin, abilityRegistry);
+                stoneSkinSettings, stoneSkin, shieldBashSettings, shieldBash, abilityRegistry);
             var command = java.util.Objects.requireNonNull(getCommand("fantasystick"), "Missing packaged fantasystick command");
             command.setExecutor(admin);
             command.setTabCompleter(admin);
@@ -234,6 +244,7 @@ public final class FantasyStickPlugin extends JavaPlugin {
             getServer().getPluginManager().registerEvents(longbow, this);
             getServer().getPluginManager().registerEvents(quickstep, this);
             getServer().getPluginManager().registerEvents(combatMitigation, this);
+            getServer().getPluginManager().registerEvents(shieldBash, this);
             getServer().getPluginManager().registerEvents(greatSword, this);
             getServer().getPluginManager().registerEvents(revive, this);
             getServer().getPluginManager().registerEvents(localBasicAttack, this);
@@ -287,6 +298,8 @@ public final class FantasyStickPlugin extends JavaPlugin {
         var closingQuickstepSettings = quickstepSettings; quickstepSettings = null;
         secondWind = null;
         var closingStoneSkin = stoneSkin; stoneSkin = null;
+        var closingShieldBash = shieldBash; shieldBash = null;
+        var closingShieldBashSettings = shieldBashSettings; shieldBashSettings = null;
         var closingCombatMitigation = combatMitigation; combatMitigation = null;
         var closingStoneSkinSettings = stoneSkinSettings; stoneSkinSettings = null;
         var closingSecondWindSettings = secondWindSettings; secondWindSettings = null;
@@ -305,6 +318,7 @@ public final class FantasyStickPlugin extends JavaPlugin {
         if (closingQuickstepSettings != null) cleanup("Quickstep configuration", closingQuickstepSettings::close);
         if (closingSecondWindSettings != null) cleanup("Second Wind configuration", closingSecondWindSettings::close);
         if (closingStoneSkinSettings != null) cleanup("Stone Skin configuration", closingStoneSkinSettings::close);
+        if (closingShieldBashSettings != null) cleanup("Shield Bash configuration", closingShieldBashSettings::close);
         configurationDrain = java.util.concurrent.CompletableFuture.allOf(
             closingSettings == null ? java.util.concurrent.CompletableFuture.completedFuture(null)
                 : closingSettings.drained().toCompletableFuture(),
@@ -317,7 +331,9 @@ public final class FantasyStickPlugin extends JavaPlugin {
             closingSecondWindSettings == null ? java.util.concurrent.CompletableFuture.completedFuture(null)
                 : closingSecondWindSettings.drained().toCompletableFuture(),
             closingStoneSkinSettings == null ? java.util.concurrent.CompletableFuture.completedFuture(null)
-                : closingStoneSkinSettings.drained().toCompletableFuture());
+                : closingStoneSkinSettings.drained().toCompletableFuture(),
+            closingShieldBashSettings == null ? java.util.concurrent.CompletableFuture.completedFuture(null)
+                : closingShieldBashSettings.drained().toCompletableFuture());
         if (closingBooks != null) cleanup("character book", closingBooks::close);
         if (closingBasicAttack != null) cleanup("basic attack", closingBasicAttack::close);
         if (closingCombatExperience != null) cleanup("combat experience", closingCombatExperience::close);
@@ -326,6 +342,7 @@ public final class FantasyStickPlugin extends JavaPlugin {
         if (closingLongbow != null) cleanup("Longbow", closingLongbow::close);
         if (closingQuickstep != null) cleanup("Quickstep", closingQuickstep::close);
         if (closingStoneSkin != null) cleanup("Stone Skin", closingStoneSkin::close);
+        if (closingShieldBash != null) cleanup("Shield Bash", closingShieldBash::close);
         if (closingCombatMitigation != null) cleanup("combat mitigation", closingCombatMitigation::close);
         if (closingGreatSword != null) cleanup("Great Sword", closingGreatSword::close);
         if (closingRevive != null) cleanup("Revive", closingRevive::close);
@@ -348,6 +365,7 @@ public final class FantasyStickPlugin extends JavaPlugin {
         unregister(closingLongbow);
         unregister(closingQuickstep);
         unregister(closingCombatMitigation);
+        unregister(closingShieldBash);
         unregister(closingGreatSword);
         unregister(closingRevive);
         unregister(closingBasicAttack);
@@ -470,6 +488,16 @@ public final class FantasyStickPlugin extends JavaPlugin {
         return java.util.Map.copyOf(values);
     }
 
+    private java.util.Map<String, String> shieldBashConfiguration() {
+        var values = new java.util.LinkedHashMap<String, String>();
+        for (String key : games.dmg.fantasystick.persistence.ShieldBashSettings.keys()) {
+            values.put(key, getConfig().getString(key,
+                games.dmg.fantasystick.persistence.ShieldBashSettings.defaultValue(key)));
+        }
+        games.dmg.fantasystick.persistence.ShieldBashSettings.parse(values);
+        return java.util.Map.copyOf(values);
+    }
+
     private games.dmg.fantasystick.ability.GreatSword.Settings greatSwordSettings() {
         try {
             var base = new java.math.BigInteger(getConfig().getString("great-sword-base-damage", "7"));

