Skip to content
For the complete documentation index, see llms.txt. Markdown versions of documentation pages are available by appending .md to the page URL.
Primary navigation
Theme

Suggested
Overview Models Agents Tools Audio & voice Production API reference

Compact conversation

POST
/responses/compact

Compact a conversation. Returns a compacted response object.

Learn when and how to compact long-running conversations in the conversation state guide. For ZDR-compatible compaction details, see Compaction (advanced).

Compact conversation

curl -X POST https://api.openai.com/v1/responses/compact \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer $OPENAI_API_KEY" \
    -d '{
      "model": "gpt-6-astra",
      "input": [
        {
          "role": "user",
          "content": "Create a simple landing page for a dog petting café."
        },
        {
          "id": "msg_001",
          "type": "message",
          "status": "completed",
          "content": [
            {
              "type": "output_text",
              "annotations": [],
              "logprobs": [],
              "text": "Below is a single file, ready-to-use landing page for a dog petting café:..."
            }
          ],
          "role": "assistant"
        }
      ]
    }'
Response example
{
  "id": "resp_001",
  "object": "response.compaction",
  "created_at": 1764967971,
  "output": [
    {
      "id": "msg_000",
      "type": "message",
      "status": "completed",
      "content": [
        {
          "type": "input_text",
          "text": "Create a simple landing page for a dog petting cafe."
        }
      ],
      "role": "user"
    },
    {
      "id": "cmp_001",
      "type": "compaction",
      "encrypted_content": "gAAAAABpM0Yj-...="
    }
  ],
  "usage": {
    "input_tokens": 139,
    "input_tokens_details": {
      "cached_tokens": 0,
      "cache_write_tokens": 0
    },
    "output_tokens": 438,
    "output_tokens_details": {
      "reasoning_tokens": 64
    },
    "total_tokens": 577
  }
}
Body Parameters
JSON
model: "gpt-6-astra" or "gpt-6.1-sol" or "gpt-6.1-terra" or 109 more or string or null

Model ID used to generate the response, like gpt-6-astra. OpenAI offers a wide range of models with different capabilities, performance characteristics, and price points. Refer to the model guide to browse and compare available models.

image: optional object { context_compression }

Request level image options.

input: optional string or array of EasyInputMessage { content, role, phase, type } or Message { content, role, status, type } or ResponseOutputMessage { id, content, role, 3 more } or 30 more or null

Text, image, or file inputs to the model, used to generate a response

instructions: optional string or null

Deprecated.

A system (or developer) message inserted into the model’s context. When used along with previous_response_id, the instructions from a previous response will not be carried over to the next response. This makes it simple to swap out system (or developer) messages in new responses.

previous_response_id: optional string or null

The unique ID of the previous response to the model. Use this to create multi-turn conversations. Learn more about conversation state. Cannot be used in conjunction with conversation.

prompt_cache_key: optional string or null

A key to use when reading from or writing to the prompt cache.

maxLength64
prompt_cache_options: optional object { mode, ttl } or null

Options for prompt caching. Supported for gpt-5.6 and later models. By default, OpenAI automatically chooses one implicit cache breakpoint. You can add explicit breakpoints to content blocks with prompt_cache_breakpoint. Each request can write up to four breakpoints. For cache matching, OpenAI considers up to the latest 80 breakpoints in the conversation, without a content-block lookback limit. Set mode to explicit to disable the implicit breakpoint. The ttl defaults to 30m. Supported lifetimes depend on the API. See the prompt caching guide for current details.

prompt_cache_retention: optional "in_memory" or "24h" or null

Deprecated.

How long to retain a prompt cache entry created by this request.

One of the following:
"in_memory"
"24h"
service_tier: optional "auto" or "default" or "fast" or 2 more or null

Specifies the processing type used for serving the request. - If set to ‘auto’, then the request will be processed with the service tier configured in the Project settings. Unless otherwise configured, the Project will use ‘default’. - If set to ‘default’, then the request will be processed with the standard pricing and performance for the selected model. - If set to ‘flex’, then the request will be processed with the Flex Processing service tier. - To opt-in to Fast mode at the request level, include the service_tier=fast or service_tier=priority parameter for Responses or Chat Completions. For models with a dedicated Fast tier, either value resolves to service_tier=fast; for other models, either value resolves to service_tier=priority. - When not set, the default behavior is ‘auto’. When the service_tier parameter is set, the response body will include the service_tier value based on the processing mode actually used to serve the request. This response value may be different from the value set in the parameter.

Returns
CompactedResponse object { id, created_at, object, 3 more }
Returns Examples
Response example
{
  "id": "resp_001",
  "object": "response.compaction",
  "created_at": 1764967971,
  "output": [
    {
      "id": "msg_000",
      "type": "message",
      "status": "completed",
      "content": [
        {
          "type": "input_text",
          "text": "Create a simple landing page for a dog petting cafe."
        }
      ],
      "role": "user"
    },
    {
      "id": "cmp_001",
      "type": "compaction",
      "encrypted_content": "gAAAAABpM0Yj-...="
    }
  ],
  "usage": {
    "input_tokens": 139,
    "input_tokens_details": {
      "cached_tokens": 0,
      "cache_write_tokens": 0
    },
    "output_tokens": 438,
    "output_tokens_details": {
      "reasoning_tokens": 64
    },
    "total_tokens": 577
  }
}