[TimStewartJ]

Summary

• Pin Minecraft 26.3 to stable NeoForge 26.3.0.76, replacing 26.3.0.6-beta.
• Update ModDevGradle 2.0.143 -> 2.0.148: this brings NeoForm Runtime 2.0.31 and JavaSourceTransformer 2.0.11, the upstream fix actually needed to remove the workaround.
• Remove the neoforge_disable_recompilation property and its entire buildscript opt-out.
• Add a 26.3-only CI check of the real local-development source path: CI=false, fresh NeoForm intermediates, Minecraft source recompilation, and compilation of the mod and both test companions. The check explicitly rejects disabled recompilation.
• Keep the ordinary full-matrix binary-patched build, dedicated-server checks, and both dev and packaged-jar client lanes.
• Fix cached HeadlessMc selection to require the exact loader-version name and Minecraft parent, with seven regression cases in CI. A cached older NeoForge is no longer accepted just because its name contains neoforge.

Investigation

NeoForge's authoritative Maven metadata lists 26.3.0.76 as the release, and its Gradle module metadata identifies the artifact as release. The universal jar's SHA-256 matches the published metadata:
02620022710df8f62038839b1743ef32033579762831b8b0bb84caee5b3b99de.

The reference scanner checked the published 2.1.0 NeoForge 26.3 jar against both the old and new loader: 26/26 loader references resolve on both, with no broken references. The actual ModDevGradle 2.0.143 bytecode confirms that CI=true disables source recompilation by default, so an ordinary green build alone would not justify removing the local workaround.

The claim needed a correction: a non-beta loader does not fix source recompilation by itself. Fresh CI reproduces HolderSet$1.contents() attempting to override the now-public HolderSet.Named.contents() with weaker access on both 26.3.0.6-beta and 26.3.0.76 with ModDevGradle 2.0.143. The loader's relevant access transformers are identical. The root cause is JavaSourceTransformer failing to apply access transformers to anonymous class members, fixed in neoforged/JavaSourceTransformer#67. ModDevGradle 2.0.148 supplies that fix through NeoForm Runtime 2.0.31.

Checking the actual runtime caught a second trap: the first green matrix with the updated toolchain recompiled Minecraft successfully and ran the dev client/server on 26.3.0.76, but its packaged client silently reused cached 26.3.0.6-beta. The HeadlessMc initializer previously checked only Minecraft parent plus a loader substring, ignoring the requested loader version when a cache existed. This PR fixes that selection rather than invalidating the cache to hide the bug. The seven regression cases cover stale loaders, exact pins, old/new co-existence, wrong Minecraft parent, Forge versus NeoForge, and an installer that fails to provide the requested version.

Sources:

• https://maven.neoforged.net/releases/net/neoforged/neoforge/maven-metadata.xml
• https://maven.neoforged.net/releases/net/neoforged/neoforge/26.3.0.76/neoforge-26.3.0.76.module
• Fix application of ATs to anonymous class members neoforged/JavaSourceTransformer#67
• Update dependency net.neoforged.jst:jst-cli-bundle to v2.0.11 neoforged/NeoFormRuntime#134
• Update dependency net.neoforged:neoform-runtime to v2.0.31 (main) neoforged/ModDevGradle#355

Validation

All positive results below are on 02f900a:

Check	Result	Evidence
Full matrix, all 14 Minecraft versions / 27 targets	Green, including JUnit, metadata, dedicated servers, dev clients and packaged clients	Build 38213547559
Fresh NeoForge 26.3 source recompilation	Green, JST 2.0.11; actual recompile completed in 32.77 s, then the mod and both test companions compiled	Same build, Verify NeoForge source recompilation
Actual stable NeoForge runtime	Dedicated server 17 checks, dev client 55 checks, packaged client 55 checks	Downloadable mightyarchitect-runtime-tests-26.3 artifact; both server and packaged client log NeoForge mod loading, version 26.3.0.76, for MC 26.3
Cached loader selection	7 regression cases green, locally and in the required source-check job	Same build, Cached production loader matches the pin
Publication dry run	27 publications, 20 release / 7 beta, all live=false	Release 38213553526
Recorded real-input journeys, Fabric 1.20.2 and 26.3	Both green	Journey 38213553014

Negative controls:

• Old-beta source baseline 38211778241: red at HolderSet$1.contents() with ModDevGradle 2.0.143.
• The stable loader alone also reproduced that same source failure with ModDevGradle 2.0.143 (38211762711, completed 26.3 job). That superseded overall run was cancelled; the source failure is preserved in the job log.
• Disabled source-recompilation mutation 38212204960: red with NeoForge 26.3 source recompilation must be enabled on the updated toolchain.
• Cached old-loader mutation 38213582602: red at cached different loader must install the pinned version: selected 'neoforge-26.3.0.6-beta', and the required aggregate failed too.
• All throwaway mutation branches and worktrees have been removed.

Try it

Branch: maintenance/neoforge-26.3-stable
Local worktree: E:\TMA-neoforge-26.3-stable

Download the mightyarchitect-26.3 artifact from the final build above. Use the NeoForge jar on Minecraft 26.3 / NeoForge 26.3.0.76 / Java 25, replacing the existing Mighty Architectury jar rather than installing both. This is a trial build, not a new published release; its embedded mod version remains 2.1.0.

Trial NeoForge jar SHA-256:
d1a3f4ea1d330f633f46dd25adba796d150499df7c4dfb6acfdef30109a6dc2f.

Scope

This removes all of the beta-loader source-recompilation workaround, not Minecraft 26.3 compatibility code. SDL text input, shader variants, StackShadowPages, and Xvfb/EGL support still address the game's own changes and must remain. Other Minecraft/loader pins, metadata minimums, and release channels are unchanged.

ModDevGradle is shared by NeoForge and legacy Forge, so the full matrix verifies all of those targets too. No merge, mod version bump, tag, upload, or modification of the already-published 2.1.0 jars is part of this PR.