diff --git a/lib/error-tracking.ts b/lib/error-tracking.ts
index b78033b..8c3b16f 100644
--- a/lib/error-tracking.ts
+++ b/lib/error-tracking.ts
@@ -38,6 +38,35 @@ export function addBreadcrumb(crumb: ErrorBreadcrumb): void {
   }
 }
 
+// ── PII & Key Scrubber (#752) ────────────────────────────────────────────────
+
+const STELLAR_PUBLIC_KEY_REGEX = /\bG[A-Z2-7]{55}\b/g;
+const STELLAR_SECRET_KEY_REGEX = /\bS[A-Z2-7]{55}\b/g;
+
+/**
+ * Scrub sensitive Stellar public and secret keys from strings before telemetry dispatch (#752).
+ */
+export function scrubSensitiveData(text: string): string {
+  if (!text) return text;
+  return text
+    .replace(STELLAR_SECRET_KEY_REGEX, '[REDACTED_SECRET_KEY]')
+    .replace(STELLAR_PUBLIC_KEY_REGEX, '[REDACTED_PUBLIC_KEY]');
+}
+
+export function scrubObject<T>(obj: T): T {
+  if (!obj || typeof obj !== 'object') {
+    return typeof obj === 'string' ? (scrubSensitiveData(obj) as unknown as T) : obj;
+  }
+  if (Array.isArray(obj)) {
+    return obj.map(scrubObject) as unknown as T;
+  }
+  const result: Record<string, unknown> = {};
+  for (const [key, value] of Object.entries(obj)) {
+    result[key] = scrubObject(value);
+  }
+  return result as T;
+}
+
 /**
  * Capture an error with optional context and breadcrumbs.
  * When Sentry is not configured, this is a no-op that just logs to console.
@@ -49,21 +78,28 @@ export function captureError(
     extra?: Record<string, unknown>
   },
 ): void {
-  const err = error instanceof Error ? error : new Error(String(error))
+  const rawErr = error instanceof Error ? error : new Error(String(error))
+  const cleanMessage = scrubSensitiveData(rawErr.message)
+  const err = rawErr.message === cleanMessage ? rawErr : new Error(cleanMessage)
+  if (rawErr.stack) {
+    err.stack = scrubSensitiveData(rawErr.stack)
+  }
+
+  const cleanContext = context ? scrubObject(context) : context
 
   if (!SENTRY_DSN) {
-    console.error('[error-tracking]', err.message, { context, breadcrumbs: breadcrumbs.slice(-5) })
+    console.error('[error-tracking]', err.message, { context: cleanContext, breadcrumbs: breadcrumbs.slice(-5) })
     return
   }
 
   Sentry.withScope(scope => {
-    if (context?.tags) {
-      Object.entries(context.tags).forEach(([k, v]) => scope.setTag(k, v))
+    if (cleanContext?.tags) {
+      Object.entries(cleanContext.tags).forEach(([k, v]) => scope.setTag(k, v))
     }
-    if (context?.extra) {
-      Object.entries(context.extra).forEach(([k, v]) => scope.setExtra(k, v))
+    if (cleanContext?.extra) {
+      Object.entries(cleanContext.extra).forEach(([k, v]) => scope.setExtra(k, v))
     }
-    breadcrumbs.forEach(c => scope.addBreadcrumb(c))
+    breadcrumbs.forEach(c => scope.addBreadcrumb({ ...c, message: scrubSensitiveData(c.message) }))
     Sentry.captureException(err)
   })
   breadcrumbs = []
diff --git a/lib/notifications.ts b/lib/notifications.ts
new file mode 100644
index 0000000..2b502aa
--- /dev/null
+++ b/lib/notifications.ts
@@ -0,0 +1,55 @@
+/**
+ * Browser Web Push / Notifications API helper for stream milestones and claims (#754).
+ */
+
+export type NotificationPermissionState = NotificationPermission | 'unsupported';
+
+/**
+ * Check if the browser supports the Notifications API.
+ */
+export function isNotificationSupported(): boolean {
+  return typeof window !== 'undefined' && 'Notification' in window;
+}
+
+/**
+ * Request notification permissions from the user.