src/main/java/games/dmg/fantasystick/ability/ShieldBash.java

@@ -0,0 +1,144 @@
+package games.dmg.fantasystick.ability;
+
+import games.dmg.fantasystick.progression.Stat;
+import games.dmg.fantasystick.session.ControlInput;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.time.Duration;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.function.Consumer;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.damage.DamageSource;
+import org.bukkit.damage.DamageType;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.entity.EntityDamageByEntityEvent;
+import org.bukkit.event.player.PlayerVelocityEvent;
+import org.bukkit.util.Vector;
+
+/** Shield Bash's contained short-range custom strike and post-damage knockback. */
+public final class ShieldBash implements AbilityEffect, Listener, AutoCloseable {
+    public record Settings(BigInteger baseDamage, Duration cooldown, double range,
+                           double horizontalKnockback, double minimumVerticalKnockback) {
+        public Settings {
+            Objects.requireNonNull(baseDamage); Objects.requireNonNull(cooldown);
+            if (baseDamage.signum() < 0 || cooldown.isNegative() || cooldown.compareTo(Duration.ofDays(365)) > 0
+                    || !Double.isFinite(range) || range <= 0 || range > 64
+                    || !Double.isFinite(horizontalKnockback) || horizontalKnockback < 0 || horizontalKnockback > 8
+                    || !Double.isFinite(minimumVerticalKnockback) || minimumVerticalKnockback < 0
+                    || minimumVerticalKnockback > 8) throw new IllegalArgumentException("Invalid Shield Bash settings");
+        }
+        public static Settings defaults() {
+            return new Settings(BigInteger.valueOf(4), Duration.ofSeconds(6), 3, 0.8, 0.35);
+        }
+    }
+    private static final class Attempt {
+        final AbilityExecution execution; final LivingEntity target; final Settings settings; boolean accepted;
+        Attempt(AbilityExecution execution, LivingEntity target, Settings settings) {
+            this.execution = execution; this.target = target; this.settings = settings;
+        }
+    }
+
+    private volatile Settings settings;
+    private final Consumer<PlayerVelocityEvent> velocityEvents;
+    private Attempt damaging;
+    private boolean closed;
+
+    public ShieldBash(Settings settings, Consumer<PlayerVelocityEvent> velocityEvents) {
+        this.settings = Objects.requireNonNull(settings); this.velocityEvents = Objects.requireNonNull(velocityEvents);
+    }
+    public void configure(Settings settings) { this.settings = Objects.requireNonNull(settings); }
+
+    public AbilityDefinition definition() {
+        var current = settings;
+        return new AbilityDefinition("shield_bash", "Shield Bash", Material.SHIELD,
+            List.of("Strike within " + decimal(current.range()) + " blocks for " + current.baseDamage() + " + STR modifier damage.",
+                "Accepted damage adds knockback; this shield never enables ordinary blocking."),
+            "Attack a visible hostile at short range.", Map.of(Stat.STR, BigInteger.valueOf(12), Stat.CON, BigInteger.valueOf(12)),
+            BigInteger.ONE, AbilityDefinition.Activation.DELAYED, ControlInput.Gesture.ATTACK, current.cooldown(),
+            Map.of("base-damage", new BigDecimal(current.baseDamage()), "range", decimalValue(current.range()),
+                "horizontal-knockback", decimalValue(current.horizontalKnockback()),
+                "minimum-vertical-knockback", decimalValue(current.minimumVerticalKnockback())),
+            AbilityDefinition.TargetPolicy.HOSTILE, this);
+    }
+
+    @Override public boolean accepts(ControlInput input) {
+        return !closed && input.target() instanceof LivingEntity target && inRange(input.player(), target, settings.range());
+    }
+
+    public static BigInteger damage(BigInteger strength) { return damage(BigInteger.valueOf(4), strength); }
+    static BigInteger damage(BigInteger base, BigInteger strength) {
+        Objects.requireNonNull(base); Objects.requireNonNull(strength);
+        if (base.signum() < 0 || strength.signum() < 0) throw new IllegalArgumentException("Invalid Shield Bash damage input");
+        var delta = strength.subtract(BigInteger.TEN); var divided = delta.divideAndRemainder(BigInteger.TWO);
+        var modifier = divided[0];
+        if (delta.signum() < 0 && divided[1].signum() != 0) modifier = modifier.subtract(BigInteger.ONE);
+        return base.add(modifier);
+    }
+
+    @Override public void activate(AbilityExecution execution) {
+        if (closed || !execution.stillCurrent() || !(execution.input().target() instanceof LivingEntity target)) return;
+        var current = from(execution.definition()); var player = execution.input().player();
+        if (!inRange(player, target, current.range())) { execution.finish(); return; }
+        var exact = damage(current.baseDamage(), execution.character().stats().get(Stat.STR));
+        double amount = exact.bitLength() > 1023 ? Double.MAX_VALUE : exact.doubleValue();
+        if (!Double.isFinite(amount) || amount <= 0) { execution.finish(); return; }
+        var source = DamageSource.builder(DamageType.PLAYER_ATTACK).withCausingEntity(player).withDirectEntity(player).build();
+        var attempt = new Attempt(execution, target, current); damaging = attempt;
+        try { target.damage(amount, source); }
+        finally { if (damaging == attempt) damaging = null; execution.finish(); }
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void acceptedDamage(EntityDamageByEntityEvent event) {
+        var attempt = damaging;
+        if (closed || attempt == null || attempt.accepted || event.isCancelled() || event.getFinalDamage() <= 0
+                || !Double.isFinite(event.getFinalDamage()) || event.getDamager() != attempt.execution.input().player()
+                || event.getEntity() != attempt.target || !attempt.execution.stillCurrent()) return;
+        attempt.accepted = true;
+        attempt.execution.report(AbilityReport.Type.DAMAGE, event.getEntity(),
+            BigDecimal.valueOf(event.getFinalDamage()).stripTrailingZeros());
+        knockback(attempt);
+    }
+
+    private void knockback(Attempt attempt) {
+        var player = attempt.execution.input().player(); var target = attempt.target;
+        Vector away = target.getLocation().toVector().subtract(player.getLocation().toVector()); away.setY(0);
+        if (!finite(away) || away.lengthSquared() < 1.0e-12) return;
+        Vector current = target.getVelocity();
+        Vector proposed = current.clone().add(away.normalize().multiply(attempt.settings.horizontalKnockback()));
+        proposed.setY(Math.max(current.getY(), attempt.settings.minimumVerticalKnockback()));
+        if (!finite(proposed)) return;
+        if (target instanceof Player targetPlayer) {
+            var event = new PlayerVelocityEvent(targetPlayer, proposed.clone()); velocityEvents.accept(event);
+            if (event.isCancelled() || !finite(event.getVelocity())) return;
+            proposed = event.getVelocity().clone();
+        }
+        target.setVelocity(proposed);
+    }
+
+    private static boolean inRange(Player player, LivingEntity target, double range) {
+        try {
+            Location source = player.getLocation(); Location destination = target.getLocation();
+            return source.getWorld() == destination.getWorld() && source.distanceSquared(destination) <= range * range
+                && player.hasLineOfSight(target);
+        } catch (RuntimeException invalid) { return false; }
+    }
+    private static boolean finite(Vector value) {
+        return Double.isFinite(value.getX()) && Double.isFinite(value.getY()) && Double.isFinite(value.getZ());
+    }
+    private static Settings from(AbilityDefinition definition) {
+        var p = definition.parameters();
+        return new Settings(p.get("base-damage").toBigIntegerExact(), definition.cooldown(), p.get("range").doubleValue(),
+            p.get("horizontal-knockback").doubleValue(), p.get("minimum-vertical-knockback").doubleValue());
+    }
+    private static BigDecimal decimalValue(double value) { return BigDecimal.valueOf(value).stripTrailingZeros(); }
+    private static String decimal(double value) { return decimalValue(value).toPlainString(); }
+    @Override public void close() { closed = true; damaging = null; }
+}

