diff --git a/library/i18n/locales/ar/messages.json b/library/i18n/locales/ar/messages.json
index e332976a8..4603232e7 100644
--- a/library/i18n/locales/ar/messages.json
+++ b/library/i18n/locales/ar/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "انقر على الأقاليم في الخريطة أو صفوف وسيلة الإيضاح لإضافتها · انقر مجددًا لإزالتها",
   "territoriesSelected": "الأقاليم: {count}",
   "bandInRange": "✓ النطاق 50–100",
-  "bandOutOfRange": "النطاق 50–100"
+  "bandOutOfRange": "النطاق 50–100",
+  "mapContextLost": "تم إلغاء تحميل هذه الخريطة لتحرير ذاكرة الرسوميات."
 }
diff --git a/library/i18n/locales/de/messages.json b/library/i18n/locales/de/messages.json
index 776036ca0..6e0983351 100644
--- a/library/i18n/locales/de/messages.json
+++ b/library/i18n/locales/de/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Tippen Sie auf Gebiete auf der Karte oder auf Legendenzeilen, um sie hinzuzufügen · erneut tippen zum Entfernen",
   "territoriesSelected": "Gebiete: {count}",
   "bandInRange": "✓ Bereich 50–100",
-  "bandOutOfRange": "Bereich 50–100"
+  "bandOutOfRange": "Bereich 50–100",
+  "mapContextLost": "Diese Karte wurde entladen, um Grafikspeicher freizugeben."
 }
diff --git a/library/i18n/locales/en/messages.json b/library/i18n/locales/en/messages.json
index dd4cadd28..6ea00cad6 100644
--- a/library/i18n/locales/en/messages.json
+++ b/library/i18n/locales/en/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Tap territories on the map or legend rows to add · tap again to remove",
   "territoriesSelected": "Territories: {count}",
   "bandInRange": "✓ 50–100 band",
-  "bandOutOfRange": "band 50–100"
+  "bandOutOfRange": "band 50–100",
+  "mapContextLost": "This map was unloaded to free graphics memory."
 }
diff --git a/library/i18n/locales/es/messages.json b/library/i18n/locales/es/messages.json
index ea4bc16e3..602a36880 100644
--- a/library/i18n/locales/es/messages.json
+++ b/library/i18n/locales/es/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Toque territorios en el mapa o filas de la leyenda para añadirlos · toque de nuevo para quitarlos",
   "territoriesSelected": "Territorios: {count}",
   "bandInRange": "✓ franja 50–100",
-  "bandOutOfRange": "franja 50–100"
+  "bandOutOfRange": "franja 50–100",
+  "mapContextLost": "Este mapa se descargó para liberar memoria gráfica."
 }
diff --git a/library/i18n/locales/fr/messages.json b/library/i18n/locales/fr/messages.json
index cb82fb0ff..80cd06128 100644
--- a/library/i18n/locales/fr/messages.json
+++ b/library/i18n/locales/fr/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Touchez des territoires sur la carte ou des lignes de la légende pour les ajouter · touchez à nouveau pour les retirer",
   "territoriesSelected": "Territoires : {count}",
   "bandInRange": "✓ tranche 50–100",
-  "bandOutOfRange": "tranche 50–100"
+  "bandOutOfRange": "tranche 50–100",
+  "mapContextLost": "Cette carte a été déchargée pour libérer de la mémoire graphique."
 }
diff --git a/library/i18n/locales/hi/messages.json b/library/i18n/locales/hi/messages.json
index 3adcf86c7..8cc8e4d96 100644
--- a/library/i18n/locales/hi/messages.json
+++ b/library/i18n/locales/hi/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "जोड़ने के लिए मानचित्र पर क्षेत्रों या लेजेंड की पंक्तियों पर टैप करें · हटाने के लिए फिर से टैप करें",
   "territoriesSelected": "क्षेत्र: {count}",
   "bandInRange": "✓ 50–100 दायरा",
-  "bandOutOfRange": "50–100 दायरा"
+  "bandOutOfRange": "50–100 दायरा",
+  "mapContextLost": "ग्राफ़िक्स मेमोरी खाली करने के लिए यह मानचित्र अनलोड कर दिया गया।"
 }
diff --git a/library/i18n/locales/it/messages.json b/library/i18n/locales/it/messages.json
index eb40723bf..3c9dc9ef6 100644
--- a/library/i18n/locales/it/messages.json
+++ b/library/i18n/locales/it/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Tocca i territori sulla mappa o le righe della legenda per aggiungerli · tocca di nuovo per rimuoverli",
   "territoriesSelected": "Territori: {count}",
   "bandInRange": "✓ fascia 50–100",
-  "bandOutOfRange": "fascia 50–100"
+  "bandOutOfRange": "fascia 50–100",
+  "mapContextLost": "Questa mappa è stata scaricata per liberare memoria grafica."
