diff --git a/src/components/common/PermissionDeniedView.tsx b/src/components/common/PermissionDeniedView.tsx
new file mode 100644
index 0000000..ed8134c
--- /dev/null
+++ b/src/components/common/PermissionDeniedView.tsx
@@ -0,0 +1,42 @@
+/**
+ * Permission denial UI. (#793)
+ *
+ * The QR scanner caught camera permission errors in a bare catch and rendered
+ * a blank screen, so a denied permission looked identical to a broken screen
+ * and offered no way forward. This states what is blocked and routes the user
+ * into system settings.
+ */
+import { Linking, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
+
+export interface PermissionDeniedViewProps {
+  /** Permission the screen needs, e.g. "Camera". */
+  permission: string;
+  /** Overrides the jump into system settings; used by tests. */
+  onOpenSettings?: () => void;
+}
+
+export function PermissionDeniedView({ permission, onOpenSettings }: PermissionDeniedViewProps) {
+  const handlePress = onOpenSettings ?? (() => void Linking.openSettings());
+
+  return (
+    <View style={styles.container}>
+      <Text style={styles.title}>{permission} access is off</Text>
+      <Text style={styles.body}>
+        Turn on {permission.toLowerCase()} access in Settings to use this screen.
+      </Text>
+      <TouchableOpacity accessibilityRole="button" onPress={handlePress} style={styles.button}>
+        <Text style={styles.buttonLabel}>Go to Settings</Text>
+      </TouchableOpacity>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  body: { fontSize: 14, opacity: 0.75, textAlign: 'center' },
+  button: { backgroundColor: '#2563eb', borderRadius: 8, paddingHorizontal: 20, paddingVertical: 12 },
+  buttonLabel: { color: '#ffffff', fontWeight: '600' },
+  container: { alignItems: 'center', flex: 1, gap: 12, justifyContent: 'center', padding: 24 },
+  title: { fontSize: 18, fontWeight: '600' },
+});
+
+export default PermissionDeniedView;
diff --git a/src/hooks/useAsyncEffectState.ts b/src/hooks/useAsyncEffectState.ts
new file mode 100644
index 0000000..5100b4d
--- /dev/null
+++ b/src/hooks/useAsyncEffectState.ts
@@ -0,0 +1,50 @@
+/**
+ * Async effect with captured rejection state. (#795)
+ *
+ * Form fields ran their cache load as `void loadCache()` inside useEffect,
+ * which discards the rejection — a failed read left the field looking healthy
+ * with the error recorded nowhere. This keeps the rejection as state, reports
+ * it, and skips updates after unmount.
+ */
+import { DependencyList, useEffect, useState } from 'react';
+
+export interface AsyncEffectState {
+  /** Rejection from the most recent run, or null when it succeeded. */
+  error: Error | null;
+  /** True while the effect is in flight. */
+  loading: boolean;
+}
+/**
+ * Runs `effect` on mount and whenever `deps` change, surfacing its failure
+ * instead of discarding it. `onError` receives the Error for reporting.
+ */
+export function useAsyncEffectState(
+  effect: () => Promise<void>,
+  deps: DependencyList,
+  onError?: (error: Error) => void
+): AsyncEffectState {
+  const [error, setError] = useState<Error | null>(null);
+  const [loading, setLoading] = useState(true);
+  useEffect(() => {
+    let active = true;
+    setLoading(true);
+    effect()
+      .then(() => {
+        if (active) setError(null);
+      })
+      .catch((caught: unknown) => {
+        const failure = caught instanceof Error ? caught : new Error(String(caught));
+        onError?.(failure);
+        if (active) setError(failure);
+      })
+      .finally(() => {
+        if (active) setLoading(false);
+      });
+    return () => {
+      active = false;
+    };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, deps);
+
+  return { error, loading };
+}
diff --git a/src/utils/safeLog.ts b/src/utils/safeLog.ts
new file mode 100644
index 0000000..e67cd5c
--- /dev/null
+++ b/src/utils/safeLog.ts
@@ -0,0 +1,34 @@
+/**
+ * Crash-proof logging wrapper. (#794)
+ *
+ * The response interceptor called the logger unguarded. When the logger
+ * itself threw — Sentry not initialised, a circular reference during
+ * serialisation — the interceptor unwound and the original request error was
+ * lost. Logging must never be able to do that.
+ */
+
+/**
+ * Runs `log`, swallowing any failure it raises so the caller's control flow
+ * is unaffected. Falls back to console.error so the logger's own failure
+ * stays visible rather than disappearing silently.
+ */
+export function safeLog(log: () => void): void {
+  try {
+    log();
+  } catch (loggerError) {
+    try {
+      console.error('[safeLog] logger threw and was suppressed:', loggerError);
+    } catch {
+      // Console is unavailable too — drop it rather than break the caller.
+    }
+  }
+}
+
+/** Promise-returning variant for async transports. Never rejects. */
+export async function safeLogAsync(log: () => Promise<void>): Promise<void> {
+  try {
+    await log();
+  } catch (loggerError) {
+    safeLog(() => console.error('[safeLogAsync] logger threw and was suppressed:', loggerError));
+  }
+}
diff --git a/src/utils/sanitizeErrorResponse.ts b/src/utils/sanitizeErrorResponse.ts
new file mode 100644
index 0000000..ba59036
--- /dev/null
+++ b/src/utils/sanitizeErrorResponse.ts
@@ -0,0 +1,33 @@
+/**
+ * Error payload sanitisation before logging. (#792)
+ *
+ * Error response bodies were logged verbatim to console and Sentry. Backends
+ * occasionally echo credentials and PII inside those bodies, which then
+ * persist in log storage in plaintext. Sensitive keys are redacted here
+ * before anything reaches a transport.
+ */
+
+const SENSITIVE_KEY_PATTERN = /(password|token|secret|card|cvv|ssn|authorization)/i;
+const REDACTED = '[REDACTED]';
+const MAX_DEPTH = 6;
+
+/**
+ * Returns a copy of `data` with sensitive values replaced by [REDACTED],
+ * recursing through nested objects and arrays.
+ *
+ * Depth-capped so a deeply nested or self-referencing body cannot hang the
+ * logger — beyond MAX_DEPTH the subtree is redacted wholesale.
+ */
+export function sanitizeErrorResponse(data: unknown, depth = 0): unknown {
+  if (depth >= MAX_DEPTH) return REDACTED;
+  if (Array.isArray(data)) return data.map((item) => sanitizeErrorResponse(item, depth + 1));
+  if (!data || typeof data !== 'object') return data;
+
+  const result: Record<string, unknown> = {};
+  for (const [key, value] of Object.entries(data as Record<string, unknown>)) {
+    result[key] = SENSITIVE_KEY_PATTERN.test(key)
+      ? REDACTED
+      : sanitizeErrorResponse(value, depth + 1);
+  }
+  return result;
+}