diff --git a/src/lnurlcash/storage/activityLog.ts b/src/lnurlcash/storage/activityLog.ts
index 4b763e7..139a2c8 100644
--- a/src/lnurlcash/storage/activityLog.ts
+++ b/src/lnurlcash/storage/activityLog.ts
@@ -2,9 +2,10 @@
 // AES-GCM under the same bearer key, append-only, capped so a wallet used
 // for years doesn't grow localStorage without limit.
 
-import type { EncryptedRecordParts } from '../keys';
-import { encryptRecord, decryptRecord } from '../keys';
-import { withStorageLock } from '../storageLock';
+import type {EncryptedRecordParts} from '../keys'
+import {encryptRecord, decryptRecord} from '../keys'
+import {isJsonObject} from '../jsonParsing'
+import {withStorageLock} from '../storageLock'
 
 // `message` is the full human-readable sentence rather than structured
 // fields the UI reassembles, so the log stays simple to read and to extend
@@ -19,56 +20,87 @@ export type ActivityKind =
   | 'spent'
   | 'deleted'
   // a payment or mint initiated by a Nostr Wallet Connect client (M5)
-  | 'nwc';
+  | 'nwc'
 
 export type ActivityEvent = {
-  id: string;
-  kind: ActivityKind;
-  message: string;
-  createdAt: number;
-};
+  id: string
+  kind: ActivityKind
+  message: string
+  createdAt: number
+}
 
-export type EncryptedActivityRecord = { id: string } & EncryptedRecordParts;
+export type EncryptedActivityRecord = {id: string} & EncryptedRecordParts
 
-const ACTIVITY_STORAGE_KEY = 'sattle_activity';
+const isActivityKind = (value: unknown): value is ActivityKind => {
+  switch (value) {
+    case 'mint':
+    case 'split':
+    case 'combine':
+    case 'melt':
+    case 'transfer':
+    case 'receive':
+    case 'spent':
+    case 'deleted':
+    case 'nwc':
+      return true
+    default:
+      return false
+  }
+}
+
+const isEncryptedActivityRecord = (value: unknown): value is EncryptedActivityRecord =>
+  isJsonObject(value) &&
+  typeof value.id === 'string' &&
+  typeof value.iv === 'string' &&
+  typeof value.ciphertext === 'string'
+
+const isStoredActivity = (value: unknown): value is Omit<ActivityEvent, 'id'> =>
+  isJsonObject(value) &&
+  isActivityKind(value.kind) &&
+  typeof value.message === 'string' &&
+  typeof value.createdAt === 'number'
+
+const ACTIVITY_STORAGE_KEY = 'sattle_activity'
 // bounds how far back the log ever reaches - the oldest entries simply
 // roll off once this many are kept
-export const MAX_ACTIVITY_ENTRIES = 500;
+export const MAX_ACTIVITY_ENTRIES = 500
 
 export const newActivityId = (): string =>
   Array.from(crypto.getRandomValues(new Uint8Array(8)))
     .map((b) => b.toString(16).padStart(2, '0'))
-    .join('');
+    .join('')
 
 export const readEncryptedActivity = (): EncryptedActivityRecord[] => {
-  const raw = localStorage.getItem(ACTIVITY_STORAGE_KEY);
-  if (!raw) return [];
+  const raw = localStorage.getItem(ACTIVITY_STORAGE_KEY)
+  if (!raw) return []
   try {
-    const parsed: unknown = JSON.parse(raw);
-    return Array.isArray(parsed) ? parsed : [];
+    const parsed: unknown = JSON.parse(raw)
+    return Array.isArray(parsed) ? parsed.filter(isEncryptedActivityRecord) : []
   } catch {
-    return [];
+    return []
   }
-};
+}
 
 const writeEncryptedActivity = (records: EncryptedActivityRecord[]): void => {
-  localStorage.setItem(ACTIVITY_STORAGE_KEY, JSON.stringify(records));
-};
+  localStorage.setItem(ACTIVITY_STORAGE_KEY, JSON.stringify(records))
+}
 
 // same tolerance as loadBearers - an entry that fails to decrypt with this
 // key (written by a different seed) is skipped, not destroyed
 export const loadActivity = async (aesKey: CryptoKey): Promise<ActivityEvent[]> => {
-  const events: ActivityEvent[] = [];
+  const events: ActivityEvent[] = []
   for (const record of readEncryptedActivity()) {
     try {
-      const event = await decryptRecord<Omit<ActivityEvent, 'id'>>(aesKey, record);
-      events.push({ ...event, id: record.id });
-    } catch {
+      const event = await decryptRecord(aesKey, record)
+      if (!isStoredActivity(event)) throw new Error('Malformed encrypted activity record.')
+      events.push({...event, id: record.id})
+    } catch (error) {
       // undecryptable with this key - leave it in place
+      if (!(error instanceof Error)) throw error
     }
   }
-  return events.sort((a, b) => b.createdAt - a.createdAt);
-};
+  return events.sort((a, b) => b.createdAt - a.createdAt)
+}
 
 // append-only (the log never edits or removes a single entry, only clears
 // outright - see clearAllActivity) - records are stored oldest-first so
@@ -77,15 +109,15 @@ export const persistActivityEvent = async (
   aesKey: CryptoKey,
   event: ActivityEvent,
 ): Promise<void> => {
-  const { id, ...plain } = event;
-  const parts = await encryptRecord(aesKey, plain);
+  const {id, ...plain} = event
+  const parts = await encryptRecord(aesKey, plain)
   await withStorageLock(ACTIVITY_STORAGE_KEY, () => {
-    const records = readEncryptedActivity();
-    records.push({ id, ...parts });
-    writeEncryptedActivity(records.slice(-MAX_ACTIVITY_ENTRIES));
-  });
-};
+    const records = readEncryptedActivity()
+    records.push({id, ...parts})
+    writeEncryptedActivity(records.slice(-MAX_ACTIVITY_ENTRIES))
+  })
+}
 
 export const clearAllActivity = (): void => {
-  localStorage.removeItem(ACTIVITY_STORAGE_KEY);
-};
+  localStorage.removeItem(ACTIVITY_STORAGE_KEY)
+}
diff --git a/src/lnurlcash/storage/settings.ts b/src/lnurlcash/storage/settings.ts
index fa44848..ec226c5 100644
--- a/src/lnurlcash/storage/settings.ts
+++ b/src/lnurlcash/storage/settings.ts
@@ -20,15 +20,12 @@ export const loadSettings = (): WalletSettings => {
     if (typeof parsed !== 'object' || parsed === null) return {}
     const s = parsed as Record<string, unknown>
     return {
-      defaultMint:
-        typeof s.defaultMint === 'string' ? s.defaultMint : undefined,
+      defaultMint: typeof s.defaultMint === 'string' ? s.defaultMint : undefined,
       nostrBackupEnabled:
-        typeof s.nostrBackupEnabled === 'boolean'
-          ? s.nostrBackupEnabled
-          : undefined,
+        typeof s.nostrBackupEnabled === 'boolean' ? s.nostrBackupEnabled : undefined,
       nostrBackupRelays: Array.isArray(s.nostrBackupRelays)
         ? s.nostrBackupRelays.filter((r): r is string => typeof r === 'string')
-        : undefined
+        : undefined,
     }
   } catch {
     return {}