Index resolution and origin membership

internal/engine/inheritance_origin_test.go

@@ -87,6 +87,51 @@ func TestInheritedOriginsKeepSourcePathsPresenceAndIndependentReplacement(t *tes
 	}
 }
 
+func TestOriginMembershipPreservesLocationAndSourceCoverageRules(t *testing.T) {
+	location := Location{SourceID: "source", Line: 4, Column: 2}
+	otherCoordinates := location
+	otherCoordinates.Line++
+
+	container := Origin{
+		Layer:     LayerOverlay,
+		Operation: ChangeNormalization,
+		Locations: []Location{location},
+	}
+	if !originContainedBy(container, container) {
+		t.Fatal("identical location evidence was not contained")
+	}
+	coordinateDifference := container
+	coordinateDifference.Locations = []Location{otherCoordinates}
+	if originContainedBy(coordinateDifference, container) {
+		t.Fatal("location containment ignored differing coordinates")
+	}
+
+	parent := Keys("parent")
+	child := parent.Key("child")
+	change := Change{Path: parent, Origin: container}
+	descendantOrigin := Origin{
+		Layer:     container.Layer,
+		Operation: container.Operation,
+		Locations: []Location{otherCoordinates},
+	}
+	if !originRepresentedByChange(child, descendantOrigin, change) {
+		t.Fatal("descendant source coverage rejected matching SourceID with different coordinates")
+	}
+	descendantOrigin.Locations[0].SourceID = "another-source"
+	if originRepresentedByChange(child, descendantOrigin, change) {
+		t.Fatal("descendant source coverage accepted an unrecorded SourceID")
+	}
+
+	withContributor := container
+	withContributor.contributors = []inheritanceContributor{{source: parent, location: location}}
+	if originContainedBy(withContributor, container) {
+		t.Fatal("exact location containment ignored the contributor-empty mismatch")
+	}
+	if !originRepresentedByChange(child, withContributor, change) {
+		t.Fatal("descendant source coverage was conflated with contributor containment")
+	}
+}
+
 func TestProjectedInheritanceStepsMatchScanAndRetainOwnership(t *testing.T) {
 	sourcePath := Keys("source", "a/b", "01")
 	firstLocations := []Location{{SourceID: "first;:source", Line: -1, Column: 2}}