Agent: one turn path, tools and history in their own modules; SDK: one parser

sdk/src/lib.rs

@@ -26,6 +26,14 @@ impl Message {
     }
 }
 
+fn parse(line: &[u8]) -> Option<Message> {
+    serde_json::from_slice::<Message>(line).ok()
+}
+
+fn is_shutdown(message: &Message) -> bool {
+    message.from == "broker" && message.kind() == "shutdown"
+}
+
 /// Return this actor's ID from `SAUSAGE_ACTOR`, or an empty string if unset.
 pub fn me() -> String {
     std::env::var("SAUSAGE_ACTOR").unwrap_or_default()
@@ -39,17 +47,13 @@ pub fn messages() -> impl Iterator<Item = Message> {
     let mut lines = stdin.lock().lines();
     std::iter::from_fn(move || {
         loop {
-            let line = match lines.next()? {
-                Ok(line) => line,
-                Err(_) => continue,
-            };
-            let Ok(message) = serde_json::from_str::<Message>(&line) else {
+            let Ok(line) = lines.next()? else {
                 continue;
             };
-            if message.from == "broker" && message.kind() == "shutdown" {
-                return None;
-            }
-            return Some(message);
+            let Some(message) = parse(line.as_bytes()) else {
+                continue;
+            };
+            return (!is_shutdown(&message)).then_some(message);
         }
     })
 }
@@ -153,11 +157,12 @@ async fn read_messages(tx: async_channel::Sender<Message>) {
         }
         buf.extend_from_slice(&chunk[..n]);
         while let Some(pos) = buf.iter().position(|b| *b == b'\n') {
-            let line: Vec<_> = buf.drain(..=pos).collect();
-            let Ok(message) = serde_json::from_slice::<Message>(&line) else {
+            let message = parse(&buf[..pos]);
+            buf.drain(..=pos);
+            let Some(message) = message else {
                 continue;
             };
-            if message.from == "broker" && message.kind() == "shutdown" {
+            if is_shutdown(&message) {
                 tx.close();
                 return;
             }
@@ -166,13 +171,6 @@ async fn read_messages(tx: async_channel::Sender<Message>) {
             }
         }
     }
-    if let Ok(message) = serde_json::from_slice::<Message>(&buf) {
-        if message.from == "broker" && message.kind() == "shutdown" {
-            tx.close();
-            return;
-        }
-        let _ = tx.send(message).await;
-    }
     tx.close();
 }