> ## Documentation Index > Fetch the complete documentation index at: https://docs.droplinked.com/llms.txt > Use this file to discover all available pages before exploring further. # Schema C — Repayment-history attestation > On-chain reference for the append-only repayment-history schema. Per-event evidence powering merchant credit-tier upgrades and the new attestationCoveragePctBps field on /v2/merchant/orders. Schema C is the **reader / repayment-history attestation** — a registered lender's append-only record of a merchant's settlement performance against credit lines that lender has issued. Every settlement event mints a new row; the latest row per `(merchantId, lenderId)` is the active view, and the chain preserves the full history. This is the per-order evidence schema. It powers the `attestationCoveragePctBps` field on [`/v2/merchant/orders`](/api-reference/public/monetization/orders) — the fraction of credit-leg-bearing orders that have a corresponding Schema C attestation, in basis points. | | | | -------------------- | ---------------------------------------------------------------------------------------- | | **Schema name** | `RepaymentHistoryAttestation` | | **EAS revocable** | **no** — append-only | | **Expiry semantics** | none | | **Issued by** | A wallet currently `ACTIVE` in [`LenderRegistry`](/api-reference/public/lender-registry) | | **Subject** | Merchant (`subjectRootUid`) | | **MCP tool** | [`verify_repayment_history`](/agentic/mcp-server) | | **Verifier API** | `GET /v2/attestations/repayment-history/:merchantId` | | **Composite read** | [`GET /v2/underwriting-signals/:merchantId`](/api-reference/public/underwriting-signals) | ## Why append-only Schema C is registered as `revocable: false` on chain. Corrections are issued as a **new attestation with updated counts**; the chain preserves the full history; latest-by-`attestedAt` per `(merchantId, lenderId)` wins for read-time queries. The counters are monotonically non-decreasing — `settledOnTimeCount`, `lateCount`, `defaultCount`, `totalLinesUsdCents` all only ever go up. ## Network & UIDs | Network | EAS contract | Schema UID | Explorer | | ------------ | -------------------------------------------- | ----------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Base mainnet | `0x4200000000000000000000000000000000000021` | `0x090a64afc751696ba228f82225f084f73949644921e286108c86d3ea4d37f24c` | [basescan](https://basescan.org/address/0x4200000000000000000000000000000000000021) · [easscan schema](https://base.easscan.org/schema/view/0x090a64afc751696ba228f82225f084f73949644921e286108c86d3ea4d37f24c) | | Base Sepolia | `0x4200000000000000000000000000000000000021` | resolve via `chain` field on `/v2/attestations/repayment-history/:merchantId` | [sepolia.basescan](https://sepolia.basescan.org/address/0x4200000000000000000000000000000000000021) | EAS registry version: **v1.4.0**. ## Field reference ABI schema string: ``` string subjectRootUid, uint64 totalLinesUsdCents, uint32 settledOnTimeCount, uint32 lateCount, uint32 defaultCount, uint256 lastSettlementAt ``` | Field | Solidity type | Semantic | Mutability | | -------------------- | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------- | | `subjectRootUid` | `string` | Subject anchor. Production form: `"merchant:"`. | immutable per attestation | | `totalLinesUsdCents` | `uint64` | Running total credit drawn across the merchant-lender relationship. Monotonically non-decreasing. | snapshot — monotonic across the chain of attestations | | `settledOnTimeCount` | `uint32` | Running count of settlement events that settled within term. Monotonically non-decreasing. | snapshot — monotonic | | `lateCount` | `uint32` | Running count of settlements past `expectedRepaymentDate` but within the default cutoff (default 30d post-due). Monotonically non-decreasing. | snapshot — monotonic | | `defaultCount` | `uint32` | Running count of credit lines that defaulted (>30d past due or written off). Monotonically non-decreasing. | snapshot — monotonic | | `lastSettlementAt` | `uint256` | Unix seconds of the most recent settlement event captured by this row. Read consumers compute "freshest signal per lender" via `MAX(lastSettlementAt)`. | snapshot | EAS envelope fields: | Envelope field | Type | Semantic | | ---------------- | --------- | ------------------------------------------------ | | `uid` | `bytes32` | Attestation UID. | | `schema` | `bytes32` | Schema UID (above). | | `attester` | `address` | Lender's on-chain signing wallet. | | `recipient` | `address` | Conventionally merchant wallet or `0x0`. | | `time` | `uint64` | Block-mined `attestedAt`. | | `expirationTime` | `uint64` | `0` (no expiry). | | `revocationTime` | `uint64` | Always `0` — Schema C is non-revocable. | | `revocable` | `bool` | `false`. | | `data` | `bytes` | ABI-encoded payload per the schema string above. | ## Order-level evidence — `attestationCoveragePctBps` The merchant orders endpoint exposes a top-line coverage metric derived from Schema C: ```json theme={null} { "summary": { "attestationCoveragePctBps": 9650, "creditLegBearingOrdersCount": 200, "ordersWithSchemaCAttestationCount": 193 } } ``` `9650` bps = 96.50% of credit-leg-bearing orders have a matching Schema C attestation (via `orderId` cross-reference). A drop in coverage means the lender's settlement-event emitter is lagging or has stopped — it's a freshness probe for the merchant's underwriting signal stream. ## Reading running totals: snapshot vs delta A single Schema C row is a **cumulative snapshot** as of `lastSettlementAt`. To compute the delta added by the most recent settlement, fetch the previous attestation for the same `(merchantId, lenderId)` and subtract counters. The Droplinked API's `verify_repayment_history` already does this aggregation: ```json theme={null} { "merchantId": "6a0001a08692425bd9fd571b", "perLender": [ { "lenderId": "crediblex-uae", "latest": { "attestationUid": "0x…", "totalLinesUsdCents": 125000000, "settledOnTimeCount": 12, "lateCount": 1, "defaultCount": 0, "lastSettlementAt": "2026-06-14T11:00:00Z" } } ], "aggregate": { "totalLinesUsdCents": 125000000, "settledOnTimeCount": 12, "lateCount": 1, "defaultCount": 0 } } ``` The aggregate sums latest-row counters across lenders for credit-tier upgrade decisions: T1→T2 requires 3+ settled-on-time; T2→T3 requires 10+ settled with 0 defaults in 24mo. ## Read via Droplinked API ```bash theme={null} curl -s https://apiv3.droplinked.com/v2/attestations/repayment-history/6a0001a08692425bd9fd571b | jq . ``` ## Read via viem (TypeScript) ```ts theme={null} import { createPublicClient, http, parseAbi, decodeAbiParameters } from "viem"; import { base } from "viem/chains"; const EAS = "0x4200000000000000000000000000000000000021" as const; const SCHEMA_C = "0x090a64afc751696ba228f82225f084f73949644921e286108c86d3ea4d37f24c" as const; const client = createPublicClient({ chain: base, transport: http() }); const easAbi = parseAbi([ "function getAttestation(bytes32 uid) view returns (tuple(bytes32 uid, bytes32 schema, uint64 time, uint64 expirationTime, uint64 revocationTime, bytes32 refUID, address recipient, address attester, bool revocable, bytes data))", ]); const uid = "0x…"; // UID from /v2/attestations/repayment-history/:merchantId const att = await client.readContract({ address: EAS, abi: easAbi, functionName: "getAttestation", args: [uid], }); if (att.schema !