Improve item occurrence holder corrections

assets/dnd/item-occurrences/prompts/instructions.md

@@ -18,12 +18,20 @@ when the transcript explicitly describes it being physically destroyed or
 expended as a non-payment component. Use `transferred` only when possession
 moves between two distinct named party members.
 
-Return both `from` and `to` for every occurrence, using `null` when a holder does not
+Return both `from` and `to` for every occurrence. Use JSON `null`, not an empty
-apply. For `discovered`, set both holders to `null`. For `acquired`, set `from`
+string, whenever a holder does not apply. Follow this holder matrix exactly:
-to `null` and provide `to`; for `lost` and `consumed`, provide `from` and set
+
-`to` to `null`; and for `transferred`, provide both holders. Use `party` only
+| `kind` | required `from` | required `to` |
-for collective or unresolved party possession, never for either side of a
+| --- | --- | --- |
-transfer. Do not emit a transfer for a gift, sale, or payment outside the party.
+| `discovered` | `null` | `null` |
+| `acquired` | `null` | `party` or the named party member gaining possession |
+| `lost` | `party` or the named party member losing possession | `null` |
+| `consumed` | `party` or the named party member consuming the item | `null` |
+| `transferred` | one named party member | a different named party member |
+
+Use `party` only for collective or unresolved party possession, never for
+either side of a transfer. Do not emit a transfer for a gift, sale, or payment
+outside the party.
 
 Ordinary non-depleting use is not an occurrence. Do not infer acquisition from a
 discovery, or discovery from an acquisition: emit both only when each is

assets/dnd/item-occurrences/schemas/dnd_item_occurrences_llm.v1.json

@@ -13,7 +13,10 @@
         "required": ["name", "kind", "quantity", "from", "to", "source_refs"],
         "properties": {
           "name": {"type": "string"},
-          "kind": {"type": "string"},
+          "kind": {
+            "type": "string",
+            "enum": ["discovered", "acquired", "lost", "consumed", "transferred"]
+          },
           "quantity": {"type": ["integer", "null"]},
           "from": {"type": ["string", "null"]},
           "to": {"type": ["string", "null"]},

docs/internal/dnd.md

@@ -201,6 +201,13 @@ hashes, validator module keys, or reason codes. Those identifiers remain in
 ordinary validation provenance; only the actionable semantic guidance is
 eligible for the correction prompt.
 
+Item-occurrence shape validation groups repeated holder mistakes by occurrence
+kind and gives the producer the required JSON null/non-null relationship. It
+identifies affected records by contextual item name and cited transcript range,
+never by the deterministically attached durable item ID. Holder mistakes remain
+semantic rejections rather than silent rewrites because changing a holder can
+also change the meaning of the occurrence kind.
+
 Enemy-event extraction additionally rejects a second `engaged` observation for
 the same comparison identity within one scene-scoped result. Normalization may
 combine results from distinct scenes, so it intentionally does not apply that

docs/roadmap/future.md

@@ -15,7 +15,7 @@ diagnostics. The remaining near-term work applies those completed foundations
 to domain review and empirical evaluation.
 
 The active D&D reliability work is defined by
-[D&D Source-Reference Endpoint Canonicalization](source-reference-canonicalization.md).
+[D&D Item-Occurrence Holder Reliability](item-occurrence-holder-reliability.md).
 
