const keyData = await optimismClient.readContract({
      address: KEY_REGISTRY_ADDRESS,
      abi: keyRegistryABI,
      functionName: 'keyDataOf',
      args: [BigInt(fid), header.data.key as Hex],
    });

    if (!keyData || keyData.keyType !== 1 || keyData.state !== 1) {
      return NextResponse.json(
        { success: false, errors: ['Invalid signer key'] },
        { status: 400 },
      );
    }