diff --git a/mobile/src/components/CustomKeyModal.tsx b/mobile/src/components/CustomKeyModal.tsx
index cded289e692..c4464bc54d2 100644
--- a/mobile/src/components/CustomKeyModal.tsx
+++ b/mobile/src/components/CustomKeyModal.tsx
@@ -12,7 +12,7 @@ import {
   type TerminalShortcutSpecialKey
 } from '../terminal/terminal-accessory-keys'
 import { customKeyModalStyles as styles } from './CustomKeyModal.styles'
-import { noteMirroredWrite } from '../storage/mirrored-storage-keys'
+import { noteMirroredWrite, readMirroredStorage } from '../storage/mirrored-storage-keys'
 
 const CUSTOM_ACCESSORY_KEYS_STORAGE_KEY = 'orca:custom-accessory-keys'
 
@@ -79,8 +79,19 @@ export async function saveCustomKeys(keys: CustomKey[]): Promise<void> {
   const value = JSON.stringify(keys)
   // Noted before it is persisted: the hybrid shell hands this key to the page on every `init`,
   // built synchronously, so a write that only reached the store would be one `init` behind.
+  const held = readMirroredStorage([CUSTOM_ACCESSORY_KEYS_STORAGE_KEY])[
+    CUSTOM_ACCESSORY_KEYS_STORAGE_KEY
+  ]
   noteMirroredWrite(CUSTOM_ACCESSORY_KEYS_STORAGE_KEY, value)
-  await AsyncStorage.setItem(CUSTOM_ACCESSORY_KEYS_STORAGE_KEY, value)
+  try {
+    await AsyncStorage.setItem(CUSTOM_ACCESSORY_KEYS_STORAGE_KEY, value)
+  } catch (error) {
+    // Rolled back, because the note is what the next `init` reads: on the page a write over the
+    // cap rejects rather than dropping, and a note left standing would hand the page — and every
+    // native reader answered from this map — the value the store refused.
+    noteMirroredWrite(CUSTOM_ACCESSORY_KEYS_STORAGE_KEY, held ?? null)
+    throw error
+  }
 }
 
 export function CustomKeyModal({ visible, onClose, onKeysChanged, onManageShortcuts }: Props) {
diff --git a/mobile/src/components/custom-key-modal-save-refusal.test.tsx b/mobile/src/components/custom-key-modal-save-refusal.test.tsx
index a66d38f95e2..c1c96edda1e 100644
--- a/mobile/src/components/custom-key-modal-save-refusal.test.tsx
+++ b/mobile/src/components/custom-key-modal-save-refusal.test.tsx
@@ -53,6 +53,14 @@ vi.mock('lucide-react-native', () => ({ ChevronLeft: hosts.View }))
 vi.mock('./BottomDrawer', () => ({ BottomDrawer: hosts.View }))
 
 import { CustomKeyModal } from './CustomKeyModal'
+import { readMirroredStorage } from '../storage/mirrored-storage-keys'
+
+const CUSTOM_KEYS = 'orca:custom-accessory-keys'
+
+/** What a later `init` would carry for this key, which is the map and not the store. */
+function mirrored(): string | undefined {
+  return readMirroredStorage([CUSTOM_KEYS])[CUSTOM_KEYS]
+}
 
 /** The one label a node renders, flattened, without walking a fiber into a cycle. */
 function labelOf(node: { props: { children?: unknown } }): string {
@@ -117,6 +125,7 @@ beforeEach(() => {
 describe('adding a custom key when the store refuses the write', () => {
   it('does not let the refusal escape as an unhandled rejection', async () => {
     store.refuse = true
+    const before = mirrored()
     const unhandled = vi.fn()
     process.on('unhandledRejection', unhandled)
     const onKeysChanged = vi.fn()
@@ -140,6 +149,10 @@ describe('adding a custom key when the store refuses the write', () => {
     // is the failure the allowlist exists to avoid.
     expect(onKeysChanged).not.toHaveBeenCalled()
     expect(onClose).not.toHaveBeenCalled()
+    // And the mirror is back where it started. `saveCustomKeys` notes the write before it
+    // persists, because a reader is answered from the map; a refused write that left the note
+    // standing would put the key the store rejected into the next `init`.
+    expect(mirrored()).toBe(before)
   })
 
   it('reports the key and closes when the store takes it, so the case above is the refusal', async () => {