feat: opt-in to vercel ai gateway leaderboard (#9259)

crates/goose/src/config/declarative_providers.rs

@@ -849,6 +849,16 @@ mod tests {
         );
         assert_eq!(config.supports_streaming, Some(true));
         assert!(!config.models.is_empty());
+
+        let headers = config
+            .headers
+            .as_ref()
+            .expect("vercel_ai_gateway should set attribution headers");
+        assert_eq!(
+            headers.get("http-referer").map(String::as_str),
+            Some("https://goose-docs.ai")
+        );
+        assert_eq!(headers.get("x-title").map(String::as_str), Some("goose"));
     }
 
     #[test]

crates/goose/src/providers/declarative/vercel_ai_gateway.json

@@ -5,6 +5,10 @@
   "description": "Unified gateway to OpenAI, Anthropic, Google, xAI, and many more frontier models via Vercel AI Gateway",
   "api_key_env": "AI_GATEWAY_API_KEY",
   "base_url": "https://ai-gateway.vercel.sh/v1/chat/completions",
+  "headers": {
+    "http-referer": "https://goose-docs.ai",
+    "x-title": "goose"
+  },
   "models": [
     {
       "name": "anthropic/claude-sonnet-4.6",