Myelin

A CKB-aligned off-chain session runtime for finite Cell execution.

Run high-throughput Cell transitions off-chain, keep them finite and typed, and emit evidence that can be inspected and projected toward CKB-style transaction contexts.

not a CKB full node · not a new L1 · not a finished permissionless L2

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What problem does Myelin solve?

CKB-VM is now powerful enough to run complex, real-time logic — xxuejie's Teeworlds on CKB experiment proved a full multiplayer game can execute inside the VM as a single chunk. But proving one chunk executes is not the same as running a session: you still need to schedule many chunks, finalise them into a block, dispute a bad chunk, and project the result back to L1. That session-and-evidence layer is what xuejie explicitly deferred, and it is what Myelin builds.

Myelin is the off-chain runtime that sits above a single verified chunk:

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    "fontFamily": "Inter, system-ui, sans-serif",
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  },
  "flowchart": { "curve": "basis", "padding": 12 }
}}%%
flowchart LR
    A["CellScript source"]:::source
    B["typed-cell metadata<br/>+ VM artefact"]:::artefact
    C["CellTx<br/>(Myelin)"]:::tx
    D["CellDAG<br/>scheduler"]:::sched
    E["Deterministic<br/>VM verification"]:::vm
    F["Session Cell<br/>state root"]:::state
    G["Evidence bundle<br/>(projection · DA ·<br/>court · settle)"]:::evidence

    A --> B --> C --> D --> E --> F --> G
    F --> C

    classDef source   fill:#A5B4FC,stroke:#4F46E5,color:#1E293B;
    classDef artefact fill:#C7D2FE,stroke:#6366F1,color:#1E293B;
    classDef tx       fill:#C7D2FE,stroke:#4F46E5,color:#1E293B;
    classDef sched    fill:#C7D2FE,stroke:#6366F1,color:#1E293B;
    classDef vm       fill:#A5B4FC,stroke:#4F46E5,color:#1E293B;
    classDef state    fill:#C7D2FE,stroke:#6366F1,color:#1E293B;
    classDef evidence fill:#C7D2FE,stroke:#7C3AED,color:#1E293B;

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Every box on that spine is a real crate in this workspace.

How it stays close to CKB

CKB uses the Cell Model, not an account model: a transaction consumes live Cells and creates new Cells; state changes happen through Cell replacement. Cells carry data, a lock script, and an optional type script, and scripts run in CKB-VM. Myelin follows that mental model — it does not hide session state inside an account-style contract. Instead it treats off-chain execution as a finite Cell session that can always report:

• what Cells were consumed or created,
• which lock/type-script-like rules were checked,
• which VM/profile assumptions were used,
• whether the transition can be projected into a CKB-style context,
• and which evidence would be relevant during a dispute.

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flowchart TB
    subgraph off["Off-chain session (Myelin)"]
        direction LR
        S1["CellTx batch"] --> S2["CellDAG<br/>parallel scheduling"] --> S3["CKB-VM<br/>verification"] --> S4["session block<br/>+ state root"]
    end
    subgraph l1["L1 (CKB)"]
        direction LR
        L1A["court script<br/>(future)"] -.-> L1B["disputed-chunk<br/>adjudication"]
    end
    S4 -->|"projection<br/>+ court bundle"| L1A
    S4 -->|"DA commitment"| L1C["data availability<br/>(future external)"]

    classDef off fill:#C7D2FE,stroke:#6366F1,color:#1E293B;
    classDef l1  fill:#E0E7FF,stroke:#4F46E5,color:#1E293B;
    class S1,S2,S3,S4 off;
    class L1A,L1B,L1C l1;

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Official CKB references: docs map · Cell Model · CKB-VM

Demo

Two runnable demos, from zero-dependency to the full reference workload:

	Demo	What it shows	Needs
①	First run	CellTx → session open → commit → court bundle → DA manifest, all local	Rust only
②	Teeworlds end-to-end (flagship)	xxuejie's CKB-VM replayer through Myelin's verifier, chunked, projected to CKB, court bundle (22 checks)	teeworlds fork + built replayer

To see the CellDAG + parallel VM verification path, run session commit-multi after the first-run demo (see the concurrency plan).