+ */
+export async function requestNotificationPermission(): Promise<NotificationPermissionState> {
+  if (!isNotificationSupported()) return 'unsupported';
+  try {
+    return await Notification.requestPermission();
+  } catch {
+    return 'denied';
+  }
+}
+
+/**
+ * Dispatch a browser notification when a stream milestone or claim completes.
+ */
+export function notifyStreamMilestone(title: string, options?: NotificationOptions): Notification | null {
+  if (!isNotificationSupported()) return null;
+  if (Notification.permission !== 'granted') return null;
+
+  try {
+    return new Notification(title, {
+      icon: '/favicon.ico',
+      badge: '/favicon.ico',
+      ...options,
+    });
+  } catch (error) {
+    console.warn('[notifications] Failed to dispatch notification:', error);
+    return null;
+  }
+}
+
+/**
+ * Convenience helper to notify user when a stream claim or milestone is confirmed.
+ */
+export function notifyClaimConfirmed(streamId: string, amount?: string): void {
+  notifyStreamMilestone('Stream Claim Confirmed', {
+    body: amount
+      ? `Your claim of ${amount} for stream ${streamId.slice(0, 8)}... has been confirmed.`
+      : `Your stream milestone claim for ${streamId.slice(0, 8)}... has been confirmed.`,
+    tag: `claim-${streamId}`,
+  });
+}
diff --git a/lib/offline-transactions.ts b/lib/offline-transactions.ts
index 2da5215..610fe2c 100644
--- a/lib/offline-transactions.ts
+++ b/lib/offline-transactions.ts
@@ -51,3 +51,93 @@ export async function flushQueuedTransactions(signTx: SignTransaction): Promise<
     }
   }
 }
+
+// ── IndexedDB Storage Adapter for Draft Streams (#753) ─────────────────────────
+
+const IDB_NAME = 'conduit-offline-db';
+const IDB_VERSION = 1;
+const DRAFTS_STORE = 'draft-stream-batches';
+
+export interface DraftStreamBatch {
+  id: string;
+  name: string;
+  streams: Array<Record<string, unknown>>;
+  createdAt: number;
+  updatedAt: number;
+}
+
+function openIndexedDB(): Promise<IDBDatabase> {
+  return new Promise((resolve, reject) => {
+    if (typeof indexedDB === 'undefined') {
+      return reject(new Error('IndexedDB not supported'));
+    }
+    const request = indexedDB.open(IDB_NAME, IDB_VERSION);
+    request.onupgradeneeded = () => {
+      const db = request.result;
+      if (!db.objectStoreNames.contains(DRAFTS_STORE)) {
+        db.createObjectStore(DRAFTS_STORE, { keyPath: 'id' });
+      }
+    };
+    request.onsuccess = () => resolve(request.result);
+    request.onerror = () => reject(request.error);
+  });
+}
+
+export async function saveDraftStreamBatch(batch: DraftStreamBatch): Promise<void> {
+  try {
+    const db = await openIndexedDB();
+    await new Promise<void>((resolve, reject) => {
+      const tx = db.transaction(DRAFTS_STORE, 'readwrite');
+      tx.objectStore(DRAFTS_STORE).put(batch);
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(tx.error);
+    });
+  } catch {
+    if (typeof localStorage !== 'undefined') {
+      const drafts = getLocalDraftBatches();
+      const updated = drafts.filter((d) => d.id !== batch.id).concat(batch);
+      localStorage.setItem(`${KEY}-drafts`, JSON.stringify(updated));
+    }
+  }
+}
+
+export async function getDraftStreamBatches(): Promise<DraftStreamBatch[]> {
+  try {
+    const db = await openIndexedDB();
+    return await new Promise<DraftStreamBatch[]>((resolve, reject) => {
+      const tx = db.transaction(DRAFTS_STORE, 'readonly');
+      const req = tx.objectStore(DRAFTS_STORE).getAll();
