Validate final identity fields as application payload

internal/engine/compose.go

@@ -406,7 +406,7 @@ func validateRegisteredSequences(claims []compositionClaim, identityFieldsByPath
 		contribution := validatedSequence{items: node.Sequence}
 		records, diagnostics := validateNormalizedSequenceIdentityFrom(node, claim.path, identityFields, sequenceIdentityDiagnosticCodes{
 			invalid: CodeComposeInvalid, conflict: CodeComposeConflict,
-		}, start)
+		}, start, sequenceStructuralRecord)
 		if len(diagnostics) != 0 {
 			return nil, nil, diagnostics
 		}

internal/engine/final_identity.go

@@ -23,7 +23,7 @@ func validateFinalSequenceIdentities(root *document.Node, policy sequencePolicy)
 			if fields != nil {
 				_, issues := validateNormalizedSequenceIdentityFrom(node, path, fields, sequenceIdentityDiagnosticCodes{
 					invalid: CodeSequenceInvalid, conflict: CodeSequenceConflict,
-				}, 0)
+				}, 0, sequencePayloadRecord)
 				diagnostics = append(diagnostics, issues...)
 			}
 			return

internal/engine/inheritance_identified.go

@@ -59,7 +59,7 @@ func analyzeIdentifiedInheritanceGraph(sequence *document.Node, scopePath Path,
 		}}
 	}
 	lookup, diagnostics := validateNormalizedSequenceIdentityFrom(
-		sequence, scopePath, fields, sequenceCombinationIdentityCodes, 0,
+		sequence, scopePath, fields, sequenceCombinationIdentityCodes, 0, sequenceStructuralRecord,
 	)
 	if len(diagnostics) != 0 {
 		return nil, diagnostics
@@ -136,7 +136,7 @@ func identifiedInheritanceReference(reference *document.Node, path Path, identit
 			)}
 		}
 	}
-	index := newSequenceMappingIndex(reference)
+	index := newSequenceMappingIndex(reference, sequencePayloadRecord)
 	tuple, _, missing, invalid := index.identity(identityFields)
 	if missing != "" || invalid >= 0 || invalid == -2 {
 		value := reference

internal/engine/sequence_identity.go

@@ -28,6 +28,13 @@ type sequenceIdentityRecord struct {
 	location document.Location
 }
 
+type sequenceIdentityContext uint8
+
+const (
+	sequenceStructuralRecord sequenceIdentityContext = iota
+	sequencePayloadRecord
+)
+
 // normalizeSequenceIdentityFields treats identity field names as a set.
 func normalizeSequenceIdentityFields(fields []string) ([]string, error) {
 	if len(fields) == 0 {
@@ -150,21 +157,21 @@ func sequenceIdentityTuple(values []*document.Node) (string, error) {
 	return encoded.String(), nil
 }
 
-// sequenceMappingIndex is built once per record. Structural fields are omitted
-// by entry index, so a directive is excluded only at its actual occurrence.
+// sequenceMappingIndex is built once per record. Structural lookup excludes the
+// directive's occurrence; effective payload and reference mappings keep all keys.
 type sequenceMappingIndex struct {
 	entries []document.Entry
 	byKey   map[string]int
 }
 
-func newSequenceMappingIndex(record *document.Node) sequenceMappingIndex {
+func newSequenceMappingIndex(record *document.Node, context sequenceIdentityContext) sequenceMappingIndex {
 	index := sequenceMappingIndex{byKey: make(map[string]int)}
 	if record == nil || record.Kind != document.Mapping {
 		return index
 	}
 	index.entries = record.Mapping
 	directiveIndex := -1
-	if directive, exists := inheritanceDirective(record); exists {
+	if directive, exists := inheritanceDirective(record); context == sequenceStructuralRecord && exists {
 		for entryIndex := range record.Mapping {
 			if record.Mapping[entryIndex].Key == directive.Key && record.Mapping[entryIndex].KeyLocation == directive.KeyLocation {
 				directiveIndex = entryIndex
@@ -227,10 +234,10 @@ func validateSequenceIdentityFrom(sequence *document.Node, path Path, fields []s
 		}
 		return nil, []Diagnostic{{Code: codes.invalid, Severity: SeverityError, Path: path, Message: "sequence identity requires at least one field", Primary: location}}
 	}
-	return validateNormalizedSequenceIdentityFrom(sequence, path, normalized, codes, startIndex)
+	return validateNormalizedSequenceIdentityFrom(sequence, path, normalized, codes, startIndex, sequenceStructuralRecord)
 }
 
-func validateNormalizedSequenceIdentityFrom(sequence *document.Node, path Path, normalized []string, codes sequenceIdentityDiagnosticCodes, startIndex int) (map[string]sequenceIdentityRecord, []Diagnostic) {
+func validateNormalizedSequenceIdentityFrom(sequence *document.Node, path Path, normalized []string, codes sequenceIdentityDiagnosticCodes, startIndex int, context sequenceIdentityContext) (map[string]sequenceIdentityRecord, []Diagnostic) {
 	if sequence == nil || sequence.Kind != document.Sequence {
 		location := (*Location)(nil)
 		if sequence != nil {
@@ -251,7 +258,7 @@ func validateNormalizedSequenceIdentityFrom(sequence *document.Node, path Path,
 			}
 			return nil, []Diagnostic{{Code: codes.invalid, Severity: SeverityError, Path: itemPath, Message: "identified collection items must be mappings", Primary: primary}}
 		}
-		mapping := newSequenceMappingIndex(item)
+		mapping := newSequenceMappingIndex(item, context)
 		tuple, locations, missing, entryIndex := mapping.identity(normalized)
 		if entryIndex == -1 {
 			location := publicLocation(item.Location)