Canton-Fastlane

Milestone 1 snapshot for the Canton Fast Lane proposal: the protocol and client foundation for low-latency, explicitly non-final signaling between Canton-connected systems.

This repo intentionally includes only the Milestone 1 scope from the proposal:

• a schema library for SignalEnvelope, acknowledgements, and session control messages
• a JVM channel adapter boundary shaped around Canton's current sequencer-channel client surface
• a TypeScript SDK boundary for point-to-point signaling integration
• technical documentation that clearly separates non-final signaling from ledger-backed finality

This repo intentionally does not include the later milestone work:

• reconnect and resume orchestration
• replay protection and stale-message recovery flows
• bounded resend policies
• reference apps and live proof harnesses
• DevNet tooling, dashboards, and operator packaging

Milestone 1 Deliverables

These files map directly to the proposal’s Milestone 1 promises:

• packages/protocol
• packages/sdk
• jvm/adapter
• docs/milestone-1-scope.md

What This Toolkit Is For

Use this foundation when:

• the message is advisory, preparatory, or operational
• low latency matters more than ledger durability for the signal itself
• the real business commitment will still happen later through normal Canton or Daml execution

Do not use this toolkit as:

• a settlement layer
• a payment or custody protocol
• proof that a Canton business event has already committed
• a replacement for ledger-backed finality

How To Run

Prerequisites

• Node.js 24.x recommended
• npm 11.x
• Java 17

Install

npm install

Build

npm run build

Test

npm test

Repo Layout

• packages/protocol: protobuf schema, typed signaling envelopes, payload hashing, validation, and codec helpers
• packages/sdk: Milestone 1 TypeScript client boundary with session hello, signal send/receive, acknowledgement tracking, and an in-memory store
• jvm/adapter: Milestone 1 JVM adapter seam and compatibility surface for a future Canton-backed gateway
• docs/milestone-1-scope.md: usage boundary and Milestone 1 scope notes

Milestone Boundary

This repository is deliberately scoped to Milestone 1 only. Later proposal milestones cover:

• reconnect and replay handling
• recovery after restart
• reference applications
• use-case packs
• operator integration guides

Those are intentionally left out here so this repo stays aligned with the Milestone 1 acceptance slice.