Marketplace

Browse the onchain order book, buy CCT with payment token, or sell CCT into a buy order.

Route: /app/marketplace. Trades CCT (the ERC-20 wrapper of carbon credit NFTs, 18 decimals) against payment token through CarbonMarketplace. Prices are quoted in payment token per tonne. The app reads decimals() of the payment token once (6 for real payment token) and never assumes 18; onchain a price is stored in payment-token base units per tonne ($15 = 15000000 for 6-decimal payment token) and cost is amount × price / 1e18.

What it shows

Header: a Create listing button (links to Sell Credits) and the settlement note. Every order trades CCT-VCS (the Verra VCS pool, the only token CarbonMarketplace accepts) against payment token. Orders do not carry a methodology, so there is no per-standard filter.
Summary cards: active listings, available volume (tonnes), volume-weighted average price and best ask, and the settlement currency (payment token).
Fee tier line: when NEXT_PUBLIC_CARB_STAKING is configured, an informational line shows your CARB fee tier and the discount from feeDiscountBpsOf(wallet). The discount applies to the trading fee paid by the CCT seller (not to the price, not to AMM swaps). See Staking and tiers.
Balance bar (connected only): your payment token and CCT-VCS balances and a refresh button.
Claim banner: when pendingWithdrawals(you) > 0 (a refund or proceeds the payment token refused to deliver, for example a payment token blacklist) a banner offers Claim, which calls claim() and pays the amount out.
For sale tab: open sell orders in a sortable table (order, trader, available volume with a fill bar, price, total value, relative expiry, Buy). On mobile each order is a card.
Buy requests tab: open buy orders with Sell buttons, same layout.
My orders tab (connected only): every order you created, read with getUserOrders (no event-window limit), with status (open, partially filled, filled, cancelled, expired), total / filled / remaining tonnes, relative expiry and Cancel order.
Search by trader address or order number, quick filter chips (all, partially filled, expiring in under 24 hours, KYC only) and sorting by price, volume, expiry or newest. Column headers are clickable.
Trader addresses are shortened with a copy button; your own orders are tagged You and cannot be filled by you.

Public tabs list only orders that are active, have remaining volume and have not expired.

Cancelling an order

Cancel order calls cancelOrder(orderId) after an inline confirmation. The contract refunds the unfilled part: your locked CCT for a sell order, or the escrowed payment token for a buy order. An order that expired but is still isActive stays locked until you cancel it, so it is shown as Expired with a Cancel & reclaim funds button.

Actions

Both actions open a modal where you enter a tonne amount (max = remaining). The page computes price × amount and compares it with your balance.

Button	Approval it requests first	Contract call	Result
Buy (on a sell order)	payment token `approve(marketplace, cost)` if the freshly read allowance is lower; `cost = amount × price / 1e18` rounded up	`fillOrder(orderId, amount)`	You pay `cost` payment token and receive `amount` CCT. The seller receives the payment token minus the trading fee.
Sell to Order (on a buy order)	CCT `approve(marketplace, amount)` if allowance is lower	`fillOrder(orderId, amount)`	Your CCT goes to the buyer; you receive `cost` payment token minus the fee. The buyer's payment token was escrowed when the order was created.

The page waits for each approval receipt and the fill receipt, shows toasts, fires a browser notification (if permitted), and reloads orders and balances. Approvals are exact amounts (not unlimited), the allowance is re-read before each transaction and re-approved when it is short, and Max fills the exact remaining wei.

Fee: tradingFeePercent is 25 basis points (0.25 %) by default, adjustable by the admin up to 100 (1 %). The fee rate is snapshotted when an order is created, so later changes do not affect existing orders. It is deducted from the proceeds of the party who receives payment token and accrues in the contract until the fee manager withdraws it.

Preconditions and reverts

Condition	Contract message
Order was cancelled or fully filled	`Order not active`
Order has an expiry in the past	`Order expired`
Amount is 0 or above the remaining amount	`Invalid fill amount`
Order was created with `requiresKYC` and you are not KYC-verified	`KYC required`
Marketplace is paused	revert from `whenNotPaused`
Not enough payment token / CCT or allowance	ERC-20 transfer revert
Fill so small the cost rounds to zero	`Fill too small`
Order was created with `requiresKYC` and the maker's KYC was revoked	`Maker KYC revoked`

KYC in the UI

The app always creates orders with requiresKYC = false and no expiry (expiresIn = 0), so orders made through the web app never require KYC. A KYC flag only appears on orders created directly against the contract. A KYC_ROLE holder sets verification with setKYCStatus.

Data sources

All onchain. getMarketplaceOrders scans OrderCreated events from the last 20,000 blocks and reads each order with getOrder. Orders created earlier than that window do not appear, even if still active. No backend call.

States

State	Behaviour
Wallet not connected	Orders are still readable; an amber notice asks you to connect, the balance bar is hidden and My orders shows a connect prompt.
Loading	Skeleton cards / table.
No matching orders	Empty state with a Create listing link (for sale tab).
Order load failed	Empty state asking you to use the refresh button.
Contracts not configured	Banner in the app shell; order and balance reads return empty.

Buy credits · Sell credits · Credit Requests · CarbonMarketplace reference