Index inherited compound identity restoration

docs/roadmap/implementation.md

@@ -1030,6 +1030,14 @@ templates remain correct. Source review establishes O(K + C + M) lookup work plu
 required copied values for K identity fields and C/M mapping entries.
 Focused check: `go test ./internal/engine -run 'Identified|Identity|Inheritance'`.
 
+Status: **complete** (E05). Prior completed commits include `549fca2`,
+`3a1b6ff`, `d172a5e`, `1dd94a3`, and `75e209e`. Validation passed:
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test ./internal/engine -run 'Identified|Identity|Inheritance' -count=1`,
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test ./internal/engine -count=1`,
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test ./... -count=1`,
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test -race ./...`,
+and `git diff --check`.
+
 ## Stage 32 — Index Secret Failure Locations Only When Needed
 
 Finding: **F08**.

internal/engine/inheritance_identified_test.go

@@ -24,6 +24,83 @@ func parseIdentifiedInheritanceSequence(t *testing.T, sourceID, input string) *d
 	return sequence
 }
 
+func TestPreserveInheritanceIdentityIndexesCompoundFields(t *testing.T) {
+	t.Parallel()
+
+	mergedEntries := []document.Entry{
+		{Key: "before", Value: &document.Node{Kind: document.String, Text: "keep"}},
+		{Key: "id", KeyLocation: document.Location{SourceID: "parent", Line: 2}, ValueLocation: document.Location{SourceID: "parent", Line: 2}, Value: &document.Node{Kind: document.String, Text: "parent-id"}},
+	}
+	for index := 0; index < 64; index++ {
+		key := "setting-" + string(rune('a'+index))
+		mergedEntries = append(mergedEntries, document.Entry{Key: key, Value: &document.Node{Kind: document.String, Text: key}})
+	}
+	mergedEntries = append(mergedEntries,
+		document.Entry{Key: "a/b~c", KeyLocation: document.Location{SourceID: "parent", Line: 70}, ValueLocation: document.Location{SourceID: "parent", Line: 70}, Value: &document.Node{Kind: document.String, Text: "parent-literal"}},
+		document.Entry{Key: "missing", Value: &document.Node{Kind: document.String, Text: "retained"}},
+		document.Entry{Key: "after", Value: &document.Node{Kind: document.String, Text: "keep"}},
+	)
+	merged := &document.Node{Kind: document.Mapping, Mapping: mergedEntries}
+	child := &document.Node{Kind: document.Mapping, Mapping: []document.Entry{
+		{Key: "a/b~c", KeyLocation: document.Location{SourceID: "child", Line: 9, Column: 3}, ValueLocation: document.Location{SourceID: "child", Line: 9, Column: 10}, Value: &document.Node{Kind: document.String, Text: "child-literal", Location: document.Location{SourceID: "child", Line: 9, Column: 10}}},
+		{Key: "id", KeyLocation: document.Location{SourceID: "child", Line: 3, Column: 3}, ValueLocation: document.Location{SourceID: "child", Line: 3, Column: 7}, Value: &document.Node{Kind: document.String, Text: "child-id", Location: document.Location{SourceID: "child", Line: 3, Column: 7}}},
+	}}
+	beforeKeys := make([]string, len(merged.Mapping))
+	for index, entry := range merged.Mapping {
+		beforeKeys[index] = entry.Key
+	}
+	untouched := merged.Mapping[2].Value
+
+	preserveInheritanceIdentityFields(merged, child, []string{"id", "a/b~c", "missing"})
+
+	for index, entry := range merged.Mapping {
+		if entry.Key != beforeKeys[index] {
+			t.Fatalf("mapping order changed at %d: %q, want %q", index, entry.Key, beforeKeys[index])
+		}
+	}
+	for _, want := range []struct {
+		key       string
+		text      string
+		keyLine   int
+		keyColumn int
+		valueLine int
+		valueColumn int
+	}{
+		{key: "id", text: "child-id", keyLine: 3, keyColumn: 3, valueLine: 3, valueColumn: 7},
+		{key: "a/b~c", text: "child-literal", keyLine: 9, keyColumn: 3, valueLine: 9, valueColumn: 10},
+	} {
+		var got document.Entry
+		for _, entry := range merged.Mapping {
+			if entry.Key == want.key {
+				got = entry
+				break
+			}
+		}
+		if got.Value == nil || got.Value.Text != want.text || got.KeyLocation.SourceID != "child" || got.KeyLocation.Line != want.keyLine || got.KeyLocation.Column != want.keyColumn ||
+			got.ValueLocation.SourceID != "child" || got.ValueLocation.Line != want.valueLine || got.ValueLocation.Column != want.valueColumn ||
+			got.Value.Location.SourceID != "child" || got.Value.Location.Line != want.valueLine || got.Value.Location.Column != want.valueColumn {
+			t.Fatalf("restored identity %q = %#v", want.key, got)
+		}
+		if got.Value == child.Mapping[0].Value || (want.key == "id" && got.Value == child.Mapping[1].Value) {
+			t.Fatalf("restored identity %q borrows its child value", want.key)
+		}
+	}
+	if merged.Mapping[2].Value != untouched {
+		t.Fatal("nonidentity sibling was replaced")
+	}
+	for _, entry := range merged.Mapping {
+		if entry.Key == "missing" && entry.Value.Text != "retained" {
+			t.Fatalf("identity absent from child was changed: %#v", entry)
+		}
+	}
+	child.Mapping[0].Value.Text = "mutated"
+	for _, entry := range merged.Mapping {
+		if entry.Key == "a/b~c" && entry.Value.Text != "child-literal" {
+			t.Fatal("restored identity value aliases the child template")
+		}
+	}
+}
+
 func TestIdentifiedInheritanceGraphSchedulesForwardReferencesInPlace(t *testing.T) {
 	sequence := parseIdentifiedInheritanceSequence(t, "identified-graph", `- id: 2
   tenant: acme

internal/engine/inheritance_scope.go

@@ -144,18 +144,24 @@ func preserveInheritanceIdentityFields(merged, child *document.Node, fields []st
 	if len(fields) == 0 || merged == nil || merged.Kind != document.Mapping || child == nil || child.Kind != document.Mapping {
 		return
 	}
+	identityFields := make(map[string]struct{}, len(fields))
 	for _, field := range fields {
+		identityFields[field] = struct{}{}
+	}
+	positions := make(map[string]int, len(merged.Mapping))
+	for index, entry := range merged.Mapping {
+		if _, exists := positions[entry.Key]; !exists {
+			positions[entry.Key] = index
+		}
+	}
 	for _, entry := range child.Mapping {
-			if entry.Key != field {
+		if _, identity := identityFields[entry.Key]; !identity {
 			continue
 		}
-			for index := range merged.Mapping {
+		delete(identityFields, entry.Key)
-				if merged.Mapping[index].Key == field {
+		if index, exists := positions[entry.Key]; exists {
-					merged.Mapping[index] = document.Entry{Key: field, Value: document.Clone(entry.Value)}
+			entry.Value = document.Clone(entry.Value)
-					break
+			merged.Mapping[index] = entry
-				}
-			}
-			break
 		}
 	}
 }