Add NPC interaction normalization

internal/modules/dnd/normalize/npcinteractions/normalizer.go

@@ -0,0 +1,439 @@
+// Package npcinteractions normalizes merged D&D NPC interaction candidates.
+package npcinteractions
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/identity"
+	npcregistry "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/registry"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared/diagnostics"
+)
+
+const (
+	Key                 = "dnd/npc-interactions"
+	normalizationPolicy = "dnd.npc_interactions.normalize.v1"
+	NormalizationPolicy = normalizationPolicy
+
+	ReasonCodeNameCanonicalized     = "npc_interaction_name_canonicalized"
+	ReasonCodeSourceRefsNormalized  = "source_references_normalized"
+	ReasonCodeInteractionsReordered = "npc_interactions_reordered"
+	ReasonCodeDuplicateCollapsed    = "duplicate_npc_interaction_collapsed"
+)
+
+const (
+	NPCRegistryReferenceSlot = npcregistry.ReferenceSlot
+	NPCRegistryMaxBytes      = npcregistry.MaxBytes
+)
+
+var requiredCapabilities = []string{"merged"}
+var providedCapabilities = []string{"normalized"}
+
+var referenceSlotDescriptions = shared.ReferenceSlotDescriptions{
+	Glossary: "Optional campaign glossary reference material used only for interaction disambiguation.",
+	Party:    "Optional party roster reference material used only for interaction disambiguation.",
+	Players:  "Optional player list reference material used only for interaction disambiguation.",
+	Roster:   "Deprecated alias for party roster reference material used only for interaction disambiguation.",
+}
+
+var _ contracts.Normalizer[dnd.NPCInteractionList] = (*Normalizer)(nil)
+var _ contracts.ManifestMetadataProvider = (*Normalizer)(nil)
+var _ pipeline.CheckpointFingerprintProvider = (*Normalizer)(nil)
+
+type Options struct{}
+
+type Normalizer struct {
+	npcResolver *npcregistry.Resolver
+}
+
+func New(_ Options, references ...contracts.ReferenceSet) (*Normalizer, error) {
+	if len(references) > 1 {
+		return nil, normalizerErrorf("at most one reference set may be supplied")
+	}
+	var referenceSet contracts.ReferenceSet
+	if len(references) == 1 {
+		referenceSet = references[0]
+	}
+	resolver, err := npcregistry.NewResolver(referenceSet)
+	if err != nil {
+		return nil, normalizerErrorf("prepare NPC registry: %w", err)
+	}
+	return &Normalizer{npcResolver: resolver}, nil
+}
+
+func (n *Normalizer) Key() string { return Key }
+
+func (n *Normalizer) ReferenceSlots() []contracts.ReferenceSlot { return referenceSlots() }
+
+func (n *Normalizer) ManifestMetadata() map[string]any {
+	if n == nil || n.npcResolver == nil {
+		return nil
+	}
+	metadata := map[string]any{
+		"normalization_policy": normalizationPolicy,
+		"identity_policy":      identity.Policy,
+	}
+	seeded := n.npcResolver.Seeded()
+	if seeded.Bound() {
+		metadata["npc_registry_digest"] = seeded.Digest()
+		metadata["npc_count"] = seeded.Count()
+	}
+	return metadata
+}
+
+func (n *Normalizer) CheckpointFingerprints() []pipeline.CheckpointFingerprint {
+	if n == nil || n.npcResolver == nil {
+		return nil
+	}
+	return []pipeline.CheckpointFingerprint{
+		{Name: "normalization_policy", Value: normalizationPolicy},
+		{Name: "identity_policy", Value: identity.Policy},
+		{Name: "npc_registry", Value: n.npcResolver.Seeded().ProjectionDigest()},
+	}
+}
+
+func (n *Normalizer) Normalize(ctx context.Context, req contracts.TypedNormalizeRequest[dnd.NPCInteractionList]) (contracts.TypedNormalizeResult[dnd.NPCInteractionList], error) {
+	if n == nil || n.npcResolver == nil {
+		return contracts.TypedNormalizeResult[dnd.NPCInteractionList]{}, normalizerErrorf("normalizer must not be nil")
+	}
+	if ctx == nil {
+		return contracts.TypedNormalizeResult[dnd.NPCInteractionList]{}, normalizerErrorf("context must not be nil")
+	}
+	if err := ctx.Err(); err != nil {
