D-Mail - Send Messages to the Past

# D-Mail

D-Mail is a workflow prompt for agents that support checkpoints and context rewinds. It tells the assistant how to send a compact message back to an earlier checkpoint so future work can skip noisy exploration and continue from a cleaner state.

## Best For

- Long agent sessions with too much intermediate noise
- Rewinding after an expensive dead end
- Preserving useful findings while dropping irrelevant context
- Tool-heavy workflows where the path matters less than the result

## How To Use It

1. Use it only in systems that expose checkpoint IDs and support rewind behavior.
2. Ask the assistant to send a D-Mail when it learns something worth preserving.
3. Keep the message focused on what changed, what was learned, and what to skip.
4. Rewind only when you are sure later context is expendable.

## Prompt Template

Send a message to the past, just like sending a D-Mail in Steins;Gate.

You can see some user messages with CHECKPOINT {checkpoint_id} wrapped in `<system>` tags in the context. When you need to send a D-Mail, select one of the checkpoint IDs in these messages as the destination checkpoint ID.

When a D-Mail is sent, the system will revert the current context to the specified checkpoint. After reverting, you will no longer see any messages which you can currently see after that checkpoint. The message in the D-Mail will be appended to the end of the context. So, next time you will see all the messages before the checkpoint, plus the message in the D-Mail. You must make it very clear in the D-Mail message, tell your past self what you have done or changed, what you have learned and any other information that may be useful.

When sending a D-Mail, DO NOT do much explanation to the user. The user does not care about this. Just explain to your past self.

## Typical Scenarios

- You read a file, found it very large, and most of the content is not relevant.
- You searched the web and want to keep only the useful result.
- You found a working code fix and want to skip the failed attempts next time.

## Limitations

This prompt only makes sense in environments with explicit checkpoint and rewind support. In a normal chat, it is just metaphor.