Question: Why are special tokens added to the prompt being sent to replicate?

[hershalb]

In Replicate, the Llama-3-8b-instruct model takes in a "system_prompt" and "prompt_template" param. The replicate docs mentioned that system_prompt is prepended to the text being sent, and I'm assuming the prompt_template is also used to format the prompt data since there's a default value that includes the special tokens. Is there a reason this application is formatting the prompt to also use these special tokens? I guess I'm just a little confused how this is being handled by Replicate behind the scenes.

For example, for the message "Can you tell me about the story of David and Goliath" the front-end sends:

{
  system_prompt: "You are a helpful assistant.",
  prompt: "<|begin_of_text|><|start_header_id|>system<|end_header_id|>
You are a helpful assistant.<|eot_id|>
<|start_header_id|>user<|end_header_id|>

Can you tell me about the story of David and Goliath<|eot_id|>"
}

The default "prompt_template" seems to be:

<|begin_of_text|><|start_header_id|>system<|end_header_id|>

{system_prompt}<|eot_id|><|start_header_id|>user<|end_header_id|>

{prompt}<|eot_id|><|start_header_id|>assistant<|end_header_id|>

So, behind the scenes, it seems like what gets passed to the model becomes:

<|begin_of_text|><|start_header_id|>system<|end_header_id|>

You are a helpful assistant.<|eot_id|><|start_header_id|>user<|end_header_id|>

<|begin_of_text|><|start_header_id|>system<|end_header_id|>
You are a helpful assistant.<|eot_id|>
<|start_header_id|>user<|end_header_id|>

Can you tell me about the story of David and Goliath<|eot_id|><|eot_id|><|start_header_id|>assistant<|end_header_id|>

since the prompt and system_prompt are possibly directly passed into the prompt template. Is this a correct understanding?