Sophisticated Building Update – 4.1.1 (hotfix)

What this fixes

NeoForge crash on login with Sophisticated Backpacks 3.26.0 or newer. If you ran sophisticatedbuilding-neoforge 4.1.0 together with sophisticatedbackpacks-1.21.1 3.26.0, 3.26.1, 3.26.2 or 3.26.3, the server crashed shortly after a player logged in with:

NoSuchMethodError: PlayerInventoryProvider.runOnBackpacks(Player, BackpackInventorySlotConsumer)

Root cause: Sophisticated Backpacks 3.26.0 changed runOnBackpacks to return boolean instead of void. That is a source-compatible but binary-incompatible change — our 4.1.0 jar was compiled against the old void signature, so it could no longer link against the new one and the whole server tick loop died instead of just disabling the Building Upgrade feature.

The fix

• The mod now calls runOnBackpacks through a small reflection/MethodHandle shim (BackpackScanCompat) that ignores the declared return type. Both older Backpacks builds (<= 3.25.x, including every Fabric port) and newer ones (>= 3.26.0) now work with the same jar — no more recompiling every time this one method's return type changes upstream.
• Every place that touches Sophisticated Backpacks/Core code now catches LinkageError in addition to Exception/NoClassDefFoundError. NoSuchMethodError and friends are LinkageErrors, not plain exceptions, so the old guards let this kind of upstream break straight through to the server tick loop. If the next upstream release breaks something else we call, the mod now degrades to "no Building Upgrade found" instead of crashing the server.
• One-time warning instead of silence. The first time the Backpacks scan can't be linked at all, you get a single WARN line in the log naming the installed Backpacks version and saying the Building Upgrade / Tool Swapper backpack scan is disabled until the mod is rebuilt against it. Later occurrences in the same session are logged quietly at DEBUG instead of repeating the WARN.
• NeoForge now compiles against the current upstream (Sophisticated Core 1.5.1.2341, Sophisticated Backpacks 3.26.3.2158) so a future binary break in this API would show up as a compile error during development, not a runtime crash for players. The mod's own compatibility declarations (neoforge.mods.toml version ranges) are unchanged, so both older and newer Backpacks/Core installs are still accepted at runtime.
• Removed a harmless but noisy startup WARN on NeoForge: Reference map 'sophisticatedbuilding.refmap.json' for sophisticatedbuilding.mixins.json could not be read. Our NeoForge mixin config never generates a refmap (NeoForge 1.21 runs on Mojang names and doesn't need one), so the stale reference is simply removed. Fabric is unaffected — Loom still generates its own refmap there.
• Removed stale loot-modifier data for items that no longer exist in this fork (muscles, elastic_hand, building_techniques_book, building_techniques_book_library — leftovers from the original Effortless Building mod). These produced four "Could not decode GlobalLootModifier" warnings on every world load on NeoForge.

Who is affected

• NeoForge users running sophisticatedbuilding 4.1.0 together with Sophisticated Backpacks 3.26.0 or later. If that was you, this is the crash-fix you need.
• Fabric was not affected (the unofficial Fabric port is frozen at an older, void-returning build), but gets the same shim for parity and to protect against a future port update.

Update recommendation

Update to 4.1.1 on NeoForge if you use Sophisticated Backpacks 3.26.0+. Fabric users can update at their convenience; there is no behavior change for the currently supported Fabric port.