+		return contracts.TypedNormalizeResult[dnd.NPCInteractionList]{}, normalizerErrorf("context error before normalize: %w", err)
+	}
+
+	registry, err := n.npcResolver.Resolve(req.References)
+	if err != nil {
+		return contracts.TypedNormalizeResult[dnd.NPCInteractionList]{}, normalizerErrorf("resolve NPC registry: %w", err)
+	}
+	if !registry.Bound() {
+		return contracts.TypedNormalizeResult[dnd.NPCInteractionList]{}, normalizerErrorf("NPC registry reference is required")
+	}
+	value, warnings := normalizeList(req.MergeOutput.Value, req.Source, registry)
+	return contracts.TypedNormalizeResult[dnd.NPCInteractionList]{Value: value, Warnings: warnings}, nil
+}
+
+type normalizedRecord struct {
+	interaction dnd.NPCInteraction
+	inputIndex  int
+	earliest    int
+	hasEvidence bool
+}
+
+type nameCanonicalization struct {
+	from string
+	to   string
+}
+
+func normalizeList(input dnd.NPCInteractionList, doc *source.SourceDocument, registry *npcregistry.Registry) (dnd.NPCInteractionList, []contracts.Warning) {
+	if input.Interactions == nil {
+		return dnd.NPCInteractionList{}, nil
+	}
+
+	records := make([]normalizedRecord, len(input.Interactions))
+	warnings := make([]contracts.Warning, 0)
+	for index, inputInteraction := range input.Interactions {
+		interaction, nameChange, refsChanged := normalizeInteraction(inputInteraction, doc, registry)
+		earliest, hasEvidence := earliestSourcePosition(doc, interaction)
+		records[index] = normalizedRecord{interaction: interaction, inputIndex: index, earliest: earliest, hasEvidence: hasEvidence}
+		if nameChange != nil {
+			warnings = append(warnings, contracts.Warning{
+				Scope:      interactionScope(index),
+				ReasonCode: ReasonCodeNameCanonicalized,
+				Message: fmt.Sprintf("input index %d: NPC name canonicalized from %s to %s",
+					index, diagnostics.Quote(nameChange.from), diagnostics.Quote(nameChange.to)),
+			})
+		}
+		if refsChanged {
+			warnings = append(warnings, contracts.Warning{
+				Scope:      interactionScope(index),
+				ReasonCode: ReasonCodeSourceRefsNormalized,
+				Message: fmt.Sprintf("input index %d: source references normalized (original count %d, final count %d)",
+					index, len(inputInteraction.SourceRefs), len(interaction.SourceRefs)),
+			})
+		}
+	}
+
+	sort.SliceStable(records, func(left, right int) bool { return recordLess(doc, records[left], records[right]) })
+	for position, record := range records {
+		if position == record.inputIndex {
+			continue
+		}
+		warnings = append(warnings, contracts.Warning{
+			Scope:      interactionScope(record.inputIndex),
+			ReasonCode: ReasonCodeInteractionsReordered,
+			Message:    fmt.Sprintf("input index %d moved to normalized position %d by source chronology", record.inputIndex, position),
+		})
+	}
+
+	output, duplicateWarnings := collapseDuplicates(records, doc)
+	warnings = append(warnings, duplicateWarnings...)
+	return dnd.NPCInteractionList{Interactions: output}, warnings
+}
+
+func normalizeInteraction(input dnd.NPCInteraction, doc *source.SourceDocument, registry *npcregistry.Registry) (dnd.NPCInteraction, *nameCanonicalization, bool) {
+	output := cloneInteraction(input)
+	if canonical, ok := registry.Lookup(identity.NormalizeDisplay(input.Name)); ok {
+		output.Name = canonical.Name
+	}
+	var nameChange *nameCanonicalization
+	if input.Name != output.Name {
+		nameChange = &nameCanonicalization{from: input.Name, to: output.Name}
+	}
+	output.SourceRefs = canonicalizeSourceRefs(doc, input.SourceRefs)
+	return output, nameChange, !sourceRefsEqual(input.SourceRefs, output.SourceRefs)
+}
+
+func cloneInteraction(input dnd.NPCInteraction) dnd.NPCInteraction {
+	output := input
+	if input.SourceRefs != nil {
+		output.SourceRefs = append([]source.SourceRef(nil), input.SourceRefs...)
+	}
+	return output
+}
+
+func canonicalizeSourceRefs(doc *source.SourceDocument, input []source.SourceRef) []source.SourceRef {
