When the primary button cannot be pressed yet, a bold line above it says "還差:…" ("Still needed: …"), followed by a link to where to fix it. Write what is still needed as concrete tasks and numbers: "至少要 2 個波次的檔案,目前只有 1 個" ("Need files from at least 2 waves; there is only 1 now").
Examples
kit_ready_line(c("至少要 2 個波次的檔案,目前只有 1 個", "選 ID 欄"))
#> <p class="kit-ready todo">還差:至少要 2 個波次的檔案,目前只有 1 個;選 ID 欄。</p>