Install the toolchain¶

This page walks you through everything you need to build the Myelin workspace and run the CLI. The smoke test (live CKB devnet submission) needs extra pieces — those are documented at the bottom.

1. Rust¶

Myelin tracks stable Rust. The workspace is built against the same rust-version as the parent CellScript project.

# Install rustup if you don't already have it
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# Add the RISC-V target that CKB scripts use
rustup target add riscv64imac-unknown-none-elf

# Verify
cargo --version
rustc --version

[!TIP] If you're on macOS and cargo build panics about rlimit, see the project-level notes in AGENTS.md — ulimit -n 16384 before invoking cargo fixes it.

2. Clone and build Myelin¶

git clone https://github.com/Myelin-Labs/Myelin.git
cd Myelin

# Sanity check: formatting, clippy, tests
cargo fmt --all --check
cargo check --locked --workspace --all-targets
cargo clippy --locked --workspace --all-targets -- -D warnings
cargo test --locked --workspace

If all four pass, you have a working Myelin workspace.

3. Build the CLI¶

cargo build -p myelin-cli --release

The binary lands at target/release/myelin-cli. From here on, the docs will just say cargo run -p myelin-cli -- … for brevity, but you can swap that for the release binary whenever you want a faster shell.

4. (Optional) Local CKB devnet for live smoke tests¶

The scripts/myelin_ckb_devnet_smoke.sh script submits carrier transactions to a real CKB devnet. To run it locally:

# Either use OffCKB (the recommended path)
# see https://docs.nervos.org/docs/node/install-ckb for current install
offckb init --ckb-version latest
offckb start

# ... or use a parent ckb checkout, if you maintain one
cd ../ckb
cargo build --release
target/release/ckb init --testnet
target/release/ckb run --testnet --tmp --listen 127.0.0.1:8114

You should see CKB's RPC listener on 127.0.0.1:8114. The smoke script will talk to it over JSON-RPC.

5. Verify¶

A one-liner to confirm everything is plumbed correctly:

cargo run -p myelin-cli -- celltx simple-report

This writes a MyelinExecutionReport and a CkbProjectionReport for a trivial CellTx. If you see semantic_profile = "ckb-compatible" and ckb_projection_possible = true, the toolchain is good. Head to First run for the longer end-to-end path.