 }
diff --git a/library/i18n/locales/pt/messages.json b/library/i18n/locales/pt/messages.json
index a29b5860b..009ee0029 100644
--- a/library/i18n/locales/pt/messages.json
+++ b/library/i18n/locales/pt/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Toque em territórios no mapa ou em linhas da legenda para adicionar · toque de novo para remover",
   "territoriesSelected": "Territórios: {count}",
   "bandInRange": "✓ faixa 50–100",
-  "bandOutOfRange": "faixa 50–100"
+  "bandOutOfRange": "faixa 50–100",
+  "mapContextLost": "Este mapa foi descarregado para libertar memória gráfica."
 }
diff --git a/library/i18n/locales/ro/messages.json b/library/i18n/locales/ro/messages.json
index b5b235b12..ac25455dc 100644
--- a/library/i18n/locales/ro/messages.json
+++ b/library/i18n/locales/ro/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Atingeți teritorii pe hartă sau rânduri din legendă pentru a le adăuga · atingeți din nou pentru a le elimina",
   "territoriesSelected": "Teritorii: {count}",
   "bandInRange": "✓ interval 50–100",
-  "bandOutOfRange": "interval 50–100"
+  "bandOutOfRange": "interval 50–100",
+  "mapContextLost": "Această hartă a fost descărcată pentru a elibera memoria grafică."
 }
diff --git a/library/i18n/locales/ru/messages.json b/library/i18n/locales/ru/messages.json
index ff98c1755..fa2346f05 100644
--- a/library/i18n/locales/ru/messages.json
+++ b/library/i18n/locales/ru/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "Нажимайте на территории на карте или строки легенды, чтобы добавить · нажмите ещё раз, чтобы убрать",
   "territoriesSelected": "Территории: {count}",
   "bandInRange": "✓ диапазон 50–100",
-  "bandOutOfRange": "диапазон 50–100"
+  "bandOutOfRange": "диапазон 50–100",
+  "mapContextLost": "Эта карта выгружена, чтобы освободить графическую память."
 }
diff --git a/library/i18n/locales/zh/messages.json b/library/i18n/locales/zh/messages.json
index 3e464c825..d1a128dff 100644
--- a/library/i18n/locales/zh/messages.json
+++ b/library/i18n/locales/zh/messages.json
@@ -30,5 +30,6 @@
   "tapTerritoriesHint": "点按地图上的区域或图例行即可添加 · 再次点按即可移除",
   "territoriesSelected": "区域：{count}",
   "bandInRange": "✓ 50–100 区间",
-  "bandOutOfRange": "50–100 区间"
+  "bandOutOfRange": "50–100 区间",
+  "mapContextLost": "已卸载此地图以释放显存。"
 }
diff --git a/library/layouts/VerticalTabsLayout.vue b/library/layouts/VerticalTabsLayout.vue
index feac6a28f..cd76cd0b9 100644
--- a/library/layouts/VerticalTabsLayout.vue
+++ b/library/layouts/VerticalTabsLayout.vue
@@ -243,6 +243,18 @@
             :ref="el => { if (el) hostEls[row.key] = el; else delete hostEls[row.key] }">
             <div class="vtl-host-slot" :ref="el => setHostSlot(row.key, el)"></div>
             <div v-if="hostState[row.key] === 'loading'" class="vtl-host-hint">{{ T('messages.loadingNamed', 'Loading {name}…').replace('{name}', row.label) }}</div>
+            <!-- ★ A LOST GL CONTEXT IS SHOWN, NOT SWALLOWED. The browser's WebGL budget is commonly
+                 8-16 and this tree has 19 map-bearing profiles, so a reader who visits enough map
+                 tabs crosses it. What the browser then does is the problem: it kills the OLDEST
+                 context silently — getContext() never returns null and nothing fires on the NEW
+                 canvas — so a map that worked a minute ago is simply blank when you go back to it.
+                 This turns that into a visible, actionable state under either of the caps on row 107. -->
+            <div v-else-if="hostState[row.key] === 'lost'" class="vtl-host-hint">
+              {{ T('messages.mapContextLost', 'This map was unloaded to free graphics memory.') }}
+              <button type="button" class="vtl-host-reload" @click="reloadHostElement(row.key)">
+                {{ T('buttons.reloadMap', 'Reload Map') }}
+              </button>
+            </div>
             <div v-else-if="hostState[row.key] === 'error'" class="vtl-host-hint err">
               {{ T('messages.couldNotLoadNamed', 'Could not load {name}.').replace('{name}', row.label) }}<br><small>{{ hostError[row.key] }}</small>
             </div>
@@ -461,6 +473,7 @@ const VTL_SHADOW_CSS = `
 .vtl-host-slot > * { min-height:0; max-height:none; }
 .vtl-host-hint { position:absolute; inset:0; display:grid; place-items:center; text-align:center; color:var(--dx-muted, #6d766e); font-size:13px; padding:20px; }
 .vtl-host-hint.err { color:#f87171; }
+.vtl-host-reload { margin-block-start:10px; font:inherit; padding:4px 12px; border-radius:6px; cursor:pointer; background:var(--vtl-accent, #3b463d); color:#fff; border:none; }
 .vtl-host-hint small { color:var(--dx-muted, #6d766e); }
 /* MATERIAL MINI-VARIANT RAIL = 72px (2026-09-21), up from 60px.
