feat: local engine (#10803)

crates/payload/primitives/src/lib.rs

@@ -15,7 +15,9 @@ pub use error::{EngineObjectValidationError, PayloadBuilderError, VersionSpecifi
 /// Contains traits to abstract over payload attributes types and default implementations of the
 /// [`PayloadAttributes`] trait for ethereum mainnet and optimism types.
 mod traits;
-pub use traits::{BuiltPayload, PayloadAttributes, PayloadBuilderAttributes};
+pub use traits::{
+    BuiltPayload, PayloadAttributes, PayloadAttributesBuilder, PayloadBuilderAttributes,
+};
 
 mod payload;
 pub use payload::PayloadOrAttributes;

crates/payload/primitives/src/traits.rs

@@ -145,3 +145,14 @@ impl PayloadAttributes for OptimismPayloadAttributes {
         Ok(())
     }
 }
+
+/// A builder that can return the current payload attribute.
+pub trait PayloadAttributesBuilder: std::fmt::Debug + Send + Sync + 'static {
+    /// The payload attributes type returned by the builder.
+    type PayloadAttributes: PayloadAttributes;
+    /// The error type returned by [`PayloadAttributesBuilder::build`].
+    type Error: std::error::Error + Send + Sync;
+
+    /// Return a new payload attribute from the builder.
+    fn build(&self) -> Result<Self::PayloadAttributes, Self::Error>;
+}