Add support to create a pached Minecraft Jar on Startup by shartte · Pull Request #383 · neoforged/FancyModLoader

shartte · 2025-10-26T11:22:45Z

This PR will add support for automatically installing / producing the Minecraft jar if it is missing, assuming the installer is available in the libraries folder. This only applies to production and intends to replace https://github.com/PrismLauncher/ForgeWrapper for launchers.

The first phase of changes removes the locator for Minecraft/NeoForge and instead makes detecting "the game" an explicit first step, before FMLLoader is constructed. For this, most of the previous game locator code is moved into net.neoforged.fml.loading.game.GameDiscovery. In the same vein, VersionInfo is removed, since no CLI args except fml.neoForgeVersion are now required to launch. (no fml.mcVersion/fml.neoFormVersion) This information is now part of the NeoForge version properties file that is baked into NF.

As previously, if an unobfuscated MC is detected on the classpath, FML assumes it is launching in development mode, and skips the production logic. This PR will change nothing about how development detection works. For production, two modes are supported: NF can be on the startup classpath, in which case not even the fml.neoForgeVersion argument is required, or it can be loaded from the libraries folder.

Assuming FML is launching production, and NF was found. FML then only has to check if the single patched Minecraft Jar exists within the libraries folder, using the detected NeoForge version. The artifact paths are: net/neoforged/minecraft-client-patched/<neoForgeVersion>/minecraft-client-patched-<neoForgeVersion>.jar (and server, respectively).

If it exists, launch just continues as before. If it does not exist, and a system property for auto-installation is set, FML will proceed with the auto-installation.

The pre-requisite PRs for this were:

Refactor how NeoForge version information is built into the jar NeoForge#2751 (To be able to discover the required MC version from just NeoForge being found)
Installer Enhancements NeoForge#2547 (To be able to rely on the installer producing a single file we can check for based on the NeoForge version and required distribution)

neoforged-pr-publishing · 2025-10-26T11:22:58Z

Publish PR to GitHub Packages

Last commit published: e7928868d85f4c81d0a3ce3625d263fd751474db - version: 11.0.31-pr--

PR Publishing

The artifacts published by this PR:

Repository Declaration

In order to use the artifacts published by the PR, add the following repository to your buildscript:

repositories {
    maven {
        name = "Maven for PR #383" // https://github.com/neoforged/FancyModLoader/pull/383
        url = uri("https://prmaven.neoforged.net/FancyModLoader/pr383")
        content {
            includeModule("net.neoforged.fancymodloader", "earlydisplay")
            includeModule("net.neoforged.fancymodloader", "junit-fml")
            includeModule("net.neoforged.fancymodloader", "loader")
        }
    }
}

neoforged-compatibility-checks · 2025-10-26T14:33:33Z

@shartte, this PR introduces breaking changes.
Fortunately, this project is currently accepting breaking changes, but if they are not intentional, please revert them.
Last checked commit: e7928868d85f4c81d0a3ce3625d263fd751474db.