+	if input == nil {
+		return nil
+	}
+	canonical := append([]source.SourceRef(nil), input...)
+	sort.SliceStable(canonical, func(left, right int) bool { return sourceRefLess(doc, canonical[left], canonical[right]) })
+	unique := make([]source.SourceRef, 0, len(canonical))
+	for _, ref := range canonical {
+		if len(unique) == 0 || unique[len(unique)-1] != ref {
+			unique = append(unique, ref)
+		}
+	}
+	return unique
+}
+
+func sourceRefsEqual(left, right []source.SourceRef) bool {
+	if (left == nil) != (right == nil) || len(left) != len(right) {
+		return false
+	}
+	for index := range left {
+		if left[index] != right[index] {
+			return false
+		}
+	}
+	return true
+}
+
+func sourceRefLess(doc *source.SourceDocument, left, right source.SourceRef) bool {
+	if left.SourceID != right.SourceID {
+		return left.SourceID < right.SourceID
+	}
+	leftStart, leftStartOK := source.UnitIndex(doc, left.StartUnitID)
+	rightStart, rightStartOK := source.UnitIndex(doc, right.StartUnitID)
+	if leftStartOK != rightStartOK {
+		return leftStartOK
+	}
+	if leftStartOK && leftStart != rightStart {
+		return leftStart < rightStart
+	}
+	if left.StartUnitID != right.StartUnitID {
+		return left.StartUnitID < right.StartUnitID
+	}
+	leftEnd, leftEndOK := source.UnitIndex(doc, left.EndUnitID)
+	rightEnd, rightEndOK := source.UnitIndex(doc, right.EndUnitID)
+	if leftEndOK != rightEndOK {
+		return leftEndOK
+	}
+	if leftEndOK && leftEnd != rightEnd {
+		return leftEnd < rightEnd
+	}
+	return left.EndUnitID < right.EndUnitID
+}
+
+func earliestSourcePosition(doc *source.SourceDocument, interaction dnd.NPCInteraction) (int, bool) {
+	found := false
+	earliest := 0
+	for _, ref := range interaction.SourceRefs {
+		if source.ValidateRef(doc, ref) != nil {
+			continue
+		}
+		position, ok := source.UnitIndex(doc, ref.StartUnitID)
+		if !ok || (found && position >= earliest) {
+			continue
+		}
+		earliest = position
+		found = true
+	}
+	return earliest, found
+}
+
+func recordLess(doc *source.SourceDocument, left, right normalizedRecord) bool {
+	if left.hasEvidence != right.hasEvidence {
+		return left.hasEvidence
+	}
+	if left.hasEvidence && left.earliest != right.earliest {
+		return left.earliest < right.earliest
+	}
+	leftKey := identity.ComparisonKey(left.interaction.Name)
+	rightKey := identity.ComparisonKey(right.interaction.Name)
+	if leftKey != rightKey {
+		return leftKey < rightKey
+	}
+	if left.interaction.Name != right.interaction.Name {
+		return left.interaction.Name < right.interaction.Name
+	}
+	if left.interaction.Kind != right.interaction.Kind {
+		return left.interaction.Kind < right.interaction.Kind
+	}
+	return sourceRefsLess(doc, left.interaction.SourceRefs, right.interaction.SourceRefs)
+}
+
+func sourceRefsLess(doc *source.SourceDocument, left, right []source.SourceRef) bool {
+	for index := 0; index < len(left) && index < len(right); index++ {
+		if left[index] == right[index] {
+			continue
+		}
+		return sourceRefLess(doc, left[index], right[index])
+	}
+	return len(left) < len(right)
+}
+
+type duplicateGroup struct {
+	retainedIndex int
+	removed       []int
+}
+
+func collapseDuplicates(records []normalizedRecord, doc *source.SourceDocument) ([]dnd.NPCInteraction, []contracts.Warning) {
+	if len(records) == 0 {
+		return make([]dnd.NPCInteraction, 0), nil
+	}
+	keep := make([]bool, len(records))
+	groups := make([]duplicateGroup, 0)
+	groupByKey := make(map[string]int)
+	for index, record := range records {
+		key, eligible := duplicateKey(record.interaction, doc)
+		if !eligible {
+			keep[index] = true
+			continue
+		}
+		groupIndex, exists := groupByKey[key]
+		if !exists {
+			groupByKey[key] = len(groups)
+			groups = append(groups, duplicateGroup{retainedIndex: record.inputIndex})
+			keep[index] = true
+			continue
+		}
