Table of Contents

• What Is a Time-Travel Agent
• Time-Travel vs. ReAct (web search example)
• Why use time-travel checkpoints
• When to time-travel vs. append results
• Challenges: side-effects and filesystem rollback
• Conclusion and outlook

What Is a Time-Travel Agent

A time‑travel agent is a normal agent loop with one extra skill: it can set checkpoints before running tools, and jump back to them if things start to go wrong. When it jumps back, it also adds simple rules (like “prefer X” or “avoid Y”) so the next attempt is more focused.

Table of Contents

• Introduction
  • Why Context Matters
  • Context Stack at a Glance
• Gemini CLI Context Layers
  • Layer 1: Environment & Workspace State
  • Layer 2: Project Memory
  • Layer 3: Tooling & System Persona
  • Request/Response Timeline
  • Layer 4: Active IDE Context
  • Layer 5: Conversation Management
  • Layer 6: Subagents in the Same Ecosystem
• Context Refresh & Unload
• Design Takeaways

Introduction

Written against repository Gemini CLI at revision dc0e0b416592860bdc0846aed0386e1a9637a51e.

Why Context Matters

This guide is aimed at engineers and architects who build or operate LLM-powered developer tools. Gemini CLI is more than a chat wrapper. It assembles environment facts, project knowledge, user memory, IDE state, and agent-specific instructions into a cohesive context bundle—the structured payload that accompanies every user prompt. The following sections dissect that engine, layer by layer, and show how the pieces interact in code.