Build, install and debug

Release 0.2.1

These instructions apply to WWPG 0.2.1 / API 1.0.0 and its pinned dependencies. Choose a release.

This is the supported external-instance workflow for the examples and adjustable-load starter. It uses Java 21, Minecraft 1.21.1, WWPG 0.2.1 and the tested dependency set. The source projects compile/package jars; they do not define game-run tasks.

Prepare once

Keep source, extracted SDK Maven repository, and game instance in separate directories. Use a throwaway Creative world for development. Install the required runtime mods, your add-on jar and the general example if you need its ideal 20 V source. Use the same versions on a dedicated server and its clients. SDK jars do not go in mods.

Repeat after an edit

1. Edit your Java or resources. Build from the project root with the quoted absolute -PapiRepository=... argument from the tutorial.
2. Stop the client/server cleanly. Copy the new build/libs/tutorial-load-0.1.0.jar into its mods directory, replacing the previous starter. If you renamed archivesName or version, use the resulting <archivesName>-<version>.jar instead. Do not leave duplicate jars.
3. Start the instance and reopen the small 20 V circuit. Check the settings, lamp, current and power against the tutorial. Check logs/latest.log if the mod fails to load or a device is isolated.
4. For server testing, copy the same rebuilt jar to the server and every client, then restart all of them. Run settings/interaction checks from a connected client.

NeoForge hot code replacement is not assumed. Rebuild and restart after topology, registration, saved-format or resource changes. Back up any world you intend to keep.

Attach a debugger

First import the starter as a Gradle project using Java 21. Add apiRepository=C:/Dev/WWPG API Maven (Unix: its absolute path) to your local gradle.properties before the first IDE sync; property values in this file are not quoted. Do not commit your machine’s path. The same value can be supplied through the IDE’s Gradle arguments as a quoted -PapiRepository=.... Build sdkProvenance and compare its jar_sha256 with the installed jar before debugging; source and installed bytecode must match.

Use your IDE’s Remote JVM / Attach configuration on localhost:5005. Add this JVM argument to the separate launcher’s Java/JVM options, before game arguments:

-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=127.0.0.1:5005

For a dedicated server, place the same JVM argument in its user_jvm_args.txt, then start it normally. Use a different local port, such as 5006, if you debug client and server together. suspend=y waits before startup and lets you catch registration; attach to resume. Remove the option when you finish. Keep the debugger bound to localhost.

Useful breakpoints: TutorialLoadMod.registerElectricalDevice, LoadDevice.prepare, LoadDevice.commit, and the native loadAdditional / saveAdditional methods. Registration occurs on the mod bus during startup. Electrical preparation and commit run on the logical server; a client breakpoint may never be reached in multiplayer. Inspect immutable terminal records, status and element keys. Avoid holding the server at a breakpoint for long periods: stopped ticks can disconnect clients and change observed timing.

Inspect restored data before it can be changed

Set a breakpoint on the final assignment in LoadDevice.loadAdditional(), then restart and load the saved chunk. Step past resistanceIndex = restored and stop before the method returns. Inspect enabled == false and resistanceIndex == 2 (400 Ω); reading should still begin with unavailable. Do this on the logical server before prepare()/commit() runs. A breakpoint in onLoad() confirms chunk reload; it can fire during initial startup too, so compare the two visits. Resume promptly. For a storage device, inspect the restored charge/current fields at the equivalent point. A later lit lamp cannot prove persistence.

Where to look

Evidence	Location or command
Compiler error	Gradle console; reported source file and line
Mod-loading exception	Instance/server logs/latest.log; crash-reports if generated
Actual solver/backend	/wwpg
One device’s identity, terminals and status	/wwpg at x y z
Recent compatibility errors	/wwpg errors
Structural connection changes	/wwpg topology

WWPG commands require operator permission level 2. Run them in the dimension containing the device. A missing wire and an invalid device can look similar; read the status and error before changing circuit values. Troubleshooting gives the next checks.