chore: 修复 clippy 错误（loop never loops → if-let）并应用自动修复

src/llm/provider.rs

@@ -159,16 +159,16 @@ pub(crate) fn parse_chat_chunk(line: &str) -> Option<ParsedChunk> {
     };
 
     // 提取 usage（可能在最后一个 chunk）
-    if let Some(ref usage) = parsed.usage {
-        if usage.total_tokens > 0 {
+    if let Some(ref usage) = parsed.usage
+        && usage.total_tokens > 0 {
             return Some(ParsedChunk::Usage(usage.clone()));
         }
-    }
 
-    for choice in parsed.choices {
+    // SSE 流式响应中每个 chunk 只包含一个 choice 的 delta
+    if let Some(choice) = parsed.choices.into_iter().next() {
         // 工具调用 delta
-        if let Some(tool_calls) = &choice.delta.tool_calls {
-            for tc in tool_calls {
+        if let Some(tool_calls) = &choice.delta.tool_calls
+            && let Some(tc) = tool_calls.first() {
                 let idx = tc.index.unwrap_or(0);
                 let args = tc
                     .function
@@ -183,23 +183,19 @@ pub(crate) fn parse_chat_chunk(line: &str) -> Option<ParsedChunk> {
                     arguments: args,
                 });
             }
-        }
 
-        if let Some(reasoning) = &choice.delta.reasoning_content {
-            if !reasoning.is_empty() {
+        if let Some(reasoning) = &choice.delta.reasoning_content
+            && !reasoning.is_empty() {
                 return Some(ParsedChunk::Reasoning(reasoning.clone()));
             }
-        }
-        if let Some(content) = &choice.delta.content {
-            if !content.is_empty() {
+        if let Some(content) = &choice.delta.content
+            && !content.is_empty() {
                 return Some(ParsedChunk::Text(content.clone()));
             }
-        }
-        if let Some(reason) = &choice.finish_reason {
-            if !reason.is_empty() {
+        if let Some(reason) = &choice.finish_reason
+            && !reason.is_empty() {
                 return Some(ParsedChunk::FinishReason(reason.clone()));
             }
-        }
     }
 
     None