Ensure we distinguish between listing resources and listing resource templates errors

Author: peteski22

internal/api/resources.go

@@ -283,10 +283,10 @@ func handleServerResourceTemplates(
 		if strings.Contains(err.Error(), methodNotFoundMessage) {
 			return nil, fmt.Errorf("%w: %s", errors.ErrResourcesNotImplemented, name)
 		}
-		return nil, fmt.Errorf("%w: %s: %w", errors.ErrResourceListFailed, name, err)
+		return nil, fmt.Errorf("%w: %s: %w", errors.ErrResourceTemplateListFailed, name, err)
 	}
 	if result == nil {
-		return nil, fmt.Errorf("%w: %s: no result", errors.ErrResourceListFailed, name)
+		return nil, fmt.Errorf("%w: %s: no result", errors.ErrResourceTemplateListFailed, name)
 	}
 
 	templates := make([]ResourceTemplate, 0, len(result.ResourceTemplates))

internal/api/resources_test.go

@@ -196,6 +196,23 @@ func TestAPI_HandleServerResourceTemplates_ServerNotFound(t *testing.T) {
 	require.True(t, errors.Is(err, internalerrors.ErrServerNotFound))
 }
 
+func TestAPI_HandleServerResourceTemplates_ListError(t *testing.T) {
+	t.Parallel()
+
+	mockClient := &mockMCPClient{
+		listTemplatesError: errors.New("template list failed"),
+	}
+
+	accessor := newMockMCPClientAccessor()
+	accessor.Add("test-server", mockClient, []string{})
+
+	result, err := handleServerResourceTemplates(accessor, "test-server", "")
+
+	require.Error(t, err)
+	require.Nil(t, result)
+	require.True(t, errors.Is(err, internalerrors.ErrResourceTemplateListFailed))
+}
+
 func TestAPI_HandleServerResourceContent_TextContent(t *testing.T) {
 	t.Parallel()
 

internal/daemon/api_server.go

@@ -212,6 +212,9 @@ func mapError(logger hclog.Logger, err error) huma.StatusError {
 	case stdErrors.Is(err, errors.ErrResourceListFailed):
 		logger.Error("Resource list failed", "error", err)
 		return huma.Error502BadGateway("MCP server error listing resources", err)
+	case stdErrors.Is(err, errors.ErrResourceTemplateListFailed):
+		logger.Error("Resource template list failed", "error", err)
+		return huma.Error502BadGateway("MCP server error listing resource templates", err)
 	case stdErrors.Is(err, errors.ErrResourceReadFailed):
 		logger.Error("Resource read failed", "error", err)
 		return huma.Error502BadGateway("MCP server error reading resource", err)

internal/daemon/api_server_test.go

@@ -377,6 +377,11 @@ func TestMapError(t *testing.T) {
 			err:            errors.ErrResourceListFailed,
 			expectedStatus: 502,
 		},
+		{
+			name:           "ErrResourceTemplateListFailed maps to 502",
+			err:            errors.ErrResourceTemplateListFailed,
+			expectedStatus: 502,
+		},
 		{
 			name:           "ErrResourceReadFailed maps to 502",
 			err:            errors.ErrResourceReadFailed,

internal/errors/errors.go

@@ -88,6 +88,11 @@ var (
 	// Recommended to map to HTTP 502 Bad Gateway.
 	ErrResourceListFailed = errors.New("resource list failed")
 
+	// ErrResourceTemplateListFailed indicates that listing resource templates from an MCP server failed.
+	// This represents a communication or protocol error with the external MCP server.
+	// Recommended to map to HTTP 502 Bad Gateway.
+	ErrResourceTemplateListFailed = errors.New("resource template list failed")
+
 	// ErrResourceReadFailed indicates that reading a resource from an MCP server failed.
 	// This represents a communication or protocol error with the external MCP server.
 	// Recommended to map to HTTP 502 Bad Gateway.