 ## Near-Term D&D Pipeline
 

docs/roadmap/item-occurrence-holder-reliability.md

@@ -0,0 +1,95 @@
+# D&D Item-Occurrence Holder Reliability
+
+## Purpose
+
+Improve item-occurrence extraction reliability for smaller models by making
+holder rules easier to follow and semantic retry feedback specific enough to
+correct a rejected response.
+
+## Problem
+
+The item-occurrence prompt correctly defines the permitted `from` and `to`
+values for every occurrence kind, but presents the rules in dense prose. The
+private schema requires both nullable fields but cannot express their
+cross-field relationship. The deterministic shape validator correctly rejects
+incompatible combinations, yet its model-facing correction guidance only asks
+for generally valid holder combinations. Notarius therefore resends the
+defective response without telling the model which contextual records failed or
+what their corrected holder shape must be.
+
+## Target State
+
+- The module instructions present one compact, unambiguous holder matrix:
+  `discovered` uses two nulls; `acquired` uses a null `from` and non-null `to`;
+  `lost` and `consumed` use a non-null `from` and null `to`; and `transferred`
+  uses two distinct named party members.
+- The private LLM schema continues requiring `quantity`, `from`, and `to` with
+  nullable types, and constrains `kind` to the five supported values. The
+  durable v1 artifact contract remains unchanged.
+- A holder-combination rejection supplies bounded, semantically meaningful
+  correction guidance that identifies affected occurrences by contextual item
+  name and transcript evidence where useful, states the required JSON
+  null/non-null shape, and requests a complete corrected replacement.
+- Correction guidance never exposes durable item IDs, hashes, validator keys,
+  reason codes, or other opaque implementation identifiers. It does not rely
+  solely on mapped array indexes, because canonical extraction ordering may
+  differ from the raw response order appended to the retry prompt.
+- Operator-facing validation messages remain specific and include enough
+  information to distinguish a missing holder from an extra or misplaced
+  holder.
+- The existing validator remains strict. Holder combinations are not silently
+  rewritten: unlike reversed evidence endpoints, changing a holder can conceal
+  a misclassified discovery, acquisition, loss, consumption, or transfer.
+
+## Required Work
+
+1. Rewrite the holder paragraph in
+   `assets/dnd/item-occurrences/prompts/instructions.md` as a compact matrix,
+   retaining the existing classification and currency rules without adding
+   contradictory repetition.
+2. Add the five supported `kind` values as an enum in the private item-occurrence
+   response schema. Keep every listed field required and keep `quantity`,
+   `from`, and `to` explicitly nullable.
+3. Refactor the item-occurrence shape validator to build detailed bounded
+   operator issues and separate actionable correction guidance from the same
+   evaluated candidate. Group repeated holder failures where practical while
+   retaining contextual record identification and every distinct correction
+   rule needed by the model.
+4. Preserve the generic validation retry protocol: the complete original
+   prompt, exact defective assistant response, and one user correction message.
+   Do not add a module-local retry loop.
+5. Ensure the changed prompt and schema produce new computed fingerprints, and
+   bump the validator policy fingerprint so stale checkpoints cannot be reused
+   across the behavior change. Update internal documentation where needed; the
+   external item-occurrence contract requires no semantic change.
+6. Add lean offline regression coverage for the holder matrix, schema enum,
+   contextual correction guidance, bounded aggregation, absence of opaque IDs,
+   and a rejected-then-corrected extraction attempt. Avoid exact prose snapshots
+   and live-provider tests.
+
+## Non-Goals
+
+- Automatically deleting, moving, or inferring holder values.
+- Changing the durable item-occurrence schema or event taxonomy.
+- Encoding the complete semantic holder matrix through provider-sensitive
+  conditional JSON Schema constructs.
+- Adding warnings for ordinary semantic rejection or successful correction.
+- Tuning unrelated D&D extraction prompts or validators.
+
+## Acceptance Criteria
+
+- The maintained item-occurrence prompt shows the clear holder matrix,
+  and the private schema rejects unsupported kind strings while remaining
+  compatible with strict structured-output providers.
+- A rejected `acquired` occurrence receives guidance that explicitly requires
+  `from: null` and a non-null `to`; equivalent exact guidance exists for the
+  other four kinds.
+- Multiple invalid occurrences yield one bounded correction request containing
+  all distinct required fixes and contextual identifiers that can be matched to
+  the appended raw response.
+- No correction message contains an item ID, hash, validator key, or reason
+  code, and the raw model candidate remains byte-faithful.
+- Valid candidates and the durable output contract are unchanged; invalid
+  holder combinations still fail after configured retries are exhausted.
+- Focused tests, `go test ./...`, `go vet ./...`, and `go build ./cmd/notarius`
+  pass.

