Step 1 — Why AI tools now

Early ChatGPT was a copy-paste chatbot. Late 2024 onward brought agents that read codebases, call tools, and edit dozens of files in one go.

1. 2023 vs 2025+

2023	2025+
Human asks → AI answers	AI edits and runs code directly
One file at a time	Dozens of files simultaneously
Terminal separate, AI separate	AI calls shell / DB / browser
Context = chat	Context = MCP / CLAUDE.md / memory
Static replies	Iteration, self-verification, tool chaining

2. Three IDE flavors

• Agent CLIs — Claude Code, Aider, Codex CLI, Gemini CLI
• Agent IDEs — Cursor, Windsurf, Zed
• Browser / desktop agents — Comet, Atlas, Dia

This course centers on Claude Code (CLI); concepts transfer.

3. Model landscape (2026)

Vendor	Model	Strengths	Tier
Anthropic	Claude Opus 4 · Sonnet 4	code, long context, agents	Pro $20 · Max $200
OpenAI	GPT-5 · o3-pro	reasoning, multimodal	Plus $20 · Pro $200
Google	Gemini 2.5 · 3.0	multimodal, cheap, fast	free quota · Pro $20
Meta	Llama 4	open, local	free
xAI	Grok 4	realtime, X integration	paid

Claude is the coding leader; Gemini wins on volume; Llama wins on local autonomy.

4. First command

npm install -g @anthropic-ai/claude-code
cd my-project
claude
# or
claude -p "translate the README to English"

5. Learning curve — three shifts

CLAUDE.md

# Project rules

## Stack
- Next.js 16 · TypeScript strict · Tailwind v4

## Rules
- Only pnpm
- Korean commit messages
- Use logger.info, not console.log

Skills

Repeatable workflows invoked via slash commands.

MCP

Standard protocol to connect DBs / Slack / Figma / GitHub to the agent.

Later steps cover each in turn.

6. Real workflow

User: "add a comments feature"
↓
AI:
1. Read project structure
2. Analyze existing Post model / API
3. Write Comment schema + migration
4. Add service / repository
5. Add controller / DTO
6. Add frontend form + component
7. Write tests
8. Run, verify
↓
User reviews → requests tweaks → AI revises
↓
Commit (by user or AI)

7. Costs

Service	Monthly	Daily use
Claude Pro	$20	2–4 hours
Claude Max	$200	all-day
OpenAI Plus	$20	2–4 hours
Cursor Free	$0	limited
Cursor Pro	$20	all-day

8. Safety

• Never paste API keys / secrets — system-prompt leaks possible
• No production DB from AI — use read-only accounts
• Don't blindly approve destructive commands (rm -rf, git push --force)
• Verify package names (typosquatting)

9. Limits

• Creative architecture — humans still
• Deep domain knowledge — may miss post-training content
• Rare libraries / cutting edge — hallucination risk
• Security / performance — final judgment stays human

Treat AI as a fast junior; you stay senior.

10. Psychology

The hardest shift is ego. "I didn't write that."

• Shift into code-review mindset
• Reading, understanding, revising is the skill
• Judgment, direction, verification are where value lives

11. Why now

• 2026 models are stable
• Tool ecosystem (MCP, Skills) is mature
• Productivity gap opens up at multi-x levels
• Foundation + AI beats either alone

Deeper

• AI IDE comparison
• AI CLI tools
• AI workflow tools
• LLM landscape

Next

Step 2 — spin up Claude Code and run your first command.