修复DeepSeek Anthropic 端点在 thinking 模式下，多轮对话返回 HTTP 400

desktop/gateway/src/policy.rs

@@ -21,17 +21,35 @@ pub fn normalize_thinking(body: &mut Value) {
         body["thinking"] = serde_json::json!({"type": "disabled"});
         return;
     }
-    if body
-        .get("thinking")
-        .and_then(Value::as_object)
-        .and_then(|th| th.get("type"))
-        .and_then(Value::as_str)
-        == Some("auto")
-    {
-        if let Some(thinking) = body.get_mut("thinking").and_then(Value::as_object_mut) {
-            thinking.insert("type".to_string(), Value::String("adaptive".to_string()));
+    // Claude Science sends "auto"; DeepSeek's Anthropic endpoint handles it
+    // natively — no provider-specific remapping needed.
+}
+
+/// Check whether the thinking chain is broken: any assistant message that
+/// contains tool_use but is missing thinking blocks means Claude Science
+/// already stripped them (native Anthropic semantics). DeepSeek requires
+/// thinking to be echoed back when tool_use was present, so further
+/// thinking must be disabled for this request.
+fn thinking_chain_broken(messages: &Value) -> bool {
+    let Some(arr) = messages.as_array() else {
+        return false;
+    };
+    arr.iter().any(|msg| {
+        let role = msg.get("role").and_then(Value::as_str).unwrap_or("");
+        if role != "assistant" {
+            return false;
         }
-    }
+        let Some(items) = msg.get("content").and_then(Value::as_array) else {
+            return false;
+        };
+        let has_tool_use = items
+            .iter()
+            .any(|item| item.get("type").and_then(Value::as_str) == Some("tool_use"));
+        let has_thinking = items
+            .iter()
+            .any(|item| item.get("type").and_then(Value::as_str) == Some("thinking"));
+        has_tool_use && !has_thinking
+    })
 }
 
 pub fn transform_request(mut body: Value, target_model: &str) -> Result<Vec<u8>, String> {
@@ -51,12 +69,15 @@ pub fn transform_request(mut body: Value, target_model: &str) -> Result<Vec<u8>,
         );
     }
     normalize_thinking(&mut body);
+    if thinking_chain_broken(&body["messages"]) {
+        body["thinking"] = serde_json::json!({"type": "disabled"});
+    }
     serde_json::to_vec(&body).map_err(|e| e.to_string())
 }
 
 #[cfg(test)]
 mod tests {
-    use super::{clamp_max_tokens, transform_request};
+    use super::{clamp_max_tokens, thinking_chain_broken, transform_request};
     use serde_json::json;
 
     #[test]
@@ -80,7 +101,7 @@ mod tests {
         let v: serde_json::Value = serde_json::from_slice(&bytes).unwrap();
         assert_eq!(v["model"], "deepseek-v4-pro");
         assert_eq!(v["max_tokens"], 65536);
-        assert_eq!(v["thinking"]["type"], "adaptive");
+        assert_eq!(v["thinking"]["type"], "auto");
     }
 
     #[test]
@@ -95,4 +116,62 @@ mod tests {
         let v: serde_json::Value = serde_json::from_slice(&bytes).unwrap();
         assert_eq!(v["thinking"]["type"], "disabled");
     }
+
+    #[test]
+    fn chain_intact_when_tool_use_has_thinking() {
+        let messages = json!([
+            {"role": "user", "content": "hello"},
+            {"role": "assistant", "content": [
+                {"type": "thinking", "thinking": "I'll use a tool", "signature": "sig"},
+                {"type": "tool_use", "id": "t1", "name": "read", "input": {}}
+            ]},
+            {"role": "user", "content": "more"}
+        ]);
+        assert!(!thinking_chain_broken(&messages));
+    }
+
+    #[test]
+    fn chain_broken_when_tool_use_missing_thinking() {
+        // Science stripped thinking → broken
+        let messages = json!([
+            {"role": "user", "content": "hello"},
+            {"role": "assistant", "content": [
+                {"type": "tool_use", "id": "t1", "name": "read", "input": {}}
+            ]},
+            {"role": "user", "content": "more"}
+        ]);
+        assert!(thinking_chain_broken(&messages));
+    }
+
+    #[test]
+    fn chain_intact_without_tool_use() {
+        let messages = json!([
+            {"role": "user", "content": "hello"},
+            {"role": "assistant", "content": [
+                {"type": "thinking", "thinking": "hmm", "signature": "sig"},
+                {"type": "text", "text": "hi"}
+            ]},
+            {"role": "user", "content": "more"}
+        ]);
+        assert!(!thinking_chain_broken(&messages));
+    }
+
+    #[test]
+    fn chain_broken_disables_thinking_in_transform() {
+        let raw = json!({
+            "model": "claude-sonnet-5",
+            "max_tokens": 1000,
+            "thinking": {"type": "auto"},
+            "messages": [
+                {"role": "user", "content": "hello"},
+                {"role": "assistant", "content": [
+                    {"type": "tool_use", "id": "t1", "name": "read", "input": {}}
+                ]},
+                {"role": "user", "content": "more"}
+            ]
+        });
+        let bytes = transform_request(raw, "deepseek-v4-pro").unwrap();
+        let v: serde_json::Value = serde_json::from_slice(&bytes).unwrap();
+        assert_eq!(v["thinking"]["type"], "disabled");
+    }
 }