feat: neuron-rs — Rust runtime, Engram-backed, Axon protocol

crates/neuron-protocol/src/sse.rs

@@ -0,0 +1,47 @@
+use crate::axon::AxonEvent;
+use tokio::sync::broadcast;
+
+/// SSE channel — broadcasts AxonEvents to all connected SSE clients.
+#[derive(Clone)]
+pub struct SseChannel {
+    sender: broadcast::Sender<String>,
+}
+
+impl SseChannel {
+    pub fn new(capacity: usize) -> Self {
+        let (sender, _) = broadcast::channel(capacity);
+        Self { sender }
+    }
+
+    /// Send an event to all subscribers.
+    pub fn send(&self, event: &AxonEvent) -> Result<(), String> {
+        let json = serde_json::to_string(event).map_err(|e| e.to_string())?;
+        // Ignore errors when no receivers are connected
+        let _ = self.sender.send(json);
+        Ok(())
+    }
+
+    /// Subscribe to the SSE channel.
+    pub fn subscribe(&self) -> broadcast::Receiver<String> {
+        self.sender.subscribe()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn sse_channel_broadcast() {
+        let ch = SseChannel::new(16);
+        let mut rx = ch.subscribe();
+
+        let event = AxonEvent::new("test", serde_json::json!({ "msg": "hello" }));
+        ch.send(&event).unwrap();
+
+        let received = rx.recv().await.unwrap();
+        let parsed: serde_json::Value = serde_json::from_str(&received).unwrap();
+        assert_eq!(parsed["event_type"], "test");
+        assert_eq!(parsed["payload"]["msg"], "hello");
+    }
+}