diff --git a/frontend/src/components/AppSheet.test.ts b/frontend/src/components/AppSheet.test.ts
index d1d70dc..bb9e4a7 100644
--- a/frontend/src/components/AppSheet.test.ts
+++ b/frontend/src/components/AppSheet.test.ts
@@ -1,4 +1,5 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
+import { readFileSync } from 'node:fs'
 import { createApp, h, nextTick, ref } from 'vue'
 import AppSheet from './AppSheet.vue'
 import AppDialog from './AppDialog.vue'
@@ -273,4 +274,11 @@ describe('AppSheet', () => {
     await nextTick()
     expect(calls).toEqual(['two'])
   })
+
+  it('keys each render branch so modal/inline/bare switches remount instead of cross-patching', () => {
+    const source = readFileSync('src/components/AppSheet.vue', 'utf8')
+    expect(source).toContain(`:key="'app-sheet-modal'"`)
+    expect(source).toContain(`:key="'app-sheet-inline'"`)
+    expect(source).toContain(`:key="'app-sheet-bare'"`)
+  })
 })
diff --git a/frontend/src/components/AppSheet.vue b/frontend/src/components/AppSheet.vue
index d85dfaf..100129a 100644
--- a/frontend/src/components/AppSheet.vue
+++ b/frontend/src/components/AppSheet.vue
@@ -91,7 +91,7 @@ onBeforeUnmount(deactivate)
 </script>
 
 <template>
-  <Teleport v-if="modal" :to="overlayRoot()">
+  <Teleport v-if="modal" :key="'app-sheet-modal'" :to="overlayRoot()">
     <Transition name="app-sheet">
     <div v-if="open" class="app-overlay app-sheet-mask" :style="{ zIndex: layerZIndex }" :aria-busy="busy || undefined" @click="scrimClose">
       <component :is="$attrs.onSubmit ? 'form' : 'section'" ref="panel" class="app-sheet" :class="[`app-sheet--${variant}`, panelClass]" role="dialog" aria-modal="true" :aria-labelledby="titleId" :aria-describedby="descriptionId" :aria-label="label" tabindex="-1" v-bind="$attrs" @keydown="keydown">
@@ -100,12 +100,12 @@ onBeforeUnmount(deactivate)
     </div>
     </Transition>
   </Teleport>
-  <Teleport v-else-if="inlineTarget" :to="inlineTarget">
+  <Teleport v-else-if="inlineTarget" :key="'app-sheet-inline'" :to="inlineTarget">
     <component v-if="open" :is="$attrs.onSubmit ? 'form' : 'section'" ref="panel" class="app-sheet" :class="[`app-sheet--${variant}`, panelClass]" role="dialog" :aria-labelledby="titleId" :aria-describedby="descriptionId" :aria-label="label" :aria-busy="busy || undefined" tabindex="-1" v-bind="$attrs" @keydown="keydown">
       <slot />
     </component>
   </Teleport>
-  <component v-else-if="open" :is="$attrs.onSubmit ? 'form' : 'section'" ref="panel" class="app-sheet" :class="[`app-sheet--${variant}`, panelClass]" role="dialog" :aria-labelledby="titleId" :aria-describedby="descriptionId" :aria-label="label" tabindex="-1" v-bind="$attrs" @keydown="keydown">
+  <component v-else-if="open" :key="'app-sheet-bare'" :is="$attrs.onSubmit ? 'form' : 'section'" ref="panel" class="app-sheet" :class="[`app-sheet--${variant}`, panelClass]" role="dialog" :aria-labelledby="titleId" :aria-describedby="descriptionId" :aria-label="label" tabindex="-1" v-bind="$attrs" @keydown="keydown">
     <slot />
   </component>
 </template>
diff --git a/frontend/src/style.test.ts b/frontend/src/style.test.ts
index 7f8c37c..e883915 100644
--- a/frontend/src/style.test.ts
+++ b/frontend/src/style.test.ts
@@ -1532,7 +1532,7 @@ describe('desktop task and habit detail disclosure', () => {
     expect(mvpPanel).toContain('if (busy.value && !force) return')
     expect(mvpPanel).toContain(':modal="compactLayout"')
     expect(mvpPanel).toContain('inline-target=".shell"')
-    expect(appSheet).toContain('<Teleport v-else-if="inlineTarget" :to="inlineTarget">')
+    expect(appSheet).toContain(`<Teleport v-else-if="inlineTarget" :key="'app-sheet-inline'" :to="inlineTarget">`)
     expect(mvpPanel).toContain("watch(selectedHabit, (habit) => emit('detail', Boolean(habit)))")
     expect(app).toContain('@click="closeTaskDetail"')
     expect(app).toContain('function closeTaskDetail()')
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index 1b55e4c..6fca409 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -1,9 +1,34 @@
-import { defineConfig } from 'vite'
+import { defineConfig, type Plugin } from 'vite'
 import vue from '@vitejs/plugin-vue'
 import tailwindcss from '@tailwindcss/vite'
 
+const GUARD_MARKER = '[dodo:vue-guard]'
+
+// vuejs/core#5184/#8146: a stale component vnode that never mounted (component === null)
+// reaches processComponent -> updateComponent -> shouldUpdateComponent and crashes on
+// `component.emitsOptions`. Detect it here and self-heal with a clean remount instead,
+// logging the component pair so the next production occurrence names itself in console.
+function vueNullComponentGuard(): Plugin {
+  return {
+    name: 'dodo:vue-null-component-guard',
+    enforce: 'pre',
+    transform(code, id) {
+      if (!id.includes('runtime-core.esm-bundler.js')) return null
+      const header = code.indexOf('const processComponent = ')
+      if (header < 0) throw new Error(`${GUARD_MARKER} processComponent not found in runtime-core — Vue internals changed, update the guard anchor`)
+      const anchor = code.indexOf('if (n1 == null) {', header)
+      if (anchor < 0 || anchor - header > 400) throw new Error(`${GUARD_MARKER} mount-branch anchor not found — update the guard anchor`)
+      if (code.slice(header, anchor).includes(GUARD_MARKER)) return null
+      const inject = `if (n1 != null && n1.component == null) {\n      try { const nm = (x) => (x && (x.name || x.__name)) || (typeof x === "string" ? x : typeof x === "symbol" ? (x.description || "symbol") : "?"); console.error("${GUARD_MARKER} never-mounted component vnode — self-healing remount", { oldType: nm(n1.type), newType: nm(n2.type), oldKey: n1.key, newKey: n2.key, el: !!n1.el, oldChildren: Array.isArray(n1.children) ? n1.children.map((c) => nm(c.type)) : String(n1.children).slice(0, 60) }); } catch (e) {}\n      n1 = null;\n    }\n    `
+      return { code: code.slice(0, anchor) + inject + code.slice(anchor), map: null }
+    },
+  }
+}
+
 export default defineConfig({
-  plugins: [vue(), tailwindcss()],
+  plugins: [vue(), tailwindcss(), vueNullComponentGuard()],
+  // Serve vue through the normal transform pipeline so the guard applies in dev too.
+  optimizeDeps: { exclude: ['vue', '@vue/runtime-dom', '@vue/runtime-core', '@vue/reactivity', '@vue/shared'] },
   server: { proxy: { '/api': 'http://localhost:8781', '/health': 'http://localhost:8781' } },
   test: { environment: 'jsdom', setupFiles: ['./vitest.setup.ts'] },
 })