Build "Keel Spin": a Foundry project with two contracts, KeelSpinVault and KeelFwaRouter. Users pool small ETH bets into rounds; a funded round spins once on the Fake World Assets V2 (FWAV2) main pool. For each won position the vault keeps the NFT or accepts the ETH bid, based on the NFT's real sellable value. Kept NFTs go to the Keel team wallet, which sells them and returns the proceeds to the round's bettors. Ethereum mainnet, contracts only.

EXTERNAL CONTRACTS (constructor args, owner-settable later)

FWAV2 main pool 0x958C41181182e76F221331b2755b77D9e1426A98; FWA CollectionFloorOracle 0xaA4D9009a4664604b57644bF13e447E9036727DC; IMD Intake v2 0xa43e6f75ee006411f79ac1c84120606c2330de82; IMD token 0xd34a99bc0f67ae1bbd63c660e6d0b0dd03e263b7; IMD oracle signer (attester from GET /oracle/requests); teamWallet ($owner by default). Compile against their verified sources. Use github.com/adamlizek/fwa-examples (FWAV2BuilderBase) for acquire forwarding, refunds and builder reward claims.

ROUNDS

bet() with ETH; min bet owner-set (default 0.001 ETH); max 500 bettors per round. No fixed target: liveTarget = FWAV2.quoteAcquisitionPrice() total for count 1 (pool fee + VRF fee, at the current tx.gasprice) * (10000 + bufferBps) / 10000 (default 500) + spinReward. A bet fills the current round up to liveTarget; any excess goes to the next round for that bettor. If the price rises, the round stays Open and keeps taking bets; never lock a round at a stale price. Withdraw allowed while Open. States: Open, Spinning, Allocated, AwaitingSale, Settled, Refunded.

SPIN

Anyone calls spin(roundId) on an Open round. In the same call read the live quote and require round balance >= quote total + spinReward and tx.gasprice <= maxSpinGasPrice (owner-set); otherwise revert and the round stays Open. Pay the caller spinReward (owner-set, default 0.002 ETH, max 2% of the quote) to cover this transaction's gas. Spend exactly the quote total; the buffer is never spent and stays credited to the round's bettors pro rata. The vault funds KeelFwaRouter, which calls FWAV2.acquire(purchaser = vault, count = 1, maxAcquisitionFee = the pool fee just quoted, minWeightedValue, maxNegativeSlippageBps) with owner-set slippage bounds. Router as caller earns FWA builder revenue; only the vault may call it; the owner claims builder rewards to teamWallet. spin() reverts during FWA blackouts 11:45-12:00 and 23:45-00:00 UTC. Overpayment refunds stay credited to the round pro rata. On a refunded request (empty pool, drift, late VRF), claim the refund credit as purchaser and return the round to Open; the lost VRF fee is shared pro rata. Map requestId to listingId.

DEPLOYMENT

Deploy KeelSpinVault first, then KeelFwaRouter with $contract:KeelSpinVault. Constructors take only static address/uint/bool args and $owner, receive no ETH; the owner calls vault.setRouter(router) after deployment.

DECISION: ETH bid vs the NFT's net sellable value

ethBid = backing * FWAV2.settlementDiscountBps() / 10000, read live.

Step 1, free onchain pre-check in requestDecision(roundId): read the collection floor and its observation time from CollectionFloorOracle. If missing, or older than maxFloorAge (owner-set, default 24h), treat it as unavailable. If available and floor * (10000 - haircutBps) / 10000 >= ethBid * obviousKeepMultiple (defaults: haircut 1500, multiple 3), keep immediately with no oracle call.

Step 2, otherwise ask the IMD oracle: the vault pays 0.5 IMD from its own balance via Intake.requestWithFailure("oracle.request@oracle-1", body, onOracleResult, onFailure). Build the body onchain: v 1, chainId 1, answerType "uint256", evidence "panel", window {hours: 1}, panelSize 5, quorum 4, toleranceBps 500, validForSeconds 3600, guards {min "0", max "10000000000000000000000"}. Question: "What is the highest live offer, in wei, that the owner of token could accept right now, after marketplace fees and creator royalties?" Definitions are owner-settable, one key per topic, each value at most 512 characters:

• offers: best of token-specific, collection and trait offers matching this token; WETH counts as ETH; ignore offers expiring within 2 hours.
• sources: OpenSea and Blur. If the token is a CryptoPunk or a CryptoPunks wrapper, bids on the native CryptoPunks market 0xb47e3cd837ddf8e4c57f05d70ab865de6e193bbb for the underlying punk must also be checked.
• net: the amount the seller would actually receive on acceptance, after that marketplace's fee and the royalty it enforces.
• missing: only real, currently acceptable offers count; never invent or estimate one; answer 0 if none exists. onOracleResult stores the uint256 value only and never executes the decision: only from Intake, only for a pending requestId of this vault, verify the EIP-712 OracleAttestation signature, require agreed >= quorum and block.timestamp <= expiresAt. executeDecision(roundId), callable by anyone: keep if netOffer * 10000 > ethBid * (10000 + marginBps) (default 500), else accept the ETH bid; re-read ethBid at execution.

Expose imdBalance() and needsImdTopUp() (balance below an owner-set threshold, default 2 IMD); emit LowImdBalance when it drops below.

DEADLINE (critical)

After the purchaser's FWA settlementWindow, the depositor can reclaim the NFT and pay only the ETH bid. decisionDeadline = allocatedAt + FWAV2 settlementWindow - safetyMargin (owner-set, default 2h); executeDecision must run before it. If no valid oracle value exists by decisionDeadline - fallbackL