+		groups[groupIndex].removed = append(groups[groupIndex].removed, record.inputIndex)
+	}
+	output := make([]dnd.NPCInteraction, 0, len(records))
+	for index, record := range records {
+		if keep[index] {
+			output = append(output, cloneInteraction(record.interaction))
+		}
+	}
+	warnings := make([]contracts.Warning, 0)
+	for _, group := range groups {
+		if len(group.removed) != 0 {
+			warnings = append(warnings, duplicateWarning(group.retainedIndex, group.removed))
+		}
+	}
+	return output, warnings
+}
+
+func duplicateKey(interaction dnd.NPCInteraction, doc *source.SourceDocument) (string, bool) {
+	if len(interaction.SourceRefs) == 0 {
+		return "", false
+	}
+	for _, ref := range interaction.SourceRefs {
+		if source.ValidateRef(doc, ref) != nil {
+			return "", false
+		}
+	}
+	var key strings.Builder
+	writeKeyString(&key, interaction.Name)
+	writeKeyString(&key, string(interaction.Kind))
+	for _, ref := range interaction.SourceRefs {
+		writeKeyString(&key, ref.SourceID)
+		writeKeyInt(&key, ref.StartUnitID)
+		writeKeyInt(&key, ref.EndUnitID)
+	}
+	return key.String(), true
+}
+
+func writeKeyString(builder *strings.Builder, value string) {
+	builder.WriteString(strconv.Itoa(len(value)))
+	builder.WriteByte(':')
+	builder.WriteString(value)
+}
+
+func writeKeyInt(builder *strings.Builder, value int) {
+	builder.WriteString(strconv.Itoa(value))
+	builder.WriteByte(';')
+}
+
+func duplicateWarning(retainedIndex int, removed []int) contracts.Warning {
+	issues := make([]string, len(removed))
+	for index, removedIndex := range removed {
+		issues[index] = fmt.Sprintf("removed input index %d", removedIndex)
+	}
+	return contracts.Warning{
+		Scope:      interactionScope(retainedIndex),
+		ReasonCode: ReasonCodeDuplicateCollapsed,
+		Message: diagnostics.Aggregate(
+			fmt.Sprintf("duplicate NPC interaction collapsed; retained input index %d", retainedIndex), issues),
+	}
+}
+
+func interactionScope(index int) string { return fmt.Sprintf("interactions[%d]", index) }
+
+func referenceSlots() []contracts.ReferenceSlot {
+	slots := shared.ReferenceSlots(referenceSlotDescriptions)
+	slots = append(slots, contracts.ReferenceSlot{
+		Name:                  NPCRegistryReferenceSlot,
+		Description:           "Required normalized NPC registry used only for interaction identity grounding, never as interaction evidence.",
+		Required:              true,
+		AcceptedMediaTypes:    []string{"application/json"},
+		AcceptedArtifactKinds: []contracts.ArtifactKind{dnd.NPCListKind},
+		MaxBytes:              NPCRegistryMaxBytes,
+	})
+	sort.Slice(slots, func(left, right int) bool { return slots[left].Name < slots[right].Name })
+	return slots
+}
+
+func ModuleSpec() pipeline.ModuleSpec {
+	return pipeline.ModuleSpec{
+		Key:            Key,
+		Stage:          pipeline.StageNormalize,
+		Requires:       append([]string(nil), requiredCapabilities...),
+		Provides:       append([]string(nil), providedCapabilities...),
+		ArtifactKind:   dnd.NPCInteractionListKind,
+		ReferenceSlots: referenceSlots(),
+	}
+}
+
+func Register(registry *pipeline.NormalizerRegistry) error {
+	return pipeline.RegisterNormalizerBuilder(registry, ModuleSpec(), validateOptions, func(request pipeline.BuildRequest) (contracts.Normalizer[dnd.NPCInteractionList], error) {
+		options, err := DecodeOptions(request.Options)
+		if err != nil {
+			return nil, err
+		}
+		return New(options, request.References)
+	})
+}
+
+func DecodeOptions(options map[string]any) (Options, error) {
+	if err := pipeline.RejectUnknownOptions(options); err != nil {
+		return Options{}, normalizerErrorf("%w", err)
+	}
+	return Options{}, nil
+}
+
+func validateOptions(options map[string]any) error { _, err := DecodeOptions(options); return err }
+
+func normalizerErrorf(format string, args ...any) error {
+	return fmt.Errorf("dnd NPC interactions normalizer: "+format, args...)
+}

