Attach file by ID (OpenAI Responses, Anthropic, Mistral)

[ashatrov]

OpenAI API has functionality to upload a file and reuse it in future requests https://platform.openai.com/docs/api-reference/files/create (same functionality is available for Mistral and Claude)

This saves a lot of time and tokens when you need to use the same file in a few prompts. E.g., I use it once to get a summary and then one more time to validate this summary against the document.

Upload file:

curl https://api.openai.com/v1/files \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -F purpose="fine-tune" \
  -F file="@mydata.jsonl"
  -F expires_after[anchor]="created_at"
  -F expires_after[seconds]=2592000

Then this file can be used by ID in future requests to the API https://platform.openai.com/docs/guides/pdf-files?api-mode=responses#uploading-files

Use previously uploaded file by id "file_id": "file-6F2ksmvXxt4VdoqmHRw6kL":

curl "https://api.openai.com/v1/responses" \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer $OPENAI_API_KEY" \
    -d '{
        "model": "gpt-5",
        "input": [
            {
                "role": "user",
                "content": [
                    {
                        "type": "input_file",
                        "file_id": "file-6F2ksmvXxt4VdoqmHRw6kL"
                    },
                    {
                        "type": "input_text",
                        "text": "What is the first dragon in the book?"
                    }
                ]
            }
        ]
    }'

[andrey-cosmos]

#412 (partial implementation)

[ilvalerione]

I can't find the Anthropic documentation for sending a content block as a file ID. Do you have a link?

Found here: https://platform.claude.com/docs/en/build-with-claude/files#using-a-file-in-messages

[ilvalerione]

@andrey-cosmos why do you think it's incomplete?

[ashatrov]

@ilvalerione PR is fine, but since I linked it to this Issue, they do not match 100%.

Clarification:
In the Issue, I mentioned Mistral as well, because they have a file attachment by ID. So I wrote "partial implementation" in the Issue, not in the PR.

PS: I am completely fine if you close this Issue after merging #412

[ashatrov]

Info about file attachment in the Mistral:

1. Upload file with the right purpose "fine-tune"|"batch"|"ocr"
   https://docs.mistral.ai/api/endpoint/files#operation-files_api_routes_upload_file

2. Use it in the batch or ocr or fine-tune API

Batch API: https://docs.mistral.ai/api/endpoint/batch?property=operation-jobs_api_routes_batch_create_batch_job_request_input_files#operation-jobs_api_routes_batch_create_batch_job_request_input_files
OCR API: https://docs.mistral.ai/api/endpoint/ocr#operation-ocr_v1_ocr_post_request_document_filechunk
Batch API: https://docs.mistral.ai/api/endpoint/fine-tuning#operation-jobs_api_routes_fine_tuning_create_fine_tuning_job_request_training_files_trainingfile

[ilvalerione]

It was released with 2.9.2 and it supports OpenAI, OpenAI responses API, Anthropic, and Mistral.

https://docs.neuron-ai.dev/the-basics/attachments-documents-and-images#file-id