Workflow: pdf input defaults to empty (dry run falls back to the Clark regression sample)

_pipeline/ci/run.sh

@@ -24,6 +24,12 @@ if [ -n "${PDF_INPUT:-}" ]; then
 else
   while IFS= read -r f; do pdfs+=("$f"); done < <(find _incoming -maxdepth 1 -type f -iname '*.pdf' | sort)
 fi
+CLARK_PDF="books/clark-glenn/the-man-who-tapped-the-secrets-of-the-universe/The Man Who Tapped the Secrets of the Universe - by Glenn Clark (Walter Russell).pdf"
+if [ "${#pdfs[@]}" -eq 0 ] && [ "$DRY_RUN" = "true" ]; then
+  echo "Dry run with nothing in _incoming/: using the Clark book as a regression sample."
+  sparse_add "/$(esc "$CLARK_PDF")"
+  pdfs=("$CLARK_PDF")
+fi
 if [ "${#pdfs[@]}" -eq 0 ]; then
   echo "Nothing to do: no PDF in _incoming/."
   exit 0