Compatibility checks

`loader (:loader)`

net/neoforged/fml/loading/FMLLoader$LaunchContextAdapter
- getVersions()Lnet/neoforged/fml/loading/VersionInfo;: ❗ API method was removed
- loadServices(Ljava/lang/Class;)Ljava/util/stream/Stream;: ❗ API method was removed
net/neoforged/neoforgespi/ILaunchContext
- getMinecraftVersion()Ljava/lang/String;: ❗ Method was made abstract
- getVersions()Lnet/neoforged/fml/loading/VersionInfo;: ❗ API method was removed
- getNeoForgeVersion()Ljava/lang/String;: ❗ Method was made abstract
- loadServices(Ljava/lang/Class;)Ljava/util/stream/Stream;: ❗ API method was removed
- LOGGER:Lorg/slf4j/Logger;: ❗ API field was removed
net/neoforged/fml/loading/LibraryFinder
- ❗ API class no longer exists
net/neoforged/fml/loading/FMLLoader
- getVersionInfo()Lnet/neoforged/fml/loading/VersionInfo;: ❗ API method was removed
net/neoforged/fml/util/ServiceLoaderUtil
- loadEarlyServices(Lnet/neoforged/neoforgespi/ILaunchContext;Ljava/lang/Class;Ljava/util/Collection;)Ljava/util/List;: ⚠ API method was removed
- loadServices(Lnet/neoforged/neoforgespi/ILaunchContext;Ljava/lang/Class;Ljava/util/Collection;)Ljava/util/List;: ⚠ API method was removed
- loadServices(Lnet/neoforged/neoforgespi/ILaunchContext;Ljava/lang/Class;Ljava/util/function/Predicate;)Ljava/util/List;: ⚠ API method was removed
- loadServices(Lnet/neoforged/neoforgespi/ILaunchContext;Ljava/lang/Class;Ljava/util/Collection;Ljava/util/function/Predicate;)Ljava/util/List;: ⚠ API method was removed
- loadServices(Lnet/neoforged/neoforgespi/ILaunchContext;Ljava/lang/Class;)Ljava/util/List;: ⚠ API method was removed
net/neoforged/fml/loading/moddiscovery/locators/GameLocator
- ❗ API class no longer exists
net/neoforged/fml/loading/ImmediateWindowHandler
- load(Lnet/neoforged/neoforgespi/ILaunchContext;ZLnet/neoforged/fml/loading/ProgramArgs;)V: ⚠ API method was removed
net/neoforged/fml/loading/VersionInfo
- ❗ API class no longer exists
net/neoforged/fml/loading/VersionSupportMatrix
- <init>(Lnet/neoforged/fml/loading/VersionInfo;)V: ❗ API method was removed
net/neoforged/fml/loading/moddiscovery/ModDiscoverer
- <init>(Lnet/neoforged/neoforgespi/ILaunchContext;)V: ❗ API method was removed
- <init>(Lnet/neoforged/neoforgespi/ILaunchContext;Ljava/util/Collection;)V: ❗ API method was removed

neoforged-automation · 2025-11-07T08:25:11Z

@shartte, this pull request has conflicts, please resolve them for this PR to move forward.

…tion result. Allow the external discovery service to return null as a result, which indicates failure or disinterest with the discovery.

…eption with a cause is thrown.

…interface.

…when logged to the console or log files by logging a cause.

Technici4n

Some comments are potentially inaccurate, to be double-checked later.

loader/src/main/java/net/neoforged/fml/ModLoadingException.java

...src/main/java/net/neoforged/neoforgespi/installation/GameDiscoveryOrInstallationService.java

loader/src/main/java/net/neoforged/fml/loading/EarlyServiceDiscovery.java

loader/src/main/java/net/neoforged/fml/loading/FMLLoader.java

Technici4n · 2025-12-08T23:22:45Z

loader/src/main/java/net/neoforged/fml/loading/moddiscovery/ModDiscoverer.java

-    public ModDiscoverer(ILaunchContext launchContext) {
-        this(launchContext, List.of());
-    }
+    private final GameDiscoveryResult gameDiscoveryResult;


Technically we don't need to store it?

loader/src/main/java/net/neoforged/fml/loading/game/GameDiscovery.java

neoforged-automation · 2025-12-18T12:23:40Z

@shartte, this pull request has conflicts, please resolve them for this PR to move forward.

# Conflicts: # loader/src/main/java/net/neoforged/fml/loading/game/GameDiscovery.java

…process before discovering mods.

…e they are not absolute

shartte · 2026-01-07T18:56:41Z

loader/build.gradle

    api "net.neoforged:JarJarSelector:${jarjar_version}"
    api "net.neoforged:JarJarMetadata:${jarjar_version}"
    api("net.neoforged:bus:${eventbus_version}")
+    api("net.neoforged.installertools:binarypatch-applier:${installer_tools_version}")


implementation?

loader/src/main/java/net/neoforged/fml/loading/game/AutoInstallationService.java

…ELS Error Screen

neoforged-automation bot added the needs rebase This Pull Request needs to be rebased before being merged label Nov 7, 2025

shartte force-pushed the feature/autoinstall branch from 4af4974 to d1f0f98 Compare November 27, 2025 16:16

shartte added 4 commits November 27, 2025 18:00

Start working on auto installer.

