update-fabric-mod

name	update-fabric-mod
description	Update Fabric Minecraft mod to new version

Update

Update Fabric mod to versions in reference template at /fabric-mod-template

0. Template and Target locations

• Template (source of truth): /fabric-mod-template/gradle.properties If path missing, stop and tell user template mount is not available (it mounted into dev container by run.sh)
• Target mod: mod being updated located at /workspace

1. Record starting state

1a. Before changing anything, read target mod gradle.properties, build.gradle, and src/**/fabric.mod.json. Note old Minecraft version, the before-after delta helps diagnose build failures (mappings/intermediary mismatches surface clearly when you know what moved)

1b. Backup and extract minecraft source code *sources.jar from both target and template. If you can't find the .jar file, you may need to run ./gradlew genSources --no-daemon first. Extract the jar file to /tmp/template-mc-code and /tmp/target-mc-code respectively. Note this is minecraft/mojang source code and not the mod jar file.

2. Update gradle.properties

• In target mod, set keys to the template values (preserve existing comments/formatting, only change values)
• Leave mod-specific keys untouched (e.g. mod_version, maven_group, mod id)
• Bump the mc part of mod_version. For example, if updating minecraft from 26.1 to 26.2 it should look like e.x. mod_version=XXX_mc26.1 -> mod_version=XXX_mc26.2. This is purely visual for jar file name.

3. Update build.gradle

Align target with template where versions/toolchain are involved:

• Java version: Match template options.release, sourceCompatibility, and targetCompatibility. A Minecraft version bump may raise Java version.

Never blindly overwrite whole file. Target may have mod-specific dependencies, mixins, etc.

4. Bump the fabric.mod.json depends constraints

In target src/**/fabric.mod.json, update depends block to match these:

• minecraft → *
• fabricloader → >=<template loader ver>
• java → >=<template java ver>
• fabric-api → *

5. Build to verify

Run the build from the target mod directory. I have a bash alias, so can just do "build" and it will build.

• A clean BUILD SUCCESSFUL means the update is complete and the jar in build/libs/ is valid for the new version.
• On BUILD FAILED, read the error. Common cases:
  • Toolchain / Java release errors: Java version in step 3 doesn't match new requirements. Recheck against template.
  • Loom / Gradle plugin errors: loom_version mismatch. Confirm it matches the template.
  • Compilation errors against Minecraft classes: Mod source uses APIs that changed between Minecraft versions. Find out what changed and fix until build succeeds.
    • Search through /tmp/template-mc-code and /tmp/target-mc-code that was created in step 1 to help debug.
    • Can also look at https://fabricmc.net/blog for help
    • If above suggestions dont work think of other methods and try them!

If class / method / field names were renamed, run bash command for search and replace renaming.

Re-run the build after any fix until it passes.

6. You're done

No need to summarize changes. Just say "Done" when updated and built successfully.