internal/modules/dnd/normalize/npcinteractions/normalizer_test.go

@@ -0,0 +1,169 @@
+package npcinteractions
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
+	npccodec "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/codec/npcs"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/identity"
+)
+
+func TestNormalizeCanonicalizesAndClones(t *testing.T) {
+	doc := testDocument()
+	normalizer, err := New(Options{}, npcReferences(t))
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	input := dnd.NPCInteractionList{Interactions: []dnd.NPCInteraction{{
+		Name: "  áRIA  ", Kind: dnd.NPCInteractionKindDialogue,
+		SourceRefs: []source.SourceRef{{SourceID: doc.ID, StartUnitID: 30, EndUnitID: 30}, {SourceID: doc.ID, StartUnitID: 10, EndUnitID: 10}, {SourceID: doc.ID, StartUnitID: 30, EndUnitID: 30}},
+	}}}
+	original := append([]source.SourceRef(nil), input.Interactions[0].SourceRefs...)
+	result, err := normalizer.Normalize(context.Background(), contracts.TypedNormalizeRequest[dnd.NPCInteractionList]{Source: doc, MergeOutput: contracts.MergeArtifact[dnd.NPCInteractionList]{Value: input}})
+	if err != nil {
+		t.Fatalf("Normalize() error = %v", err)
+	}
+	got := result.Value.Interactions[0]
+	if got.Name != "Ária" || !reflect.DeepEqual(got.SourceRefs, []source.SourceRef{{SourceID: doc.ID, StartUnitID: 10, EndUnitID: 10}, {SourceID: doc.ID, StartUnitID: 30, EndUnitID: 30}}) {
+		t.Fatalf("normalized interaction = %#v", got)
+	}
+	if !hasWarning(result.Warnings, ReasonCodeNameCanonicalized) || !hasWarning(result.Warnings, ReasonCodeSourceRefsNormalized) {
+		t.Fatalf("warnings = %#v", result.Warnings)
+	}
+	if !reflect.DeepEqual(input.Interactions[0].SourceRefs, original) {
+		t.Fatalf("Normalize() mutated input: %#v", input)
+	}
+	second, err := normalizer.Normalize(context.Background(), contracts.TypedNormalizeRequest[dnd.NPCInteractionList]{Source: doc, MergeOutput: contracts.MergeArtifact[dnd.NPCInteractionList]{Value: result.Value}})
+	if err != nil || !reflect.DeepEqual(second.Value, result.Value) || len(second.Warnings) != 0 {
+		t.Fatalf("second normalization = %#v, %v; want idempotent output without warnings", second, err)
+	}
+	result.Value.Interactions[0].SourceRefs[0].StartUnitID = 999
+	if input.Interactions[0].SourceRefs[0].StartUnitID == 999 {
+		t.Fatal("normalized source refs share input storage")
+	}
+}
+
+func TestNormalizeRequiresOperationRegistryAndPreservesEmptyRepresentation(t *testing.T) {
+	normalizer, err := New(Options{})
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	if _, err := normalizer.Normalize(context.Background(), contracts.TypedNormalizeRequest[dnd.NPCInteractionList]{}); err == nil {
+		t.Fatal("Normalize() accepted an unbound NPC registry")
+	}
+	for _, input := range []dnd.NPCInteractionList{{}, {Interactions: []dnd.NPCInteraction{}}} {
+		result, err := normalizer.Normalize(context.Background(), contracts.TypedNormalizeRequest[dnd.NPCInteractionList]{
+			MergeOutput: contracts.MergeArtifact[dnd.NPCInteractionList]{Value: input}, References: npcReferences(t),
+		})
+		if err != nil || (result.Value.Interactions == nil) != (input.Interactions == nil) {
+			t.Fatalf("Normalize() = %#v, %v for input %#v", result, err, input)
+		}
+	}
+	if metadata := normalizer.ManifestMetadata(); metadata["npc_registry_digest"] != nil || metadata["npc_count"] != nil {
+		t.Fatalf("operation registry leaked into metadata: %#v", metadata)
+	}
+}
+
+func TestNormalizeLeavesUnrecognizedNamesUntouched(t *testing.T) {
+	doc := testDocument()
+	normalizer, err := New(Options{}, npcReferences(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	input := dnd.NPCInteractionList{Interactions: []dnd.NPCInteraction{interaction("  Unknown NPC  ", dnd.NPCInteractionKindOther, source.SourceRef{SourceID: doc.ID, StartUnitID: 10, EndUnitID: 10})}}
+	result, err := normalizer.Normalize(context.Background(), contracts.TypedNormalizeRequest[dnd.NPCInteractionList]{Source: doc, MergeOutput: contracts.MergeArtifact[dnd.NPCInteractionList]{Value: input}})
+	if err != nil || result.Value.Interactions[0].Name != input.Interactions[0].Name || hasWarning(result.Warnings, ReasonCodeNameCanonicalized) {
+		t.Fatalf("Normalize() = %#v, %v; want untouched unrecognized name", result, err)
