fix(antigravity): preserve tool_result images, native Gemini functionCall/thoughtSignature, and composite /v1beta routing

backend/internal/pkg/antigravity/request_transformer.go

@@ -588,6 +588,7 @@ func buildParts(content json.RawMessage, toolIDToName map[string]string, allowDu
 					ID: block.ToolUseID,
 				},
 			})
+			parts = append(parts, extractToolResultInlineParts(block.Content)...)
 		}
 	}
 
@@ -638,6 +639,31 @@ func parseToolResultContent(content json.RawMessage, isError bool) string {
 	return string(content)
 }
 
+func extractToolResultInlineParts(content json.RawMessage) []GeminiPart {
+	if len(content) == 0 {
+		return nil
+	}
+	var innerBlocks []ContentBlock
+	if err := json.Unmarshal(content, &innerBlocks); err != nil {
+		return nil
+	}
+	var inlineParts []GeminiPart
+	for _, item := range innerBlocks {
+		if (item.Type == "image" || item.Type == "document") &&
+			item.Source != nil &&
+			item.Source.Type == "base64" &&
+			strings.TrimSpace(item.Source.Data) != "" {
+			inlineParts = append(inlineParts, GeminiPart{
+				InlineData: &GeminiInlineData{
+					MimeType: item.Source.MediaType,
+					Data:     item.Source.Data,
+				},
+			})
+		}
+	}
+	return inlineParts
+}
+
 // buildGenerationConfig 构建 generationConfig
 const (
 	defaultMaxOutputTokens    = 64000

backend/internal/pkg/antigravity/request_transformer_test.go

@@ -694,3 +694,64 @@ func TestToolConfigAlwaysPresent(t *testing.T) {
 		})
 	}
 }
+
+func TestTransformClaudeToGemini_ToolResultImagesReachUpstream(t *testing.T) {
+	claudeReq := &ClaudeRequest{
+		Model: "claude-sonnet-4-5",
+		Messages: []ClaudeMessage{
+			{
+				Role: "assistant",
+				Content: json.RawMessage(`[
+					{"type":"tool_use","id":"toolu_img_1","name":"read_image","input":{"path":"colors.png"}}
+				]`),
+			},
+			{
+				Role: "user",
+				Content: json.RawMessage(`[
+					{
+						"type":"tool_result",
+						"tool_use_id":"toolu_img_1",
+						"content":[
+							{"type":"text","text":"loaded colors.png"},
+							{"type":"image","source":{"type":"base64","media_type":"image/png","data":"aGVsbG8="}}
+						]
+					},
+					{
+						"type":"tool_result",
+						"tool_use_id":"toolu_img_1",
+						"content":[
+							{"type":"image","source":{"type":"base64","media_type":"image/jpeg","data":"d29ybGQ="}}
+						]
+					}
+				]`),
+			},
+		},
+	}
+
+	body, err := TransformClaudeToGeminiWithOptions(claudeReq, "project-1", "claude-sonnet-4-5", DefaultTransformOptions())
+	require.NoError(t, err)
+
+	var req V1InternalRequest
+	require.NoError(t, json.Unmarshal(body, &req))
+	require.Len(t, req.Request.Contents, 2)
+
+	userParts := req.Request.Contents[1].Parts
+	require.Len(t, userParts, 4)
+
+	require.NotNil(t, userParts[0].FunctionResponse)
+	require.Equal(t, "read_image", userParts[0].FunctionResponse.Name)
+	require.Equal(t, "toolu_img_1", userParts[0].FunctionResponse.ID)
+	require.Equal(t, "loaded colors.png", userParts[0].FunctionResponse.Response["result"])
+
+	require.NotNil(t, userParts[1].InlineData)
+	require.Equal(t, "image/png", userParts[1].InlineData.MimeType)
+	require.Equal(t, "aGVsbG8=", userParts[1].InlineData.Data)
+
+	require.NotNil(t, userParts[2].FunctionResponse)
+	require.Equal(t, "read_image", userParts[2].FunctionResponse.Name)
+	require.Equal(t, "Command executed successfully.", userParts[2].FunctionResponse.Response["result"])
+
+	require.NotNil(t, userParts[3].InlineData)
+	require.Equal(t, "image/jpeg", userParts[3].InlineData.MimeType)
+	require.Equal(t, "d29ybGQ=", userParts[3].InlineData.Data)
+}