Quick Start

Prerequisites: a Rust toolchain (1.85+), Python 3, and optionally Node.js/npm for the website.

# verify the workspace builds and tests pass
cargo check --locked --workspace --all-targets
cargo test --locked --workspace
cargo clippy --locked --workspace --all-targets -- -D warnings

# generate a simple CellTx report
cargo run -p myelin-cli -- celltx simple-report

# open a deterministic session, commit a chunk, build + verify a court bundle
cargo run -p myelin-cli -- session open-fixture --consensus static-closed-committee --out /tmp/open.json
cargo run -p myelin-cli -- session commit-fixture --session /tmp/open.json --out /tmp/commit.json
cargo run -p myelin-cli -- session court-bundle --commit /tmp/commit.json --chunk-index 0 --out /tmp/court.json
cargo run -p myelin-cli -- session verify-court-bundle --bundle /tmp/court.json --out /tmp/court-verify.json

The full local production gate (broad; includes the Teeworlds acceptance gate when the teeworlds checkout is present):

scripts/myelin_production_gate.sh

What is in this repository

Path	Role
exec/	Cell transactions, script verification, VM/syscall glue, scheduler witnesses, and CellDAG conflict scheduling.
state/	Live Cell state roots (incremental MuHash) and data-availability proof primitives.
mempool/	Cell transaction pool and deterministic conflict scoring.
consensus/	Static closed committee and Tendermint-style weighted precommit finality.
cli/	Command-line fixtures and report generation for CellTx, session, DA, settlement, and submission flows.
cellscript/	CellScript compiler, vendored in sync with upstream (0.21.1). Myelin's typed-cell model lives in exec/, not in a compiler fork.
docs/ and MYELIN_*.md	Architecture notes, evidence reports, positioning, and rehearsal records.
website/	Myelin marketing/docs landing site (Astro).

Support crates live under core-utils/, crypto/, and math/.

Security boundary (read before relying on this)

Myelin's current fast paths use closed-validator finality — useful for benchmarking and pressure testing, not a permissionless security claim.

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flowchart LR
    T0["Tier 0<br/>designed close<br/>to CKB"]:::reached --> T1["Tier 1<br/>projectable to<br/>CKB-style tx"]:::reached --> T2["Tier 2<br/>court-verifiable<br/>chunk shape"]:::reached --> T3["Tier 3<br/>on-chain court<br/>verdict"]:::future

    classDef reached fill:#C7D2FE,stroke:#6366F1,color:#1E293B;
    classDef future  fill:#FECACA,stroke:#DC2626,color:#1E293B,stroke-dasharray: 4 3;

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Today Myelin sits at Tier 2. See the claim ladder for the full boundary, and Introducing Myelin for the long-form narrative.

Where Myelin fits in the research line

xxuejie proved complex real-time logic runs inside CKB-VM and explicitly deferred the session/trust/dispute layer. Myelin builds exactly that layer — the off-chain runtime above a verified chunk. We do not improve on the in-VM work; we reuse the replayer binary unchanged. See Introducing Myelin for the full positioning, and Teeworlds reproducibility for the measured values (tape_bytes: 2162, vm_cycles: 15,139,695, court_checks: 22).

Evidence & reports

Start with these documents when reviewing the protocol state:

• MYELIN_PRODUCTION_GATE.md · MYELIN_PRODUCTION_REHEARSAL_REPORT.md
• MYELIN_TEEWORLDS_REPRODUCIBILITY.md · MYELIN_USE_CASE_POSITIONING.md
• docs/MYELIN_ARCHITECTURE.md · docs/TEEWORLDS_FIXTURE.md
• docs/releases/nervos-talk-introducing-myelin.md — the canonical public introduction (Nervos Talk draft)

For CellScript upstream parity:

scripts/check_cellscript_parent_parity.py

Development notes

• Keep CKB-related claims aligned with the official CKB docs.
• Prefer ckb-compatible evidence for public demos.
• Do not describe closed-validator fast paths as permissionless L2 security.
• Keep generated reports out of commits unless they are intentional evidence artefacts.
• Keep cellscript/ changes auditable against the parent checkout.

Licence

MIT. See LICENSE.