feat: add handling for function call finish reasons in OpenAI response conversion

Author: luispater

internal/translator/gemini-cli/openai/chat-completions/cli_openai_response.go

@@ -97,6 +97,7 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 
 	// Process the main content part of the response.
 	partsResult := gjson.GetBytes(rawJSON, "response.candidates.0.content.parts")
+	hasFunctionCall := false
 	if partsResult.IsArray() {
 		partResults := partsResult.Array()
 		for i := 0; i < len(partResults); i++ {
@@ -118,6 +119,7 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 				template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
 			} else if functionCallResult.Exists() {
 				// Handle function call content.
+				hasFunctionCall = true
 				toolCallsResult := gjson.Get(template, "choices.0.delta.tool_calls")
 				functionCallIndex := (*param).(*convertCliResponseToOpenAIChatParams).FunctionIndex
 				(*param).(*convertCliResponseToOpenAIChatParams).FunctionIndex++
@@ -169,6 +171,11 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 		}
 	}
 
+	if hasFunctionCall {
+		template, _ = sjson.Set(template, "choices.0.finish_reason", "tool_calls")
+		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
+	}
+
 	return []string{template}
 }
 

internal/translator/gemini/openai/chat-completions/gemini_openai_response.go

@@ -100,6 +100,7 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 
 	// Process the main content part of the response.
 	partsResult := gjson.GetBytes(rawJSON, "candidates.0.content.parts")
+	hasFunctionCall := false
 	if partsResult.IsArray() {
 		partResults := partsResult.Array()
 		for i := 0; i < len(partResults); i++ {
@@ -121,6 +122,7 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 				template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
 			} else if functionCallResult.Exists() {
 				// Handle function call content.
+				hasFunctionCall = true
 				toolCallsResult := gjson.Get(template, "choices.0.delta.tool_calls")
 				functionCallIndex := (*param).(*convertGeminiResponseToOpenAIChatParams).FunctionIndex
 				(*param).(*convertGeminiResponseToOpenAIChatParams).FunctionIndex++
@@ -172,6 +174,11 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 		}
 	}
 
+	if hasFunctionCall {
+		template, _ = sjson.Set(template, "choices.0.finish_reason", "tool_calls")
+		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
+	}
+
 	return []string{template}
 }
 
@@ -231,6 +238,7 @@ func ConvertGeminiResponseToOpenAINonStream(_ context.Context, _ string, origina
 
 	// Process the main content part of the response.
 	partsResult := gjson.GetBytes(rawJSON, "candidates.0.content.parts")
+	hasFunctionCall := false
 	if partsResult.IsArray() {
 		partsResults := partsResult.Array()
 		for i := 0; i < len(partsResults); i++ {
@@ -252,6 +260,7 @@ func ConvertGeminiResponseToOpenAINonStream(_ context.Context, _ string, origina
 				template, _ = sjson.Set(template, "choices.0.message.role", "assistant")
 			} else if functionCallResult.Exists() {
 				// Append function call content to the tool_calls array.
+				hasFunctionCall = true
 				toolCallsResult := gjson.Get(template, "choices.0.message.tool_calls")
 				if !toolCallsResult.Exists() || !toolCallsResult.IsArray() {
 					template, _ = sjson.SetRaw(template, "choices.0.message.tool_calls", `[]`)
@@ -297,5 +306,10 @@ func ConvertGeminiResponseToOpenAINonStream(_ context.Context, _ string, origina
 		}
 	}
 
+	if hasFunctionCall {
+		template, _ = sjson.Set(template, "choices.0.finish_reason", "tool_calls")
+		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
+	}
+
 	return template
 }