src/main/java/games/dmg/fantasystick/persistence/ShieldBashSettings.java

@@ -0,0 +1,192 @@
+package games.dmg.fantasystick.persistence;
+
+import games.dmg.fantasystick.ability.ShieldBash;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.channels.OverlappingFileLockException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.LinkOption;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.StandardOpenOption;
+import java.time.Duration;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.Executors;
+import java.util.concurrent.RejectedExecutionException;
+import org.yaml.snakeyaml.LoaderOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.constructor.SafeConstructor;
+
+/** Serialized durable Shield Bash settings; publication remains a server-thread caller decision. */
+public final class ShieldBashSettings implements AutoCloseable {
+    private static final int MAX_BYTES = 1_048_576;
+    public static final String BASE_DAMAGE = "shield-bash-base-damage";
+    public static final String COOLDOWN = "shield-bash-cooldown-seconds";
+    public static final String RANGE = "shield-bash-range-blocks";
+    public static final String HORIZONTAL = "shield-bash-horizontal-knockback";
+    public static final String VERTICAL = "shield-bash-minimum-vertical-knockback";
+    private static final List<String> KEYS = List.of(BASE_DAMAGE, COOLDOWN, RANGE, HORIZONTAL, VERTICAL);
+    private static final Map<String, String> DEFAULTS = Map.of(BASE_DAMAGE, "4", COOLDOWN, "6", RANGE, "3",
+        HORIZONTAL, "0.8", VERTICAL, "0.35");
+
+    @FunctionalInterface interface Replacement { void move(Path from, Path to) throws IOException; }
+    public record Update(String key, String value, ShieldBash.Settings settings,
+                         Map<String, String> values, long sequence) {
+        public Update { values = Map.copyOf(values); }
+    }
+
+    private final Path directory;
+    private final Replacement replacement;
+    private final java.util.concurrent.ExecutorService worker = Executors.newSingleThreadExecutor(
+        task -> new Thread(task, "fantasy-shield-bash-configuration"));
+    private volatile Map<String, String> effectiveValues;
+    private Map<String, String> persistedValues;
+    private long persistedSequence;
+    private long publishedSequence;
+    private boolean closed;
+    private int pending;
+    private final CompletableFuture<Void> drained = new CompletableFuture<>();
+
+    public ShieldBashSettings(Path directory, Map<String, String> initial) {
+        this(directory, initial, (from, to) -> Files.move(from, to,
+            StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING));
+    }
+
+    ShieldBashSettings(Path directory, Map<String, String> initial, Replacement replacement) {
+        this.directory = Objects.requireNonNull(directory).toAbsolutePath();
+        this.replacement = Objects.requireNonNull(replacement);
+        var copy = new LinkedHashMap<String, String>();
+        for (String key : KEYS) copy.put(key, Objects.requireNonNull(initial.get(key)));
+        parse(copy);
+        effectiveValues = Map.copyOf(copy); persistedValues = Map.copyOf(copy);
+    }
+
+    public static List<String> keys() { return KEYS; }
+    public static String defaultValue(String key) { return DEFAULTS.get(key); }
+    public String value(String key) { return effectiveValues.get(key); }
+    public ShieldBash.Settings settings() { return parse(effectiveValues); }
+
+    /** Publish only after the caller returns the durable acknowledgment to the server thread. */
+    public synchronized void publish(Update update) {
+        Objects.requireNonNull(update);
+        if (update.sequence() <= publishedSequence) return;
+        parse(update.values());
+        effectiveValues = update.values(); publishedSequence = update.sequence();
+    }
+
+    public CompletionStage<Update> set(String key, String value) {
+        Objects.requireNonNull(key); Objects.requireNonNull(value);
+        if (!KEYS.contains(key)) return CompletableFuture.failedStage(new IllegalArgumentException("Unknown setting"));
+        String accepted = canonical(key, value);
+        var preview = new LinkedHashMap<>(effectiveValues); preview.put(key, accepted);
+        parse(preview); // Fail malformed/out-of-range command input before queueing accepted persistence.
+        synchronized (this) {
+            if (closed) return CompletableFuture.failedStage(new IOException("Configuration store is closed"));
+            pending++;
+        }
+        try {
+            return CompletableFuture.supplyAsync(() -> {
+                try {
+                    var next = new LinkedHashMap<>(persistedValues);
+                    next.put(key, accepted);
+                    var parsed = parse(next);
+                    save(key, accepted);
+                    persistedValues = Map.copyOf(next);
+                    return new Update(key, accepted, parsed, persistedValues, ++persistedSequence);
+                } catch (IOException | RuntimeException failure) {
+                    throw new java.util.concurrent.CompletionException(failure instanceof IllegalArgumentException
+                        ? failure : new IOException("Shield Bash configuration save refused or failed; effective settings unchanged"));
+                } finally { finished(); }
+            }, worker).minimalCompletionStage();
+        } catch (RejectedExecutionException rejected) {
+            finished();
+            return CompletableFuture.failedStage(new IOException("Configuration store is closed"));
+        }
+    }
+
+    private static String canonical(String key, String raw) {
+        try {
+            if (key.equals(BASE_DAMAGE)) return new java.math.BigInteger(raw).toString();
+            return new java.math.BigDecimal(raw).stripTrailingZeros().toPlainString();
+        } catch (NumberFormatException invalid) { throw new IllegalArgumentException("Invalid value", invalid); }
+    }
+
+    public static ShieldBash.Settings parse(Map<String, String> values) {
+        try {
+            var base = new java.math.BigInteger(values.get(BASE_DAMAGE));
+            var cooldown = seconds(values.get(COOLDOWN));
+            return new ShieldBash.Settings(base, cooldown, finite(values.get(RANGE)),
+                finite(values.get(HORIZONTAL)), finite(values.get(VERTICAL)));
+        } catch (ArithmeticException | NumberFormatException | NullPointerException invalid) {
+            throw new IllegalArgumentException("Shield Bash settings must use supported numeric values", invalid);
+        }
+    }
+
+    private static Duration seconds(String value) {
+        var nanos = new java.math.BigDecimal(value).movePointRight(9).toBigIntegerExact().longValueExact();
+        return Duration.ofNanos(nanos);
+    }
+
+    private static double finite(String value) {
+        double result = new java.math.BigDecimal(value).doubleValue();
+        if (!Double.isFinite(result)) throw new IllegalArgumentException("Setting is not finite");
+        return result;
+    }
+
+    private void save(String key, String value) throws IOException {
+        Files.createDirectories(directory);
+        if (!Files.isDirectory(directory, LinkOption.NOFOLLOW_LINKS)) throw new IOException("Unsafe directory");
+        var file = directory.resolve("config.yml");
+        var lockFile = directory.resolve(".config.lock");
+        if (Files.exists(lockFile, LinkOption.NOFOLLOW_LINKS)
+                && !Files.isRegularFile(lockFile, LinkOption.NOFOLLOW_LINKS)) throw new IOException("Unsafe lock");
+        try (var channel = FileChannel.open(lockFile, StandardOpenOption.CREATE, StandardOpenOption.WRITE,
+                LinkOption.NOFOLLOW_LINKS); var lock = channel.tryLock()) {
+            if (lock == null) throw new IOException("Configuration busy");
+            var options = new LoaderOptions(); options.setAllowDuplicateKeys(false);
+            options.setMaxAliasesForCollections(20); options.setCodePointLimit(MAX_BYTES);
+            var yaml = new Yaml(new SafeConstructor(options));
+            Map<String, Object> document = new LinkedHashMap<>();
+            if (Files.exists(file, LinkOption.NOFOLLOW_LINKS)) {
+                if (!Files.isRegularFile(file, LinkOption.NOFOLLOW_LINKS)) throw new IOException("Unsafe configuration");
+                byte[] bytes;
+                try (var input = Files.newInputStream(file, LinkOption.NOFOLLOW_LINKS)) { bytes = input.readNBytes(MAX_BYTES + 1); }
+                if (bytes.length > MAX_BYTES) throw new IOException("Configuration too large");
+                Object loaded = yaml.load(StandardCharsets.UTF_8.newDecoder().decode(ByteBuffer.wrap(bytes)).toString());
+                if (loaded != null) {
+                    if (!(loaded instanceof Map<?, ?> map)) throw new IOException("Invalid configuration root");
+                    for (var entry : map.entrySet()) {
+                        if (!(entry.getKey() instanceof String savedKey)) throw new IOException("Invalid configuration key");
+                        document.put(savedKey, entry.getValue());
+                    }
+                }
+            }
+            document.put(key, value);
+            byte[] bytes = yaml.dump(document).getBytes(StandardCharsets.UTF_8);
+            if (bytes.length > MAX_BYTES) throw new IOException("Configuration too large");
+            Path temporary = Files.createTempFile(directory, ".config-", ".tmp");
+            try {
+                try (var output = FileChannel.open(temporary, StandardOpenOption.WRITE, LinkOption.NOFOLLOW_LINKS)) {
+                    var buffer = ByteBuffer.wrap(bytes); while (buffer.hasRemaining()) output.write(buffer); output.force(true);
+                }
+                replacement.move(temporary, file);
+            } finally { Files.deleteIfExists(temporary); }
+        } catch (OverlappingFileLockException busy) { throw new IOException("Configuration busy"); }
+    }
+
+    private synchronized void finished() {
+        pending--;
+        if (closed && pending == 0) drained.complete(null);
+    }
+    public CompletionStage<Void> drained() { return drained.minimalCompletionStage(); }
+    @Override public synchronized void close() {
+        closed = true; worker.shutdown(); if (pending == 0) drained.complete(null);
+    }
+}

src/main/java/games/dmg/fantasystick/session/EquipmentAdminCommand.java

@@ -32,6 +32,8 @@ public final class EquipmentAdminCommand implements TabExecutor, AutoCloseable {
     private games.dmg.fantasystick.ability.SecondWind secondWind;
     private games.dmg.fantasystick.persistence.StoneSkinSettings stoneSkinSettings;
     private games.dmg.fantasystick.ability.StoneSkin stoneSkin;
+    private games.dmg.fantasystick.persistence.ShieldBashSettings shieldBashSettings;
+    private games.dmg.fantasystick.ability.ShieldBash shieldBash;
 
     public EquipmentAdminCommand(EquipmentSessionStore receipts, EquipmentSessions sessions, Server server,
                                  Consumer<Runnable> nextTick, Consumer<Failure> diagnostics) {
@@ -128,6 +130,29 @@ public final class EquipmentAdminCommand implements TabExecutor, AutoCloseable {
         this.stoneSkin = Objects.requireNonNull(stoneSkin);
     }
 
