Sparkle Morpher 1.2.1

Sparkle Morpher 1.2.1 fixes a singleplayer crash on the Fabric 26.x line, aligns the 26.2 branch with the real 26.2 APIs, and brings the rendering/network/Maid refactor series R0–R11 (recorded between 2026-08-10 and 2026-08-13, including everything from the 08-12 prerelease 1.2.0-beta-R11MAID) into a formal release across Fabric and NeoForge × 1.21.1 / 26.1.2 / 26.2.

Highlights

Crash fixes (focus of this release)

• Fixed IncompatibleClassChangeError on joining singleplayer (Fabric 26.1.2 / 26.2): removed the compile-time shadow stubs where Minecraft.execute/submit/isLocalServer were wrongly declared static, which made Minecraft.getInstance().execute(...) compile to invokestatic and crash at runtime against the real instance methods. Everything is now compiled back to invokevirtual (verified by a full ASM scan: 0 remaining).
• Fa26.2 stub cleanup & alignment with real 26.2 APIs: removed 24 vestigial/shadowing stubs, keeping only 4 runtime compat layers (MultiBufferSource / IrisApi / ModConfig / IForgeGuiGraphicsExtractor); 6 call sites (getScoreboard / renderNames / renderBuffers / getMainRenderTarget / screen etc.) moved to the real 26.2 APIs.
• Sync packet queue overflow → bounded backpressure: bursts no longer abort the whole sync when the queue briefly fills; the enqueue side now waits with a bounded budget (server bandwidth limiting + outbound drain form a backpressure loop).

Rendering & performance

• Classic HUD deep performance rewrite: FBO partial physical-pixel offscreen cache (was ~35 ms full CPU render per frame → ~0.17 ms); GPU path with a 60 Hz independent refresh budget, SIMD/compat path at 10 Hz throttle; 8-slot bone SSBO ring + GL_STREAM_DRAW streaming uploads, eliminating shared-buffer sync stalls; explicit alpha compositing and batching isolation.
• First-person hand rendering fix (26.x): the hand always uses the entityTranslucent pass.
• Preview rotation pollution fix (1.21.1): entity yaw and preview mode are reset even on exception paths (try/finally).
• Hand rendering NPE guard: getAnimationBundle()==null mid-state protection (12 sites across 6 branches).
• R10-series internal refactors: RenderBackend interface isolation (Blaze3D / OpenGL / SIMD / Java implementations), GpuMeshRegistry leases + orphan sweeps, unified resource ownership for model assemblies (deterministic release), weighted-LRU audio cache.

Networking & model sync

• Fixed crash when clients without SPM join: per-player channel pre-checks before sending (NeoForge/Fabric) + batch send fallback.
• Systemic fix for sync timeouts / stuck "receiving model data": LegacySyncFlowControl 64 KiB burst backpressure + 512 MiB in-flight budget; a dedicated single-threaded sync executor with a bounded ordered packet queue (decrypt/verify/disk-write no longer blocks network/main threads); termination frame sent when the server cache is unavailable so the client never hangs forever; the watchdog no longer reports false success.
• neo1.21.1 stuck-at-LOADING fix: toClientboundPacket null packet → wrapped in ClientboundCustomPayloadPacket.
• R9 networking modularization (internal): send-entry pre-checks, connection-state split, upload-transport interfaces.

Maid (TLM) compatibility (R11)

• MaidModelSync divergence converged across branches (byte-identical in all six).
• C2SSetMaidModelPacket (id 24) ported to all branches: maid model switching now uses SPM's own chain (auth pipeline); the official TLM protocol remains as fallback.
• TLM-environment startup crash fixed (@Mixin(targets=...) to avoid MixinTargetAlreadyLoaded).
• 26.x GUI maid preview not replacing YSM models — fixed.
• R11 compat.api service layer (internal, no startup-order dependencies).

GUI / HUD

• Classic / Modern HUD dual toggles: independent switches in settings; the legacy keybinding and old screen were removed.
• ClassicHudLayoutScreen layout editor: drag, unbounded scaling, scroll zoom, yaw rotation, one-click reset.
• ModernHudRenderer independent entry contract (off by default, internal).

Other fixes

• Abnormal head rotation while riding (RiderRotationMath pure-angle helper, verified on 6 branches).
• 1.21.1 default model rotation not following the camera (cross-frame cache registry retained).
• Server model pack name JSON-quote display fix.

Internal refactors (R0–R9, core of 1.2.1)

• S0 security hotfixes: YSM folder path-escape sandbox, atomic audio-cache dedup.
• R2 unified thread pools (SmExecutors bounded queues + CallerRuns backpressure + TaskScope).
• R3 ModelStoragePaths centralization + PersistentStore atomic writes.
• R4 unified resource container (folder / zip GBK / limits) + zip-bomb protection.
• R5 Model Domain / R6 EntityModelResolver (priority + revision race protection).
• R7 ClientModelManager split (3024 lines → 5 focused classes).
• R8 ServerModelManager split (1899 lines → 8 focused classes, atomic file moves + upload policy).
• Tests grown from 45 → 201 per branch (YsmCrypt golden vectors, model corpus, race acceptance).