Release notesalpha

What changed in each moxzi release, and what to do when upgrading.

The CHANGELOG.md file in each release has the complete list of changes.

Versions#

The compiler, moxzid, moxzi-web and the on-chain builder share one version number. During the alpha, any release can change behaviour; changes that need action are listed under "Upgrading". Each release's SHA256SUMS lists the hashes of compiler.wasm and linker.wasm, which are the same on every platform.

moxzi.game has its own version numbers.

0.1.0-alpha.10 (2026-10-25)#

Native kernels: fast code from existing Rust crates, linked only into the canisters that call it. Candid encoding is several times faster with the same bytes, and on-chain builds are byte-identical to local builds again.

New

• Native kernels. A package can back a Motoko function with a kernel built from a Rust crate. Opt in from your application with moxzi kernel add <package>, which pins the kernel's exact bytes under [kernels] in your mops.toml. Without the opt-in, or under moc, the Motoko body runs. A dependency can never add a kernel for you, and a pin that does not match stops the build. See Native kernels.
• Ten kernel packages: moxzi-hash (SHA-256/512, HMAC, RIPEMD-160, BLAKE3), moxzi-secp256k1, moxzi-p256, moxzi-ed25519, moxzi-bls12-381, moxzi-ml-dsa, moxzi-rsa, moxzi-base58, moxzi-bech32 and moxzi-bitcoin. Their source is at icdevsorg/moxzi-kernels and rebuilds to the pinned bytes. They have not had an independent security audit yet.
• mo:ic-agent 0.3.0 verifies a mainnet certificate in about 0.37 billion instructions with its kernel, against about 2 billion with its Motoko code.
• moxzi kernel build, kernel verify, kernel add and kernel sdk: build a kernel from your own Rust crate, and rebuild any kernel to check it against its pin.
• A kernel moxzi does not publish asks before its first build (--accept-kernel in scripts), and every built module lists its kernels with their source and commit in public metadata; moxzi verify shows them for an on-chain build.
• to_candid, and the encoding of every message argument and reply, run several times faster (about 5 times for records, up to 20 times for large variants) and produce the same bytes as moc. --candid-fast-path also decodes directly when the incoming types match yours.

Changed

• A kernel declaration that names a function the package does not define stops the build (M0291), and a kernel that returns a Bool other than 0 or 1 traps.
• moxzi-rsa signs only with standard 3072-bit keys (two 1,536-bit primes, reduced CRT values) and refuses other key shapes with a clear error.
• The compiler canister finishes a paid build's settlement even with no donation sinks configured, and removes earlier files in one call before a new upload.

Fixed

• An on-chain build is byte-identical to a local one however the work is split into messages.
• A stable signature never gives two different types the same name. One program's signature described a Text field as Bool.
• A project that imports from several folders beside it (../lib-a/src, ../lib-b/src) builds, locally and on chain.
• On the shared on-chain compiler, one caller's build could compile another caller's library file.
• moxzi build --remote keeps the compiler canister's link attestation, and no longer calls a delivered refund "pending".
• Wrong values: a negative literal at a numeric type declared through an alias, let … else on a nested option, and a negative Float32 literal passed as an argument.
• A label with the same name as a variable no longer traps, to_candid writes its type table in moc's order, and three kinds of program moc accepts no longer fail.

Upgrading

• A package that declares kernels must name functions that exist; a typo now fails with M0291 instead of silently running the Motoko body.
• moxzi-rsa users with non-standard keys (for example 1,535/1,537-bit primes) need standard 3072-bit keys.

0.1.0-alpha.9 (2026-10-17)#

moxzi now compiles Motoko 2.0.0: the same programs moc 2.0.0 accepts, with the same behaviour and error codes, plus moxzi's own additions.

New

• Motoko 2.0 syntax: if a and not b { … }, while i < n { … }, switch x.kind { … } and case #ok(v) v need no parentheses, and the ; between cases is optional. Outside a body, braces are a record literal; write a block as do { … }.
• A function returning async has an async body without saying so: func f() : async Nat = 1. A function passed where an async function is expected takes its parameter types from that type.
• Contextual dot (x.f()) and implicit arguments find functions in nested modules, such as a package's lib.mo that re-exports others.
• { r with … } copies var fields into the new record.
• a == b on a type parameter compares at its bound.
• moxzi build accepts moc's single-dash spelling of long flags (-measure-rts-stack).
• An actor* class can be named explicitly with (with id = "…"), and a persistent one is found again by its name, so moving or renaming its file keeps its instances.
• The hosts bundle includes moxzi-actor-host with the tensor device.

