diff --git a/pkg/providers/openai_compat/provider.go b/pkg/providers/openai_compat/provider.go
index 22cd98bb4..4555c4267 100644
--- a/pkg/providers/openai_compat/provider.go
+++ b/pkg/providers/openai_compat/provider.go
@@ -283,10 +283,11 @@ func parseResponse(body []byte) (*LLMResponse, error) {
 // It mirrors protocoltypes.Message but omits SystemParts, which is an
 // internal field that would be unknown to third-party endpoints.
 type openaiMessage struct {
-	Role       string     `json:"role"`
-	Content    string     `json:"content"`
-	ToolCalls  []ToolCall `json:"tool_calls,omitempty"`
-	ToolCallID string     `json:"tool_call_id,omitempty"`
+	Role             string     `json:"role"`
+	Content          string     `json:"content"`
+	ReasoningContent string     `json:"reasoning_content,omitempty"`
+	ToolCalls        []ToolCall `json:"tool_calls,omitempty"`
+	ToolCallID       string     `json:"tool_call_id,omitempty"`
 }
 
 // stripSystemParts converts []Message to []openaiMessage, dropping the
@@ -296,10 +297,11 @@ func stripSystemParts(messages []Message) []openaiMessage {
 	out := make([]openaiMessage, len(messages))
 	for i, m := range messages {
 		out[i] = openaiMessage{
-			Role:       m.Role,
-			Content:    m.Content,
-			ToolCalls:  m.ToolCalls,
-			ToolCallID: m.ToolCallID,
+			Role:             m.Role,
+			Content:          m.Content,
+			ReasoningContent: m.ReasoningContent,
+			ToolCalls:        m.ToolCalls,
+			ToolCallID:       m.ToolCallID,
 		}
 	}
 	return out