fix: wrong thinking labels appear in non-thinking models (#861)

relay/channel/openai/adaptor.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/gin-gonic/gin"
 	"io"
 	"mime/multipart"
 	"net/http"
@@ -23,6 +22,8 @@ import (
 	"one-api/relay/constant"
 	"one-api/service"
 	"strings"
+
+	"github.com/gin-gonic/gin"
 )
 
 type Adaptor struct {
@@ -48,6 +49,15 @@ func (a *Adaptor) ConvertClaudeRequest(c *gin.Context, info *relaycommon.RelayIn
 
 func (a *Adaptor) Init(info *relaycommon.RelayInfo) {
 	a.ChannelType = info.ChannelType
+
+	// initialize ThinkingContentInfo when thinking_to_content is enabled
+	if think2Content, ok := info.ChannelSetting[constant2.ChannelSettingThinkingToContent].(bool); ok && think2Content {
+		info.ThinkingContentInfo = relaycommon.ThinkingContentInfo{
+			IsFirstThinkingContent:  true,
+			SendLastThinkingContent: false,
+			HasSentThinkingContent:  false,
+		}
+	}
 }
 
 func (a *Adaptor) GetRequestURL(info *relaycommon.RelayInfo) (string, error) {

relay/channel/openai/relay-openai.go

@@ -65,6 +65,7 @@ func sendStreamData(c *gin.Context, info *relaycommon.RelayInfo, data string, fo
 				response.Choices[i].Delta.Reasoning = nil
 			}
 			info.ThinkingContentInfo.IsFirstThinkingContent = false
+			info.ThinkingContentInfo.HasSentThinkingContent = true
 			return helper.ObjectData(c, response)
 		}
 	}
@@ -76,7 +77,8 @@ func sendStreamData(c *gin.Context, info *relaycommon.RelayInfo, data string, fo
 	// Process each choice
 	for i, choice := range lastStreamResponse.Choices {
 		// Handle transition from thinking to content
-		if hasContent && !info.ThinkingContentInfo.SendLastThinkingContent {
+		// only send `</think>` tag when previous thinking content has been sent
+		if hasContent && !info.ThinkingContentInfo.SendLastThinkingContent && info.ThinkingContentInfo.HasSentThinkingContent {
 			response := lastStreamResponse.Copy()
 			for j := range response.Choices {
 				response.Choices[j].Delta.SetContentString("\n</think>\n")
@@ -87,7 +89,7 @@ func sendStreamData(c *gin.Context, info *relaycommon.RelayInfo, data string, fo
 			helper.ObjectData(c, response)
 		}
 
-		// Convert reasoning content to regular content
+		// Convert reasoning content to regular content if any
 		if len(choice.Delta.GetReasoningContent()) > 0 {
 			lastStreamResponse.Choices[i].Delta.SetContentString(choice.Delta.GetReasoningContent())
 			lastStreamResponse.Choices[i].Delta.ReasoningContent = nil