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The mirror ledger is the mechanism that lets ClearBox approve a payment at a Web3-blind terminal before the underlying blockchain has confirmed anything. It’s why a customer can tap and walk away with their coffee while settlement completes asynchronously.

The problem it solves

On-chain confirmation is slow relative to a checkout counter. Waiting for a block to finalize can take minutes, which is unworkable when a guest is standing at a register. Legacy point-of-sale terminals also expect a fiat-style authorization response in well under a second — they have no concept of a pending transaction hash.

How it works

The mirror ledger maintains a real-time internal balance for each wallet that mirrors the on-chain state. When an authorization request arrives, ClearBox decides against the mirror, not the chain.
1

Authorization request

The card network routes an authorization request for a given amount to ClearBox.
2

Validate against the mirror

ClearBox checks the wallet’s mirrored available balance — for example, “is 15.00availableagainsta15.00 available against a 100.00 balance?” — and places a hold.
3

Approve in real time

If funds are available, ClearBox returns an approval (typically in roughly 0.2 seconds) and the terminal completes the sale.
4

Settle on-chain in the background

ClearBox burns the equivalent stablecoin from the wallet and reconciles the on-chain state asynchronously, after the customer has already left.

Why it’s safe

The hold placed at authorization prevents double-spending the same balance across concurrent transactions. The mirror is continuously reconciled against the chain, so any divergence is detected and resolved. Because the wallet is non-custodial, the on-chain settlement is the authoritative record — the mirror is an accelerated view of it, not a replacement for it.
The mirror ledger is a ClearBox-internal system. Its internal reconciliation endpoints are not part of the public API; integrators interact with it only indirectly, through the authorization and settlement flow and webhooks.