feat(router): support fields with arguments and @requires (Cosmo Connect)

demo/pkg/subgraphs/projects/generated/mapping.json

@@ -189,6 +189,21 @@
           "request": "RequireEmployeeTaggedProjectSummaryByIdRequest",
           "response": "RequireEmployeeTaggedProjectSummaryByIdResponse"
         },
+        {
+          "fieldMapping": {
+            "original": "filteredProjectSummary",
+            "mapped": "filtered_project_summary",
+            "argumentMappings": [
+              {
+                "original": "tag",
+                "mapped": "tag"
+              }
+            ]
+          },
+          "rpc": "RequireEmployeeFilteredProjectSummaryById",
+          "request": "RequireEmployeeFilteredProjectSummaryByIdRequest",
+          "response": "RequireEmployeeFilteredProjectSummaryByIdResponse"
+        },
         {
           "fieldMapping": {
             "original": "workItemInfo",
@@ -1177,6 +1192,16 @@
           "mapped": "tagged_project_summary",
           "argumentMappings": []
         },
+        {
+          "original": "filteredProjectSummary",
+          "mapped": "filtered_project_summary",
+          "argumentMappings": [
+            {
+              "original": "tag",
+              "mapped": "tag"
+            }
+          ]
+        },
         {
           "original": "primaryWorkItem",
           "mapped": "primary_work_item",

demo/pkg/subgraphs/projects/generated/service.proto

@@ -38,6 +38,7 @@ service ProjectsService {
   rpc QueryTasks(QueryTasksRequest) returns (QueryTasksResponse) {}
   rpc QueryTasksByPriority(QueryTasksByPriorityRequest) returns (QueryTasksByPriorityResponse) {}
   rpc RequireEmployeeDeepWorkItemInfoById(RequireEmployeeDeepWorkItemInfoByIdRequest) returns (RequireEmployeeDeepWorkItemInfoByIdResponse) {}
+  rpc RequireEmployeeFilteredProjectSummaryById(RequireEmployeeFilteredProjectSummaryByIdRequest) returns (RequireEmployeeFilteredProjectSummaryByIdResponse) {}
   rpc RequireEmployeeReviewReportById(RequireEmployeeReviewReportByIdRequest) returns (RequireEmployeeReviewReportByIdResponse) {}
   rpc RequireEmployeeTaggedProjectSummaryById(RequireEmployeeTaggedProjectSummaryByIdRequest) returns (RequireEmployeeTaggedProjectSummaryByIdResponse) {}
   rpc RequireEmployeeWorkItemHandlerInfoById(RequireEmployeeWorkItemHandlerInfoByIdRequest) returns (RequireEmployeeWorkItemHandlerInfoByIdResponse) {}
@@ -847,6 +848,35 @@ message RequireEmployeeTaggedProjectSummaryByIdFields {
   string expertise = 1;
 }
 
+message RequireEmployeeFilteredProjectSummaryByIdRequest {
+  // RequireEmployeeFilteredProjectSummaryByIdContext provides the context for the required fields method RequireEmployeeFilteredProjectSummaryById.
+  repeated RequireEmployeeFilteredProjectSummaryByIdContext context = 1;
+  // RequireEmployeeFilteredProjectSummaryByIdArgs provides the field arguments for the required field with method RequireEmployeeFilteredProjectSummaryById.
+  RequireEmployeeFilteredProjectSummaryByIdArgs field_args = 2;
+}
+
+message RequireEmployeeFilteredProjectSummaryByIdContext {
+  LookupEmployeeByIdRequestKey key = 1;
+  RequireEmployeeFilteredProjectSummaryByIdFields fields = 2;
+}
+
+message RequireEmployeeFilteredProjectSummaryByIdArgs {
+  string tag = 1;
+}
+
+message RequireEmployeeFilteredProjectSummaryByIdResponse {
+  // RequireEmployeeFilteredProjectSummaryByIdResult provides the result for the required fields method RequireEmployeeFilteredProjectSummaryById.
+  repeated RequireEmployeeFilteredProjectSummaryByIdResult result = 1;
+}
+
+message RequireEmployeeFilteredProjectSummaryByIdResult {
+  string filtered_project_summary = 1;
+}
+
+message RequireEmployeeFilteredProjectSummaryByIdFields {
+  string expertise = 1;
+}
+
 message RequireEmployeeWorkItemInfoByIdRequest {
   // RequireEmployeeWorkItemInfoByIdContext provides the context for the required fields method RequireEmployeeWorkItemInfoById.
   repeated RequireEmployeeWorkItemInfoByIdContext context = 1;

demo/pkg/subgraphs/projects/src/schema.graphql

@@ -301,6 +301,7 @@ type Employee @key(fields: "id") {
 
   # Field requiring expertise from employees subgraph
   taggedProjectSummary: String! @requires(fields: "expertise")
+  filteredProjectSummary(tag: String!): String! @requires(fields: "expertise")
 
