Add HIP-4 outcome market support

README.md

@@ -6,6 +6,37 @@ SDK for Hyperliquid API trading with Rust.
 
 See `src/bin` for examples. You can run any example with `cargo run --bin [EXAMPLE]`.
 
+### HIP-4 outcomes
+
+The SDK exposes `InfoClient::outcome_meta()` and outcome helpers through
+`MarketMetaStore`. Enable outcome metadata explicitly when building a store:
+
+```rust
+use hyperliquid_rust_sdk::{MarketMetaStore, MarketMetaStoreOptions};
+
+let store = MarketMetaStore::new(
+    None,
+    None,
+    Some(MarketMetaStoreOptions {
+        outcomes: true,
+        ..Default::default()
+    }),
+)
+.await?;
+
+let yes = store.resolve_outcome_market("#20");
+let asset_id = store.outcome_asset_id("#20"); // 100000020
+```
+
+Outcome identifiers follow Hyperliquid's HIP-4 asset ID rules:
+`encoding = 10 * outcome + side`, coin `#<encoding>`, token `+<encoding>`,
+and order/cancel asset ID `100_000_000 + encoding`. Direct limit order,
+modify, and cancel helpers can resolve prefixed HIP-4 identifiers such as
+`#20` or `+20`, as well as asset IDs such as `100000020`. Bare numeric
+encodings like `20` are supported by the outcome helpers but may overlap
+existing spot aliases in order conversion. Market-order slippage helpers remain
+conservative until Hyperliquid publishes stable outcome size precision.
+
 ## Installation
 
 `cargo add hyperliquid_rust_sdk`