Switchcraft — 26.4-snapshot-6 / Vulkan

main targets Minecraft 26.4-snapshot-6, Java 25 and Vulkan. The previous OpenGL/Java-8 research baseline is preserved on branch legacy/1.12.2. Java runtime work now lives in java-switch, consumed at an immutable commit from dependencies.lock.json.

GitHub's default branch is main. Use legacy/1.12.2 for the preserved older implementation.

The snapshot reaches its title screen in the Linux Java-25/Vulkan reference. A genuine Horizon Java 25 VM is cross-linked in diagnostic NROs; its startup, Java execution and the Minecraft title on Switch remain NOT TESTED.

The reference uses the official Demo mode, no account credentials, and Mesa llvmpipe Vulkan. The image below is HOST ONLY, not a Switch screenshot:

Implemented and built

The launcher provides a controller/touch UI and a portable Prism instance/component backend. It supports creation/editing, settings-only duplication, online version catalogs, verified installation/repair, integrity checks, folder import and archive/restore. Download the launcher-manager overlay and follow the launcher tests. Account flows, mod management and the full Qt framework are not ported. The UI is cross-built and host-tested; Horizon UI/network execution remains NOT TESTED.

Artifact	Actual behavior
switch-diagnostics.nro	Input, SD roundtrip, process/malloc memory, native threads and next-load navigation
vulkan-test.nro	NVK enumeration, transfer/readback, offscreen triangle
vulkan-present.nro	Exact snapshot-6 base-feature capture; SDL3 window/gamepad, VI surface, swapchain and presentation loop
minecraft-launcher.nro	Prism instances, controller/touch UI, verified online installation/repair, import/archive and honest Java-25 launch status
java-test.nro	Independent java-switch Java-8 interpreter diagnostic; this is not a Java-25 VM
ffi-test.nro	AAPCS64 downcalls, libnx RW/RX upcall closures and whole-region virtual-memory probe
zero-services-test.nro	Independent native VM service probes; no VM
java25-test.nro	Genuine Zero VM with Hello, JNI/FFM and startup-agent actions; hardware untested
switchcraft-java25.nro	Genuine VM and composed JDK/SDL/Vulkan resolver; Hello and Java JNI/FFM SDL version attempts; hardware untested
switchcraft-lwjgl-horizon.jar	Horizon platform identity and JNI load dispatch; native FFM SharedLibrary remains unavailable
switchcraft-launcher-bridge.jar	Hash-pinned renderer-method transformation; one Vulkan backend, no OpenGL fallback; host tested

SDL3 is built without EGL, OpenGL or OpenGL ES. Its Switch port's unconditional EGL dependency was fixed in patches/sdl3-vulkan-only.patch. The original client still contains an OpenGL fallback; the bundled Java transformation restricts that single renderer-selection method without modifying authentication code. No Minecraft class bytes, assets, native desktop libraries or account data are redistributed. The bridge requires Java 25 and java.instrument, cross-built in the pinned runtime image; Horizon startup/instrumentation are NOT TESTED.

Build and install

bash scripts/build-all.sh

Linux x86_64, Python 3.12+, GCC/G++, Make, patch, Git and HTTPS access are required. The toolchain image, NVK archive, SDL3 source, host CMake wheel and Java repository revision are pinned. Access to the private java-switch repository is required. The toolchain and hash-verified caches can be reused; no root installation is needed. See BUILD.md.

The pipeline builds nine real NROs, tests the native/Java boundaries on the host, verifies AArch64/NRO/ASET/NACP/build IDs and creates:

• dist/switch-minecraft-test-package.zip and dist/COPY_TO_SD/
• dist/switchcraft-corresponding-source.tar.gz
• dist/manifest.json, dist/SHA256SUMS and dist/DELIVERY_REPORT.md
• dist/switchcraft-debug-symbols.zip and dist/switchcraft-native-sdk.tar.gz

Merge the package onto the SD root and preserve existing saves/configuration. Use application-mode hbmenu under Atmosphère on Switch 1. Start native memory/SD/thread tests, then vulkan-present A for feature capture and X for SDL3/VI presentation; then NVK offscreen and FFI tests. The detailed TEST_PLAN.md defines independent cases and recovery steps. For the first physical session, use the shorter device checklist for controls, pass markers and per-attempt log collection. No kernel patches, overclocking, Linux/Android installation or remote game execution are required by the NROs.

Use the launcher's Versions > Install / repair action, or copy a legitimately obtained installation's versions/, libraries/ and assets/ to sdmc:/minecraft/.minecraft. Settings selects the shared installation root. Runtime settings/logs remain under sdmc:/switch/mc-runtime. Integrity checks and plan generation are read-only; explicit install/repair manages downloaded cache resources. Existing configuration is preserved until Save preferences. The base-package console inspector uses its original controls documented in the device checklist.

Validation and remaining work

The main host suite tests metadata, artifact rejection, strict renderer behavior and profile gates. The independent runtime suite tests Java 8 and actual host Java 25 JNI creation/native registration/FFM downcalls/upcalls/teardown. The baseline SDK and minecraft-launcher remain VM-free and report runtime-not-linked. Separate experimental NROs link the genuine VM; their availability query proves symbol presence, not startup. The game launch remains blocked on tested VM execution and LWJGL/FFM/native bindings. All Switch Vulkan/SDL/FFI/runtime execution awaits physical testing.

To reproduce the host reference, prepare a Linux X11/Vulkan environment and run:

python3 tools/snapshot6-reference.py --download-assets
python3 tools/snapshot6-reference.py --run-demo

This downloads official game files into ignored .cache/, validates hashes, uses the built-in Demo mode and logs the actual renderer. It is a host reference, not a proposed way to execute the Switch game on another computer. See HOST_REFERENCE.md for exact evidence and limitations.

• Architecture and diagram
• Upstream research
• Status and evidence
• Compatibility
• Known issues
• Decisions and next steps
• Java SDK handoff and native bindings

Original source is MIT. The combined launcher now incorporates GPL-covered Prism code and is distributed under GPL-3.0-only with the applicable Apache-2.0 notices; see the port/source notes. Third-party notices and the full miniJVM Java/C and libffi source accompany distributions. The Java class library retains GPL terms; binary-only redistribution does not remove source obligations.