diff --git a/internal/check-selection-kinds.mjs b/internal/check-selection-kinds.mjs
index ee4ef0079..7dff731d2 100644
--- a/internal/check-selection-kinds.mjs
+++ b/internal/check-selection-kinds.mjs
@@ -131,8 +131,17 @@ for (const fn of ['onLegendExport', 'makeSelectionPacket', 'makeSelectionPoster'
     'onLegendExport no longer splits the kind — a packet:<variant> emit would fall through as an unknown kind and print nothing')
   for (const kind of emitted) {
     const [base] = kind.split(':')
-    ok(base === 'poster' || base === 'packet',
-      `the legend emits '${kind}', whose base '${base}' is neither poster nor packet — the plugin's handler has no branch for it`)
+    if (base === 'poster' || base === 'packet') continue
+    // ★ AN OPT-IN ITEM IS ONLY THIS PLUGIN'S PROBLEM IF THIS PLUGIN OPTS IN. The card deck ('cards') sits
+    // behind v-if="exportCards", a prop that defaults to false: countries-map passes it and handles it,
+    // and a legend here that never shows the item cannot emit it. So an item guarded by a prop is
+    // required to have a handler branch only when upg-100-list.vue passes that prop.
+    const line = LEGEND.split('\n').find((l) => l.includes(`emitExport('${kind}')`)) || ''
+    const guard = (line.match(/v-if="(\w+)"/) || [])[1]
+    const kebab = guard && guard.replace(/[A-Z]/g, (c) => '-' + c.toLowerCase())
+    const optedIn = !!guard && new RegExp(`[\\s:](?:${kebab}|${guard})\\b`).test(VUE)
+    ok(guard && !optedIn,
+      `the legend emits '${kind}', whose base '${base}' is neither poster nor packet — ${optedIn ? `upg-100-list passes ${guard}, but ` : ''}the plugin's handler has no branch for it`)
   }
   // The variant must actually travel to the renderer. Asserting the split alone would pass while
   // the parsed value was dropped on the floor.