+	}
+}
+
+func TestNormalizeOrdersAndCollapsesExactDuplicatesOnly(t *testing.T) {
+	doc := &source.SourceDocument{ID: "session", Units: []source.SourceUnit{{ID: 50}, {ID: 10}, {ID: 90}}}
+	ref := func(unit int) source.SourceRef {
+		return source.SourceRef{SourceID: doc.ID, StartUnitID: unit, EndUnitID: unit}
+	}
+	first := interaction("Ária", dnd.NPCInteractionKindDialogue, ref(50))
+	input := dnd.NPCInteractionList{Interactions: []dnd.NPCInteraction{
+		interaction("Borin", dnd.NPCInteractionKindMentioned, ref(90)),
+		first,
+		first,
+		interaction("Ária", dnd.NPCInteractionKindCombatAlly, ref(50)),
+		interaction("Ária", dnd.NPCInteractionKindDialogue, ref(10)),
+		interaction("Ária", dnd.NPCInteractionKindDialogue, ref(999)),
+	}}
+	normalizer, err := New(Options{}, npcReferences(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	result, err := normalizer.Normalize(context.Background(), contracts.TypedNormalizeRequest[dnd.NPCInteractionList]{Source: doc, MergeOutput: contracts.MergeArtifact[dnd.NPCInteractionList]{Value: input}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := result.Value.Interactions
+	if len(got) != 5 {
+		t.Fatalf("interaction count = %d, want 5: %#v", len(got), got)
+	}
+	if got[0].Kind != dnd.NPCInteractionKindCombatAlly || got[0].SourceRefs[0].StartUnitID != 50 || got[1].SourceRefs[0].StartUnitID != 50 || got[2].SourceRefs[0].StartUnitID != 10 || got[3].SourceRefs[0].StartUnitID != 90 || got[4].SourceRefs[0].StartUnitID != 999 {
+		t.Fatalf("canonical order = %#v", got)
+	}
+	if !hasWarning(result.Warnings, ReasonCodeInteractionsReordered) || !hasWarning(result.Warnings, ReasonCodeDuplicateCollapsed) {
+		t.Fatalf("warnings = %#v", result.Warnings)
+	}
+}
+
+func TestNormalizerContractAndDeterministicWarnings(t *testing.T) {
+	normalizer, err := New(Options{}, npcReferences(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if spec := ModuleSpec(); spec.Key != Key || spec.Stage != pipeline.StageNormalize || spec.ArtifactKind != dnd.NPCInteractionListKind || len(spec.ReferenceSlots) == 0 {
+		t.Fatalf("ModuleSpec() = %#v", spec)
+	}
+	if metadata := normalizer.ManifestMetadata(); metadata["normalization_policy"] != normalizationPolicy || metadata["identity_policy"] != identity.Policy || metadata["npc_registry_digest"] == "" || metadata["npc_count"] != 2 {
+		t.Fatalf("metadata = %#v", metadata)
+	}
+	if fingerprints := normalizer.CheckpointFingerprints(); len(fingerprints) != 3 || fingerprints[2].Name != "npc_registry" || fingerprints[2].Value == "" {
+		t.Fatalf("fingerprints = %#v", fingerprints)
+	}
+	if _, err := DecodeOptions(map[string]any{"unexpected": true}); err == nil {
+		t.Fatal("DecodeOptions() accepted an unknown option")
+	}
+}
+
+func interaction(name string, kind dnd.NPCInteractionKind, ref source.SourceRef) dnd.NPCInteraction {
+	return dnd.NPCInteraction{Name: name, Kind: kind, SourceRefs: []source.SourceRef{ref}}
+}
+
+func testDocument() *source.SourceDocument {
+	return &source.SourceDocument{ID: "session", Units: []source.SourceUnit{{ID: 10}, {ID: 20}, {ID: 30}}}
+}
+
+func npcReferences(t *testing.T) contracts.ReferenceSet {
+	t.Helper()
+	value := dnd.NPCList{NPCs: []dnd.NPC{
+		{ID: identity.DeriveID("Ária"), Name: "Ária", SourceRefs: []source.SourceRef{{SourceID: "registry", StartUnitID: 1, EndUnitID: 1}}},
+		{ID: identity.DeriveID("Borin"), Name: "Borin", SourceRefs: []source.SourceRef{{SourceID: "registry", StartUnitID: 1, EndUnitID: 1}}},
+	}}
+	content, err := npccodec.New().Encode(value)
+	if err != nil {
+		t.Fatalf("encode registry: %v", err)
+	}
+	return contracts.ReferenceSet{Slots: map[string]contracts.ResolvedReferenceSlot{NPCRegistryReferenceSlot: {
+		Slot:  contracts.ReferenceSlot{Name: NPCRegistryReferenceSlot, Required: true, AcceptedMediaTypes: []string{npccodec.MediaType}, AcceptedArtifactKinds: []contracts.ArtifactKind{dnd.NPCListKind}, MaxBytes: NPCRegistryMaxBytes},
+		Items: []contracts.ReferenceItem{{SlotName: NPCRegistryReferenceSlot, MediaType: npccodec.MediaType, Content: content}},
+	}}}
+}
+
+func hasWarning(warnings []contracts.Warning, reason string) bool {
+	for _, warning := range warnings {
+		if warning.ReasonCode == reason {
+			return true
+		}
+	}
+	return false
+}