+    public EquipmentAdminCommand(EquipmentSessionStore receipts, EquipmentSessions sessions, Server server,
+                                 Consumer<Runnable> nextTick, Consumer<Failure> diagnostics,
+                                 games.dmg.fantasystick.persistence.AdventureSettings settings,
+                                 games.dmg.fantasystick.persistence.FrostShardSettings frostSettings,
+                                 games.dmg.fantasystick.ability.FrostShard frostShard,
+                                 games.dmg.fantasystick.persistence.LongbowSettings longbowSettings,
+                                 games.dmg.fantasystick.ability.Longbow longbow,
+                                 games.dmg.fantasystick.persistence.QuickstepSettings quickstepSettings,
+                                 games.dmg.fantasystick.ability.Quickstep quickstep,
+                                 games.dmg.fantasystick.persistence.SecondWindSettings secondWindSettings,
+                                 games.dmg.fantasystick.ability.SecondWind secondWind,
+                                 games.dmg.fantasystick.persistence.StoneSkinSettings stoneSkinSettings,
+                                 games.dmg.fantasystick.ability.StoneSkin stoneSkin,
+                                 games.dmg.fantasystick.persistence.ShieldBashSettings shieldBashSettings,
+                                 games.dmg.fantasystick.ability.ShieldBash shieldBash,
+                                 games.dmg.fantasystick.ability.AbilityRegistry abilities) {
+        this(receipts, sessions, server, nextTick, diagnostics, settings, frostSettings, frostShard,
+            longbowSettings, longbow, quickstepSettings, quickstep, secondWindSettings, secondWind,
+            stoneSkinSettings, stoneSkin, abilities);
+        this.shieldBashSettings = Objects.requireNonNull(shieldBashSettings);
+        this.shieldBash = Objects.requireNonNull(shieldBash);
+    }
+
     @Override public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
         if (closed) return true;
         if (!sender.hasPermission(PERMISSION)) {
@@ -213,6 +238,9 @@ public final class EquipmentAdminCommand implements TabExecutor, AutoCloseable {
         if (stoneSkinSettings != null && games.dmg.fantasystick.persistence.StoneSkinSettings.keys().contains(args[1])) {
             stoneSkinConfiguration(sender, args); return;
         }
+        if (shieldBashSettings != null && games.dmg.fantasystick.persistence.ShieldBashSettings.keys().contains(args[1])) {
+            shieldBashConfiguration(sender, args); return;
+        }
         if (frostSettings == null || !games.dmg.fantasystick.persistence.FrostShardSettings.keys().contains(args[1])) {
             configurationUsage(sender); return;
         }
@@ -310,6 +338,29 @@ public final class EquipmentAdminCommand implements TabExecutor, AutoCloseable {
         });
     }
 
+    private void shieldBashConfiguration(CommandSender sender, String[] args) {
+        String key = args[1];
+        if (args.length == 2) { sender.sendMessage(key + "=" + shieldBashSettings.value(key) + " (applies to future Shield Bash strikes only)"); return; }
+        java.util.concurrent.CompletionStage<games.dmg.fantasystick.persistence.ShieldBashSettings.Update> operation;
+        try { operation = shieldBashSettings.set(key, args[2]); }
+        catch (IllegalArgumentException invalid) { sender.sendMessage("Shield Bash setting is invalid; the effective value is unchanged."); return; }
+        operation.whenComplete((saved, failure) -> {
+            if (failure != null) report(null, "config-" + key, failure);
+            if (closed) return;
+            try { nextTick.accept(() -> {
+                if (closed) return;
+                if (failure == null) {
+                    shieldBash.configure(saved.settings()); abilities.replace(shieldBash.definition()); shieldBashSettings.publish(saved);
+                }
+                if (!sender.hasPermission(PERMISSION)
+                        || sender instanceof org.bukkit.entity.Player player && !player.isOnline()) return;
+                sender.sendMessage(failure == null
+                    ? "Saved " + key + "=" + saved.value() + " for future Shield Bash strikes; active work and deadlines are unchanged."
+                    : "Shield Bash configuration save failed; the effective setting is unchanged.");
+            }); } catch (RuntimeException rejected) { report(null, "config-response", rejected); }
+        });
+    }
+
     private void stoneSkinConfiguration(CommandSender sender, String[] args) {
         String key = args[1];
         if (args.length == 2) {
@@ -409,6 +460,7 @@ public final class EquipmentAdminCommand implements TabExecutor, AutoCloseable {
             keys.addAll(games.dmg.fantasystick.persistence.QuickstepSettings.keys());
             keys.addAll(games.dmg.fantasystick.persistence.SecondWindSettings.keys());
             keys.addAll(games.dmg.fantasystick.persistence.StoneSkinSettings.keys());
+            keys.addAll(games.dmg.fantasystick.persistence.ShieldBashSettings.keys());
             return matching(keys, args[1]);
         }
         if (args.length == 3 && args[0].equals("config")) {
@@ -438,6 +490,11 @@ public final class EquipmentAdminCommand implements TabExecutor, AutoCloseable {
                 String defaults = games.dmg.fantasystick.persistence.StoneSkinSettings.defaultValue(args[1]);
                 return matching(current.equals(defaults) ? List.of(current) : List.of(current, defaults), args[2]);
             }
+            if (shieldBashSettings != null && games.dmg.fantasystick.persistence.ShieldBashSettings.keys().contains(args[1])) {
+                String current = shieldBashSettings.value(args[1]);
+                String defaults = games.dmg.fantasystick.persistence.ShieldBashSettings.defaultValue(args[1]);
+                return matching(current.equals(defaults) ? List.of(current) : List.of(current, defaults), args[2]);
+            }
         }
         return List.of();
     }

src/main/java/games/dmg/fantasystick/session/EquipmentSessionEvents.java

@@ -449,7 +449,8 @@ public final class EquipmentSessionEvents implements Listener, AutoCloseable {
         if (special(item)) event.setCancelled(true);
         if (willAttack) {
             var selected = sessions.selectedControl(player, item).orElse(null);
-            if (selected != null && (selected.slot() == 1 || selected.ability().equals("great_sword"))) {
+            if (selected != null && (selected.slot() == 1 || selected.ability().equals("great_sword")
+                    || selected.ability().equals("shield_bash"))) {
                 emit(player, item, selected, ControlInput.Gesture.ATTACK, event.getAttacked(), 0, player.getAttackCooldown());
             }
         }

src/main/resources/config.yml

@@ -62,3 +62,11 @@ second-wind-cooldown-seconds: 15
 stone-skin-cooldown-seconds: 14
 stone-skin-duration-seconds: 4
 stone-skin-damage-reduction-percent: 25
+
+# Shield Bash defaults from the reviewed remaining-development packet.
+# Admin command: /fantasystick config <key> [value]
+shield-bash-base-damage: 4
+shield-bash-cooldown-seconds: 6
+shield-bash-range-blocks: 3
+shield-bash-horizontal-knockback: 0.8
+shield-bash-minimum-vertical-knockback: 0.35

