Add hand-written Anchor-compatible IDL

Cargo.toml

@@ -27,13 +27,15 @@ solana-program-pack = "3"
 solana-rpc-client = "4"
 derive_more = { version = "1", features = ["deref"] }
 hex-literal = "1"
+jsonschema = "0.30"
 litesvm = "0.15"
 litesvm-token = "0.15"
 num_enum = "0.7"
 pinocchio = "0.11"
 pinocchio-system = "0.6"
 pinocchio-token = "0.6"
 proptest = "1"
+serde_json = { version = "1", features = ["preserve_order"] }
 cow-settlement-client = { path = "client", version = "0.2.0" }
 cow-settlement-interface = { path = "interface", version = "0.2.0" }
 solana-account-view = "2"
@@ -57,6 +59,7 @@ solana-system-interface = "3"
 spl-associated-token-account-interface = "2"
 spl-token = "9"
 spl-token-interface = "3"
+syn = { version = "2", features = ["full"] }
 
 [workspace.metadata.cli]
 # Used to help solana-verify identify the correct build image.

interface/src/data/intent.rs

@@ -32,6 +32,9 @@ pub enum OrderKind {
     Buy = 1,
 }
 
+/// Canonical order intent. Also the exact bytes hashed (SHA-256) to produce the order UID used in the order PDA's seeds,
+/// and the exact wire format of create_order's `intent` argument. Field order and encoding here are load-bearing: they
+/// must match this program's Rust definition exactly.
 #[derive(Clone, Debug, Eq, PartialEq, Default)]
 pub struct OrderIntent {
     /// Account authorized to create and invalidate this order and whose