internal/modules/dnd/register/merge.go

@@ -57,6 +57,27 @@ func appendCombatTurnLists(values []dnd.CombatTurnList) (dnd.CombatTurnList, err
 	return combined, nil
 }
 
+func appendNPCInteractionLists(values []dnd.NPCInteractionList) (dnd.NPCInteractionList, error) {
+	count := 0
+	present := false
+	for _, value := range values {
+		if value.Interactions != nil {
+			present = true
+		}
+		count += len(value.Interactions)
+	}
+	if !present {
+		return dnd.NPCInteractionList{}, nil
+	}
+	combined := dnd.NPCInteractionList{Interactions: make([]dnd.NPCInteraction, 0, count)}
+	for _, value := range values {
+		for _, interaction := range value.Interactions {
+			combined.Interactions = append(combined.Interactions, cloneNPCInteraction(interaction))
+		}
+	}
+	return combined, nil
+}
+
 func cloneCombatTurn(value dnd.CombatTurn) dnd.CombatTurn {
 	clone := value
 	if value.SourceRefs != nil {
@@ -64,3 +85,11 @@ func cloneCombatTurn(value dnd.CombatTurn) dnd.CombatTurn {
 	}
 	return clone
 }
+
+func cloneNPCInteraction(value dnd.NPCInteraction) dnd.NPCInteraction {
+	clone := value
+	if value.SourceRefs != nil {
+		clone.SourceRefs = append([]source.SourceRef(nil), value.SourceRefs...)
+	}
+	return clone
+}

internal/modules/dnd/register/register_test.go

@@ -185,6 +185,33 @@ func TestAppendNPCListsPreservesOrderAndArrayPresence(t *testing.T) {
 	}
 }
 
+func TestAppendNPCInteractionListsPreservesOrderPresenceAndOwnership(t *testing.T) {
+	refs := []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 10}}
+	input := []dnd.NPCInteractionList{
+		{},
+		{Interactions: []dnd.NPCInteraction{}},
+		{Interactions: []dnd.NPCInteraction{{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, SourceRefs: refs}}},
+		{Interactions: []dnd.NPCInteraction{{Name: "Borin", Kind: dnd.NPCInteractionKindMentioned, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}}}}},
+	}
+	got, err := appendNPCInteractionLists(input)
+	if err != nil {
+		t.Fatalf("appendNPCInteractionLists() error = %v", err)
+	}
+	if got.Interactions == nil || !reflect.DeepEqual([]string{got.Interactions[0].Name, got.Interactions[1].Name}, []string{"Aria", "Borin"}) {
+		t.Fatalf("combined interactions = %#v", got)
+	}
+	got.Interactions[0].SourceRefs[0].StartUnitID = 999
+	if input[2].Interactions[0].SourceRefs[0].StartUnitID == 999 {
+		t.Fatal("merged interactions share source reference storage")
+	}
+	for _, values := range [][]dnd.NPCInteractionList{nil, []dnd.NPCInteractionList{{}, {}}} {
+		result, err := appendNPCInteractionLists(values)
+		if err != nil || result.Interactions != nil {
+			t.Fatalf("nil-only merge = %#v, %v; want nil interactions", result, err)
+		}
+	}
+}
+
 func TestAppendCombatTurnListsPreservesOrderPresenceAndOwnership(t *testing.T) {
 	refs := []source.SourceRef{{SourceID: "session", StartUnitID: 1, EndUnitID: 1}}
 	input := []dnd.CombatTurnList{