src/nativeTest/java/games/dmg/fantasystick/ShieldBashNativeTest.java

@@ -0,0 +1,329 @@
+package games.dmg.fantasystick;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.*;
+
+import games.dmg.fantasystick.persistence.CharacterRecord;
+import games.dmg.fantasystick.persistence.CharacterStorage;
+import games.dmg.fantasystick.progression.Stat;
+import java.math.BigInteger;
+import java.nio.file.Path;
+import java.util.EnumMap;
+import java.util.List;
+import net.minecraft.network.chat.ClickEvent;
+import org.bukkit.Location;
+import org.bukkit.event.entity.EntityDamageByEntityEvent;
+import org.bukkit.event.entity.EntityDamageEvent;
+import org.bukkit.util.Vector;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class ShieldBashNativeTest {
+    @TempDir Path data;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test void bookAcquisitionAndEquippedAttackReplaceVanillaDamageThenKnockBack() throws Exception {
+        try (var f = new FantasyStickLifecycleNativeTest.Fixture(data)) {
+            f.plugin.setEnabled(true);
+            var a = new FantasyStickLifecycleNativeTest.Actor(data); withShieldBash(data, a, false);
+            f.players.put(a.core.id, a.player); f.activate(a);
+            a.core.inventory.getInventory().setSelectedSlot(0); PartyBookNativeTest.open(f, a);
+            String book = PartyBookNativeTest.text(a).replaceAll("\\s+", "");
+            assertTrue(book.contains("ShieldBash")); assertTrue(book.contains("STR12")); assertTrue(book.contains("CON12"));
+            assertTrue(book.contains("Cost:1")); assertTrue(book.contains("3")); assertTrue(book.contains("6s"));
+            PartyBookNativeTest.click(f, a, abilityButton(a, "[Learn]", "shield_bash"));
+            PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f);
+            PartyBookNativeTest.click(f, a, abilityButton(a, "[3]", "shield_bash"));
+            PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f);
+            var storage = (CharacterStorage) FantasyStickLifecycleNativeTest.Fixture.field(f.plugin, "characters");
+            assertEquals(BigInteger.valueOf(39), storage.find(a.core.record.id()).get().orElseThrow().unspentPoints());
+            assertEquals(org.bukkit.Material.SHIELD, a.core.inventory.getItem(2).getType());
+            a.core.inventory.getInventory().setSelectedSlot(2);
+            var block = new org.bukkit.event.player.PlayerInteractEvent(a.player,
+                org.bukkit.event.block.Action.RIGHT_CLICK_AIR, a.core.inventory.getItem(2), null,
+                org.bukkit.block.BlockFace.SELF, org.bukkit.inventory.EquipmentSlot.HAND);
+            f.dispatcher.accept(block); assertTrue(block.isCancelled(), "Contained shield cannot start ordinary blocking");
+            assertFalse(storage.find(a.core.record.id()).get().orElseThrow().cooldowns().containsKey("shield_bash"));
+
+            var target = mock(org.bukkit.entity.LivingEntity.class);
+            when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID()); when(target.getType()).thenReturn(org.bukkit.entity.EntityType.ZOMBIE);
+            when(a.world.getUID()).thenReturn(java.util.UUID.randomUUID());
+            var origin = new Location(a.world, 0, 64, 0); var destination = new Location(a.world, 2, 64, 0);
+            doReturn(origin).when(a.player).getLocation(); when(target.getLocation()).thenReturn(destination);
+            doReturn(true).when(a.player).hasLineOfSight(target); when(target.getVelocity()).thenReturn(new Vector(0.1, 0.2, 0));
+            var applied = new java.util.concurrent.atomic.AtomicReference<Vector>();
+            doAnswer(call -> { applied.set(call.getArgument(0)); return null; }).when(target).setVelocity(any(Vector.class));
+            var damages = new java.util.ArrayList<EntityDamageByEntityEvent>();
+            doAnswer(call -> {
+                var source = (org.bukkit.damage.DamageSource) call.getArgument(1);
+                var event = new EntityDamageByEntityEvent(a.player, target, EntityDamageEvent.DamageCause.ENTITY_ATTACK,
+                    source, (Double) call.getArgument(0)); damages.add(event); f.dispatcher.accept(event); return null;
+            }).when(target).damage(anyDouble(), any(org.bukkit.damage.DamageSource.class));
+            a.core.inventory.getInventory().setSelectedSlot(2);
+            var attack = new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, target, true);
+            f.dispatcher.accept(attack); PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f);
+            assertTrue(attack.isCancelled(), "Contained shield cannot continue into vanilla damage/blocking");
+            assertEquals(1, damages.size()); assertEquals(5, damages.getFirst().getDamage(), 1.0e-9);
+            assertEquals(new Vector(0.9, 0.35, 0), applied.get());
+            assertNotNull(storage.find(a.core.record.id()).get().orElseThrow().cooldowns().get("shield_bash"));
+            f.dispatcher.accept(new org.bukkit.event.entity.EntityDeathEvent(target, damages.getFirst().getDamageSource(),
+                new java.util.ArrayList<>(), 0)); PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f);
+            assertEquals(BigInteger.TEN, storage.find(a.core.record.id()).get().orElseThrow().experience());
+            f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, target, true));
+            PartyBookNativeTest.drain(f); assertEquals(1, damages.size());
+            assertTrue(a.messages.stream().anyMatch(message -> message.contains("ready in")));
+        }
+    }
+
+    @Test void outOfRangeOrObstructedTargetRefusesBeforeCooldownWhileStillContainingShield() throws Exception {
+        for (int route = 0; route < 2; route++) {
+            var directory = data.resolve("refused-" + route);
+            try (var f = new FantasyStickLifecycleNativeTest.Fixture(directory)) {
+                f.plugin.setEnabled(true); var a = new FantasyStickLifecycleNativeTest.Actor(directory);
+                withShieldBash(directory, a, true); f.players.put(a.core.id, a.player); f.activate(a);
+                var target = mock(org.bukkit.entity.LivingEntity.class);
+                when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID()); when(target.getType()).thenReturn(org.bukkit.entity.EntityType.ZOMBIE);
+                doReturn(new Location(a.world, 0, 64, 0)).when(a.player).getLocation();
+                when(target.getLocation()).thenReturn(new Location(a.world, route == 0 ? 4 : 2, 64, 0));
+                doReturn(route == 0).when(a.player).hasLineOfSight(target);
+                a.core.inventory.getInventory().setSelectedSlot(2);
+                var attack = new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, target, true);
+                f.dispatcher.accept(attack); assertTrue(attack.isCancelled());
+                verify(target, never()).damage(anyDouble(), any(org.bukkit.damage.DamageSource.class));
+                var storage = (CharacterStorage) FantasyStickLifecycleNativeTest.Fixture.field(f.plugin, "characters");
+                assertFalse(storage.find(a.core.record.id()).get().orElseThrow().cooldowns().containsKey("shield_bash"));
+            }
+        }
+    }
+
+    @Test void partyAndMixedModePlayerTargetsAreRefusedWithoutFreeVanillaHits() throws Exception {
+        try(var f=new FantasyStickLifecycleNativeTest.Fixture(data)){
+            f.plugin.setEnabled(true);var a=new FantasyStickLifecycleNativeTest.Actor(data);var b=new FantasyStickLifecycleNativeTest.Actor(data);
+            withShieldBash(data,a,true);f.players.put(a.core.id,a.player);f.players.put(b.core.id,b.player);f.activate(a);f.activate(b);
+            var parties=PartyLifecycleNativeTest.parties(f);var party=parties.create(a.core.id).orElseThrow();
+            assertTrue(parties.accept(b.core.id,parties.invite(a.core.id,party.id(),b.core.id).orElseThrow().id()));
+            a.core.inventory.getInventory().setSelectedSlot(2);
+            var friendly=new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player,b.player,true);f.dispatcher.accept(friendly);
+            assertTrue(friendly.isCancelled());verify(b.player,never()).damage(anyDouble(),any(org.bukkit.damage.DamageSource.class));
+            var ordinary=mock(org.bukkit.entity.Player.class);when(ordinary.getUniqueId()).thenReturn(java.util.UUID.randomUUID());
+            var mixed=new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player,ordinary,true);f.dispatcher.accept(mixed);
+            assertTrue(mixed.isCancelled());verify(ordinary,never()).damage(anyDouble(),any(org.bukkit.damage.DamageSource.class));
+            var storage=(CharacterStorage)FantasyStickLifecycleNativeTest.Fixture.field(f.plugin,"characters");
+            assertFalse(storage.find(a.core.record.id()).get().orElseThrow().cooldowns().containsKey("shield_bash"));
+        }
+    }
+
+    @Test void cancelledDamageAppliesNoKnockbackAndNeverRefundsAcknowledgedCooldown() throws Exception {
+        try (var f = new FantasyStickLifecycleNativeTest.Fixture(data)) {
+            f.plugin.setEnabled(true); var a = new FantasyStickLifecycleNativeTest.Actor(data);
+            withShieldBash(data, a, true); f.players.put(a.core.id, a.player); f.activate(a);
+            var target = mock(org.bukkit.entity.LivingEntity.class); when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID());
+            when(target.getType()).thenReturn(org.bukkit.entity.EntityType.ZOMBIE);
