Proposal: Canton Payment Streams

Development Fund Proposal Submission

Proposal file: /proposals/canton-payment-streams.md

Summary

This proposal requests funding for Canton Payment Streams, an open-source reference implementation for privacy-preserving continuous payment streaming, vesting, and programmable payment flows on Canton.

It provides Daml smart contract templates, a TypeScript SDK, a reproducible demo environment, and a thin web dashboard for creating, monitoring, and withdrawing from prefunded streams. The goal is to deliver shared ecosystem infrastructure for payroll, vesting, and recurring payment use cases that benefits multiple Canton builders.

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

This proposal is scoped as shared ecosystem infrastructure, not a billing platform or proprietary product.

It addresses a clear ecosystem gap: payment streaming is a well-known primitive on other networks, but Canton does not yet have an open-source, reusable streaming reference implementation for teams that need payroll, vesting, contributor compensation, or subscription-style payment flows.

The proposal is intentionally scoped as a phase 1 reference implementation for prefunded, single-domain streams so the initial milestone set remains verifiable and realistic.

The main differentiators are:

• privacy-preserving streaming using Canton and Daml visibility rules, so stream terms and balances are visible only to authorized parties
• on-ledger enforcement of stream lifecycle logic through Daml templates, rather than off-chain automation or proprietary backend services
• prefunded escrow-based settlement model aligned with Canton Coin and a reference CIP-56-compatible token path
• reusable developer-facing deliverables including Daml packages, SDK, demo environment, integration examples, and deployment documentation
• milestone-based delivery with clear acceptance criteria, ecosystem validation, and public release under Apache 2.0

Policy-based delegated automation is listed only as a future roadmap item and is not part of the requested phase 1 milestone scope.