[BUG] Got System.ArgumentOutOfRangeException when calling ModelScope's OpenAI compatible API

[beginor]

Describe the bug

I use OpanAI dotnet sdk to call ModelScope's OpenAI compatible API , and get deserialization error:

Unhandled exception. System.ArgumentOutOfRangeException: Valid values are between -62135596800 and 253402300799, inclusive. (Parameter 'seconds')
   at System.DateTimeOffset.FromUnixTimeSeconds(Int64 seconds)
   at OpenAI.Chat.StreamingChatCompletionUpdate.DeserializeStreamingChatCompletionUpdate(JsonElement element, ModelReaderWriterOptions options)
   at OpenAI.AsyncSseUpdateCollection`1.<>c__DisplayClass13_0`1.<DeserializeSseToSingleViaJson>b__0(JsonElement e, ModelReaderWriterOptions o)
   at OpenAI.AsyncSseUpdateCollection`1.<>c__DisplayClass12_0`1.<DeserializeSseToMultipleViaJson>b__0(SseItem`1 item)
   at OpenAI.AsyncSseUpdateCollection`1.AsyncSseUpdateEnumerator`1.System.Collections.Generic.IAsyncEnumerator<U>.MoveNextAsync()
   at OpenAI.AsyncSseUpdateCollection`1.GetValuesFromPageAsync(ClientResult page)+MoveNext()
   at OpenAI.AsyncSseUpdateCollection`1.GetValuesFromPageAsync(ClientResult page)+MoveNext()
   at OpenAI.AsyncSseUpdateCollection`1.GetValuesFromPageAsync(ClientResult page)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+MoveNext()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+MoveNext()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+MoveNext()
   at System.ClientModel.AsyncCollectionResult`1.GetAsyncEnumerator(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
   at Program.<Main>$(String[] args) in /Users/zhang/Developer/dotnet/mcp/AgentDemo/Program.cs:line 39
   at Program.<Main>$(String[] args) in /Users/zhang/Developer/dotnet/mcp/AgentDemo/Program.cs:line 39
   at Program.<Main>(String[] args)

Steps to reproduce

Just run the flowing code:

using System.ClientModel;
using OpenAI;

var apiKey = Environment.GetEnvironmentVariable("MODEL_SCOPE_API_KEY"); 
var baseUrl = Environment.GetEnvironmentVariable("MODEL_SCOPE_BASE_URL");  // https://api-inference.modelscope.cn/v1/
var model = "Qwen/Qwen3-235B-A22B-Thinking-2507";

var openai = new OpenAIClient(
    new ApiKeyCredential(apiKey!),
    new OpenAIClientOptions {
        Endpoint = new Uri(baseUrl!)
    }
);
var chat = openai.GetChatClient(model);

var messages = new List<OpenAI.Chat.ChatMessage> {
    OpenAI.Chat.ChatMessage.CreateUserMessage("hello")
};

var stream = chat.CompleteChatStreamingAsync(messages);

await foreach (var update in stream) {
    Console.Write(update.ContentUpdate[0].Text);
}

The timestamp returned for created is 1760171895500 , which is larger than 253402300799, is a milli second timestamp, should use DateTimeOffset.FromUnixTimeMilliseconds() to deserialize.

Code snippets

OS

macOS

.NET version

9.0

Library version

2.5.0

[jsquire]

@beginor: For this scenario, the created field is documented as an integer representing time in seconds and is explicitly defined by the spec as an int32. The service that you're using is not following that contract.

The goal of the OpenAI client library is to enable support the OpenAI, following its REST API specification. While we do not explicitly block use with other services/models, neither are we able to offer support for them. Unfortunately, we are unable to assist with your issue.