Add password-remember + warning on save

frontend/src/hooks/useRememberedServerPassword.ts

@@ -0,0 +1,79 @@
+import { useCallback, useEffect, useMemo, useState } from 'react';
+
+type ServerLoginKind = 'repeater' | 'room';
+
+const STORAGE_KEY_PREFIX = 'remoteterm-server-password';
+
+type StoredPassword = {
+  password: string;
+};
+
+function getStorageKey(kind: ServerLoginKind, publicKey: string): string {
+  return `${STORAGE_KEY_PREFIX}:${kind}:${publicKey}`;
+}
+
+function loadStoredPassword(kind: ServerLoginKind, publicKey: string): StoredPassword | null {
+  try {
+    const raw = localStorage.getItem(getStorageKey(kind, publicKey));
+    if (!raw) return null;
+    const parsed = JSON.parse(raw) as Partial<StoredPassword>;
+    if (typeof parsed.password !== 'string' || parsed.password.length === 0) {
+      return null;
+    }
+    return { password: parsed.password };
+  } catch {
+    return null;
+  }
+}
+
+export function useRememberedServerPassword(kind: ServerLoginKind, publicKey: string) {
+  const storageKey = useMemo(() => getStorageKey(kind, publicKey), [kind, publicKey]);
+  const [password, setPassword] = useState('');
+  const [rememberPassword, setRememberPassword] = useState(false);
+
+  useEffect(() => {
+    const stored = loadStoredPassword(kind, publicKey);
+    if (!stored) {
+      setPassword('');
+      setRememberPassword(false);
+      return;
+    }
+    setPassword(stored.password);
+    setRememberPassword(true);
+  }, [kind, publicKey]);
+
+  const persistAfterLogin = useCallback(
+    (submittedPassword: string) => {
+      if (!rememberPassword) {
+        try {
+          localStorage.removeItem(storageKey);
+        } catch {
+          // localStorage may be unavailable
+        }
+        setPassword('');
+        return;
+      }
+
+      const trimmedPassword = submittedPassword.trim();
+      if (!trimmedPassword) {
+        return;
+      }
+
+      try {
+        localStorage.setItem(storageKey, JSON.stringify({ password: trimmedPassword }));
+      } catch {
+        // localStorage may be unavailable
+      }
+      setPassword(trimmedPassword);
+    },
+    [rememberPassword, storageKey]
+  );
+
+  return {
+    password,
+    setPassword,
+    rememberPassword,
+    setRememberPassword,
+    persistAfterLogin,
+  };
+}