internal/modules/dnd/extract/itemoccurrences/extractor_test.go

@@ -6,7 +6,9 @@ import (
 	"testing"
 
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
 	itemidentity "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/items/identity"
+	itemoccurrenceshape "gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/validate/itemoccurrences/shape"
 )
 
 func TestExtractGroundsOccurrencesInRequiredRegistry(t *testing.T) {
@@ -146,3 +148,46 @@ func TestExtractUsesOnlySupportedPromptInputs(t *testing.T) {
 		t.Fatalf("unexpected prompt input: %#v", client.requests[0].Inputs)
 	}
 }
+
+func TestExtractCarriesRejectedHolderGuidanceIntoCorrectedAttempt(t *testing.T) {
+	references := itemRegistryReferences(t)
+	req := extractionRequest()
+	req.References = references
+	defectiveResponse := []byte(`{"occurrences":[{"name":"Torch","kind":"acquired","quantity":null,"from":"Chest","to":"party","source_refs":[{"start_unit_id":2,"end_unit_id":2}]}]}`)
+	defective, err := newExtractor(t, &fakeItemOccurrencesLLMClient{content: defectiveResponse}, references).Extract(context.Background(), req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	validation, err := itemoccurrenceshape.New(itemoccurrenceshape.Options{}).Validate(context.Background(), contracts.TypedValidationRequest[dnd.ItemOccurrenceList]{Value: defective.Value})
+	if err != nil || validation.Approved {
+		t.Fatalf("holder validation = %#v, %v; want rejection", validation, err)
+	}
+	for _, fragment := range []string{"For `acquired` occurrences", "`from` to JSON null", "item \"Torch\"", "source unit 2"} {
+		if !strings.Contains(validation.CorrectionGuidance, fragment) {
+			t.Fatalf("CorrectionGuidance = %q, want %q", validation.CorrectionGuidance, fragment)
+		}
+	}
+	for _, forbidden := range []string{defective.Value.Occurrences[0].ItemID, "item_id", "sha256", itemoccurrenceshape.Key, itemoccurrenceshape.ReasonCode} {
+		if strings.Contains(validation.CorrectionGuidance, forbidden) {
+			t.Fatalf("CorrectionGuidance leaked implementation identifier %q: %q", forbidden, validation.CorrectionGuidance)
+		}
+	}
+	correction, err := contracts.NewSemanticCorrection(defective.ModelCandidate.Response, validation.CorrectionGuidance)
+	if err != nil {
+		t.Fatal(err)
+	}
+	correctedResponse := []byte(`{"occurrences":[{"name":"Torch","kind":"acquired","quantity":null,"from":null,"to":"party","source_refs":[{"start_unit_id":2,"end_unit_id":2}]}]}`)
+	client := &fakeItemOccurrencesLLMClient{content: correctedResponse}
+	req.Correction = correction
+	corrected, err := newExtractor(t, client, references).Extract(context.Background(), req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	accepted, err := itemoccurrenceshape.New(itemoccurrenceshape.Options{}).Validate(context.Background(), contracts.TypedValidationRequest[dnd.ItemOccurrenceList]{Value: corrected.Value})
+	if err != nil || !accepted.Approved {
+		t.Fatalf("corrected holder validation = %#v, %v; want approval", accepted, err)
+	}
+	if len(client.requests) != 1 || client.requests[0].Correction == nil || string(client.requests[0].Correction.AssistantResponse) != string(defectiveResponse) || client.requests[0].Correction.UserGuidance != validation.CorrectionGuidance {
+		t.Fatalf("corrected request = %#v, want byte-faithful defective response and semantic guidance", client.requests)
+	}
+}

