How can I retrieve only the latest assistant responses without fetching the full thread history?

Below is an explanation with some guidance on how to approach this:

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Retrieving the Latest Response

Currently, the endpoint to list messages in a thread returns all messages (with options for ordering and pagination). This means that if you simply call the list endpoint every time, you retrieve the entire conversation history—not just the latest run's messages.

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Cost Considerations

• Growing Thread: As your thread grows, the response will indeed include more messages. This can increase the payload size and potentially the cost per API call if pricing is tied to the amount of data processed.
• Pagination: Fortunately, the endpoint supports pagination (using parameters like limit and after), so you can use these to fetch only a subset (for example, messages created after a certain message ID).

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Approaches for Getting Only the Latest Run Responses

At the moment, there isn’t a dedicated endpoint that returns only the messages generated in the most recent run. Here are a couple of strategies you could consider:

1. Tracking using Timestamps or Cursors:

   • Store the Last Run’s Details: Save either the timestamp (or the latest message ID) of the last run.

   • Using the after Parameter: In subsequent calls, set the after parameter to the last message ID you received. This way, the API will return only messages created after that ID.

     BASHCopied
     curl "https://api.openai.com/v1/threads/<thread_id>/messages?after=<last_message_id>" \
     -H "Content-Type: application/json" \
     -H "Authorization: Bearer $OPENAI_API_KEY" \
     -H "OpenAI-Beta: assistants=v2"

2. Filtering Locally:

   • Fetch and Filter: You can fetch all messages, then filter them locally by comparing the created_at timestamps or by looking at the order. This might be less efficient as the thread grows.

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Handling Multiple Responses in One Run

If an assistant generates more than one message in a single run, you’ll need to identify all new messages related to that run. Some strategies include:

• Timestamps: Compare the timestamps of the messages to the time when the previous run was completed.
• Batch Fetching with Cursors: Use the pagination (after parameter) intelligently to retrieve only the new batch of messages following your last retrieval.
• Metadata or Markers: If the run metadata includes details that allow you to identify which messages belong to the latest run, this can simplify filtering. However, as of now, there is no separate field that marks messages as belonging to a particular run—you’ll have to implement your own tracking.

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Summary

• Yes, calling the list endpoint retrieves the entire thread, which may grow over time.
• There isn’t a direct endpoint to get only the latest run’s assistant messages.
• Your options are either to use pagination (i.e., the after parameter) to get only the new messages or to maintain your own state (e.g., last run timestamp or last message ID) and filter the results accordingly.
• When multiple messages are generated in one run, you’d need to check all messages after your saved state to ensure you capture every response.

This approach requires managing some local state on your end, but it’s currently the best way to ensure you capture only the new messages without incurring the cost of retrieving the entire conversation history each time.