Proposal: Canton Event Stream — real-time ledger events via WebSocket…

Proposal file: /proposals/canton-event-stream.md

Summary Canton Event Stream is a self-hostable, MIT-licensed Node.js service that connects to any Canton participant node and delivers classified, party-routed ledger events to application clients over WebSocket and SSE. It solves the missing push layer in the Canton ecosystem — the infrastructure between the raw JSON Ledger API stream and live UIs, deposit detectors, and reactive backends. The core implementation exists today inside Qasara's commercial Canton Gateway; this proposal extracts and open-sources it as a standalone package in 3 milestones over 6 weeks, funded at 300,000 CC.

Checklist

• [x] Proposal file added under /proposals/
• [x] Milestones and funding amounts defined
• [x] Acceptance criteria included
• [x] Alignment with Canton priorities described

Notes for Reviewers

• The core ingester (Splice interface subscription, Redis pub/sub fanout, WebSocket + SSE endpoints) is already running in Qasara's DevNet environment — this is an extraction + open-sourcing grant, not a greenfield build.
• This proposal complements PQS (CIP-0100, approved 2026-04-23) rather than competing with it. PQS is the pull layer (SQL ODS); Canton Event Stream is the push layer (WebSocket/SSE). The Rationale section explains the coexistence design.
• Champion: Parth (parth@canton.foundation), Canton Foundation.
• Funding request: 300,000 CC across 3 milestones (120k / 100k / 80k).