Claude Code From Scratch

Claude Code from Scratch — Chapter 4

**Conversation Management: The Art of Multi-Turn Context**

Tag: `ch04-conversation-management` | Version: `0.4.0`

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What's New in This Chapter

Building on Chapter 3's multi-turn CLI, this chapter adds:

• Conversation persistence (core/history.ts) — save/load conversations as JSON files to disk
• Resume conversations — --resume flag or /resume command to pick up where you left off
• Conversation IDs — each conversation gets a unique ID for tracking
• Auto-save on exit — conversations are automatically saved when you quit
• Budget warnings — caution at 60% window utilization, critical at 80%
• History browser — /history lists saved conversations, /resume [id] loads one

Context Engineering Concepts

• The stateless illusion — LLMs have zero memory; continuity comes from resending the full history
• Message array = state — the conversation's messages array IS the complete state
• Context pressure — history grows ~500-2000 tokens per turn while the window stays fixed
• Persistence — saving the message array to disk bridges the gap between sessions
• Long conversation strategies — sliding window, summarization, selective retention (theory; implemented in Ch 10)

Run It

npm install
npm start              # Start a new conversation
npm start -- --resume  # Resume the most recent conversation

Commands

Command	Action
/save	Save the current conversation to disk
/history	List all saved conversations
/resume [id]	Resume a saved conversation (most recent if no ID)
/clear	Start a fresh conversation
/stats	Show conversation statistics and budget status
/prompt	Display the system prompt
quit	Auto-save and exit

Project Structure

claude-from-scratch/
├── src/
│   ├── index.ts              # CLI with persistence and budget warnings
│   ├── config.ts             # Mod