Claude Code 101: Introduction to Agentic Programming

Software development as we know it The era of AI assistance From assistant to agent The agentic tooling ecosystem Agentic programming: the paradigm shift Final thoughts September 2025. I was leading a critical dependency upgrade on a mobile app with millions of users. The kind of change that breaks tests in a cascade. The deadline was October: if it wasn't ready, the app wouldn't ship to the store. The problem: nearly 10,000 tests needed to be adapted for the new version. Code owned by over 20 teams, spread across hundreds of modules. I thought "what if I give these AI tools everyone keeps talking about a real shot?" After watching a few videos and reading the docs, I spun up four terminals running Claude Code in parallel, each one migrating a slice of the tests. One week later: 2,000+ files changed, 50,000 lines of code, 85% migrated on the first pass. The following week, I cleaned up the rest. When I merged everything with the owning teams' approval, one thing was clear: I never coul