revert /reply to previous behavior (replacing session history) when full conversation provided (#6058)

crates/goose-server/src/routes/reply.rs

@@ -75,7 +75,9 @@ fn track_tool_telemetry(content: &MessageContent, all_messages: &[Message]) {
 
 #[derive(Debug, Deserialize, Serialize, utoipa::ToSchema)]
 pub struct ChatRequest {
-    messages: Vec<Message>,
+    user_message: Message,
+    #[serde(default)]
+    conversation_so_far: Option<Vec<Message>>,
     session_id: String,
     recipe_name: Option<String>,
     recipe_version: Option<String>,
@@ -233,7 +235,8 @@ pub async fn reply(
     let stream = ReceiverStream::new(rx);
     let cancel_token = CancellationToken::new();
 
-    let messages = Conversation::new_unvalidated(request.messages);
+    let user_message = request.user_message;
+    let conversation_so_far = request.conversation_so_far;
 
     let task_cancel = cancel_token.clone();
     let task_tx = tx.clone();
@@ -255,7 +258,7 @@ pub async fn reply(
             }
         };
 
-        let session = match SessionManager::get_session(&session_id, false).await {
+        let session = match SessionManager::get_session(&session_id, true).await {
             Ok(metadata) => metadata,
             Err(e) => {
                 tracing::error!("Failed to read session for {}: {}", session_id, e);
@@ -278,20 +281,21 @@ pub async fn reply(
             retry_config: None,
         };
 
-        let user_message = match messages.last() {
-            Some(msg) => msg,
-            _ => {
-                let _ = stream_event(
-                    MessageEvent::Error {
-                        error: "Reply started with empty messages".to_string(),
-                    },
-                    &task_tx,
-                    &task_cancel,
-                )
-                .await;
-                return;
+        let mut all_messages = match conversation_so_far {
+            Some(history) => {
+                let conv = Conversation::new_unvalidated(history);
+                if let Err(e) = SessionManager::replace_conversation(&session_id, &conv).await {
+                    tracing::warn!(
+                        "Failed to replace session conversation for {}: {}",
+                        session_id,
+                        e
+                    );
+                }
+                conv
             }
+            None => session.conversation.unwrap_or_default(),
         };
+        all_messages.push(user_message.clone());
 
         let mut stream = match agent
             .reply(
@@ -316,8 +320,6 @@ pub async fn reply(
             }
         };
 
-        let mut all_messages = messages.clone();
-
         let mut heartbeat_interval = tokio::time::interval(Duration::from_millis(500));
         loop {
             tokio::select! {
@@ -478,7 +480,8 @@ mod tests {
                 .header("x-secret-key", "test-secret")
                 .body(Body::from(
                     serde_json::to_string(&ChatRequest {
-                        messages: vec![Message::user().with_text("test message")],
+                        user_message: Message::user().with_text("test message"),
+                        conversation_so_far: None,
                         session_id: "test-session".to_string(),
                         recipe_name: None,
                         recipe_version: None,