fix(providers): cap deepseek-cp max_tokens for DashScope compat

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/goose-providers/src/openai.rs

@@ -439,6 +439,7 @@ impl OpenAiProvider {
     const PROVIDERS_NEEDING_MAX_TOKENS_REMAP: &[&str] = &[
         "cerebras",
         "custom_deepseek",
+        "custom_deepseek-cp",
         "groq",
         "inception",
         "kimi",
@@ -449,6 +450,23 @@ impl OpenAiProvider {
         "ovhcloud",
     ];
 
+    /// DashScope / Memind relay rejects max_tokens above 131072 for DeepSeek V4.
+    const DASHSCOPE_COMPAT_MAX_TOKENS: i32 = 131_072;
+
+    const PROVIDERS_DASHSCOPE_MAX_TOKENS_CAP: &[&str] = &["custom_deepseek", "custom_deepseek-cp"];
+
+    fn cap_token_limits_for_dashscope_compat(obj: &mut serde_json::Map<String, serde_json::Value>) {
+        for key in ["max_tokens", "max_completion_tokens"] {
+            if let Some(value) = obj.get_mut(key) {
+                if let Some(n) = value.as_i64() {
+                    if n > i64::from(Self::DASHSCOPE_COMPAT_MAX_TOKENS) {
+                        *value = json!(Self::DASHSCOPE_COMPAT_MAX_TOKENS);
+                    }
+                }
+            }
+        }
+    }
+
     const PROVIDERS_NEEDING_STANDARD_CHAT_PARAMS: &[&str] = &["nearai", "pleumrouter"];
 
     /// Providers whose reasoning models accept an OpenAI-style
@@ -524,6 +542,10 @@ impl OpenAiProvider {
                     }
                 }
             }
+
+            if Self::PROVIDERS_DASHSCOPE_MAX_TOKENS_CAP.contains(&self.name.as_str()) {
+                Self::cap_token_limits_for_dashscope_compat(obj);
+            }
         }
 
         payload
@@ -1039,6 +1061,39 @@ mod tests {
         }
     }
 
+    #[test]
+    fn sanitize_caps_deepseek_cp_max_tokens_for_dashscope() {
+        let provider = make_provider("custom_deepseek-cp");
+        let payload = json!({
+            "model": "deepseek-v4-flash",
+            "messages": [],
+            "max_tokens": 384000
+        });
+
+        let result =
+            provider.sanitize_request_for_compat(payload, &ModelConfig::new("deepseek-v4-flash"));
+        let obj = result.as_object().unwrap();
+
+        assert_eq!(obj.get("max_tokens").unwrap(), &json!(131_072));
+    }
+
+    #[test]
+    fn sanitize_caps_deepseek_cp_max_completion_tokens_for_dashscope() {
+        let provider = make_provider("custom_deepseek-cp");
+        let payload = json!({
+            "model": "deepseek-v4-flash",
+            "messages": [],
+            "max_completion_tokens": 384000
+        });
+
+        let result =
+            provider.sanitize_request_for_compat(payload, &ModelConfig::new("deepseek-v4-flash"));
+        let obj = result.as_object().unwrap();
+
+        assert_eq!(obj.get("max_tokens").unwrap(), &json!(131_072));
+        assert!(!obj.contains_key("max_completion_tokens"));
+    }
+
     #[test]
     fn sanitize_remaps_max_completion_tokens_for_compat_provider() {
         let provider = make_provider("mistral");