Core Document Model

public partial class OpenApiDocument : JsonExtensionObject, IDocumentPathProvider
{
    // Core properties
    public string Swagger { get; set; }
    public string OpenApi { get; set; }
    public OpenApiInfo Info { get; set; }
    public IDictionary<string, OpenApiPathItem> Paths { get; }
    public OpenApiComponents Components { get; set; }
    public IList<OpenApiServer> Servers { get; set; }
    public IList<OpenApiSecurityRequirement> Security { get; set; }
    public IList<OpenApiTag> Tags { get; set; }
    public OpenApiExternalDocumentation ExternalDocumentation { get; set; }
    
    // Document operations
    public static Task<OpenApiDocument> FromFileAsync(string filePath);
    public static Task<OpenApiDocument> FromJsonAsync(string json);
    public static Task<OpenApiDocument> FromUrlAsync(string url);
    public string ToJson();
    public Task<string> ToYamlAsync();
    public void GenerateOperationIds();
    
    // Utility properties
    public static string ToolchainVersion { get; }
    public string DocumentPath { get; set; }
}

// Load from file
var document = await OpenApiDocument.FromFileAsync("swagger.json");

// Load from URL
var document = await OpenApiDocument.FromUrlAsync("https://api.example.com/swagger.json");

// Create new document
var document = new OpenApiDocument
{
    Info = new OpenApiInfo
    {
        Title = "My API",
        Version = "1.0.0"
    }
};

// Generate operation IDs
document.GenerateOperationIds();

// Serialize to JSON
string json = document.ToJson();

public class OpenApiOperation : JsonExtensionObject
{
    public IList<string> Tags { get; set; }
    public string Summary { get; set; }
    public string Description { get; set; }
    public string OperationId { get; set; }
    public IList<OpenApiParameter> Parameters { get; }
    public OpenApiRequestBody RequestBody { get; set; }
    public IDictionary<string, OpenApiResponse> Responses { get; }
    public bool Deprecated { get; set; }
    public IList<OpenApiSecurityRequirement> Security { get; set; }
    public IList<OpenApiServer> Servers { get; set; }
    public OpenApiExternalDocumentation ExternalDocumentation { get; set; }
    public IDictionary<string, OpenApiCallback> Callbacks { get; set; }
    
    // Parameter management
    public OpenApiParameter GetParameter(string name, OpenApiParameterKind kind);
    public bool HasParameter(string name, OpenApiParameterKind kind);
    public void AddParameter(OpenApiParameter parameter);
    public void RemoveParameter(string name, OpenApiParameterKind kind);
}

public class OpenApiParameter : JsonSchema
{
    public string Name { get; set; }
    public OpenApiParameterKind Kind { get; set; }
    public OpenApiParameterStyle Style { get; set; }
    public bool Explode { get; set; }
    public bool AllowReserved { get; set; }
    public JsonSchema Schema { get; set; }
    public object Example { get; set; }
    public IDictionary<string, OpenApiExample> Examples { get; set; }
    public IDictionary<string, OpenApiMediaType> Content { get; set; }
    
    // Legacy Swagger 2.0 properties
    public OpenApiParameterCollectionFormat CollectionFormat { get; set; }
    public string Format { get; set; }
    public bool AllowEmptyValue { get; set; }
}

public class OpenApiResponse : JsonExtensionObject
{
    public string Description { get; set; }
    public IDictionary<string, OpenApiHeader> Headers { get; set; }
    public IDictionary<string, OpenApiMediaType> Content { get; set; }
    public IDictionary<string, OpenApiLink> Links { get; set; }
    
    // Legacy Swagger 2.0 properties
    public JsonSchema Schema { get; set; }
    public IDictionary<string, JsonSchema> Examples { get; set; }
}

public class OpenApiInfo : JsonExtensionObject
{
    public string Title { get; set; }
    public string Description { get; set; }
    public string Version { get; set; }
    public string TermsOfService { get; set; }
    public OpenApiContact Contact { get; set; }
    public OpenApiLicense License { get; set; }
}

public class OpenApiServer : JsonExtensionObject
{
    public string Url { get; set; }
    public string Description { get; set; }
    public IDictionary<string, OpenApiServerVariable> Variables { get; set; }
}

public class OpenApiComponents : JsonExtensionObject
{
    public IDictionary<string, JsonSchema> Schemas { get; set; }
    public IDictionary<string, OpenApiResponse> Responses { get; set; }
    public IDictionary<string, OpenApiParameter> Parameters { get; set; }
    public IDictionary<string, OpenApiExample> Examples { get; set; }
    public IDictionary<string, OpenApiRequestBody> RequestBodies { get; set; }
    public IDictionary<string, OpenApiHeader> Headers { get; set; }
    public IDictionary<string, OpenApiSecurityScheme> SecuritySchemes { get; set; }
    public IDictionary<string, OpenApiLink> Links { get; set; }
    public IDictionary<string, OpenApiCallback> Callbacks { get; set; }
}

public class OpenApiSecurityScheme : JsonExtensionObject
{
    public OpenApiSecuritySchemeType Type { get; set; }
    public string Description { get; set; }
    public string Name { get; set; }
    public OpenApiSecurityApiKeyLocation In { get; set; }
    public string Scheme { get; set; }
    public string BearerFormat { get; set; }
    public OpenApiOAuthFlows Flows { get; set; }
    public string OpenIdConnectUrl { get; set; }
}

public class OpenApiPathItem : JsonExtensionObject
{
    public string Summary { get; set; }
    public string Description { get; set; }
    public OpenApiOperation Get { get; set; }
    public OpenApiOperation Put { get; set; }
    public OpenApiOperation Post { get; set; }
    public OpenApiOperation Delete { get; set; }
    public OpenApiOperation Options { get; set; }
    public OpenApiOperation Head { get; set; }
    public OpenApiOperation Patch { get; set; }
    public OpenApiOperation Trace { get; set; }
    public IList<OpenApiServer> Servers { get; set; }
    public IList<OpenApiParameter> Parameters { get; }
}

public class OpenApiTag : JsonExtensionObject
{
    public string Name { get; set; }
    public string Description { get; set; }
    public OpenApiExternalDocumentation ExternalDocumentation { get; set; }
}

public class OpenApiContact : JsonExtensionObject
{
    public string Name { get; set; }
    public string Url { get; set; }
    public string Email { get; set; }
}

public class OpenApiLicense : JsonExtensionObject
{
    public string Name { get; set; }
    public string Url { get; set; }
}

public enum OpenApiParameterKind
{
    Undefined,
    Body,
    Query,
    Path,
    Header,
    FormData,
    ModelBinding,
    Cookie
}

public enum OpenApiParameterStyle
{
    Matrix,
    Label,
    Form,
    Simple,
    SpaceDelimited,
    PipeDelimited,
    DeepObject
}

public enum OpenApiParameterCollectionFormat
{
    Undefined,
    Csv,
    Ssv,
    Tsv,
    Pipes,
    Multi
}

public enum OpenApiSecuritySchemeType
{
    Undefined,
    Basic,
    ApiKey,
    OAuth2,
    OpenIdConnect
}

public enum OpenApiSecurityApiKeyLocation
{
    Undefined,
    Query,
    Header,
    Cookie
}

public static class OpenApiOperationMethod
{
    public const string Get = "get";
    public const string Post = "post";
    public const string Put = "put";
    public const string Delete = "delete";
    public const string Options = "options";
    public const string Head = "head";
    public const string Patch = "patch";
    public const string Trace = "trace";
}