XSC-0003: Streaming Payments

XSC-0003 defines recurring time-based token transfers on top of the fungible token contract.

Canonical Functions

The current canonical token exposes:

@export
def create_stream(receiver: str, rate: float, begins: str, closes: str):
    ...

@export
def create_stream_from_permit(
    sender: str,
    receiver: str,
    rate: float,
    begins: str,
    closes: str,
    deadline: str,
    signature: str,
):
    ...

@export
def balance_stream(stream_id: str):
    ...

@export
def change_close_time(stream_id: str, new_close_time: str):
    ...

@export
def finalize_stream(stream_id: str):
    ...

Convenience helpers also exist in the canonical contract:

• close_balance_finalize
• balance_finalize
• forfeit_stream

Stream Model

The canonical state tracks:

• sender
• receiver
• start time
• close time
• rate
• amount already claimed
• lifecycle status

Streams are identified by a deterministic stream_id.

Accrual is lazy. Nothing runs in the background between blocks. The owed amount is computed when balance_stream or related helpers execute in a later block using the current contract now.

Event Expectations

The canonical implementation emits:

• StreamCreated
• StreamBalance
• StreamCloseChange
• StreamForfeit
• StreamFinalized

These events are indexed into CometBFT and surfaced through the optional dashboard/WebSocket layer.