Constant Flow Agreement (CFA)

A Constant Flow Agreement (CFA) is a smart contract standard that facilitates real-time finance by allowing one party (the sender) to establish a continuous, non-discretionary flow of tokens to another party (the receiver). Unlike traditional periodic transfers, a CFA creates a per-second stream where the receiver can access the accrued tokens at any moment. The flow's rate is defined in wei per second (e.g., 1 DAI per month), and the contract automatically enforces the transfer of the exact amount that has streamed since the last on-chain interaction. This mechanism is foundational for use cases like salaries, subscriptions, and rewards that require granular, ongoing value transfer.

The CFA's architecture is built on the concept of streaming balances. Instead of holding tokens in escrow, the sender's account balance is debited, and the receiver's balance is credited, in real-time as each second passes. This is made possible by the Superfluid protocol's Super Token standard, which are ERC-20 wrapper tokens with enhanced functionality. The CFA contract calculates the net flow for any account by summing all its incoming and outgoing streams, and the account's real-time balance is its static token holdings plus this net flow. This design eliminates the need for repeated transactions, drastically reducing gas costs and enabling complex, multi-party streaming topologies.

Key operations for a CFA are createFlow, updateFlow, and deleteFlow. A flow is a persistent state until explicitly stopped or modified. The protocol's Constant Flow Agreement V1 (CFAv1) is the canonical implementation, governing the logic for these operations and the real-time balance accounting. A critical feature is automatic liquidation: if a sender's real-time balance would go negative, any account can call a function to delete the offending stream, protecting the network from insolvency. This makes streams as secure as regular token transfers while being infinitely more efficient for recurring payments.

The CFA enables novel financial primitives. For developers, it abstracts away the complexity of managing recurring transactions. Use cases include: - Real-time payroll and vesting schedules - Subscription services with per-second billing - DeFi rewards that stream continuously to liquidity providers - Cross-chain streaming via bridging protocols. By moving from discrete, batched transactions to continuous flows, the CFA model unlocks more granular, transparent, and capital-efficient economic interactions on-chain, forming the backbone of the money streaming paradigm.

A Constant Flow Agreement (CFA) is a smart contract standard, most notably implemented within the Superfluid Protocol, that facilitates the creation of ongoing, non-interactive payment or data streams. Unlike a standard transaction, which transfers a lump sum, a CFA defines a persistent flow rate—for example, 1 DAI per second—that is executed automatically on-chain. The sender locks funds in the contract, and the recipient can access the streamed value in real-time, with their balance updating continuously based on the elapsed time since the last interaction. This mechanism is powered by the concept of real-time balances, where the recipient's claimable amount is a function of the flow rate and time, not discrete transactions.

The core operation relies on two primary functions: createFlow to initiate a stream and deleteFlow to stop it. When a flow is active, the contract calculates the net flow for each user by summing all inflows and outflows. The sender's account is debited, and the recipient's is credited, based on the precise number of seconds that have passed. This accounting is gas-efficient because it uses a settlement model where balances are recalculated only when a user interacts with the chain (e.g., making a transaction). This means the stream runs perpetually without requiring constant on-chain transactions, making it ideal for use cases like subscriptions, salaries, or rewards distribution that require granular, real-time value transfer.

A key technical innovation is the Superfluid Agreement List (AL) framework, which allows the CFA contract to be notified of balance changes and enforce solvency constraints in real-time. The system ensures a sender cannot create a flow that would make their account insolvent at the moment of the next possible settlement. If a user's balance becomes insufficient, any outgoing streams are automatically deleted by the protocol to maintain system integrity. This real-time enforcement, combined with the ability to update flow rates without interrupting the stream, provides a robust foundation for building complex financial applications on Ethereum and other EVM-compatible blockchains.

Practical applications extend beyond simple payments. Developers use CFAs to create token vesting schedules that drip tokens continuously, real-time revenue sharing models for DAOs, and oracle data streams where information is paid for per-second. The composability of streams allows for complex financial logic, such as splitting a single incoming flow to multiple recipients or creating conditional flows that trigger based on external data. This transforms static, batch-based financial operations into dynamic, programmable cash flows that are natively integrated into the blockchain's execution layer.

A Constant Flow Agreement (CFA) is a smart contract standard that enables the creation of continuous, non-discretionary streams of value (like tokens) between parties on a blockchain. Unlike one-time transactions, a CFA establishes a persistent flow where tokens are transferred from a sender's account to a receiver's account at a predetermined, constant rate per second, settled in real-time. This mechanism is foundational for implementing real-time finance (RTFi) use cases such as salaries, subscriptions, and micro-payments directly on-chain, where value accrues and becomes spendable by the receiver with each passing block.

The technical mechanics of a CFA are governed by the Superfluid Protocol. When a flow is created or updated, the protocol calculates a "flow rate" (e.g., 1 DAI per second). The sender must maintain a sufficient balance in their Super Token account (an ERC-20 wrapper with superpowers) to cover the ongoing obligation. The protocol does not lock funds in escrow; instead, it uses an accounting system where the receiver's real-time balance is a function of the elapsed time and the flow rate. This balance is instantly liquid and can be transferred or used in other DeFi interactions without interrupting the incoming stream.

Settlement in a CFA is continuous and trustless. The net flow for each account is recalculated on-chain with every transaction that touches the protocol, ensuring the receiver's claim to the streamed value is always up-to-date and enforceable. A key security feature is automatic closure: if a sender's balance falls below a safety threshold, their outgoing flows are automatically stopped by the protocol to prevent overdrafts. This design eliminates the need for manual claims or periodic transactions, creating a seamless experience where cash flow becomes a programmable, persistent layer of the blockchain's state.