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Architecture & Fees

Production & Architecture (V1)

Tessera V1 is designed to be a robust, developer-friendly MVP. To ensure stability and ease of deployment, the following architectural decisions and limitations are present in this version:

Architecture: Universal Deposits (CCTP) & Arc Settlement

While Tessera requires the Arc Network to operate its core billing engine, viewers can fund their sessions from any supported network (Ethereum, Base, etc.) thanks to Circle's CCTP (Cross-Chain Transfer Protocol).

flowchart LR
    %% Custom Premium Styling
    classDef origin fill:#1A1B26,stroke:#7AA2F7,stroke-width:2px,color:#FFFFFF,rx:10,ry:10
    classDef cctp fill:#1F2335,stroke:#9ECE6A,stroke-width:2px,color:#FFFFFF,rx:10,ry:10
    classDef arc fill:#24283B,stroke:#BB9AF7,stroke-width:3px,color:#FFFFFF,rx:10,ry:10,stroke-dasharray: 5 5
    classDef blockchain fill:#24283B,stroke:#F7768E,stroke-width:2px,color:#FFFFFF,rx:10,ry:10
    classDef engine fill:#1F2335,stroke:#7DCFFF,stroke-width:2px,color:#FFFFFF,rx:5,ry:5

    subgraph Origins ["🌐 Origin Networks"]
        direction TB
        ETH["Ethereum"]:::origin
        BAS["Base"]:::origin
    end

    CCTP(("🔄 Circle CCTP")):::cctp

    subgraph ArcNet ["⚡ Arc Network"]
        direction TB
        Gateway["💎 Gateway Contract"]:::blockchain
        Engine["⚙️ Billing Engine"]:::engine
    end
    class ArcNet arc

    ETH -->|"USDC"| CCTP
    BAS -->|"USDC"| CCTP

    CCTP --->|"Route & Fund"| Gateway
    Engine -.->|"Batched settlement claims"| Gateway

Fee Structure

Because Tessera relies heavily on off-chain EIP-3009 signatures, viewers only pay network fees for two on-chain transactions during the entire lifecycle of a session:

  1. Deposit (Gateway Funding): When moving funds into the Gateway Smart Contract.
  2. Withdrawal (Cash Out): When settling the session and pulling unused funds back to their wallet.

On the Arc Network, these transactions cost approximately $0.01 USDC in network fees (gas).

Cross-Chain Forwarding Fees: If a viewer decides to bridge funds from another network (e.g., Ethereum or Base) using Circle's CCTP Forwarding Service instead of direct funding, the Forwarding Service charges a flat $0.20 USDC service fee for the transfer.

Why must the settlement engine run exclusively on Arc?

Tessera is designed for high-frequency, per-second billing. Implementing this economic model on traditional EVM networks is economically unviable due to unpredictable gas fees.

By leveraging the Arc Network combined with the x402 protocol:

  • Native USDC Gas: Forget about needing to hold a separate, volatile native token just to pay for transactions. Arc uses USDC natively for gas, meaning zero friction for users and creators.
  • Predictable, Ultra-Low Costs: Arc is specifically designed for stablecoin-native applications, targeting an average transaction fee of ~$0.01 USDC.
  • Gasless Streaming: Once the session begins, viewers sign off-chain cryptographic proofs every second without paying any gas.
  • Batched Settlement: The Circle Gateway aggregates thousands of these off-chain signatures and settles the final balances efficiently on the Arc Network.
  • Economic Viability: On traditional networks, watching a 10-minute stream could cost more in gas than the content itself. Arc's ~$0.01 fees make the math work, ensuring that network costs never consume the actual value of the stream.

Environment Configuration

  • Dynamic Routing: PUBLIC_URL is required in production to ensure the Gateway can map callbacks and references correctly, bypassing the hardcoded localhost limitations.
  • Gas Buffer: RETAINED_GAS_AMOUNT (default 0.01 USDC) is utilized to ensure the ephemeral wallet always retains enough native token for on-chain interactions without failing.

Security & Performance

  • Rate Limiting: Critical endpoints (/register-session and /end-session) are protected by IP rate limiting to prevent spam and DDoS attempts.
  • Memory Optimization: GatewayClient instances are cached in memory. Ephemeral keys and instances are strictly wiped using a safe sweep upon session termination.
  • Dynamic Top-Up: Viewers are alerted dynamically when their balance drops below 5 minutes of viewing time, allowing them to top-up without interrupting the video stream.

Observability

  • Healthcheck: A robust endpoint at GET /health provides real-time status of active sessions and connectivity to the Circle Gateway, suitable for integration with Prometheus or UptimeKuma.

V1 Limitations & Trade-offs

  • Polling over Webhooks: To maximize developer experience (DX) and allow seamless testing on localhost without tunnels (like ngrok), V1 actively polls Circle for deposit confirmations instead of relying on Webhooks.
  • Fixed Payment Scheme: The protocol currently forces the GatewayWalletBatched scheme on Arc Testnet. While x402 supports dynamic schemes like CompositeEvmScheme, they are disabled in V1 to maintain strict focus on streaming nanopayments.