Changed

• Actors are persistent by default: a plain actor keeps its fields across upgrades. Mark a field transient to reset it. persistent and stable are now redundant (M0217, M0218), and flexible is an ordinary identifier.
• actor* follows actor: instances are persistent by default, and transient actor* opts out. --experimental-local-actor-persistence is no longer needed and is ignored.
• Some warnings are now errors, as in moc 2.0.0: a pattern that does not cover every case (M0145), a dropped record field (M0215), a comparison at a type with one value (M0276), an ignored async* (M0222) and others. -W=M0145 keeps one as a warning.
• More programs moc rejects are rejected, with its codes: migrations that produce a field of the wrong type or one the actor does not declare, a system func the runtime never calls, a misspelled variant tag in a pattern, and more.
• The runtime is moc 2.0.0's. An upgrade that drops a stable variable while adding another is refused unless a migration function accounts for it.
• Compiled canisters report 2.0.0 as their compiler version.

Fixed

• A canister whose history includes classical persistence upgrades again.
• A saved game world restores again (broken in alpha.8; alpha.8 saves cannot be restored).
• A two-case switch over a variant that repeats a label checks the tag, so a value of the other case traps instead of being read as the wrong type.
• None in an actor's interface is Candid empty, not reserved.
• Two imported actor-class libraries in one program no longer swap their code on upgrade.
• A classical-persistence canister with a stable Region upgrades to enhanced persistence.
• A generated Candid type name no longer collides with one you wrote, and hex field ids in an imported .did are read correctly.
• A class field that shadows a module-level name no longer fails with M0055, and an async type over a type declared further down no longer fails with M0033.
• moxzi host new projects stop with a clear message when their port is taken by another program, or when a Restate container of the same name belongs to another project.
• moxzid -s: upgrading an actor from the manifest works, and a restart after a crash re-runs about 30 seconds of device work instead of minutes.

Upgrading

• Programs written for the 1.x grammar may not parse. The error names the fix; most cases are a missing space (if c [i] versus if c[i]) or a block that needs do { … }.
• = async { … } as a function body is now error M0277. Remove the async.
• Code that relied on the new errors being warnings needs a fix, or -W=<code> while you migrate.
• An actor field that cannot persist (a function in a var, say) must be marked transient.
• --default-persistent-actors is ignored with a warning; --trap-on-call-error is removed.
• The 22 Prim.stableMemory* functions and createActor are gone; use regions and actor classes. __motoko_stable_var_info is no longer exported.
• Upgrading a canister that still uses classical persistence needs --enhanced-orthogonal-persistence on the build.

0.1.0-alpha.8 (2026-10-08)#

New

• GPU math for actors. moxzid --device burn:metal (or burn:cuda, burn:vulkan, burn:cpu) gives every hosted actor a private tensor device: parameters, optimizers (AdamW, Muon, SGD) and stored values live on the GPU under names, one message carries a whole training step, actors share weights by name with explicit readers, devices on different machines move tensors directly, device time is charged to the caller, and the device survives a crash with the actors. moxzi-actor-host --device does the same on actor platforms. See GPU math for actors.
• The tensor device decodes with a key/value cache and can distill one model into another.

Changed

• Outcalls from moxzid are refused until you grant them: --grant-http-public for any public HTTPS host, or --outcall-public-host HOST for one. Private and loopback addresses need an explicit development grant. A package can't grant itself access.
• Actor platform hosts check requests before they reach an actor: a body must be valid JSON of the right shape (an array for an actor call), public calls are limited to 8 MiB, and control and image traffic to 192 MiB. Oversized and malformed requests get 413 or 400.
• Restate projects sign every request from the Restate server, and the host verifies it; moxzi host new restate sets this up. wasmCloud control routes always need the operator token. Dapr calls between actors are signed per call.
• Browser games and actors run under host-owned limits: instructions per message, memory per actor and in total, and saved-image size. A package can ask for less, not more.

