Session warming

Keep recently active model sessions warm with periodic transient requests.

Session warming sends periodic model requests for recently active sessions. This can preserve provider-side prompt caches or other short-lived session state while you pause between prompts.

Warming is disabled by default. Enable it with the default settings in any OpenCode configuration file:

{
  "$schema": "https://opencode.ai/config.json",
  "warming": true
}

With the defaults, OpenCode sends a warming request after a session has made no model request for four minutes. It repeats this while the session remains idle, but stops 30 minutes after the last non-warming request. New model activity starts a new 30-minute window.

Configuration

Use the object form to customize the prompt, idle interval, or active duration:

{
  "$schema": "https://opencode.ai/config.json",
  "warming": {
    "prompt": "Do not perform any work. Reply with exactly: OK",
    "interval": "4 minutes",
    "duration": "30 minutes"
  }
}

Field	Default	Description
`prompt`	Keep-alive instruction	Prompt sent in each warming request. The default instructs the model to do no work and reply with `OK`.
`interval`	`"4 minutes"`	Idle time between warming requests.
`duration`	`"30 minutes"`	Maximum warming window after the latest non-warming model request.

interval and duration accept duration strings such as "30 seconds", "4 minutes", or "1 hour". Both must be finite and greater than zero.

To disable warming explicitly:

{
  "warming": false
}

Request behavior

A warming request uses the session’s current model, agent, instructions, and conversation context. Tools are disabled. The configured prompt is appended as a transient user message, and the response is discarded.

Warming does not admit input, add messages to session history, or otherwise mutate durable session state. A warming request resets the idle interval but does not extend the active duration; without new model activity, warming still ends when the configured duration expires.

Costs and limits

Warming requests are real provider requests. They can consume tokens, incur costs, count against rate limits, and fail for the same reasons as other model requests. OpenCode logs warming failures without failing or changing the session, then waits for the next interval before trying again.

Enable warming only when the provider-side benefit is worth the additional requests. A shorter interval or longer duration increases request volume.