D-Mail

chimera.tools.dmail provides DMailTool, a context-rewind mechanism inspired by Steins;Gate. The agent creates checkpoints during a conversation, then “sends a D-Mail” to rewind context to an earlier checkpoint with a summary of what was learned — allowing it to continue from that point without the clutter of intermediate exploration.

This is context compaction disguised as time travel.

Quick Start

import chimera

dmail = chimera.DMailTool()
tools = list(chimera.AGENT_TOOLS) + [dmail]

agent = chimera.Agent(
    provider=chimera.create_provider(),
    tools=tools,
    loop=chimera.ReAct(max_steps=10),
    prompt=chimera.Prompt.from_string(
        "You have a 'dmail' tool. Use action='checkpoint' to save your "
        "position, then action='send' with a summary to rewind when you've "
        "gathered enough information."
    ),
)

result = agent.run("Explore the project, then summarize your findings.", env=env)
print(f"Checkpoints created: {dmail.checkpoint_count}")

How It Works

DMailTool is a ContextAwareTool — it needs a reference to the agent’s Context so it can truncate the message history. The Agent class calls bind_context() automatically before the loop starts.

Action: checkpoint

Saves the current position in context (just a message index — no filesystem snapshot).

tool_call: dmail(action="checkpoint")
# -> "Checkpoint 0 created at message index 5."

Action: send

Rewinds context to the given checkpoint, removes all messages after it, and appends a [D-Mail from future self] user message with the summary.

tool_call: dmail(action="send", checkpoint_id=0, message="The project uses Flask + Postgres on port 5432.")
# -> "D-Mail sent. Context rewound to checkpoint 0."

After a send:

• All messages after the checkpoint are removed
• All checkpoints created after the target are removed
• The summary is injected as a user message
• The agent continues from that point with a clean context

Parameters

{
  "action": "checkpoint | send",
  "checkpoint_id": 0,
  "message": "Summary for your past self"
}

Parameter	Required	Description
action	Always	"checkpoint" to save or "send" to rewind
checkpoint_id	For send	Which checkpoint to rewind to
message	For send	Summary message for your past self

Why DMailTool Is Not in AGENT_TOOLS

DMailTool requires context binding, which the Agent does automatically when it finds a ContextAwareTool in the tool list. Because it is a specialized tool, it must be added explicitly:

dmail = chimera.DMailTool()
tools = list(chimera.AGENT_TOOLS) + [dmail]

Import Reference

from chimera.tools.dmail import DMailTool
from chimera.core.tool import ContextAwareTool  # base class