Persist filter and auto-redact preferences to localStorage

Category toggles and the auto-redact checkbox now survive page
reloads. On mount, useFilters reads from localStorage keys
session-viewer:enabledCategories and session-viewer:autoRedact,
falling back to defaults when storage is empty, corrupted, or
contains invalid category names. Each state change writes back
to localStorage in a useEffect.

Tests cover round-trip persistence, invalid data recovery, corrupted
JSON fallback, and the boolean coercion for auto-redact.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/client/hooks/useFilters.ts

@@ -1,7 +1,40 @@
-import { useState, useCallback, useMemo } from "react";
+import { useState, useCallback, useMemo, useEffect } from "react";
 import type { MessageCategory, ParsedMessage } from "../lib/types";
 import { ALL_CATEGORIES, DEFAULT_HIDDEN_CATEGORIES } from "../lib/types";
 
+const STORAGE_KEY_CATEGORIES = "session-viewer:enabledCategories";
+const STORAGE_KEY_AUTOREDACT = "session-viewer:autoRedact";
+
+function loadEnabledCategories(): Set<MessageCategory> {
+  try {
+    const stored = localStorage.getItem(STORAGE_KEY_CATEGORIES);
+    if (stored) {
+      const arr = JSON.parse(stored) as string[];
+      const valid = arr.filter((c) =>
+        ALL_CATEGORIES.includes(c as MessageCategory)
+      ) as MessageCategory[];
+      if (valid.length > 0) return new Set(valid);
+    }
+  } catch {
+    // Fall through to default
+  }
+  const set = new Set(ALL_CATEGORIES);
+  for (const cat of DEFAULT_HIDDEN_CATEGORIES) {
+    set.delete(cat);
+  }
+  return set;
+}
+
+function loadAutoRedact(): boolean {
+  try {
+    const stored = localStorage.getItem(STORAGE_KEY_AUTOREDACT);
+    if (stored !== null) return stored === "true";
+  } catch {
+    // Fall through to default
+  }
+  return false;
+}
+
 interface FilterState {
   enabledCategories: Set<MessageCategory>;
   toggleCategory: (cat: MessageCategory) => void;
@@ -20,13 +53,7 @@ interface FilterState {
 export function useFilters(): FilterState {
   const [enabledCategories, setEnabledCategories] = useState<
     Set<MessageCategory>
-  >(() => {
-    const set = new Set(ALL_CATEGORIES);
-    for (const cat of DEFAULT_HIDDEN_CATEGORIES) {
-      set.delete(cat);
-    }
-    return set;
-  });
+  >(loadEnabledCategories);
 
   const [searchQuery, setSearchQuery] = useState("");
   const [redactedUuids, setRedactedUuids] = useState<Set<string>>(new Set());
@@ -34,7 +61,28 @@ export function useFilters(): FilterState {
     Set<string>
   >(new Set());
 
-  const [autoRedactEnabled, setAutoRedactEnabled] = useState(false);
+  const [autoRedactEnabled, setAutoRedactEnabled] = useState(loadAutoRedact);
+
+  // Persist enabledCategories to localStorage
+  useEffect(() => {
+    try {
+      localStorage.setItem(
+        STORAGE_KEY_CATEGORIES,
+        JSON.stringify([...enabledCategories])
+      );
+    } catch {
+      // Ignore storage errors
+    }
+  }, [enabledCategories]);
+
+  // Persist autoRedact to localStorage
+  useEffect(() => {
+    try {
+      localStorage.setItem(STORAGE_KEY_AUTOREDACT, String(autoRedactEnabled));
+    } catch {
+      // Ignore storage errors
+    }
+  }, [autoRedactEnabled]);
 
   const toggleCategory = useCallback((cat: MessageCategory) => {
     setEnabledCategories((prev) => {