internal/modules/dnd/extract/itemoccurrences/prompt_assets_test.go

@@ -58,6 +58,17 @@ func TestPromptAssetsPrepareItemOccurrencePrompt(t *testing.T) {
 			t.Fatalf("prepared prompt contains obsolete evidence field %q: %s", obsolete, content)
 		}
 	}
+	for _, holderRule := range []string{
+		"| `discovered` | `null` | `null` |",
+		"| `acquired` | `null` | `party` or the named party member gaining possession |",
+		"| `lost` | `party` or the named party member losing possession | `null` |",
+		"| `consumed` | `party` or the named party member consuming the item | `null` |",
+		"| `transferred` | one named party member | a different named party member |",
+	} {
+		if !strings.Contains(content, holderRule) {
+			t.Fatalf("prepared prompt does not include holder rule %q", holderRule)
+		}
+	}
 }
 
 func TestPromptAssetsDoNotLeakIntoMetadata(t *testing.T) {

internal/modules/dnd/extract/itemoccurrences/schema_test.go

@@ -19,7 +19,7 @@ func TestResponseSchemaIsStrictlyStructuralAndPrivate(t *testing.T) {
 	}
 	valid := map[string]any{"occurrences": []any{
 		map[string]any{
-			"name": "", "kind": "unsupported", "quantity": 0, "from": "party", "to": "Party",
+			"name": "", "kind": "transferred", "quantity": 0, "from": "party", "to": "Party",
 			"source_refs": []any{map[string]any{"start_unit_id": 0, "end_unit_id": -1}},
 		},
 		map[string]any{
@@ -41,6 +41,7 @@ func TestResponseSchemaIsStrictlyStructuralAndPrivate(t *testing.T) {
 		{"missing occurrences", map[string]any{}},
 		{"missing occurrence name", map[string]any{"occurrences": []any{withoutField(responseOccurrence(), "name")}}},
 		{"missing nullable field", map[string]any{"occurrences": []any{withoutField(responseOccurrence(), "quantity")}}},
+		{"unsupported kind", map[string]any{"occurrences": []any{withField(responseOccurrence(), "kind", "unsupported")}}},
 		{"opaque item identifier", map[string]any{"occurrences": []any{withField(responseOccurrence(), "item_id", "item:sha256:opaque")}}},
 		{"unknown occurrence field", map[string]any{"occurrences": []any{withField(responseOccurrence(), "extra", true)}}},
 		{"segment-named range", map[string]any{"occurrences": []any{withField(responseOccurrence(), "source_refs", []any{map[string]any{"start_segment": 1, "end_segment": 1}})}}},

internal/modules/dnd/validate/itemoccurrences/shape/validator.go

@@ -16,7 +16,7 @@ import (
 const (
 	Key        = "extract/dnd/item-occurrences/shape"
 	ReasonCode = "invalid_item_occurrence_shape"
-	policy     = "dnd.item_occurrences.shape.v1"
+	policy     = "dnd.item_occurrences.shape.v2"
 )
 
 type Options struct{}
@@ -35,47 +35,181 @@ func (v *Validator) CheckpointFingerprints() []pipeline.CheckpointFingerprint {
 }
 
 func (v *Validator) Validate(_ context.Context, req contracts.TypedValidationRequest[dnd.ItemOccurrenceList]) (contracts.ValidationResult, error) {
-	if err := Validate(req.Value); err != nil {
+	assessment := assess(req.Value)
-		return contracts.ValidationResult{Approved: false, ReasonCode: ReasonCode, Message: err.Error(), CorrectionGuidance: "Return a complete item-occurrence list with every required field present, valid contextual item names, supported event kinds and holder combinations, positive quantities, and valid source references."}, nil
+	if len(assessment.operatorIssues) != 0 {
+		return contracts.ValidationResult{
+			Approved:           false,
+			ReasonCode:         ReasonCode,
+			Message:            assessment.operatorMessage(),
+			CorrectionGuidance: assessment.correctionGuidance(),
+		}, nil
 	}
 	return contracts.ValidationResult{Approved: true}, nil
 }
 
 // Validate returns one bounded error for every owned item-occurrence shape issue.
 func Validate(value dnd.ItemOccurrenceList) error {
-	issues := issuesFor(value)
+	assessment := assess(value)
-	if len(issues) == 0 {
+	if len(assessment.operatorIssues) == 0 {
 		return nil
 	}
-	return fmt.Errorf("%s", diagnostics.Aggregate("invalid item occurrence shape", issues))
+	return fmt.Errorf("%s", assessment.operatorMessage())
 }
 
