OpenAI wire format: no name on tool messages (opencode/Anthropic rejected it)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -13,6 +13,9 @@ until 1.0, minor versions may contain breaking changes.
 
 ### Fixed
 
+- OpenAI-compatible providers: tool results no longer carry a `name` field. Gateways that
+  translate to Anthropic (opencode) rejected the request with "anthropic-messages cannot
+  preserve named conversation participants".
 - Telegram: the token field is no longer filled in by the browser's password manager, the bot
   token is found in whatever is pasted (also the whole BotFather message), and a wrong format
   gets a clear message instead of "HTTP 404".

core/src/provider/openai.rs

@@ -47,10 +47,13 @@ pub fn to_wire_messages(system: &str, messages: &[Message]) -> Vec<Value> {
                         Part::Image { image } => parts.push(json!({
                             "type": "image_url", "image_url": {"url": data_url(image)}
                         })),
-                        Part::ToolResult { call_id, name, content, images, is_error, .. } => {
+                        Part::ToolResult { call_id, content, images, is_error, .. } => {
                             let text = if *is_error { format!("ERROR: {content}") } else { content.clone() };
+                            // No "name": it is not part of the tool message in the Chat
+                            // Completions API, and gateways that translate to Anthropic
+                            // (opencode) reject named participants.
                             out.push(json!({
-                                "role": "tool", "tool_call_id": call_id, "name": name,
+                                "role": "tool", "tool_call_id": call_id,
                                 "content": if text.is_empty() { "(no output)".into() } else { text }
                             }));
                             tool_images.extend(images.iter().cloned());
@@ -328,6 +331,22 @@ mod tests {
         (text, reasoning)
     }
 
+    #[test]
+    fn tool_messages_have_no_name() {
+        use crate::types::{Message, Part, Role};
+        let call = Part::ToolCall { id: "c1".into(), name: "bash".into(), input: serde_json::json!({"command": "ls"}), extra: None };
+        let result = Part::ToolResult { call_id: "c1".into(), name: "bash".into(), content: "ok".into(), images: vec![], is_error: false, meta: None };
+        let msgs = vec![
+            Message::new(Role::User, vec![Part::Text { text: "hi".into() }]),
+            Message::new(Role::Assistant, vec![call]),
+            Message::new(Role::User, vec![result]),
+        ];
+        let wire = super::to_wire_messages("sys", &msgs);
+        let tool = wire.iter().find(|m| m["role"] == "tool").expect("tool message");
+        assert_eq!(tool["tool_call_id"], "c1");
+        assert!(wire.iter().all(|m| m.get("name").is_none()), "no message may carry a name: {wire:?}");
+    }
+
     #[test]
     fn splits_think_tags_across_chunks() {
         let (text, reasoning) = run(&["<thi", "nk>plan ", "the fix</th", "ink>Here is ", "the answer."]);