Record chunking metadata in process runs

internal/core/diagnostics/run_dir.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"time"
 
+	"gitea.maximumdirect.net/eric/audita/internal/core/chunking"
 	"gitea.maximumdirect.net/eric/audita/internal/core/normalization"
 	"gitea.maximumdirect.net/eric/audita/internal/core/reporting"
 	"gitea.maximumdirect.net/eric/audita/internal/core/schema"
@@ -119,7 +120,20 @@ func (r *RunDirectory) WriteErrorLog(errorMessage string) error {
 	return os.WriteFile(errorPath, []byte(errorMessage+"\n"), 0o644)
 }
 
-// ApplyRetention applies a minimal phase-2 retention policy.
+// WriteChunkingSummary writes the chunking summary artifact
+func (r *RunDirectory) WriteChunkingSummary(summary *chunking.DetailedSummary) error {
+	summaryPath := filepath.Join(r.path, "chunking-summary.json")
+	bytes, err := json.MarshalIndent(summary, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal chunking summary: %w", err)
+	}
+	bytes = append(bytes, '\n')
+	if err := os.WriteFile(summaryPath, bytes, 0o644); err != nil {
+		return fmt.Errorf("failed to write chunking summary: %w", err)
+	}
+	return nil
+}
+
 // TODO: In later phases, implement full "auto" semantics based on skip/report outcomes.
 func (r *RunDirectory) ApplyRetention(runSucceeded bool) error {
 	if !runSucceeded {