-func issuesFor(value dnd.ItemOccurrenceList) []string {
+type validationAssessment struct {
+	operatorIssues   []string
+	correctionGroups []correctionGroup
+	groupIndexes     map[string]int
+}
+
+type correctionGroup struct {
+	label       string
+	rule        string
+	records     []string
+	recordsSeen map[string]struct{}
+}
+
+func assess(value dnd.ItemOccurrenceList) validationAssessment {
+	assessment := validationAssessment{groupIndexes: make(map[string]int)}
 	if value.Occurrences == nil {
-		return []string{"occurrences must be present"}
+		assessment.operatorIssues = append(assessment.operatorIssues, "occurrences must be present")
+		assessment.addCorrection("occurrences", "item-occurrence list", "Return an `occurrences` array; use an empty array when the transcript establishes no occurrences.", "")
+		return assessment
 	}
-	issues := make([]string, 0)
 	for index, occurrence := range value.Occurrences {
 		prefix := fmt.Sprintf("occurrences[%d]", index)
+		context := occurrenceContext(occurrence)
 		if strings.TrimSpace(occurrence.ItemID) == "" {
-			issues = append(issues, prefix+".item_id must not be empty: "+diagnostics.Quote(occurrence.ItemID))
+			assessment.operatorIssues = append(assessment.operatorIssues, prefix+".item_id must not be empty: "+diagnostics.Quote(occurrence.ItemID))
+			assessment.addCorrection("item-name", "item name", "Select a contextual item name from the supplied item registry for every occurrence.", context)
 		}
 		if strings.TrimSpace(occurrence.Name) == "" {
-			issues = append(issues, prefix+".name must not be empty: "+diagnostics.Quote(occurrence.Name))
+			assessment.operatorIssues = append(assessment.operatorIssues, prefix+".name must not be empty: "+diagnostics.Quote(occurrence.Name))
+			assessment.addCorrection("item-name", "item name", "Select a contextual item name from the supplied item registry for every occurrence.", context)
 		}
 		if !itemoccurrences.SupportedKind(occurrence.Kind) {
-			issues = append(issues, prefix+".kind is unsupported: "+diagnostics.Quote(string(occurrence.Kind)))
+			assessment.operatorIssues = append(assessment.operatorIssues, prefix+".kind is unsupported: "+diagnostics.Quote(string(occurrence.Kind)))
+			assessment.addCorrection("kind", "occurrence kind", "Set `kind` to exactly one of `discovered`, `acquired`, `lost`, `consumed`, or `transferred`.", context)
 		} else if !itemoccurrences.ValidHolderCombination(occurrence.Kind, occurrence.From, occurrence.To) {
-			issues = append(issues, prefix+".from and .to are incompatible with "+diagnostics.Quote(string(occurrence.Kind)))
+			assessment.operatorIssues = append(assessment.operatorIssues, prefix+holderOperatorIssue(occurrence))
+			assessment.addCorrection("holders:"+string(occurrence.Kind), string(occurrence.Kind)+" holders", holderCorrection(occurrence.Kind), context)
 		}
 		if occurrence.Quantity != nil && *occurrence.Quantity < 1 {
-			issues = append(issues, prefix+".quantity must be positive when present")
+			assessment.operatorIssues = append(assessment.operatorIssues, prefix+".quantity must be positive when present")
+			assessment.addCorrection("quantity", "quantity", "Set `quantity` to a positive integer when the transcript states one, or to JSON null when it does not.", context)
 		}
 		if len(occurrence.SourceRefs) == 0 {
-			issues = append(issues, prefix+".source_refs must contain at least one reference")
+			assessment.operatorIssues = append(assessment.operatorIssues, prefix+".source_refs must contain at least one reference")
+			assessment.addCorrection("source-refs", "source references", "Provide at least one transcript source range that directly supports every occurrence.", context)
 		}
 	}
-	return issues
+	return assessment
+}
+
+func (assessment *validationAssessment) addCorrection(key, label, rule, record string) {
+	index, ok := assessment.groupIndexes[key]
+	if !ok {
+		index = len(assessment.correctionGroups)
+		assessment.groupIndexes[key] = index