+            doReturn(new Location(a.world, 0, 64, 0)).when(a.player).getLocation();
+            when(target.getLocation()).thenReturn(new Location(a.world, 2, 64, 0)); doReturn(true).when(a.player).hasLineOfSight(target);
+            doAnswer(call -> {
+                var source = (org.bukkit.damage.DamageSource) call.getArgument(1);
+                var event = new EntityDamageByEntityEvent(a.player, target, EntityDamageEvent.DamageCause.ENTITY_ATTACK,
+                    source, (Double) call.getArgument(0)); event.setCancelled(true); f.dispatcher.accept(event); return null;
+            }).when(target).damage(anyDouble(), any(org.bukkit.damage.DamageSource.class));
+            a.core.inventory.getInventory().setSelectedSlot(2);
+            f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, target, true));
+            PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f); verify(target, never()).setVelocity(any(Vector.class));
+            var storage = (CharacterStorage) FantasyStickLifecycleNativeTest.Fixture.field(f.plugin, "characters");
+            assertNotNull(storage.find(a.core.record.id()).get().orElseThrow().cooldowns().get("shield_bash"));
+        }
+    }
+
+    @Test void cancelledPlayerVelocityPreservesMovementAfterAcceptedDamage() throws Exception {
+        try (var f = new FantasyStickLifecycleNativeTest.Fixture(data)) {
+            f.plugin.setEnabled(true); var a = new FantasyStickLifecycleNativeTest.Actor(data);
+            var b = new FantasyStickLifecycleNativeTest.Actor(data); withShieldBash(data, a, true);
+            f.players.put(a.core.id, a.player); f.players.put(b.core.id, b.player); f.activate(a); f.activate(b);
+            doReturn(new Location(a.world, 0, 64, 0)).when(a.player).getLocation();
+            doReturn(new Location(a.world, 2, 64, 0)).when(b.player).getLocation();
+            doReturn(true).when(a.player).hasLineOfSight(b.player); doReturn(new Vector(0.1, 0.2, 0)).when(b.player).getVelocity();
+            class Veto implements org.bukkit.event.Listener {
+                @org.bukkit.event.EventHandler public void velocity(org.bukkit.event.player.PlayerVelocityEvent event) {
+                    if (event.getPlayer() == b.player) event.setCancelled(true);
+                }
+            }
+            f.dispatcher.register(new Veto(), f.plugin);
+            doAnswer(call -> {
+                var source = (org.bukkit.damage.DamageSource) call.getArgument(1);
+                f.dispatcher.accept(new EntityDamageByEntityEvent(a.player, b.player, EntityDamageEvent.DamageCause.ENTITY_ATTACK,
+                    source, (Double) call.getArgument(0))); return null;
+            }).when(b.player).damage(anyDouble(), any(org.bukkit.damage.DamageSource.class));
+            a.core.inventory.getInventory().setSelectedSlot(2);
+            f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, b.player, true));
+            PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f); verify(b.player, never()).setVelocity(any(Vector.class));
+        }
+    }
+
+    @Test void unlearnRelearnAndCharacterTransferRetainCooldown() throws Exception {
+        java.nio.file.Files.writeString(data.resolve("config.yml"), "shield-bash-cooldown-seconds: 60\n");
+        try (var f = new FantasyStickLifecycleNativeTest.Fixture(data)) {
+            f.plugin.setEnabled(true); var a = new FantasyStickLifecycleNativeTest.Actor(data);
+            withShieldBash(data, a, true); f.players.put(a.core.id, a.player); f.activate(a);
+            var target = mock(org.bukkit.entity.LivingEntity.class); when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID());
+            when(target.getType()).thenReturn(org.bukkit.entity.EntityType.ZOMBIE);
+            doReturn(new Location(a.world, 0, 64, 0)).when(a.player).getLocation();
+            when(target.getLocation()).thenReturn(new Location(a.world, 2, 64, 0)); doReturn(true).when(a.player).hasLineOfSight(target);
+            when(target.getVelocity()).thenReturn(new Vector()); var hits = new java.util.concurrent.atomic.AtomicInteger();
+            doAnswer(call -> { hits.incrementAndGet(); var source = (org.bukkit.damage.DamageSource) call.getArgument(1);
+                f.dispatcher.accept(new EntityDamageByEntityEvent(a.player, target, EntityDamageEvent.DamageCause.ENTITY_ATTACK,
+                    source, (Double) call.getArgument(0))); return null; }).when(target).damage(anyDouble(), any(org.bukkit.damage.DamageSource.class));
+            a.core.inventory.getInventory().setSelectedSlot(2);
+            f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, target, true));
+            PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f); assertEquals(1, hits.get());
+            var storage = (CharacterStorage) FantasyStickLifecycleNativeTest.Fixture.field(f.plugin, "characters");
+            var deadline = storage.find(a.core.record.id()).get().orElseThrow().cooldowns().get("shield_bash");
+            a.core.inventory.getInventory().setSelectedSlot(0); PartyBookNativeTest.open(f, a);
+            var unlearn = abilityButton(a, "[Unlearn]", "shield_bash");
+            PartyBookNativeTest.click(f, a, unlearn); PartyBookNativeTest.click(f, a, unlearn);
+            PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f);
+            var refunded = storage.find(a.core.record.id()).get().orElseThrow();
+            assertEquals(BigInteger.valueOf(40), refunded.unspentPoints()); assertEquals(deadline, refunded.cooldowns().get("shield_bash"));
+            learnAndAssign(f, a); a.core.inventory.getInventory().setSelectedSlot(2);
+            f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player, target, true));
+            PartyBookNativeTest.drain(f); assertEquals(1, hits.get());
+            var sheet = a.core.inventory.getItemInOffHand().clone();
+            a.core.inventory.setItemInOffHand(null); f.changed(a); PartyBookNativeTest.drain(f); f.awaitCharacterAndReceipt(a);
+            var b = new FantasyStickLifecycleNativeTest.Actor(data); b.core.inventory.setItemInOffHand(sheet);
+            f.players.put(b.core.id, b.player); f.activate(b); b.core.inventory.getInventory().setSelectedSlot(2);
+            doReturn(new Location(a.world, 0, 64, 0)).when(b.player).getLocation(); doReturn(true).when(b.player).hasLineOfSight(target);
+            f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(b.player, target, true));
+            PartyBookNativeTest.drain(f); assertEquals(1, hits.get()); assertEquals(deadline,
+                storage.find(a.core.record.id()).get().orElseThrow().cooldowns().get("shield_bash"));
+        }
+    }
+
+    @Test void exactDamageFormulaSupportsFiniteUncappedStats() {
+        assertEquals(BigInteger.valueOf(5), games.dmg.fantasystick.ability.ShieldBash.damage(BigInteger.valueOf(12)));
+        assertEquals(BigInteger.valueOf(3), games.dmg.fantasystick.ability.ShieldBash.damage(BigInteger.valueOf(9)));
+        var huge = BigInteger.TEN.pow(500);
+        assertEquals(huge.subtract(BigInteger.TEN).divide(BigInteger.TWO).add(BigInteger.valueOf(4)),
+            games.dmg.fantasystick.ability.ShieldBash.damage(huge));
+    }
+
+    @Test void failedCooldownPersistenceDealsNoDamageOrKnockback() {
+        var storage=mock(CharacterStorage.class);var sessions=mock(games.dmg.fantasystick.session.EquipmentSessions.class);
+        var parties=new games.dmg.fantasystick.party.PartyRoster(java.time.Clock.systemUTC(),ignored->true);
+        var registry=new games.dmg.fantasystick.ability.AbilityRegistry();var bash=new games.dmg.fantasystick.ability.ShieldBash(
+            games.dmg.fantasystick.ability.ShieldBash.Settings.defaults(),ignored->{});registry.register(bash.definition());
+        var base=new games.dmg.fantasystick.crafting.CharacterFactory().create(games.dmg.fantasystick.progression.ProgressionRules.defaults());
+        var stats=new EnumMap<>(base.stats());stats.put(Stat.STR,BigInteger.valueOf(12));stats.put(Stat.CON,BigInteger.valueOf(12));
+        var record=new CharacterRecord(base.id(),base.name(),base.revision(),stats,base.level(),base.experience(),base.unspentPoints(),base.health(),
+            java.util.Set.of("shield_bash"),List.of("shield_bash","","","","","",""),base.cooldowns(),base.restrictedKills(),false,null,null);
+        var active=new games.dmg.fantasystick.session.EquipmentSessions.Active(java.util.UUID.randomUUID(),java.util.UUID.randomUUID(),record.id());
+        var player=mock(org.bukkit.entity.Player.class);when(player.getUniqueId()).thenReturn(active.player());
+        var world=mock(org.bukkit.World.class);doReturn(new Location(world,0,64,0)).when(player).getLocation();
+        var target=mock(org.bukkit.entity.LivingEntity.class);when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID());
+        when(target.getType()).thenReturn(org.bukkit.entity.EntityType.ZOMBIE);when(target.getLocation()).thenReturn(new Location(world,2,64,0));
+        doReturn(true).when(player).hasLineOfSight(target);when(sessions.current(active)).thenReturn(true);
+        when(sessions.currentRecord(active)).thenReturn(java.util.Optional.of(record));
+        var failed=new java.util.concurrent.CompletableFuture<CharacterStorage.AbilityMutation>();
+        failed.completeExceptionally(new java.io.IOException("simulated cooldown failure"));
+        when(storage.commitAbilityCooldown(eq(record.id()),eq(record.revision()),eq("shield_bash"),any())).thenReturn(failed);
