Add Rust domain kernel and wire contracts

crates/remora-domain/src/id.rs

@@ -0,0 +1,73 @@
+use std::{fmt, str::FromStr};
+
+use serde::{Deserialize, Deserializer, Serialize, Serializer, de::Error as _};
+
+#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
+pub struct OpaqueId(String);
+
+impl OpaqueId {
+    pub fn parse(value: impl Into<String>) -> Result<Self, IdError> {
+        let value = value.into();
+        let mut chars = value.chars();
+        let Some(first) = chars.next() else {
+            return Err(IdError);
+        };
+        if !(8..=128).contains(&value.len())
+            || !first.is_ascii_alphanumeric()
+            || !chars.all(|character| {
+                character.is_ascii_alphanumeric() || matches!(character, '_' | '-')
+            })
+        {
+            return Err(IdError);
+        }
+        Ok(Self(value))
+    }
+
+    #[must_use]
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+impl fmt::Display for OpaqueId {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(formatter)
+    }
+}
+
+impl FromStr for OpaqueId {
+    type Err = IdError;
+
+    fn from_str(value: &str) -> Result<Self, Self::Err> {
+        Self::parse(value)
+    }
+}
+
+impl Serialize for OpaqueId {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&self.0)
+    }
+}
+
+impl<'de> Deserialize<'de> for OpaqueId {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Self::parse(String::deserialize(deserializer)?).map_err(D::Error::custom)
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct IdError;
+
+impl fmt::Display for IdError {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.write_str("invalid opaque identifier")
+    }
+}
+
+impl std::error::Error for IdError {}