# Compatibility and supported runtime
## Host requirements
The current host targets Java 21, Minecraft 1.21.1, and the NeoForge version
declared by `neo_version` in its Gradle project. The SDK and macro packages
declare Rust 1.85 as their minimum toolchain; the `sjml-cli` package requires
Rust 1.88. Guest crates must use `wasm32-unknown-unknown` and the SJML ABI;
WASI modules and ambient filesystem, process, and socket APIs are not supported.
SJML compiles WebAssembly with Endive to JVM bytecode and fails module
activation if compilation fails. It does not interpret a module as a fallback.
The host caps module size at 16 MiB and defined linear memory at 256 wasm32
pages. See [Security](SECURITY.md) for table and operation limits.
## Version compatibility
The current host ABI is `1.32.0`. ABI compatibility is major-version based:
the host accepts a requested ABI with the same major version when the host's
minor/patch version is equal or newer. A host at ABI `1.32.0` therefore accepts
`1.0.x` through `1.32.0`, but rejects a later contract it does not know.
Package manifests use SemVer ranges for `abi`, `minecraft`, and `sjml`; those
ranges are checked during package validation and activation.
## Logical side and current API coverage
Server-side world, player, entity, inventory, block-entity, event, storage,
network, command, async service, and server-menu operations run against their
owning integrated or dedicated logical server and enforce the corresponding
thread and permission checks. Save, dimension, player, entity, and block-entity
storage scopes are available to logical-server modules; physical-client modules
have a separate per-mod `client_profile` scope. Opaque non-player entity bytes
use separate `entity.data.read` and `entity.data.write` grants and are stored in
the entity's persistent NBT. World reads do not load dimensions or chunks;
block-state batches are limited to 1,024 positions and 1 MiB of encoded output.
Client modules have HUD, bounded typed OpenGL, camera-relative world-render,
active-screen input, and global no-screen input APIs loaded through client-only
integration. Guest entities and block entities can render bounded colored or
package-textured cuboid models with a host-evaluated sine rotation. Package
assets beneath `assets/<package-id>/` are mounted through an always-enabled
generated resource pack, including `sounds.json`/OGG files, particle sprites,
and model textures. Unit and host tests cover the render contracts, but no
display-backed Minecraft client run has verified visual behavior. On the
logical server, pure compute work can run in an isolated worker WASM instance
when `task.compute` is granted. Chest menus reject item movement, while
declared action slots dispatch subscribed guest callbacks. A connected
multiplayer handshake and payload session has also not been verified against a
live client and server. These limits are not implied to work by successful
compilation or unit tests.
## Checking this workspace
These commands validate the CLI, SDK, macros, and example guests:
```sh
cargo fmt --all -- --check
cargo clippy --workspace --all-targets --locked -- -D warnings
cargo test --workspace --locked
cargo check -p sjml-sdk --examples --target wasm32-unknown-unknown --locked
```
These Rust checks do not build the private NeoForge host or prove live
Minecraft compatibility. Client rendering, GPU behavior, multiplayer
handshakes, and tick-rate impact require runtime tests with the matching host.