+        var engine=new games.dmg.fantasystick.ability.AbilityEngine(registry,storage,sessions,parties,java.time.Clock.systemUTC(),Runnable::run,
+            (delay,action)->()->{},ignored->{},ignored->{});
+        engine.accept(new games.dmg.fantasystick.session.ControlInput(player,active,2,"shield_bash",
+            games.dmg.fantasystick.session.ControlInput.Kind.ABILITY,games.dmg.fantasystick.session.ControlInput.Gesture.ATTACK,
+            target,0,1,()->true));
+        verify(storage).commitAbilityCooldown(eq(record.id()),eq(record.revision()),eq("shield_bash"),any());
+        verify(target,never()).damage(anyDouble(),any(org.bukkit.damage.DamageSource.class));verify(target,never()).setVelocity(any(Vector.class));
+        engine.close();bash.close();parties.close();
+    }
+
+    @Test void configuredDefinitionAdminRoutesRestartAndFutureStrikeCoverEverySetting() throws Exception {
+        java.nio.file.Files.writeString(data.resolve("config.yml"),
+            "shield-bash-base-damage: 8\nshield-bash-cooldown-seconds: 0\nshield-bash-range-blocks: 5\n" +
+            "shield-bash-horizontal-knockback: 1.2\nshield-bash-minimum-vertical-knockback: 0.5\n");
+        try (var f = new FantasyStickLifecycleNativeTest.Fixture(data)) {
+            f.plugin.setEnabled(true); var registry = (games.dmg.fantasystick.ability.AbilityRegistry)
+                FantasyStickLifecycleNativeTest.Fixture.field(f.plugin, "abilityRegistry");
+            var definition = registry.find("shield_bash").orElseThrow(); assertEquals(java.time.Duration.ZERO, definition.cooldown());
+            assertEquals(0, new java.math.BigDecimal("8").compareTo(definition.parameters().get("base-damage")));
+            assertEquals(0, new java.math.BigDecimal("5").compareTo(definition.parameters().get("range")));
+            assertEquals(0, new java.math.BigDecimal("1.2").compareTo(definition.parameters().get("horizontal-knockback")));
+            assertEquals(0, new java.math.BigDecimal("0.5").compareTo(definition.parameters().get("minimum-vertical-knockback")));
+            var sender = new EquipmentAdminCommandNativeTest.Sender(); sender.allowed=false;
+            assertTrue(f.command.tabComplete(sender.port,"fantasystick",new String[]{"config","shield-bash"}).isEmpty());
+            f.command.execute(sender.port,"fantasystick",new String[]{"config","shield-bash-base-damage","9"});
+            assertTrue(sender.messages.getLast().contains("Permission denied")); sender.allowed=true;
+            assertEquals(List.of("shield-bash-base-damage","shield-bash-cooldown-seconds","shield-bash-horizontal-knockback",
+                "shield-bash-minimum-vertical-knockback","shield-bash-range-blocks"),
+                f.command.tabComplete(sender.port,"fantasystick",new String[]{"config","shield-bash-"}));
+            assertEquals(List.of("4","8"),f.command.tabComplete(sender.port,"fantasystick",
+                new String[]{"config","shield-bash-base-damage",""}));
+            f.command.execute(sender.port,"fantasystick",new String[]{"config","shield-bash-base-damage"});
+            assertTrue(sender.messages.getLast().contains("=8"));
+            f.command.execute(sender.port,"fantasystick",new String[]{"config","shield-bash-base-damage","9"});
+            var response=f.tasks.poll(5,java.util.concurrent.TimeUnit.SECONDS);assertNotNull(response);response.run();
+            assertEquals(0,new java.math.BigDecimal("9").compareTo(registry.find("shield_bash").orElseThrow().parameters().get("base-damage")));
+            var a=new FantasyStickLifecycleNativeTest.Actor(data);withShieldBash(data,a,true);f.players.put(a.core.id,a.player);f.activate(a);
+            var target=mock(org.bukkit.entity.LivingEntity.class);when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID());
+            when(target.getType()).thenReturn(org.bukkit.entity.EntityType.ZOMBIE);
+            doReturn(new Location(a.world,0,64,0)).when(a.player).getLocation();when(target.getLocation()).thenReturn(new Location(a.world,4,64,0));
+            doReturn(true).when(a.player).hasLineOfSight(target);when(target.getVelocity()).thenReturn(new Vector());
+            var amount=new java.util.concurrent.atomic.AtomicReference<Double>();var movement=new java.util.concurrent.atomic.AtomicReference<Vector>();
+            doAnswer(call->{amount.set(call.getArgument(0));var source=(org.bukkit.damage.DamageSource)call.getArgument(1);
+                f.dispatcher.accept(new EntityDamageByEntityEvent(a.player,target,EntityDamageEvent.DamageCause.ENTITY_ATTACK,source,(Double)call.getArgument(0)));return null;
+            }).when(target).damage(anyDouble(),any(org.bukkit.damage.DamageSource.class));
+            doAnswer(call->{movement.set(call.getArgument(0));return null;}).when(target).setVelocity(any(Vector.class));
+            a.core.inventory.getInventory().setSelectedSlot(2);f.dispatcher.accept(new io.papermc.paper.event.player.PrePlayerAttackEntityEvent(a.player,target,true));
+            PartyBookNativeTest.drain(f);PartyBookNativeTest.drain(f);assertEquals(10,amount.get(),1.0e-9);assertEquals(new Vector(1.2,0.5,0),movement.get());
+            f.command.execute(sender.port,"fantasystick",new String[]{"config","shield-bash-base-damage","-1"});
+            assertTrue(sender.messages.getLast().contains("invalid"));
+            f.command.execute(sender.port,"fantasystick",new String[]{"config","shield-bash-base-damage","9","extra"});
+            assertTrue(sender.messages.getLast().contains("Usage"));
+            f.plugin.setEnabled(false);f.plugin.setEnabled(true);var reloaded=(games.dmg.fantasystick.ability.AbilityRegistry)
+                FantasyStickLifecycleNativeTest.Fixture.field(f.plugin,"abilityRegistry");
+            assertEquals(0,new java.math.BigDecimal("9").compareTo(reloaded.find("shield_bash").orElseThrow().parameters().get("base-damage")));
+        }
+        for(String invalid:List.of("shield-bash-base-damage: -1\n","shield-bash-cooldown-seconds: -1\n",
+                "shield-bash-range-blocks: 0\n","shield-bash-horizontal-knockback: 9\n",
+                "shield-bash-minimum-vertical-knockback: 9\n")){
+            var directory=data.resolve(Integer.toHexString(invalid.hashCode()));java.nio.file.Files.createDirectories(directory);
+            java.nio.file.Files.writeString(directory.resolve("config.yml"),invalid);
+            try(var f=new FantasyStickLifecycleNativeTest.Fixture(directory)){
+                assertThrows(IllegalArgumentException.class,()->f.plugin.setEnabled(true));assertTrue(f.order.isEmpty());
+            }
+        }
+    }
+
+    private static void learnAndAssign(FantasyStickLifecycleNativeTest.Fixture fixture,
+                                       FantasyStickLifecycleNativeTest.Actor actor) throws Exception {
+        actor.core.inventory.getInventory().setSelectedSlot(0); PartyBookNativeTest.open(fixture, actor);
+        PartyBookNativeTest.click(fixture, actor, abilityButton(actor, "[Learn]", "shield_bash"));
+        PartyBookNativeTest.drain(fixture); PartyBookNativeTest.drain(fixture);
+        PartyBookNativeTest.click(fixture, actor, abilityButton(actor, "[3]", "shield_bash"));
+        PartyBookNativeTest.drain(fixture); PartyBookNativeTest.drain(fixture);
+    }
+
+    private static ClickEvent.Custom abilityButton(FantasyStickLifecycleNativeTest.Actor actor, String label, String ability) {
+        var book = org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(actor.books.getLast())
+            .get(net.minecraft.core.component.DataComponents.WRITTEN_BOOK_CONTENT); assertNotNull(book);
+        for (var page : book.pages()) { var found = abilityButton(page.raw(), label, ability); if (found != null) return found; }
+        throw new AssertionError("Missing " + label + " for " + ability);
+    }
+    private static ClickEvent.Custom abilityButton(net.minecraft.network.chat.Component component, String label, String ability) {
+        if (component.getString().equals(label) && component.getStyle().getClickEvent() instanceof ClickEvent.Custom custom
+                && custom.payload().orElse(null) instanceof net.minecraft.nbt.StringTag payload
+                && payload.value().contains(":" + ability)) return custom;
+        for (var child : component.getSiblings()) { var found = abilityButton(child, label, ability); if (found != null) return found; }
+        return null;
+    }
+    private static void withShieldBash(Path data, FantasyStickLifecycleNativeTest.Actor actor, boolean learned) throws Exception {
+        java.nio.file.Files.createDirectories(data);
+        var repository = new games.dmg.fantasystick.persistence.YamlCharacterRepository(data);
+        var old = repository.load(actor.core.record.id()).orElseThrow(); var stats = new EnumMap<>(old.stats());
+        stats.put(Stat.STR, BigInteger.valueOf(12)); stats.put(Stat.CON, BigInteger.valueOf(12));
+        repository.replace(new CharacterRecord(old.id(), old.name(), old.revision().add(BigInteger.ONE), stats,
+            old.level(), old.experience(), BigInteger.valueOf(learned ? 39 : 40), old.health(),
+            learned ? java.util.Set.of("shield_bash") : old.learned(),
+            learned ? List.of("shield_bash", "", "", "", "", "", "") : old.loadout(),
+            old.cooldowns(), old.restrictedKills(), false, null, null), old.revision());
+    }
+}

