JavaScript ChatClient Streaming Uses Callbacks, Not Async Iterators

[leestott]

JavaScript ChatClient Streaming Uses Callbacks, Not Async Iterators

Severity: Documentation gap
Component: foundry-local-sdk JavaScript v0.9.x — ChatClient.completeStreamingChat()

The ChatClient returned by model.createChatClient() provides a completeStreamingChat() method, but it uses a callback pattern rather than returning an async iterable:

// ❌ This does NOT work — throws "stream is not async iterable"
for await (const chunk of chatClient.completeStreamingChat(messages)) { ... }

// ✅ Correct pattern — pass a callback
await chatClient.completeStreamingChat(messages, (chunk) => {
  process.stdout.write(chunk.choices?.[0]?.delta?.content ?? "");
});

Impact: Developers familiar with the OpenAI SDK's async iteration pattern (for await) will encounter confusing errors. The callback must be a valid function or the SDK throws "Callback must be a valid function."

Expected: Document the callback pattern in the SDK reference. Alternatively, support the async iterable pattern for consistency with the OpenAI SDK.

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