   # External abstract type fields for @requires testing
   primaryWorkItem: EmployeeWorkItem @external

demo/pkg/subgraphs/projects/src/service/service.go

@@ -487,6 +487,69 @@ func (p *ProjectsService) LookupEmployeeById(ctx context.Context, req *service.L
 	return &service.LookupEmployeeByIdResponse{Result: result}, nil
 }
 
+// RequireEmployeeFilteredProjectSummaryById implements projects.ProjectsServiceServer.
+// It resolves the filteredProjectSummary field on Employee, which requires the `expertise` field
+// from the employees subgraph via @requires(fields: "expertise") and accepts a `tag` argument to filter.
+func (p *ProjectsService) RequireEmployeeFilteredProjectSummaryById(_ context.Context, req *service.RequireEmployeeFilteredProjectSummaryByIdRequest) (*service.RequireEmployeeFilteredProjectSummaryByIdResponse, error) {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	tagFilter := ""
+	if req.GetFieldArgs() != nil {
+		tagFilter = req.GetFieldArgs().GetTag()
+	}
+
+	result := make([]*service.RequireEmployeeFilteredProjectSummaryByIdResult, 0, len(req.Context))
+
+	for _, ctx := range req.Context {
+		keyID := ctx.GetKey().GetId()
+		if keyID == "" {
+			return nil, status.Errorf(codes.InvalidArgument, "missing employee id")
+		}
+		id, err := strconv.ParseInt(keyID, 10, 32)
+		if err != nil {
+			return nil, status.Errorf(codes.InvalidArgument, "invalid employee id %q: %v", keyID, err)
+		}
+
+		var matchingTags []string
+		emp := data.GetEmployeeByID(int32(id))
+		if emp != nil && emp.Projects != nil && emp.Projects.List != nil {
+			seen := make(map[string]struct{})
+			for _, project := range emp.Projects.List.Items {
+				if project.Tags == nil || project.Tags.List == nil {
+					continue
+				}
+				for _, tag := range project.Tags.List.Items {
+					if _, ok := seen[tag]; ok {
+						continue
+					}
+					seen[tag] = struct{}{}
+					if tagFilter == "" || strings.EqualFold(tag, tagFilter) {
+						matchingTags = append(matchingTags, tag)
+					}
+				}
+			}
+		}
+
+		employeeExpertise := ctx.GetFields().GetExpertise()
+		if employeeExpertise == "" {
+			employeeExpertise = "none"
+		}
+
+		var summary string
+		if len(matchingTags) > 0 {
+			summary = fmt.Sprintf("expertise: %s, filtered tags (tag=%s): [%s]", employeeExpertise, tagFilter, strings.Join(matchingTags, ", "))
+		} else {
+			summary = fmt.Sprintf("expertise: %s, no tags matched (tag=%s)", employeeExpertise, tagFilter)
+		}
+		result = append(result, &service.RequireEmployeeFilteredProjectSummaryByIdResult{
+			FilteredProjectSummary: summary,
+		})
+	}
+
+	return &service.RequireEmployeeFilteredProjectSummaryByIdResponse{Result: result}, nil
+}
+
 // RequireEmployeeTaggedProjectSummaryById implements projects.ProjectsServiceServer.
 // It resolves the taggedProjectSummary field on Employee, which requires the `tag` field
 // from the employees subgraph via @requires(fields: "tag").

