feat: add Hunch venue (parimutuel prediction market on Base, x402) (#1150)

Hunch (playhunch.xyz) is a parimutuel prediction market on Base, settling via
x402 / EIP-3009 USDC. Adapter mirrors the Myriad pattern: reads (markets/events/
OHLCV/trades/positions/balance) normalize the live agent API; orderbook is
emulated from the implied price + pool; createOrder runs the x402 402->sign
EIP-3009->200 loop (viem), self-hosted via a Base private key. Market-orders only
(cancel/limit/sell unsupported — parimutuel). Registered in index.ts, the server
exchange factory, the ExchangeParam enum, and COMPLIANCE.md.

Tests: core/test/normalizers/hunch-normalizer.test.ts (47) — binary + N-way
mapping, the money-critical outcomeId<->side round-trip, position/balance/OHLCV/
emulated-orderbook. tsc --noEmit clean.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: rajkaria

core/COMPLIANCE.md

@@ -34,6 +34,43 @@ This document details the feature support and compliance status for each exchang
 ## Legend
 - **Y** - Supported
 - **-** - Not supported
+- **E** - Emulated (backed by a non-native mechanism)
+
+> NOTE: the grid above is regenerated by `generate:compliance` from
+> `core/src/exchanges/*/index.ts`. The Hunch column below is documented inline
+> until the next regeneration picks it up.
+
+## Hunch
+
+Hunch is a **parimutuel** prediction market on **Base** (USDC). Markets are
+pool-based — there is no CLOB and no AMM curve; prices are *implied odds*.
+Settlement is **x402 / EIP-3009 `transferWithAuthorization`** (the bettor's
+wallet signs a USDC authorization; the relayer sponsors gas). Identity is
+keyless — the wallet IS the account, so reads need no API key.
+
+| Category | Function | Hunch | Notes |
+| :--- | :--- | :---: | :--- |
+| **Market Data** | `fetchMarkets` | Y | `GET /api/agent/v1/markets` |
+|  | `fetchEvents` | Y | No event tier — each market wrapped as a single-market event |
+|  | `fetchMarket` | Y | `GET /api/agent/v1/markets/{id}` |
+|  | `fetchEvent` | Y | Synthetic single-market event |
+| **Public Data** | `fetchOHLCV` | Y | From research `oddsHistory` (flat candles) |
+|  | `fetchOrderBook` | E | Emulated: single level at the implied price, pool as depth |
+|  | `fetchTrades` | Y | research `oddsHistory` as the public tape |
+| **Private Data** | `fetchBalance` | Y | `GET .../wallet/{address}/readiness` → USDC balance |
+|  | `fetchPositions` | Y | `GET /api/agent/v1/positions?wallet=` |
+|  | `fetchMyTrades` | - | Not exposed (use `fetchPositions` / proof) |
+| **Trading** | `createOrder` | Y | Self-hosted Base **x402** money path; **market orders only** |
+|  | `cancelOrder` | - | Parimutuel pool — bets cannot be cancelled |
+|  | `fetchOrder` | - | Parimutuel — no resting orders |
+|  | `fetchOpenOrders` | Y | Always `[]` (no resting orders) |
+| **Real-time** | `watchOrderBook` | E | Poll-based emulation |
+|  | `watchTrades` | E | Poll-based emulation |
+
+`createOrder` accepts only `side: 'buy'` and `type: 'market'`; `outcomeId`
+encodes the Hunch side as `"{marketId}:{side}"` where `side` is `yes`/`no` for
+binary markets or the parimutuel bucket key for N-way ladder / date-window
+markets. Bets above the $10 "simple tier" first fetch a price-locked quote.
 
 ## Compliance Policy
 - **Failure over Warning**: Tests must fail if no relevant data (markets, events, candles) is found. This ensures that we catch API breakages or unexpected empty responses.
@@ -52,4 +89,7 @@ MYRIAD_API_KEY=...
 MYRIAD_WALLET_ADDRESS=0x...
 # Metaculus (required for API access — unauthenticated requests return 403)
 METACULUS_API_TOKEN=...
+# Hunch (reads are keyless; privateKey signs the x402 USDC payment on Base)
+HUNCH_PRIVATE_KEY=0x...
+HUNCH_WALLET_ADDRESS=0x...   # optional; derived from HUNCH_PRIVATE_KEY when absent
 ```