v0.4.14: /videoCache clear + tighten default cap to 750 MB

- New /videoCache clear subcommand: drops every named entry from server config
  and broadcasts DeleteCachePayload per URL so each client purges its disk cache
  in one shot.
- Default max_preload_mb lowered from 1024 → 750. Sized to fit ~50 short FHD
  clips (FHD H.264 ~5 Mbps × 20 s ≈ 12.5 MB → 50 × 15 MB ≈ 750 MB with headroom).
  Config file's max_preload_mb still wins when set; the new default only
  affects fresh installs and the client-side bootstrap value before the JOIN
  policy packet arrives.

src/main/java/com/ejclaw/videoplayer/VideoPlayerConfig.java

@@ -49,7 +49,12 @@ public final class VideoPlayerConfig {
 
     private static final String FILE_NAME = "video_player.json";
 
-    private static final int DEFAULT_MAX_PRELOAD_MB = 1024;
+    /**
+     * Default per-video download cap in MB. Sized to comfortably fit ~50 short FHD clips:
+     * FHD H.264 at ~5 Mbps × 20 s ≈ 12.5 MB, so 50 × 15 MB ≈ 750 MB with headroom for
+     * higher-bitrate sources.
+     */
+    private static final int DEFAULT_MAX_PRELOAD_MB = 750;
     /** Default render-distance cap for video anchors, in blocks. 128 = the legacy hard-coded value. */
     private static final int DEFAULT_RENDER_DISTANCE = 128;
 
@@ -198,6 +203,18 @@ public final class VideoPlayerConfig {
         return removed;
     }
 
+    /**
+     * Drop every named cache entry and return the URLs that were registered so the caller
+     * can broadcast {@code DeleteCachePayload} for each. Persists on any non-empty removal.
+     */
+    public static synchronized java.util.List<String> clearCacheEntries() {
+        if (CACHE_ENTRIES.isEmpty()) return java.util.Collections.emptyList();
+        java.util.List<String> urls = new java.util.ArrayList<>(CACHE_ENTRIES.values());
+        CACHE_ENTRIES.clear();
+        save();
+        return urls;
+    }
+
     // -- io ----------------------------------------------------------------------------------
 
     private static Path configPath() {

src/main/java/com/ejclaw/videoplayer/client/playback/VideoCache.java

@@ -42,11 +42,11 @@ public final class VideoCache {
     private static final Set<String> IN_FLIGHT = ConcurrentHashMap.newKeySet();
 
     /**
-     * Hard ceiling on a single preload, in bytes. Default 1 GB so a fresh client without a
-     * policy packet (e.g. integrated server, dev test) still has a sensible cap. Overridden by
-     * {@link com.ejclaw.videoplayer.net.CachePolicyPayload} on join.
+     * Hard ceiling on a single preload, in bytes. Default 750 MB sized to fit ~50 short FHD
+     * clips; overridden per-session by {@link com.ejclaw.videoplayer.net.CachePolicyPayload}
+     * on join, which carries the server's {@code max_preload_mb} config value.
      */
-    private static volatile long MAX_BYTES = 1024L * 1024 * 1024;
+    private static volatile long MAX_BYTES = 750L * 1024 * 1024;
 
     /** Server-driven override of the per-video cap. */
     public static void setMaxBytes(long bytes) {

src/main/java/com/ejclaw/videoplayer/command/VideoCacheCommand.java

@@ -52,7 +52,9 @@ public final class VideoCacheCommand {
                 .executes(VideoCacheCommand::runList))
             .then(Commands.literal("remove")
                 .then(Commands.argument("name", StringArgumentType.word())
-                    .executes(VideoCacheCommand::runRemove)));
+                    .executes(VideoCacheCommand::runRemove)))
+            .then(Commands.literal("clear")
+                .executes(VideoCacheCommand::runClear));
     }
 
     private static int runAdd(CommandContext<CommandSourceStack> ctx) throws CommandSyntaxException {
@@ -123,6 +125,30 @@ public final class VideoCacheCommand {
         return entries.size();
     }
 
+    private static int runClear(CommandContext<CommandSourceStack> ctx) {
+        CommandSourceStack src = ctx.getSource();
+        java.util.List<String> urls = VideoPlayerConfig.clearCacheEntries();
+        if (urls.isEmpty()) {
+            src.sendSuccess(() -> Component.literal("[videocache] 저장된 항목이 없습니다")
+                .withStyle(ChatFormatting.GRAY), false);
+            return 0;
+        }
+        MinecraftServer server = src.getServer();
+        int clients = 0;
+        for (ServerPlayer p : PlayerLookup.all(server)) {
+            for (String url : urls) {
+                ServerPlayNetworking.send(p, new DeleteCachePayload(url));
+            }
+            clients++;
+        }
+        final int sentFinal = clients;
+        final int countFinal = urls.size();
+        src.sendSuccess(() -> Component.literal(
+            "[videocache] 전체 삭제: " + countFinal + "개 항목"
+                + "  (" + sentFinal + " 클라이언트에 cache_delete 전송)"), false);
+        return countFinal;
+    }
+
     private static int runRemove(CommandContext<CommandSourceStack> ctx) throws CommandSyntaxException {
         CommandSourceStack src = ctx.getSource();
         String name = StringArgumentType.getString(ctx, "name").trim();