internal/modules/dnd/validate/npcinteractions/invariants/validator.go

@@ -149,9 +149,12 @@ func issuesFor(doc *source.SourceDocument, value dnd.NPCInteractionList, npcRegi
 }
 
 func interactionLess(doc *source.SourceDocument, left, right dnd.NPCInteraction) bool {
-	leftPosition, _ := earliestSourcePosition(doc, left)
+	leftPosition, leftHasEvidence := earliestSourcePosition(doc, left)
-	rightPosition, _ := earliestSourcePosition(doc, right)
+	rightPosition, rightHasEvidence := earliestSourcePosition(doc, right)
-	if leftPosition != rightPosition {
+	if leftHasEvidence != rightHasEvidence {
+		return leftHasEvidence
+	}
+	if leftHasEvidence && leftPosition != rightPosition {
 		return leftPosition < rightPosition
 	}
 	leftKey := identity.ComparisonKey(left.Name)
@@ -182,14 +185,26 @@ func sourceRefLess(doc *source.SourceDocument, left, right source.SourceRef) boo
 	if left.SourceID != right.SourceID {
 		return left.SourceID < right.SourceID
 	}
-	leftStart, _ := source.UnitIndex(doc, left.StartUnitID)
+	leftStart, leftStartOK := source.UnitIndex(doc, left.StartUnitID)
-	rightStart, _ := source.UnitIndex(doc, right.StartUnitID)
+	rightStart, rightStartOK := source.UnitIndex(doc, right.StartUnitID)
-	if leftStart != rightStart {
+	if leftStartOK != rightStartOK {
+		return leftStartOK
+	}
+	if leftStartOK && leftStart != rightStart {
 		return leftStart < rightStart
 	}
-	leftEnd, _ := source.UnitIndex(doc, left.EndUnitID)
+	if left.StartUnitID != right.StartUnitID {
-	rightEnd, _ := source.UnitIndex(doc, right.EndUnitID)
+		return left.StartUnitID < right.StartUnitID
-	return leftEnd < rightEnd
+	}
+	leftEnd, leftEndOK := source.UnitIndex(doc, left.EndUnitID)
+	rightEnd, rightEndOK := source.UnitIndex(doc, right.EndUnitID)
+	if leftEndOK != rightEndOK {
+		return leftEndOK
+	}
+	if leftEndOK && leftEnd != rightEnd {
+		return leftEnd < rightEnd
+	}
+	return left.EndUnitID < right.EndUnitID
 }
 
 func earliestSourcePosition(doc *source.SourceDocument, interaction dnd.NPCInteraction) (int, bool) {

internal/modules/dnd/validate/npcinteractions/invariants/validator_test.go

@@ -60,6 +60,18 @@ func TestValidatorRejectsOwnedCanonicalNameReferenceOrderListOrderAndDuplicates(
 	}
 }
 
+func TestValidatorAcceptsValidEvidenceBeforeInvalidEvidence(t *testing.T) {
+	references := registryReferences(t, "Aria", "Borin")
+	value := dnd.NPCInteractionList{Interactions: []dnd.NPCInteraction{
+		{Name: "Borin", Kind: dnd.NPCInteractionKindMentioned, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}}},
+		{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 99, EndUnitID: 99}}},
+	}}
+	result, err := newValidator(t, references).Validate(context.Background(), request(references, value))
+	if err != nil || !result.Approved {
+		t.Fatalf("Validate() = %#v, %v", result, err)
+	}
+}
+
 func TestValidatorDefersShapeAndSourceReferenceFailuresAndRequiresRegistry(t *testing.T) {
 	references := registryReferences(t, "Aria", "Borin")
 	for _, value := range []dnd.NPCInteractionList{