The reserve

How a box is logged

Buying a box leaves four records on-chain and one document off it. This is what each one holds.

1. The withdrawal

ETH leaves the reserve only through withdraw(to, amount, memo). Each call gets the next withdrawal number and is stored with its destination, amount and time. The memo names the set.

2. The acquisition

recordAcquisition appends the next box. Numbers start at 1 and are never reused.

Field	What it holds
`setNumber`	The LEGO set number, like 10307.
`acquiredAt`	When the order was placed, as a unix time.
`costUsdCents`	What the box cost, in US cents.
`withdrawalId`	The withdrawal that paid for it, or 0 if it was paid another way.
`metadataURI`	Where the receipt and photos document lives.
`metadataHash`	keccak256 of that document's exact bytes.

3. The metadata file

A small JSON file holds the receipt (personal details redacted), photos, merchant and payment transaction. Its hash is fixed on-chain, so if the file is ever swapped, the Proof page shows a mismatch.

proof/0001.json

{
  "set": "10307",
  "merchant": "LEGO.com",
  "receipt": "https://bric.wtf/proof/0001-receipt.pdf",
  "photos": ["https://bric.wtf/proof/0001-card.jpg"],
  "paymentTx": "0x…"
}

Terminal

# hash the file's exact bytes
$ cast keccak 0x$(xxd -p proof/0001.json | tr -d '\n')
0x3b1c…

4. Custody

updateCustody(n, status, evidenceURI) moves a box along. A new entry starts as Ordered.

1Orderedpaid, logged
2In transittracking number
3Vaultedon its shelf, photographed

4Openeda build day: one duplicate box is opened on stream and the build displayed

Custody states, with their numbers in the contract.

The vault card

Every acquisition photo contains a printed card with the vault number and date. Its QR code opens that box's entry on the Acquisitions page, so a photo on X leads straight to the record.

Brick Reserve

Vault proof / 0001

2026-09-20

10307
Eiffel Tower

Specimen