ui exporting and docgen testing

ctrl/ui.sh

@@ -6,6 +6,7 @@
 #   ./ctrl/ui.sh scan APP_DIR...          # what an app uses; its framework copy against spr
 #   ./ctrl/ui.sh slice FILE [--only N] [--list] [--force]
 #   ./ctrl/ui.sh check FILE [--only N]    # writes nothing; exit 1 if anything is stale
+#   ./ctrl/ui.sh reference [--check|--spots|--scaffold]   # the ui-reference page of /docs, from common/ui/src
 #   ./ctrl/ui.sh selftest
 #
 # FILE is a run file (see soleprint/common/slice/ui.example.toml). It lives beside
@@ -27,7 +28,10 @@ ROOT_DIR="$(dirname "$SCRIPT_DIR")"
 
 PYTHON="${PYTHON:-python3}"
 
-args=()
+# The first word is the command, never a path — `docs` is also a directory at the
+# repo root, and resolving it turned the command into /…/docs.
+args=("${1:-}")
+shift || true
 for a in "$@"; do
     # A bare word that names an existing path is a path the caller typed.
     if [[ "$a" != -* && -e "$CALLER_DIR/$a" ]]; then