== SCHEMA_C) throw new Error("not a Schema C attestation"); const [ subjectRootUid, totalLinesUsdCents, settledOnTimeCount, lateCount, defaultCount, lastSettlementAt, ] = decodeAbiParameters( [ { name: "subjectRootUid", type: "string" }, { name: "totalLinesUsdCents", type: "uint64" }, { name: "settledOnTimeCount", type: "uint32" }, { name: "lateCount", type: "uint32" }, { name: "defaultCount", type: "uint32" }, { name: "lastSettlementAt", type: "uint256" }, ], att.data, ); console.log({ subjectRootUid, totalLinesUsdCents, settledOnTimeCount, lateCount, defaultCount, lastSettlementAt, }); ``` ## Read via ethers (TypeScript) ```ts theme={null} import { JsonRpcProvider, Contract, AbiCoder } from "ethers"; const EAS = "0x4200000000000000000000000000000000000021"; const SCHEMA_C = "0x090a64afc751696ba228f82225f084f73949644921e286108c86d3ea4d37f24c"; const provider = new JsonRpcProvider("https://mainnet.base.org"); const eas = new Contract( EAS, [ "function getAttestation(bytes32 uid) view returns (tuple(bytes32 uid, bytes32 schema, uint64 time, uint64 expirationTime, uint64 revocationTime, bytes32 refUID, address recipient, address attester, bool revocable, bytes data))", ], provider, ); const uid = "0x…"; const att = await eas.getAttestation(uid); if (att.schema.toLowerCase() !== SCHEMA_C) throw new Error("schema mismatch"); const [subjectRootUid, totalLinesUsdCents, settledOnTimeCount, lateCount, defaultCount, lastSettlementAt] = AbiCoder.defaultAbiCoder().decode( ["string", "uint64", "uint32", "uint32", "uint32", "uint256"], att.data, ); console.log({ subjectRootUid, totalLinesUsdCents, settledOnTimeCount, lateCount, defaultCount, lastSettlementAt }); ``` ## Read via Cast (Foundry) ```bash theme={null} cast call 0x4200000000000000000000000000000000000021 \ "getAttestation(bytes32)((bytes32,bytes32,uint64,uint64,uint64,bytes32,address,address,bool,bytes))" \ 0x…UID… \ --rpc-url https://mainnet.base.org cast abi-decode \ "x(string,uint64,uint32,uint32,uint32,uint256)" \ 0x…data-field… ``` ## Indexer access (EAS GraphQL) * Base mainnet: [https://base.easscan.org/graphql](https://base.easscan.org/graphql) * Base Sepolia: [https://base-sepolia.easscan.org/graphql](https://base-sepolia.easscan.org/graphql) **All Schema C attestations a lender has emitted, newest first:** ```graphql theme={null} query LenderRepaymentBook($wallet: String!) { attestations( where: { schemaId: { equals: "0x090a64afc751696ba228f82225f084f73949644921e286108c86d3ea4d37f24c" } attester: { equals: $wallet } } orderBy: { time: desc } take: 200 ) { id time recipient data } } ``` **All Schema C attestations referencing a specific order** — the on-chain `orderId` is part of the off-chain mirror, not the EAS payload. Use `GET /v2/attestations/repayment-history/:merchantId` and filter client-side on `orderId`, or use the Droplinked-side admin lineage endpoint. ## Trust assumptions A Schema C attestation is authoritative if and only if: 1. The on-chain `schema` matches the mainnet UID above. 2. The on-chain `attester` is `ACTIVE` in [`LenderRegistry`](/api-reference/public/lender-registry). 3. `revocable == false` (sanity check — a Schema C row that claims `revocable == true` is malformed). 4. Counters are **monotonically non-decreasing** relative to the prior attestation in the same `(merchantId, lenderId)` chain. A row that decreases any counter is either malformed or a write-bug; do not honor it. The Droplinked-side issuer enforces this off-chain monotonic guard before mint. Schema C does not have a `lenderCurrentStatus` mirror (Schema C is append-only history, so a status flip on a lender doesn't change a historical fact). To assess whether to consume a lender's Schema C stream **right now**, consult [`GET /v2/lenders/:lenderId`](/api-reference/public/lender-registry) directly. ## Related * [Trust Fabric overview](/concepts/trust-fabric) * [Schemas overview](/api-reference/public/eas-schemas/overview) * [Schema B — Credit-risk attestation](/api-reference/public/eas-schemas/schema-b-writer) * [`/v2/merchant/orders` — `attestationCoveragePctBps`](/api-reference/public/monetization/orders) * [`/v2/underwriting-signals/:merchantId`](/api-reference/public/underwriting-signals)