Share section lookups and replacement previews across validators

internal/framework/validators/section.go

@@ -0,0 +1,61 @@
+package validators
+
+import (
+	"math"
+
+	"gitea.maximumdirect.net/eric/audita/v3/internal/core/schema"
+	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/proposals"
+)
+
+// SectionLookup indexes the immutable source section shared by validation
+// and revalidation. Application checks its own, changing transcript.
+type SectionLookup struct {
+	segments  []schema.Segment
+	positions map[int]int
+}
+
+func NewSectionLookup(transcript *schema.Transcript) *SectionLookup {
+	section := &SectionLookup{}
+	if transcript != nil {
+		section.segments = transcript.Segments
+		section.positions = make(map[int]int, len(section.segments))
+		for i, segment := range section.segments {
+			section.positions[segment.ID] = i
+		}
+	}
+	return section
+}
+
+func (s *SectionLookup) Position(id int) (int, bool) {
+	position, ok := s.positions[id]
+	return position, ok
+}
+
+func (r Request) sectionLookup() *SectionLookup {
+	if r.Section != nil {
+		return r.Section
+	}
+	return NewSectionLookup(r.WorkingTranscript)
+}
+
+// Preview reuses the replacement preview for this proposal index within one
+// validation pass. A revision starts a new pass with its own preview map.
+func (r Request) Preview(candidate proposals.EnrichedCorrectionProposal) proposals.SegmentPreviewResult {
+	if preview, ok := r.Previews[candidate.ProposalIndex]; ok {
+		return preview
+	}
+	section := r.sectionLookup()
+	var segment *schema.Segment
+	if position, ok := section.Position(candidate.TargetSegmentID); ok {
+		segment = &section.segments[position]
+	}
+	correction := candidate.CorrectionProposal
+	if r.IndependentEvidence && (math.IsNaN(correction.Confidence) || correction.Confidence < 0 || correction.Confidence > 1) {
+		correction.Confidence = 0.5
+	}
+	preview := proposals.PreviewProposalForSegment(segment, correction, r.ReplacementPolicy)
+	if r.Previews != nil {
+		r.Previews[candidate.ProposalIndex] = preview
+	}
+	return preview
+}