router-tests/go.mod

@@ -28,7 +28,7 @@ require (
 	github.com/wundergraph/cosmo/demo/pkg/subgraphs/projects v0.0.0-20250715110703-10f2e5f9c79e
 	github.com/wundergraph/cosmo/router v0.0.0-20260319123623-f186a0f724f6
 	github.com/wundergraph/cosmo/router-plugin v0.0.0-20250808194725-de123ba1c65e
-	github.com/wundergraph/graphql-go-tools/v2 v2.0.0-rc.267
+	github.com/wundergraph/graphql-go-tools/v2 v2.0.0-rc.268
 	go.opentelemetry.io/otel v1.39.0
 	go.opentelemetry.io/otel/sdk v1.39.0
 	go.opentelemetry.io/otel/sdk/metric v1.39.0

router-tests/go.sum

@@ -357,8 +357,8 @@ github.com/wundergraph/astjson v1.1.0 h1:xORDosrZ87zQFJwNGe/HIHXqzpdHOFmqWgykCLV
 github.com/wundergraph/astjson v1.1.0/go.mod h1:h12D/dxxnedtLzsKyBLK7/Oe4TAoGpRVC9nDpDrZSWw=
 github.com/wundergraph/go-arena v1.1.0 h1:9+wSRkJAkA2vbYHp6s8tEGhPViRGQNGXqPHT0QzhdIc=
 github.com/wundergraph/go-arena v1.1.0/go.mod h1:ROOysEHWJjLQ8FSfNxZCziagb7Qw2nXY3/vgKRh7eWw=
-github.com/wundergraph/graphql-go-tools/v2 v2.0.0-rc.267 h1:qMkYR0oq0Cw61aDZs9VsCCVwNVSxRxT13ytz6WqCwJg=
-github.com/wundergraph/graphql-go-tools/v2 v2.0.0-rc.267/go.mod h1:HjTAO/cuICpu31IfHY9qmSPygx6Gza7Wt9hTSReTI+A=
+github.com/wundergraph/graphql-go-tools/v2 v2.0.0-rc.268 h1:lP9kWLiPO2U3JuwpQ/WX7nTVfKeMtVab2G3DAFblVA0=
+github.com/wundergraph/graphql-go-tools/v2 v2.0.0-rc.268/go.mod h1:HjTAO/cuICpu31IfHY9qmSPygx6Gza7Wt9hTSReTI+A=
 github.com/xrash/smetrics v0.0.0-20250705151800-55b8f293f342 h1:FnBeRrxr7OU4VvAzt5X7s6266i6cSVkkFPS0TuXWbIg=
 github.com/xrash/smetrics v0.0.0-20250705151800-55b8f293f342/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=
 github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=

router-tests/protocol/grpc_subgraph_test.go

@@ -320,6 +320,16 @@ func TestGRPCSubgraph(t *testing.T) {
 				query:    `{ employee(id: 999) { id taggedProjectSummary } }`,
 				expected: `{"data":{"employee":null}}`,
 			},
+			{
+				name:     "query employee @requires field with argument resolved with expertise",
+				query:    `{ employee(id: 1) { id filteredProjectSummary(tag: "cloud") } }`,
+				expected: `{"data":{"employee":{"id":1,"filteredProjectSummary":"expertise: Backend Architecture, filtered tags (tag=cloud): [cloud]"}}}`,
+			},
+			{
+				name:     "query employee @requires field with argument — no matching tags",
+				query:    `{ employee(id: 1) { id filteredProjectSummary(tag: "nonexistent") } }`,
+				expected: `{"data":{"employee":{"id":1,"filteredProjectSummary":"expertise: Backend Architecture, no tags matched (tag=nonexistent)"}}}`,
+			},
 			// Pattern 1: Flat abstract — interface
 			{
 				name:     "query employee @requires flat interface (technical)",

router-tests/protocol/router_plugin_test.go

@@ -510,6 +510,16 @@ func TestRouterPluginRequests(t *testing.T) {
 			query:    `{ employee(id: 999) { id taggedProjectSummary } }`,
 			expected: `{"data":{"employee":null}}`,
 		},
+		{
+			name:     "query employee @requires field with argument resolved with expertise",
+			query:    `{ employee(id: 1) { id filteredProjectSummary(tag: "cloud") } }`,
+			expected: `{"data":{"employee":{"id":1,"filteredProjectSummary":"expertise: Backend Architecture, filtered tags (tag=cloud): [cloud]"}}}`,
+		},
+		{
+			name:     "query employee @requires field with argument — no matching tags",
+			query:    `{ employee(id: 1) { id filteredProjectSummary(tag: "nonexistent") } }`,
+			expected: `{"data":{"employee":{"id":1,"filteredProjectSummary":"expertise: Backend Architecture, no tags matched (tag=nonexistent)"}}}`,
+		},
 		// Pattern 1: Flat abstract — interface
 		{
 			name:     "query employee @requires flat interface (technical)",