fix: propagate bincode encode errors instead of silently dropping payload

Cargo.toml

@@ -6,7 +6,7 @@ members = ["crates/aerro", "crates/aerro-macros"]
 # (Reserved for workspace-wide clippy overrides; currently none.)
 
 [workspace.package]
-version = "0.6.2"
+version = "0.6.3"
 edition = "2024"
 rust-version = "1.85"
 license = "MIT OR Apache-2.0"

crates/aerro-macros/src/codegen/aerro_impl.rs

@@ -88,7 +88,7 @@ pub fn emit_aerro_impl(cfg: &EnumCfg) -> TokenStream {
                 }
             }
 
-            fn encode_payload(&self, __route: ::aerro::Exposure, __buf: &mut ::std::vec::Vec<u8>) {
+            fn encode_payload(&self, __route: ::aerro::Exposure, __buf: &mut ::std::vec::Vec<u8>) -> ::core::result::Result<(), ::aerro::EncodeError> {
                 let _ = __route;
                 match self {
                     #(#encode_arms)*
@@ -132,7 +132,7 @@ fn encode_payload_arm(v: &VariantCfg) -> TokenStream {
     if v.fields.is_empty() {
         return quote! {
             Self::#variant => {
-                // No payload to encode.
+                ::core::result::Result::Ok(())
             }
         };
     }
@@ -156,11 +156,10 @@ fn encode_payload_arm(v: &VariantCfg) -> TokenStream {
         quote! {
             Self::#variant #pat => {
                 let __tup = ( #(#payload_exprs ,)* );
-                if let ::core::result::Result::Ok(__bytes) =
-                    ::bincode::encode_to_vec(&__tup, ::bincode::config::standard())
-                {
-                    __buf.extend_from_slice(&__bytes);
-                }
+                let __bytes = ::bincode::encode_to_vec(&__tup, ::bincode::config::standard())
+                    .map_err(|e| ::aerro::EncodeError(e.to_string()))?;
+                __buf.extend_from_slice(&__bytes);
+                ::core::result::Result::Ok(())
             }
         }
     } else {
@@ -177,11 +176,10 @@ fn encode_payload_arm(v: &VariantCfg) -> TokenStream {
         quote! {
             Self::#variant #pat => {
                 let __tup = ( #(#payload_exprs ,)* );
-                if let ::core::result::Result::Ok(__bytes) =
-                    ::bincode::encode_to_vec(&__tup, ::bincode::config::standard())
-                {
-                    __buf.extend_from_slice(&__bytes);
-                }
+                let __bytes = ::bincode::encode_to_vec(&__tup, ::bincode::config::standard())
+                    .map_err(|e| ::aerro::EncodeError(e.to_string()))?;
+                __buf.extend_from_slice(&__bytes);
+                ::core::result::Result::Ok(())
             }
         }
     }

crates/aerro/src/remote.rs

@@ -106,7 +106,9 @@ mod tests {
     fn downcast_recovers_known_type() {
         use crate::Exposure;
         let mut buf = Vec::new();
-        Boom { x: 7 }.encode_payload(Exposure::Internal, &mut buf);
+        Boom { x: 7 }
+            .encode_payload(Exposure::Internal, &mut buf)
+            .unwrap();
         let r = make(RemoteErrorParts {
             category: Category::System,
             type_id: "toy.boom".into(),

crates/aerro/src/test_support.rs

@@ -26,9 +26,15 @@ impl Aerro for Boom {
         Code::Internal
     }
 
-    fn encode_payload(&self, _route: Exposure, buf: &mut Vec<u8>) {
-        let bytes = bincode::encode_to_vec(self, bincode::config::standard()).unwrap();
+    fn encode_payload(
+        &self,
+        _route: Exposure,
+        buf: &mut Vec<u8>,
+    ) -> Result<(), crate::EncodeError> {
+        let bytes = bincode::encode_to_vec(self, bincode::config::standard())
+            .map_err(|e| crate::EncodeError(e.to_string()))?;
         buf.extend_from_slice(&bytes);
+        Ok(())
     }
 
     fn decode_payload(type_id: &str, bytes: &[u8]) -> Result<Self, DecodeError> {

crates/aerro/src/traits/aerro.rs

@@ -2,7 +2,10 @@
 
 use tonic::Code;
 
-use crate::{Category, Exposure, error::DecodeError};
+use crate::{
+    Category, Exposure,
+    error::{DecodeError, EncodeError},
+};
 
 /// Universal trait implemented by every typed error.
 ///
@@ -31,7 +34,7 @@ pub trait Aerro: std::error::Error + Send + Sync + 'static {
     /// Encode the variant's payload into bincode bytes. `route` is the
     /// exposure level of the destination; fields marked `#[aerro(redact)]`
     /// are replaced with `Default::default()` whenever `route != Internal`.
-    fn encode_payload(&self, route: Exposure, buf: &mut Vec<u8>);
+    fn encode_payload(&self, route: Exposure, buf: &mut Vec<u8>) -> Result<(), EncodeError>;
 
     /// Decode a typed variant from a `type_id` + bincode bytes.
     fn decode_payload(type_id: &str, bytes: &[u8]) -> Result<Self, DecodeError>

crates/aerro/src/wire/decode.rs

@@ -138,7 +138,13 @@ mod tests {
             fn code(&self) -> Code {
                 Code::NotFound
             }
-            fn encode_payload(&self, _: crate::Exposure, _: &mut Vec<u8>) {}
+            fn encode_payload(
+                &self,
+                _: crate::Exposure,
+                _: &mut Vec<u8>,
+            ) -> Result<(), crate::EncodeError> {
+                Ok(())
+            }
             fn decode_payload(_: &str, _: &[u8]) -> Result<Self, crate::DecodeError> {
                 Err(crate::DecodeError::Missing)
             }

crates/aerro/src/wire/encode.rs

@@ -1,7 +1,7 @@
 //! `ServiceFailure<E>` → `tonic::Status` encoding — see spec §6, §9.
 
 use prost::Message;
-use tonic::Status;
+use tonic::{Code, Status};
 
 use crate::{Aerro, Category, Exposure, Frame, ServiceFailure};
 
@@ -40,7 +40,9 @@ pub fn encode<E: Aerro>(sf: &ServiceFailure<E>, opts: &EncodeOptions) -> Status
     let outer_msg = redact_message(&sf.inner, route);
 
     let mut payload = Vec::new();
-    sf.inner.encode_payload(route, &mut payload);
+    if let Err(e) = sf.inner.encode_payload(route, &mut payload) {
+        return Status::new(Code::Internal, format!("aerro: encode failed: {e}"));
+    }
 
     let wire_frames = if route == Exposure::Public {
         Vec::new()