src/test/java/games/dmg/fantasystick/DistributionTest.java

@@ -68,6 +68,11 @@ class DistributionTest {
                     "stone-skin-duration-seconds: 4", "stone-skin-damage-reduction-percent: 25")) {
                 assertTrue(defaults.contains(setting), "Missing packaged Stone Skin default: " + setting);
             }
+            for (String setting : java.util.List.of("shield-bash-base-damage: 4", "shield-bash-cooldown-seconds: 6",
+                    "shield-bash-range-blocks: 3", "shield-bash-horizontal-knockback: 0.8",
+                    "shield-bash-minimum-vertical-knockback: 0.35")) {
+                assertTrue(defaults.contains(setting), "Missing packaged Shield Bash default: " + setting);
+            }
             assertTrue(JavaPlugin.class.isAssignableFrom(FantasyStickPlugin.class));
             var entrypoint = jar.getJarEntry(metadata.getMain().replace('.', '/') + ".class");
             assertNotNull(entrypoint);

src/test/java/games/dmg/fantasystick/persistence/ShieldBashSettingsTest.java

@@ -0,0 +1,57 @@
+package games.dmg.fantasystick.persistence;
+
+import static org.junit.jupiter.api.Assertions.*;
+import java.nio.file.*;
+import java.util.*;
+import java.util.concurrent.TimeUnit;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class ShieldBashSettingsTest {
+    @TempDir Path data;
+    @Test void serializesConcurrentKeysPreservesUnrelatedAndPublishesAcknowledgedSnapshots() throws Exception {
+        Files.writeString(data.resolve("config.yml"), "unrelated: retained\n");
+        try (var settings = new ShieldBashSettings(data, defaults())) {
+            var range = settings.set(ShieldBashSettings.RANGE, "5").toCompletableFuture();
+            var horizontal = settings.set(ShieldBashSettings.HORIZONTAL, "1.2").toCompletableFuture();
+            var r = range.get(5, TimeUnit.SECONDS); var h = horizontal.get(5, TimeUnit.SECONDS);
+            assertEquals(3, settings.settings().range(), 0); settings.publish(h); settings.publish(r);
+            assertEquals(5, settings.settings().range(), 0); assertEquals(1.2, settings.settings().horizontalKnockback(), 0);
+            var saved = (Map<?, ?>) new org.yaml.snakeyaml.Yaml().load(Files.readString(data.resolve("config.yml")));
+            assertEquals("retained", saved.get("unrelated")); assertEquals("5", String.valueOf(saved.get(ShieldBashSettings.RANGE)));
+            assertEquals("1.2", String.valueOf(saved.get(ShieldBashSettings.HORIZONTAL)));
+        }
+    }
+    @Test void rejectsInvalidValuesAndFailedReplacementRetainsState() throws Exception {
+        try (var settings = new ShieldBashSettings(data, defaults())) {
+            for (var entry : Map.of(ShieldBashSettings.BASE_DAMAGE, "-1", ShieldBashSettings.COOLDOWN, "-1",
+                    ShieldBashSettings.RANGE, "0", ShieldBashSettings.HORIZONTAL, "9",
+                    ShieldBashSettings.VERTICAL, "Infinity").entrySet())
+                assertThrows(IllegalArgumentException.class, () -> settings.set(entry.getKey(), entry.getValue()));
+            assertThrows(IllegalArgumentException.class, () -> settings.set(ShieldBashSettings.COOLDOWN, "0.0000000001"));
+            assertThrows(IllegalArgumentException.class, () -> settings.set(ShieldBashSettings.BASE_DAMAGE, "1.5"));
+        }
+        var fail = new java.util.concurrent.atomic.AtomicBoolean(true);
+        try (var settings = new ShieldBashSettings(data, defaults(), (from,to) -> {
+            if (fail.getAndSet(false)) throw new java.io.IOException("simulated"); Files.move(from,to,StandardCopyOption.REPLACE_EXISTING);
+        })) {
+            assertThrows(java.util.concurrent.ExecutionException.class, () ->
+                settings.set(ShieldBashSettings.RANGE, "5").toCompletableFuture().get(5,TimeUnit.SECONDS));
+            assertEquals("3", settings.value(ShieldBashSettings.RANGE));
+        }
+    }
+    @Test void unsafeFileAndClosedStoreFailSafely() throws Exception {
+        if (!System.getProperty("os.name","").toLowerCase().contains("win")) {
+            var external=data.resolveSibling(data.getFileName()+"-outside"); Files.writeString(external,"safe\n");
+            Files.createSymbolicLink(data.resolve("config.yml"),external);
+            try(var settings=new ShieldBashSettings(data,defaults())) {
+                assertThrows(java.util.concurrent.ExecutionException.class,()->settings.set(ShieldBashSettings.RANGE,"5").toCompletableFuture().get(5,TimeUnit.SECONDS));
+                assertEquals("safe\n",Files.readString(external));
+            }
+        }
+        var settings=new ShieldBashSettings(data.resolve("closed"),defaults()); settings.close();
+        assertThrows(java.util.concurrent.ExecutionException.class,()->settings.set(ShieldBashSettings.RANGE,"5").toCompletableFuture().get(5,TimeUnit.SECONDS));
+        settings.drained().toCompletableFuture().get(5,TimeUnit.SECONDS);
+    }
+    private static Map<String,String> defaults(){var result=new LinkedHashMap<String,String>();for(String key:ShieldBashSettings.keys())result.put(key,ShieldBashSettings.defaultValue(key));return result;}
+}