Seeking a champion (RFP 13): conditional x402 payments on Canton, released by a signed delivery verdict

Hi all, Amir from Predge (predge.io). The Canton Foundation suggested posting here to get feedback and find a Tech & Ops Committee champion.

Problem. x402 on Canton works today (FTP’s facilitator, PR #78, and ChainSafe’s). The payment is final at the moment of the call. If the paid call or job isn’t delivered, there is no way back short of a manual refund. That holds back larger and longer jobs: data deliveries, compute rentals, multi-step agent tasks.

What we’d build. A conditional-payment module on top of the existing facilitators, not another bridge:

• When the x402 payment is made, the amount is locked in a Daml escrow contract instead of going straight to the provider.
• A verifier checks delivery against criteria both sides agreed up front and issues an ed25519-signed verdict (predge-attest-v1) that anyone can verify offline.
• The verdict is recorded on the ledger and either releases the funds to the provider or refunds the payer. If no verdict arrives in time, the payer can reclaim on their own.
• The auditor’s party keeps its own copy of the verdict and the evidence hash, so the record survives even if a party prunes (this touches RFP 27).

What already runs. The same escrow-plus-verdict design has been live on Arc mainnet since September 2026 and on 16 EVM mainnets. A shielded 2-of-3 FROST escrow ran on Zcash mainnet on 13 Nov. On 12 Nov we settled a GPU rental per verified day on Arc mainnet: the A100 days were paid, and a day where the host swapped in an A40 was refunded by the contract (tx). Three paying business customers use the verdict engine today.

Draft plan. About 4 months, about 600,000 CC, three milestones:

1. Daml escrow and verdict templates, integration with the FTP facilitator, devnet demo, open source (Apache-2.0).
2. Mainnet: conditional x402 payments live with at least two Canton apps or agents, with the auditor copy.
3. SDK and docs. Acceptance based on adoption: conditional payments settled by external apps (we’d value the committee’s view on the right target).

Our earlier PR #784 (agent reputation) was closed in September for lacking a champion. This is a new, narrower proposal.

Asks

1. A Tech & Ops champion who covers payments (RFP 13).
2. Feedback on overlap. We see this as complementary to #78, and close in spirit to #860 (refusal record, RFP 27); happy to align with both.
3. @Daniel_FTP, would you be open to us building directly on your facilitator?

Happy to share the full proposal draft before opening the PR.

Amir · hello@predge.io · Telegram: Contact @latcom