agent_patch

diff --git a/tmp/agent-patch-flux-pr-1128.1-of-1.2026-02-21__03-36-16__gpt-5-1-codex-mini/app/pkg/engine/plan/plan.go b/app/pkg/engine/plan/plan.go
index 4725d5a..8ed4ce1 100644
--- a/tmp/agent-patch-flux-pr-1128.1-of-1.2026-02-21__03-36-16__gpt-5-1-codex-mini/app/pkg/engine/plan/plan.go
+++ b/app/pkg/engine/plan/plan.go
@@ -298,6 +298,7 @@ func (p *Planner) Plan(operation, definition *ast.Document, operationName string
 	p.planningVisitor.Config = config
 	p.planningVisitor.fetchConfigurations = p.configurationVisitor.fetches
 	p.planningVisitor.fieldBuffers = p.configurationVisitor.fieldBuffers
+	p.planningVisitor.staticTypeNameFields = p.configurationVisitor.staticTypeNameFields
 	p.planningVisitor.skipFieldPaths = p.requiredFieldsVisitor.skipFieldPaths
 
 	p.planningWalker.ResetVisitors()
@@ -383,6 +384,7 @@ type Visitor struct {
 	planners                     []plannerConfiguration
 	fetchConfigurations          []objectFetchConfiguration
 	fieldBuffers                 map[int]int
+	staticTypeNameFields         map[int][]byte
 	skipFieldPaths               []string
 	fieldConfigs                 map[int]*FieldConfiguration
 	exportedVariables            map[string]struct{}
@@ -526,6 +528,26 @@ func (v *Visitor) EnterField(ref int) {
 
 	fieldName := v.Operation.FieldNameBytes(ref)
 	fieldAliasOrName := v.Operation.FieldAliasOrNameBytes(ref)
+	if staticValue, ok := v.staticTypeNameFields[ref]; ok {
+		staticValueCopy := append([]byte(nil), staticValue...)
+		v.currentField = &resolve.Field{
+			Name: fieldAliasOrName,
+			Value: &resolve.String{
+				Path:        nil,
+				Nullable:    false,
+				IsTypeName:  true,
+				StaticValue: staticValueCopy,
+			},
+			OnTypeNames:             v.resolveOnTypeNames(),
+			Position:                v.resolveFieldPosition(ref),
+			SkipDirectiveDefined:    skip,
+			SkipVariableName:        skipVariableName,
+			IncludeDirectiveDefined: include,
+			IncludeVariableName:     includeVariableName,
+		}
+		*v.currentFields[len(v.currentFields)-1].fields = append(*v.currentFields[len(v.currentFields)-1].fields, v.currentField)
+		return
+	}
 	if bytes.Equal(fieldName, literal.TYPENAME) {
 		v.currentField = &resolve.Field{
 			Name: fieldAliasOrName,
@@ -1435,6 +1457,7 @@ type configurationVisitor struct {
 	fetches               []objectFetchConfiguration
 	currentBufferId       int
 	fieldBuffers          map[int]int
+	staticTypeNameFields  map[int][]byte
 
 	parentTypeNodes []ast.Node
 
@@ -1583,6 +1606,17 @@ func (c *configurationVisitor) EnterField(ref int) {
 	if root.Kind != ast.NodeKindOperationDefinition {
 		return
 	}
+	isRootSelection := parentPath == string(literal.QUERY) ||
+		parentPath == string(literal.MUTATION) ||
+		parentPath == string(literal.SUBSCRIPTION)
+
+	if isRootSelection && fieldName == "__typename" {
+		if c.staticTypeNameFields == nil {
+			c.staticTypeNameFields = make(map[int][]byte)
+		}
+		c.staticTypeNameFields[ref] = []byte(typeName)
+		return
+	}
 	isSubscription := c.isSubscription(root.Ref, currentPath)
 	for i, plannerConfig := range c.planners {
 		planningBehaviour := plannerConfig.planner.DataSourcePlanningBehavior()
@@ -1746,6 +1780,7 @@ func (c *configurationVisitor) EnterDocument(operation, definition *ast.Document
 			delete(c.fieldBuffers, i)
 		}
 	}
+	c.staticTypeNameFields = map[int][]byte{}
 }
 
 func (c *configurationVisitor) isSubscription(root int, path string) bool {
diff --git a/tmp/agent-patch-flux-pr-1128.1-of-1.2026-02-21__03-36-16__gpt-5-1-codex-mini/app/pkg/engine/plan/plan_test.go b/app/pkg/engine/plan/plan_test.go
index d57cad2..562c8be 100644
--- a/tmp/agent-patch-flux-pr-1128.1-of-1.2026-02-21__03-36-16__gpt-5-1-codex-mini/app/pkg/engine/plan/plan_test.go
+++ b/app/pkg/engine/plan/plan_test.go
@@ -208,6 +208,29 @@ func TestPlanner_Plan(t *testing.T) {
 		DefaultFlushIntervalMillis: 0,
 	}))
 
+	t.Run("root __typename static field", test(testDefinition, `
+		query RootTypeName {
+			__typename
+		}
+	`, "", &SynchronousResponsePlan{
+		Response: &resolve.GraphQLResponse{
+			Data: &resolve.Object{
+				Fields: []*resolve.Field{
+					{
+						Name: []byte("__typename"),
+						Value: &resolve.String{
+							Nullable:    false,
+							IsTypeName:  true,
+							StaticValue: []byte("Query"),
+						},
+					},
+				},
+			},
+		},
+	}, Configuration{
+		DisableResolveFieldPositions: true,
+	}))
+
 	t.Run("Union response type with interface fragments", test(testDefinition, `
 		query SearchResults {
 			searchResults {
diff --git a/tmp/agent-patch-flux-pr-1128.1-of-1.2026-02-21__03-36-16__gpt-5-1-codex-mini/app/pkg/engine/resolve/resolve.go b/app/pkg/engine/resolve/resolve.go
index f6b93a0..ef4b196 100644
--- a/tmp/agent-patch-flux-pr-1128.1-of-1.2026-02-21__03-36-16__gpt-5-1-codex-mini/app/pkg/engine/resolve/resolve.go
+++ b/app/pkg/engine/resolve/resolve.go
@@ -1014,6 +1014,25 @@ func (r *Resolver) resolveString(ctx *Context, str *String, data []byte, stringB
 		err       error
 	)
 
+	if str.StaticValue != nil {
+		value := str.StaticValue
+		if value == nil {
+			if !str.Nullable {
+				return errNonNullableFieldValueIsNull
+			}
+			r.resolveNull(stringBuf.Data)
+			return nil
+		}
+		if str.IsTypeName {
+			value = r.renameTypeName(ctx, str, value)
+		}
+		stringBuf.Data.WriteBytes(quote)
+		stringBuf.Data.WriteBytes(value)
+		stringBuf.Data.WriteBytes(quote)
+		r.exportField(ctx, str.Export, value)
+		return nil
+	}
+
 	value, valueType, _, err = jsonparser.Get(data, str.Path...)
 	if err != nil || valueType != jsonparser.String {
 		if err == nil && str.UnescapeResponseJson {
@@ -1544,6 +1563,7 @@ type String struct {
 	Export               *FieldExport `json:"export,omitempty"`
 	UnescapeResponseJson bool         `json:"unescape_response_json,omitempty"`
 	IsTypeName           bool         `json:"is_type_name,omitempty"`
+	StaticValue          []byte       `json:"-"`
 }
 
 func (_ *String) NodeKind() NodeKind {