3ceac95

Fix tests

383f458

Fix tests

881a66d

Remove unused

8de2cce

marchermans force-pushed the feature/autoinstall branch from d1f0f98 to 8de2cce Compare November 27, 2025 17:00

neoforged-automation bot removed the needs rebase This Pull Request needs to be rebased before being merged label Nov 27, 2025

marchermans added 10 commits November 28, 2025 21:06

Add dynamic game installation discovery service

1e3b62e

Add parameters for better detection of the game discovery or installa…

5d8e7e2

…tion result. Allow the external discovery service to return null as a result, which indicates failure or disinterest with the discovery.

Introduce a better design for the running of the GameDiscovery Test

279e2a2

Add exception handling to game discovery and installation process

58a2372

Properly handle the exception.

eb4f549

Fix the license

090bd38

Update the documentation.

ea95474

Fix immaculate.

693c1db

Introduce support for cause listing in the log when a mod loading exc…

34ee39e

…eption with a cause is thrown.

Remove the NeoForge version from the game discovery and installation …

2b41bfc

…interface.

marchermans mentioned this pull request Dec 1, 2025

Move installation of the client from the installer to runtime neoforged/NeoForge#2847

Open

3 tasks

Fix formatting and introduce better logging for ModLoadingExceptions …

0b73585

…when logged to the console or log files by logging a cause.

marchermans marked this pull request as ready for review December 2, 2025 17:50

Technici4n requested changes Dec 8, 2025

View reviewed changes

neoforged-automation bot added the needs rebase This Pull Request needs to be rebased before being merged label Dec 18, 2025

marchermans added 2 commits January 2, 2026 13:18

Merge branch 'main' into feature/autoinstall

16d9111

# Conflicts: # loader/src/main/java/net/neoforged/fml/loading/game/GameDiscovery.java

Address needed and requested Changes.

805b0ef

neoforged-automation bot removed the needs rebase This Pull Request needs to be rebased before being merged label Jan 2, 2026

marchermans added 8 commits January 2, 2026 19:41

Port to a direct variant

0ae4b67

Fix formatting and properly wire the neoforge version

dca2167

Fix license violations

fcc6ce8

Fix tests

d6a327a

Fix formatting

c5a21cb

Mark the neoforge and minecraft jar as located by the game discovery …

fa707a9

…process before discovering mods.

Handle the case where two different path objects are not equal becaus…

ad0a515

…e they are not absolute

Also normalize both paths

fd62efa

marchermans requested a review from Technici4n January 4, 2026 14:52

shartte commented Jan 7, 2026

View reviewed changes

marchermans and others added 4 commits January 9, 2026 17:03

Update to first review, add support for purging the cache dir to the …

5b9dc7c

…ELS Error Screen

Refactoring and cleanup

d265a00

Merge branch 'main' into feature/autoinstall

aea89d8

Fix incorrect assumption about dedicated server-jar

e792886

shartte changed the title ~~Auto Installation Support~~ Add support to create a pached Minecraft Jar on-the-fly Jan 11, 2026

shartte changed the title ~~Add support to create a pached Minecraft Jar on-the-fly~~ Add support to create a pached Minecraft Jar on startup Jan 11, 2026

shartte changed the title ~~Add support to create a pached Minecraft Jar on startup~~ Add support to create a pached Minecraft Jar on Startup Jan 11, 2026

shartte added 2 commits January 11, 2026 21:20

Fix a minor issue / use suppresesd exceptions

ef69cb6

Remove unused system property.

a69607a

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loader (:loader)

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shartte commented Oct 26, 2025 •

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`loader (:loader)`