    ★ THE COLLAPSE IS A TRANSLATE, NOT A WIDTH CHANGE — so FOUR numbers are coupled and must move
@@ -717,6 +730,8 @@ export default defineComponent({
       if (!row) return                       // not an element-hosting tab
       if (!this.activatedKeys[key]) {
         this.activatedKeys = { ...this.activatedKeys, [key]: true }
+        // Re-show: pick up any canvas created since the last look.
+        this.$nextTick(() => this.watchContextLoss(key))
         this.hostState = { ...this.hostState, [key]: 'loading' }
       }
       // If the pane/slot already exists (re-activation, or pane rendered), ensure it is mounted.
@@ -725,6 +740,42 @@ export default defineComponent({
     // Imperatively mount the row's custom element into its empty slot div — lazy-inject its bundle
     // first (deduped), wait for the tag to be defined, set `attrs` BEFORE append (props-in-advance),
     // then append. Runs once per key (guarded by _hostMounted).
+    /**
+     * Every canvas under a pane, INCLUDING inside shadow roots. The map's canvas belongs to the
+     * plugin's own shadow tree, and webglcontextlost does not bubble — so a listener on the pane
+     * would never hear it. The listener has to go on the canvas itself.
+     */
+    deepCanvases(root, out = []) {
+      if (!root) return out
+      for (const el of root.querySelectorAll('*')) {
+        if (el.tagName === 'CANVAS') out.push(el)
+        if (el.shadowRoot) this.deepCanvases(el.shadowRoot, out)
+      }
+      return out
+    },
+    /**
+     * Idempotent: canvases appear asynchronously after the map boots, and a pane can be re-shown
+     * many times, so this is safe to call repeatedly and marks what it has already bound.
+     */
+    watchContextLoss(key) {
+      const slot = this._hostSlots[key]
+      if (!slot) return
+      for (const c of this.deepCanvases(slot)) {
+        if (c.__vtlLossBound) continue
+        c.__vtlLossBound = true
+        c.addEventListener('webglcontextlost', () => {
+          this.hostState = { ...this.hostState, [key]: 'lost' }
+        }, { once: true })
+      }
+    },
+    /** Tear the pane down and mount it again — the only way back from a lost context. */
+    reloadHostElement(key) {
+      const slot = this._hostSlots[key]
+      if (slot) slot.innerHTML = ''
+      this._hostMounted[key] = false
+      this.hostState = { ...this.hostState, [key]: 'loading' }
+      this.$nextTick(() => this.mountHostElement(key))
+    },
     mountHostElement(key) {
       if (this._hostMounted[key]) return
       const row = this.elementRows.find(r => r.key === key)
@@ -748,6 +799,10 @@ export default defineComponent({
           }
           el.style.cssText = 'display:block;position:absolute;inset:0;width:100%;height:100%;'
           slot.appendChild(el)
+          // The map's canvas does not exist yet — the element has only just connected. Bind on the
+          // next frames as it boots, and again whenever the pane is re-activated, because a canvas
+          // created later would otherwise never be watched. watchContextLoss is idempotent.
+          for (const ms of [0, 250, 1500]) setTimeout(() => this.watchContextLoss(key), ms)
           this.hostState = { ...this.hostState, [key]: 'ready' }
         })
         .catch((e) => {
@@ -977,6 +1032,7 @@ export default defineComponent({
 .vtl-host-slot > * { min-height:0; max-height:none; }
 .vtl-host-hint { position:absolute; inset:0; display:grid; place-items:center; text-align:center; color:var(--dx-muted, #6d766e); font-size:13px; padding:20px; }
 .vtl-host-hint.err { color:#f87171; }
+.vtl-host-reload { margin-block-start:10px; font:inherit; padding:4px 12px; border-radius:6px; cursor:pointer; background:var(--vtl-accent, #3b463d); color:#fff; border:none; }
 .vtl-host-hint small { color:var(--dx-muted, #6d766e); }
 /* MATERIAL MINI-VARIANT RAIL = 72px (2026-09-21), up from 60px.
    ★ THE COLLAPSE IS A TRANSLATE, NOT A WIDTH CHANGE — so FOUR numbers are coupled and must move