+      req.onsuccess = () => resolve(req.result as DraftStreamBatch[]);
+      req.onerror = () => reject(req.error);
+    });
+  } catch {
+    return getLocalDraftBatches();
+  }
+}
+
+export async function deleteDraftStreamBatch(id: string): Promise<void> {
+  try {
+    const db = await openIndexedDB();
+    await new Promise<void>((resolve, reject) => {
+      const tx = db.transaction(DRAFTS_STORE, 'readwrite');
+      tx.objectStore(DRAFTS_STORE).delete(id);
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(tx.error);
+    });
+  } catch {
+    if (typeof localStorage !== 'undefined') {
+      const drafts = getLocalDraftBatches().filter((d) => d.id !== id);
+      localStorage.setItem(`${KEY}-drafts`, JSON.stringify(drafts));
+    }
+  }
+}
+
+function getLocalDraftBatches(): DraftStreamBatch[] {
+  if (typeof localStorage === 'undefined') return [];
+  try {
+    return JSON.parse(localStorage.getItem(`${KEY}-drafts`) ?? '[]') as DraftStreamBatch[];
+  } catch {
+    return [];
+  }
+}
+
diff --git a/lib/stream-sort.ts b/lib/stream-sort.ts
index c31bb39..e8a908a 100644
--- a/lib/stream-sort.ts
+++ b/lib/stream-sort.ts
@@ -21,29 +21,45 @@ function endValue(endTime: number): number {
   return endTime === 0 ? Infinity : endTime;
 }
 
-export function sortStreams<T extends { info: Pick<StreamInfo, "ratePerSecond" | "endTime"> }>(
-  rows: T[],
+// Memoized comparator cache for multi-key stream sorting (#751)
+const comparatorCache = new Map<SortKey, <T extends { info: Pick<StreamInfo, "ratePerSecond" | "endTime"> }>(a: T, b: T) => number>();
+
+function getComparator<T extends { info: Pick<StreamInfo, "ratePerSecond" | "endTime"> }>(
   sort: SortKey,
-): T[] {
-  if (sort === "default") return rows;
-  const sorted = [...rows];
+): (a: T, b: T) => number {
+  const cached = comparatorCache.get(sort);
+  if (cached) return cached;
+
+  let comparator: (a: T, b: T) => number;
   switch (sort) {
     case "amount-asc":
-      sorted.sort((a, b) =>
-        a.info.ratePerSecond < b.info.ratePerSecond ? -1 : a.info.ratePerSecond > b.info.ratePerSecond ? 1 : 0,
-      );
+      comparator = (a, b) =>
+        a.info.ratePerSecond < b.info.ratePerSecond ? -1 : a.info.ratePerSecond > b.info.ratePerSecond ? 1 : 0;
       break;
     case "amount-desc":
-      sorted.sort((a, b) =>
-        a.info.ratePerSecond > b.info.ratePerSecond ? -1 : a.info.ratePerSecond < b.info.ratePerSecond ? 1 : 0,
-      );
+      comparator = (a, b) =>
+        a.info.ratePerSecond > b.info.ratePerSecond ? -1 : a.info.ratePerSecond < b.info.ratePerSecond ? 1 : 0;
       break;
     case "end-asc":
-      sorted.sort((a, b) => endValue(a.info.endTime) - endValue(b.info.endTime));
+      comparator = (a, b) => endValue(a.info.endTime) - endValue(b.info.endTime);
       break;
     case "end-desc":
-      sorted.sort((a, b) => endValue(b.info.endTime) - endValue(a.info.endTime));
+      comparator = (a, b) => endValue(b.info.endTime) - endValue(a.info.endTime);
+      break;
+    default:
+      comparator = () => 0;
       break;
   }
-  return sorted;
+
+  comparatorCache.set(sort, comparator as any);
+  return comparator;
+}
+
+export function sortStreams<T extends { info: Pick<StreamInfo, "ratePerSecond" | "endTime"> }>(
+  rows: T[],
+  sort: SortKey,
+): T[] {
+  if (sort === "default" || rows.length <= 1) return rows;
+  const comparator = getComparator<T>(sort);
+  return [...rows].sort(comparator);
 }