Fixed

• In moxzid -s, what one actor's message did to another actor survives a crash exactly once. Before, a large callee could lose it, or a large caller could replay it. Timers fired between messages are recorded too.
• A timer that came due while a query was running no longer runs as a query.
• Reading stable memory no longer copies all of it on every call.
• Failed installs and image activations leave the host usable. Durable upgrades publish code, state and deployment together, so a crash mid-upgrade recovers to one or the other.
• Actor keys with /, ~, +, spaces or Unicode stay distinct on every platform.

Upgrading

• If your actors make HTTP outcalls under moxzid, add --grant-http-public or --outcall-public-host HOST to its command line. Without a grant, outcalls fail with this host cannot make HTTP requests.
• Regenerate Restate projects with moxzi host new restate, or add a request-identity key, so the Restate server signs its requests.
• Clients that sent actor calls with malformed or non-array JSON bodies now get 400 instead of a call with no arguments. An empty body still means [].

0.1.0-alpha.7 (2026-09-29)#

New

• Actor platforms: run Motoko actors inside Dapr, Restate, Orleans, Akka (Pekko), Proto.Actor, Temporal, Ray, wasmCloud and Cloudflare Durable Objects, with state stored by the platform. moxzi host new creates a working project. See Actor platforms.
• libmoxzi_rts, the runtime as a C library, in the SDK bundle.
• ic-agent: call canisters on the Internet Computer from Motoko running outside it, with certificate and signature verification. moxzi agent-bindings generates typed clients. See Calling the Internet Computer.
• moxzid JSON endpoints (/call-json, /query-json) and OpenAPI descriptions (/openapi/ACTOR).
• moxzi candid-compatible checks that a new Candid interface works for existing callers.
• Libraries can declare that they need moxzi, and which features, in mops.toml.
• Games can request network access with capabilities: [http].

Changed

• An active actor on a platform uses about 110 KiB of memory, down from about 10 MiB.
• The compiler is 347 KB smaller.

Fixed

• i<22 is now a syntax error, as in moc. Write i < 22.
• Forward references moc rejects are now rejected (M0055).
• M0157 is reported inside actor, object and module bodies.
• M0131 names the flag needed to store actor* instances in stable variables.
• No false M0194 for an import used only in types.
• Generic self tail calls run as loops instead of using stack.
• A library file with several declarations can be imported as a module, as in moc.

Upgrading

• Code that compared with < or > without spaces (a<b) no longer compiles. Add spaces.

0.1.0-alpha.6 (2026-09-22)#

New

• actor* (experimental): many actors inside one canister, each with its own id, methods and state, enabled with --experimental-local-actors N. Add --experimental-local-actor-persistence to keep them across upgrades.
• The compiler tracks moc 1.16.1.
• --wasm-tail-call and --candid-fast-path (opt-in).

Changed

• The checked array-index optimisation is on by default. --no-index-fast-path turns it off.

Fixed

• type T = A and { s : S } with S declared later is accepted; type A = B or C with B or C declared later is now checked.
• Self tail calls inside named nested functions run as loops, instead of overflowing the stack after about 24,000 iterations.
• The garbage collector handles static roots that grew during an upgrade.
• --compiler PATH with a missing file is an error.
• Upgrading a suspended actor container is refused.

0.1.0-alpha.5 (2026-09-09)#

New

• Nat256 and Nat128: fixed-width 256- and 128-bit integers, with the full set of operators, Candid nat on the wire, and stable storage.
• --compact-rts, for smaller heaps in moxzid and moxzi-web.
• moxzid --live-cap: unload idle actors to host many more.
• moxzi publish and moxzi deprecate: publish to ICRC-118 registries with build records. The compiler canister links its own output and answers attestLinked.
• --gzip.

Fixed

• A canister that moved from classical persistence to enhanced orthogonal persistence can be upgraded again.
• Several programs that compiled incorrectly, or were accepted but shouldn't have been.
• --package pointing at a missing directory is error M0012.

0.1.0-alpha.4 (2026-09-04)#

New

• blob:file: imports.
• Annotated imports.

Fixed

• .size on arrays as a first-class function, ±0.0 literals, Float32 comparisons, and integer literals declared as Float.
• shared in generic function types was being dropped.
• Ill-typed programs that crashed the compiler now get error messages.

0.1.0-alpha.3#

The first public alpha: the moxzi CLI, the on-chain builder, moxzid and moxzi-web.

Also in later alpha.3 builds:

• Pattern-coverage warnings (M0145, M0146) and unused-identifier warnings (M0194, M0198).
• Error positions use moc's format.
• x-caller for moxzid calls.