+		assessment.correctionGroups = append(assessment.correctionGroups, correctionGroup{label: label, rule: rule, recordsSeen: make(map[string]struct{})})
+	}
+	if record != "" {
+		group := &assessment.correctionGroups[index]
+		if _, seen := group.recordsSeen[record]; seen {
+			return
+		}
+		group.recordsSeen[record] = struct{}{}
+		group.records = append(group.records, record)
+	}
+}
+
+func (assessment validationAssessment) operatorMessage() string {
+	return diagnostics.Aggregate("invalid item occurrence shape", assessment.operatorIssues)
+}
+
+func (assessment validationAssessment) correctionGuidance() string {
+	issues := make([]string, 0, len(assessment.correctionGroups)+len(assessment.operatorIssues))
+	for _, group := range assessment.correctionGroups {
+		issues = append(issues, group.rule)
+	}
+	for _, group := range assessment.correctionGroups {
+		for _, record := range group.records {
+			issues = append(issues, "Affected "+group.label+" record: "+record)
+		}
+	}
+	return diagnostics.Aggregate("Correct every rejected item occurrence and return the complete replacement list", issues)
+}
+
+func holderOperatorIssue(occurrence dnd.ItemOccurrence) string {
+	return fmt.Sprintf(
+		".from and .to are incompatible with %s: expected %s; got from %s and to %s",
+		diagnostics.Quote(string(occurrence.Kind)), holderExpectation(occurrence.Kind),
+		holderDisplay(occurrence.From), holderDisplay(occurrence.To),
+	)
+}
+
+func holderExpectation(kind dnd.ItemOccurrenceKind) string {
+	switch kind {
+	case dnd.ItemOccurrenceKindDiscovered:
+		return "both holders absent"
+	case dnd.ItemOccurrenceKindAcquired:
+		return "from absent and to present"
+	case dnd.ItemOccurrenceKindLost:
+		return "from present and to absent"
+	case dnd.ItemOccurrenceKindConsumed:
+		return "from present and to absent"
+	case dnd.ItemOccurrenceKindTransferred:
+		return "distinct named non-party holders"
+	default:
+		return "a supported holder combination"
+	}
+}
+
+func holderCorrection(kind dnd.ItemOccurrenceKind) string {
+	switch kind {
+	case dnd.ItemOccurrenceKindDiscovered:
+		return "For `discovered` occurrences, set both `from` and `to` to JSON null."
+	case dnd.ItemOccurrenceKindAcquired:
+		return "For `acquired` occurrences, set `from` to JSON null and `to` to `party` or the named party member gaining possession."
+	case dnd.ItemOccurrenceKindLost:
+		return "For `lost` occurrences, set `from` to `party` or the named party member losing possession and set `to` to JSON null."
+	case dnd.ItemOccurrenceKindConsumed:
+		return "For `consumed` occurrences, set `from` to `party` or the named party member consuming the item and set `to` to JSON null."
+	case dnd.ItemOccurrenceKindTransferred:
+		return "For `transferred` occurrences, set `from` and `to` to two distinct named party members; never use `party` for either holder."
+	default:
+		return "Use the holder combination required by the selected supported occurrence kind."
+	}
+}
+
+func occurrenceContext(occurrence dnd.ItemOccurrence) string {
+	name := itemoccurrences.DisplayValue(occurrence.Name)
+	context := "item " + diagnostics.Quote(name)
+	if name == "" {
+		context = "item with a blank contextual name"
+	}
+	if len(occurrence.SourceRefs) == 0 {
+		context += " without a cited source range"
+	} else {
+		ref := occurrence.SourceRefs[0]
+		if ref.StartUnitID == ref.EndUnitID {
+			context += fmt.Sprintf(" at source unit %d", ref.StartUnitID)
+		} else {
+			context += fmt.Sprintf(" at source units %d-%d", ref.StartUnitID, ref.EndUnitID)
+		}
+		if len(occurrence.SourceRefs) > 1 {
+			context += fmt.Sprintf(" (first of %d cited ranges)", len(occurrence.SourceRefs))
+		}
+	}
+	return context + " with from " + holderDisplay(occurrence.From) + " and to " + holderDisplay(occurrence.To)
+}
+
+func holderDisplay(value string) string {
+	value = itemoccurrences.DisplayValue(value)
+	if value == "" {
+		return "JSON null"
+	}
+	return diagnostics.Quote(value)
 }
 
