Fix community link order: TG Group > TG Channel > Chat

Consistent order across all files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/FASTUTIL_CLASSLOADER_ISSUE.md

@@ -0,0 +1,113 @@
+# Singleplayer Server Crash: fastutil ClassNotFoundException
+
+## Status: Open (user-specific, Feb 24 2026)
+
+## Symptom
+
+Singleplayer server crashes immediately after DualAuth Agent installs successfully:
+
+```
+Exception in thread "main" java.lang.NoClassDefFoundError: it/unimi/dsi/fastutil/objects/ObjectArrayList
+    at com.hypixel.hytale.plugin.early.EarlyPluginLoader.<clinit>(EarlyPluginLoader.java:34)
+    at com.hypixel.hytale.Main.main(Main.java:36)
+Caused by: java.lang.ClassNotFoundException: it.unimi.dsi.fastutil.objects.ObjectArrayList
+    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(Unknown Source)
+```
+
+Server exits with code 1. Multiplayer works fine for the same user.
+
+## Affected User
+
+- Discord: ヅ𝚃 JAYED !
+- Platform: Windows (standard x86_64, NOT ARM)
+- Reproduces 100% on singleplayer, every attempt
+- Other users (including macOS/Linux) are NOT affected
+
+## What Works
+
+- Java wrapper correctly strips `-XX:+UseCompactObjectHeaders`
+- Java wrapper correctly injects `--disable-sentry`
+- DualAuth Agent v1.1.12 installs successfully (STATIC mode)
+- Multiplayer connections work fine
+- Repair and reinstall did NOT fix the issue
+
+## Root Cause Analysis
+
+`fastutil` (`it.unimi.dsi.fastutil`) should be bundled inside `HytaleServer.jar` (fat JAR). The `ClassNotFoundException` means the JVM's app classloader cannot find it despite it being in the JAR.
+
+### Ruled Out
+
+- **Wrapper issue**: Wrapper is working correctly (confirmed in logs)
+- **UseCompactObjectHeaders**: Server also has `-XX:+IgnoreUnrecognizedVMOptions`, so unrecognized flags don't crash it
+- **DualAuth Agent**: Works for all other users; agent installs successfully before the crash
+- **Corrupted game files**: Repair/reinstall didn't help
+- **ARM64/Parallels**: User is on standard Windows, not ARM
+
+### Likely Causes (user-specific)
+
+1. **Antivirus interference** — Windows Defender or third-party AV blocking Java from reading classes out of JAR files, especially with `-javaagent` active
+2. **Corrupted/incompatible JRE** — bundled JRE might be broken on their system
+3. **File locking** — another process holding HytaleServer.jar open
+
+## Debugging Steps (ask user)
+
+1. **Does official Hytale singleplayer work?** (without F2P launcher)
+   - Yes → something about our launch setup
+   - No → their system/JRE issue
+
+2. **Check antivirus** — add game directory to Windows Defender exclusions:
+   - Settings → Windows Security → Virus & threat protection → Exclusions
+   - Add their HytaleF2P install folder
+
+3. **Verify fastutil is in the JAR**:
+   ```cmd
+   jar tf "D:\path\to\Server\HytaleServer.jar" | findstr fastutil
+   ```
+   - If output shows fastutil classes → JAR is fine, classloader issue
+   - If no output → JAR is incomplete/corrupt (different from other users)
+
+4. **Try without DualAuth agent** — rename `dualauth-agent.jar` in Server/ folder, retry singleplayer
+   - If works → agent's classloader manipulation breaks fastutil on their setup
+   - If still fails → unrelated to agent
+
+5. **Check JRE version** — have them run:
+   ```cmd
+   "D:\path\to\jre\latest\bin\java.exe" -version
+   ```
+
+## Update (Feb 24): `-XX:+UseCompactObjectHeaders` stripping removed from defaults
+
+Stripping this flag did NOT fix the issue. The server already has `-XX:+IgnoreUnrecognizedVMOptions` so unrecognized flags are harmless. The flag was removed from default `stripFlags` in `backend/core/config.js`.
+
+## Using the Java Wrapper to Strip JVM Flags
+
+If a user needs to strip a specific JVM flag (e.g., for debugging or compatibility), they can do it via the launcher UI:
+
+1. Open **Settings** → scroll to **Java Wrapper Configuration**
+2. Under **JVM Flags to Remove**, type the flag (e.g. `-XX:+UseCompactObjectHeaders`) and click **Add**
+3. The flag will be stripped from all JVM invocations at launch time
+4. To inject custom arguments, use the **Arguments to Inject** section (with optional "Server Only" condition)
+5. **Restore Defaults** resets to empty strip flags + `--disable-sentry` (server only)
+
+The wrapper generates platform-specific scripts at launch time:
+- **Windows**: `java-wrapper.bat` in `jre/latest/bin/`
+- **macOS/Linux**: `java-wrapper` shell script in the same directory
+
+Config is stored in `config.json` under `javaWrapperConfig`:
+```json
+{
+  "javaWrapperConfig": {
+    "stripFlags": ["-XX:+SomeFlag"],
+    "injectArgs": [
+      { "arg": "--some-arg", "condition": "server" },
+      { "arg": "--other-arg", "condition": "always" }
+    ]
+  }
+}
+```
+
+## Related
+
+- Java wrapper config: `backend/core/config.js` (stripFlags / injectArgs)
+- DualAuth Agent: v1.1.12, package `ws.sanasol.dualauth`
+- Game version at time of report: `2026.02.19-1a311a592`