Streaming tool calls (#29179)

https://github.com/user-attachments/assets/7854a737-ef83-414c-b397-45122e4f32e8



Release Notes:

- Create file and edit file tools now stream their tool descriptions, so
you can see what they're doing sooner.

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/assistant_tools/src/edit_file_tool.rs

@@ -47,8 +47,22 @@ pub struct EditFileToolInput {
     pub new_string: String,
 }
 
+#[derive(Debug, Serialize, Deserialize, JsonSchema)]
+struct PartialInput {
+    #[serde(default)]
+    path: String,
+    #[serde(default)]
+    display_description: String,
+    #[serde(default)]
+    old_string: String,
+    #[serde(default)]
+    new_string: String,
+}
+
 pub struct EditFileTool;
 
+const DEFAULT_UI_TEXT: &str = "Edit file";
+
 impl Tool for EditFileTool {
     fn name(&self) -> String {
         "edit_file".into()
@@ -77,6 +91,22 @@ impl Tool for EditFileTool {
         }
     }
 
+    fn still_streaming_ui_text(&self, input: &serde_json::Value) -> String {
+        if let Some(input) = serde_json::from_value::<PartialInput>(input.clone()).ok() {
+            let description = input.display_description.trim();
+            if !description.is_empty() {
+                return description.to_string();
+            }
+
+            let path = input.path.trim();
+            if !path.is_empty() {
+                return path.to_string();
+            }
+        }
+
+        DEFAULT_UI_TEXT.to_string()
+    }
+
     fn run(
         self: Arc<Self>,
         input: serde_json::Value,
@@ -181,3 +211,69 @@ impl Tool for EditFileTool {
         }).into()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    #[test]
+    fn still_streaming_ui_text_with_path() {
+        let tool = EditFileTool;
+        let input = json!({
+            "path": "src/main.rs",
+            "display_description": "",
+            "old_string": "old code",
+            "new_string": "new code"
+        });
+
+        assert_eq!(tool.still_streaming_ui_text(&input), "src/main.rs");
+    }
+
+    #[test]
+    fn still_streaming_ui_text_with_description() {
+        let tool = EditFileTool;
+        let input = json!({
+            "path": "",
+            "display_description": "Fix error handling",
+            "old_string": "old code",
+            "new_string": "new code"
+        });
+
+        assert_eq!(tool.still_streaming_ui_text(&input), "Fix error handling");
+    }
+
+    #[test]
+    fn still_streaming_ui_text_with_path_and_description() {
+        let tool = EditFileTool;
+        let input = json!({
+            "path": "src/main.rs",
+            "display_description": "Fix error handling",
+            "old_string": "old code",
+            "new_string": "new code"
+        });
+
+        assert_eq!(tool.still_streaming_ui_text(&input), "Fix error handling");
+    }
+
+    #[test]
+    fn still_streaming_ui_text_no_path_or_description() {
+        let tool = EditFileTool;
+        let input = json!({
+            "path": "",
+            "display_description": "",
+            "old_string": "old code",
+            "new_string": "new code"
+        });
+
+        assert_eq!(tool.still_streaming_ui_text(&input), DEFAULT_UI_TEXT);
+    }
+
+    #[test]
+    fn still_streaming_ui_text_with_null() {
+        let tool = EditFileTool;
+        let input = serde_json::Value::Null;
+
+        assert_eq!(tool.still_streaming_ui_text(&input), DEFAULT_UI_TEXT);
+    }
+}