 func Spec() pipeline.ValidatorSpec {

internal/modules/dnd/validate/itemoccurrences/shape/validator_test.go

@@ -2,6 +2,7 @@ package shape
 
 import (
 	"context"
+	"fmt"
 	"reflect"
 	"strings"
 	"testing"
@@ -68,16 +69,94 @@ func TestValidatorRejectsOwnedSemanticBoundaries(t *testing.T) {
 	}
 }
 
+func TestValidatorProvidesActionableContextualHolderGuidance(t *testing.T) {
+	tests := []struct {
+		name         string
+		occurrence   dnd.ItemOccurrence
+		wantGuidance []string
+	}{
+		{
+			name:         "discovered",
+			occurrence:   dnd.ItemOccurrence{ItemID: "item:sha256:opaque", Name: "Ring", Kind: dnd.ItemOccurrenceKindDiscovered, From: "Aria", SourceRefs: refs(1, 2)},
+			wantGuidance: []string{"For `discovered` occurrences", "both `from` and `to` to JSON null"},
+		},
+		{
+			name:         "acquired",
+			occurrence:   dnd.ItemOccurrence{ItemID: "item:sha256:opaque", Name: "Ring", Kind: dnd.ItemOccurrenceKindAcquired, From: "Merchant", To: "party", SourceRefs: refs(1, 2)},
+			wantGuidance: []string{"For `acquired` occurrences", "`from` to JSON null", "named party member gaining possession"},
+		},
+		{
+			name:         "lost",
+			occurrence:   dnd.ItemOccurrence{ItemID: "item:sha256:opaque", Name: "Ring", Kind: dnd.ItemOccurrenceKindLost, From: "party", To: "Merchant", SourceRefs: refs(1, 2)},
+			wantGuidance: []string{"For `lost` occurrences", "named party member losing possession", "`to` to JSON null"},
+		},
+		{
+			name:         "consumed",
+			occurrence:   dnd.ItemOccurrence{ItemID: "item:sha256:opaque", Name: "Ring", Kind: dnd.ItemOccurrenceKindConsumed, SourceRefs: refs(1, 2)},
+			wantGuidance: []string{"For `consumed` occurrences", "named party member consuming the item", "`to` to JSON null"},
+		},
+		{
+			name:         "transferred",
+			occurrence:   dnd.ItemOccurrence{ItemID: "item:sha256:opaque", Name: "Ring", Kind: dnd.ItemOccurrenceKindTransferred, From: "party", To: "Borin", SourceRefs: refs(1, 2)},
+			wantGuidance: []string{"For `transferred` occurrences", "two distinct named party members", "never use `party`"},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := New(Options{}).Validate(context.Background(), contracts.TypedValidationRequest[dnd.ItemOccurrenceList]{Value: listWith(test.occurrence)})
+			if err != nil || result.Approved {
+				t.Fatalf("Validate() = %#v, %v; want rejection", result, err)
+			}
+			for _, fragment := range append(test.wantGuidance, "item \"Ring\"", "source units 1-2") {
+				if !strings.Contains(result.CorrectionGuidance, fragment) {
+					t.Fatalf("CorrectionGuidance = %q, want %q", result.CorrectionGuidance, fragment)
+				}
+			}
+			for _, forbidden := range []string{test.occurrence.ItemID, "sha256", Key, ReasonCode, "occurrences[0]"} {
+				if strings.Contains(result.CorrectionGuidance, forbidden) {
+					t.Fatalf("CorrectionGuidance leaked implementation identifier %q: %q", forbidden, result.CorrectionGuidance)
+				}
+			}
