Claude Code turns your terminal into a collaborative coding environment. Today you install it, understand what agentic mode means in practice, and make your first multi-file edit — so you know exactly what you are working with before going deeper.
By the end of this lesson you will install Claude Code via npm, understand the difference between chat mode and agentic mode, make your first autonomous multi-file edit, create a CLAUDE.md file that gives Claude project context, and understand the permission model.
Claude Code installation is the foundation of Day 1. Every concept that follows builds on the mental model you establish here. The most effective approach is to understand the principle first, then apply it — skipping straight to implementation creates gaps that compound into confusion later.
Work through each example in this lesson sequentially. The concepts connect, and the order is deliberate. If something is unclear, slow down at that point rather than pushing past it — a ten-minute pause now saves hours of debugging later.
Understanding Claude Code installation requires seeing it in motion. The code below is not a complete application — it is a minimal, working illustration of the key mechanism. Study the pattern, run it, break it deliberately, then fix it. That cycle builds real comprehension.
Once the basic pattern works, the logical next step is agentic mode. This is where the abstraction becomes useful — you move from understanding the mechanism to applying it to real problems. The transition is usually smaller than it feels. Most of the hard work happened in Section 1.
first edit completes today's picture. It is where Claude Code installation and agentic mode converge into a pattern you can apply to novel problems. This integration step is often where the day's learning consolidates — if the earlier sections felt abstract, this one typically makes them click.
Implementing Claude Code installation alone handles the happy path. Real systems encounter edge cases, invalid input, and unexpected state. Missing agentic mode means missing those guards.
Combining Claude Code installation with agentic mode gives you a complete, defensible implementation. The extra lines cost ten minutes; the robustness they add is worth hours of debugging time.
Several mistakes appear consistently when engineers encounter Setup and First Agentic Edit for the first time. Recognizing them now costs nothing; encountering them in production costs hours.
Two intensive days (Thu–Fri) with an instructor who has taught thousands of engineers. Cohorts in 5 cities, June–June–October 2026 (Thu–Fri).
Reserve Your Seat — $1,490Before moving on, you should be able to answer these without looking: