fixup! refactor(swing-store): Consolidate common behavior for span ro…

…llover and stopUsingTranscript

packages/swing-store/src/transcriptStore.js

@@ -257,6 +257,16 @@ export function makeTranscriptStore(
     WHERE vatID = ? AND position >= ? AND position < ?
   `);
 
+  /**
+   * Finalize a span, setting isCurrent to null, marking the resulting record
+   * for export, and effecting disk archival and database cleanup as
+   * configured.
+   * Note that creation of a new DB row and removal/replacement of the
+   * transcript.${vatID}.current export record are responsibility of the caller.
+   *
+   * @param {string} vatID
+   * @param {ReturnType<getCurrentSpanBounds>} bounds
+   */
   function closeSpan(vatID, bounds) {
     ensureTxn();
     const { startPos, endPos, hash, incarnation } = bounds;