sdk

@fletcher/sdk

TypeScript for Fletcher. Reads need no key and no account.

pnpm add @fletcher/sdk viem

import { FletcherClient, parseUsd, strikeForLeverage, formatLeverage, WAD } from "@fletcher/sdk";

// Pick a leverage, not a strike.
const spot = parseUsd("178.50");
const strike = strikeForLeverage(spot, 20n * WAD);        // 169.57

const fletcher = new FletcherClient(addresses);
const series = await fletcher.getSeries("0x...");
const { floorValueX8, turboValueX8, leverage } = fletcher.quote(series, spot);
formatLeverage(leverage);                                  // "20.0x"

What is in it

• math.ts the settlement split, leg valuation, leverage, the funding rate, and the corporate-action classifier. All pure, so a UI can redraw a payoff curve without an RPC round trip per frame.
• client.ts FletcherClient, batching a series' reads into one multicall and simulating every write before it sends.
• chain.ts the verified Robinhood Chain address book, and which endpoint serves archive state.
• abis.ts generated from the Foundry artifacts by scripts/extract-abis.mjs, never hand-written.

Parity with the contracts

math.ts reimplements arithmetic that also exists in Solidity. Two implementations of one calculation drift, and the drift would surface as a quoted payout the contract will not pay.

So the contracts are the source of truth: contracts/test/Fixtures.t.sol generates the answers and test/math.test.ts asserts the TypeScript reproduces them exactly. Both directions are gated, so a contract change that moves a number fails the Solidity suite too.

pnpm test                                                    # 47 tests, 17 parity cases
FLETCHER_WRITE_FIXTURES=1 forge test --root ../../contracts --match-path 'test/Fixtures.t.sol'

Full reference: ../../docs/sdk.md.