From 67e9ede5507b8d32aa85c6d83a5c61df1528ccc2 Mon Sep 17 00:00:00 2001
From: Doxa Maps <maps@doxa.example>
Date: Sun, 27 Sep 2026 06:20:41 +0000
Subject: [PATCH] Show zone, go to the map, come back: the same card shows the
 zone again

PosterWall remembered the card it had shown, so after Show zone -> Map -> back the same press toggled the
selection off instead of showing it (rega row 79; UPG-100 and country-posters share the shape). The wall
now forgets its last-shown card when its pane goes inactive: it watches its ancestor chain, through shadow
roots, for the inert / hidden / aria-hidden a composite puts on an inactive view (the PinHint contract).
dx-shepherd ruled option (a). Needs eyes: rega row 79 plus the same arm on country-posters.
---
 library/components/poster/PosterWall.vue | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/library/components/poster/PosterWall.vue b/library/components/poster/PosterWall.vue
index 14d0be893..60008fab9 100644
--- a/library/components/poster/PosterWall.vue
+++ b/library/components/poster/PosterWall.vue
@@ -39,7 +39,7 @@
  * CROSS-PANE COMMS — this wall NEVER imports a map. It dispatches a window
  * CustomEvent scoped by instanceId, so several embeds on one page never cross-talk.
  */
-import { computed, ref, watch, onBeforeUnmount } from 'vue'
+import { computed, ref, watch, onBeforeUnmount, onMounted } from 'vue'
 import { tStatic } from '../../i18n/index.js'
 
 // This component's chrome, read out of the catalogue. tStatic and not useI18n: these mount inside
@@ -284,6 +284,24 @@ const toggleSection = (name) => {
 
 const lastShown = ref(null)
 const missing   = ref({})
+// FORGET the shown card when the wall's view goes inactive (dx-shepherd, row 79). A composite marks its
+// inactive pane `inert` (the PinHint contract); after "Show zone" -> Map -> back, the same card must SHOW
+// again, not toggle off a selection the reader can no longer see. Watches the ancestor chain, through
+// shadow roots, for inert/hidden/aria-hidden; clears lastShown only (the map keeps its selection).
+const wallEl = ref(null)
+let paneMOs = []
+onMounted(() => {
+  const chain = []
+  for (let n = wallEl.value; n; n = n.parentNode || n.host || null) if (n.nodeType === 1) chain.push(n)
+  const inactive = () => chain.some((a) => a.hasAttribute('inert') || a.hasAttribute('hidden') || a.getAttribute('aria-hidden') === 'true')
+  if (typeof MutationObserver === 'undefined') return
+  for (const a of chain) {
+    const mo = new MutationObserver(() => { if (inactive()) lastShown.value = null })
+    mo.observe(a, { attributes: true, attributeFilter: ['inert', 'hidden', 'aria-hidden'] })
+    paneMOs.push(mo)
+  }
+})
+onBeforeUnmount(() => { for (const mo of paneMOs) mo.disconnect(); paneMOs = [] })
 
 function showOnMap(item) {
   // TOGGLE, not a one-way set: a control the user can turn on but not off reads as
@@ -949,7 +967,7 @@ useShadowStyles(
 </script>
 
 <template>
-  <div class="wall" :class="{ 'is-dark': isDark, 'wall--embedded': embedded }">
+  <div ref="wallEl" class="wall" :class="{ 'is-dark': isDark, 'wall--embedded': embedded }">
     <h2 class="wall-h">{{ heading }}</h2>
     <div v-if="tag" class="wall-tag">{{ tag }}</div>
     <p v-if="intro" class="wall-sub" v-html="intro"></p>