+			if !strings.Contains(result.Message, "expected") || !strings.Contains(result.Message, "got from") {
+				t.Fatalf("operator message = %q, want expected and observed holders", result.Message)
+			}
+		})
+	}
+}
+
+func TestValidatorGroupsRepeatedHolderCorrectionsAndRetainsDistinctRules(t *testing.T) {
+	value := dnd.ItemOccurrenceList{Occurrences: []dnd.ItemOccurrence{
+		{ItemID: "item-1", Name: "Silver Pieces", Kind: dnd.ItemOccurrenceKindAcquired, From: "Orc", To: "party", SourceRefs: refs(1, 1)},
+		{ItemID: "item-2", Name: "Torch", Kind: dnd.ItemOccurrenceKindAcquired, From: "Chest", To: "Aria", SourceRefs: refs(2, 2)},
+		{ItemID: "item-3", Name: "Potion", Kind: dnd.ItemOccurrenceKindConsumed, SourceRefs: refs(3, 3)},
+	}}
+	result, err := New(Options{}).Validate(context.Background(), contracts.TypedValidationRequest[dnd.ItemOccurrenceList]{Value: value})
+	if err != nil || result.Approved {
+		t.Fatalf("Validate() = %#v, %v; want rejection", result, err)
+	}
+	if strings.Count(result.CorrectionGuidance, "For `acquired` occurrences") != 1 || strings.Count(result.CorrectionGuidance, "For `consumed` occurrences") != 1 {
+		t.Fatalf("CorrectionGuidance = %q, want one rule per affected kind", result.CorrectionGuidance)
+	}
+	for _, fragment := range []string{"item \"Silver Pieces\"", "source unit 1", "item \"Torch\"", "source unit 2", "item \"Potion\"", "source unit 3"} {
+		if !strings.Contains(result.CorrectionGuidance, fragment) {
+			t.Fatalf("CorrectionGuidance = %q, want contextual fragment %q", result.CorrectionGuidance, fragment)
+		}
+	}
+}
+
 func TestValidatorAggregatesBoundedIndexedDiagnosticsAndRegistration(t *testing.T) {
 	value := dnd.ItemOccurrenceList{Occurrences: make([]dnd.ItemOccurrence, 24)}
 	for index := range value.Occurrences {
-		value.Occurrences[index] = dnd.ItemOccurrence{ItemID: "item", Name: " \n", Kind: "unsupported"}
+		value.Occurrences[index] = dnd.ItemOccurrence{ItemID: "item", Name: fmt.Sprintf("Item %d", index), Kind: "unsupported"}
 	}
 	result, err := New(Options{}).Validate(context.Background(), contracts.TypedValidationRequest[dnd.ItemOccurrenceList]{Value: value})
 	if err != nil || result.Approved || result.ReasonCode != ReasonCode || len([]byte(result.Message)) > 4096 || !utf8.ValidString(result.Message) || !strings.Contains(result.Message, "occurrences[0]") || !strings.Contains(result.Message, "additional issue(s) omitted") {
 		t.Fatalf("Validate() = %#v, %v", result, err)
 	}
-	if value.Occurrences[0].Name != " \n" {
+	if len([]byte(result.CorrectionGuidance)) > 4096 || !utf8.ValidString(result.CorrectionGuidance) || !strings.Contains(result.CorrectionGuidance, "additional issue(s) omitted") {
+		t.Fatalf("CorrectionGuidance = %q, want bounded aggregate", result.CorrectionGuidance)
+	}
+	if value.Occurrences[0].Name != "Item 0" {
 		t.Fatal("Validate() mutated input")
 	}
 	if got := New(Options{}).CheckpointFingerprints(); !reflect.DeepEqual(got, []pipeline.CheckpointFingerprint{{Name: "policy", Value: policy}}) {