24h Submission Delay for End-User CC Transactions

Motivation

Between preparing and executing a transaction, the key(s) registered in the topology state for the submitting external party must sign the transaction. This often requires explicit human approval sometimes even from multiple people. Doing that within a 10 minute window can be quite disruptive and does not match the expectations from other networks or even other assets on the global synchronizer. Supporting a 24h delay aligns Canton Coin with other CIP 56 assets.

Rationale

Propagation Delay

Supporting a longer submission delay necessarily implies that the accessed contracts need to be active for at least the duration of the submission delay. This is what the new ExternalPartyConfigState contract accomplishes.

This does however imply that changes to the values stored on that contract propagate more slowly. More specifically it takes up to 48h until the old values cannot be used anymore.

For maxNumInputs, maxNumOutputs, maxNumLockHolders this is a non-issue as those values have not been changed once and we don't expect to need any quick changes. The amuletPrice in a CC transfer is only used for converting the holding fee and from USD to CC. For holding fees, minor fluctuations play a negligible role so price changes propagating slower has negligible impact.

There is a bigger impact on traffic purchases where a price change is more significant. There is not really any way to enforce use of recent prices and support a long submission delay though so this is a necessary tradeoff.

Holding Fees

Amulet contracts created via choices relying on ExternalPartyConfigState will have the round they were created in set to the round at the point in time when ExternalPartyConfigState was created. This can be up to 48h in the past at the time the transaction gets executed. By switching expiry to be based on ExternalPartyConfigState we compensate for that by delaying expiry by the same amount so the effective expiry date of Amulet contracts is unchanged.

Additional AmuletConfig Restrictions

The additional restrictions enforced on AmuletConfig are required to make the implementation feasible. In particular switching from creating AppRewardCoupon contracts to FeaturedAppActivityMarker without changing the issued rewards requires that a CC transfer only produces featured application rewards, implied by no fees, and extraFeaturedAppRewardAmount must be identical to featuredAppActivityMarkerAmount.

Limitations

This change supports a 24h submission delay for token standard operations, traffic purchases and tap. However, reward minting is still subject to the 10 minute submission delay. Short term, the minting delegation introduced by CIP 96 allows to delegate minting to a party that can support a shorter submission delay. Longer term, we expect that as part of switching to traffic based rewards we will also be able to support a longer signing delay for reward minting.

Backwards compatibility

Token Standard APIs

Changing the CC implementation of the token standard APIs to use ExternalPartyConfigState is an implemenation-internal change. Users of the token standard APIs do not need to make any change in their application. Note however, that the choice context returned by Canton Coin Scan will change. As applications should treat this opaquely and just pass it along, this should still not require changes in applications.

Locking APIs

Applications that directly use LockedAmulet_Unlock or LockedAmulet_OwnerExpireLock will need to switch to the V2 choices when they recompile their code against the new amulet versions. Note that existing DARs compiled against the previous version will continue working so the upgrade can be done at the developer's preferred schedule.

Transaction History Parsing

App providers that parse transaction history through the token standard API no change is required.

App providers that parse the CC specific choices directly will need to adjust your parser. In particular, TransferPreapproval_SendV2 and the token standard implementation of transfers and allocations no longer exercise AmuletRules_Transfer internally and instead inline the adjusted implementation of that choice to rely on ExternalPartyConfigState.

Reference implementation

A draft PR for the Daml changes can be found on Github.

Changelog

• 2026-06-30: Final

• 2026-03-10: Approved

• 2026-01-21: Initial draft of the proposal.