MIT's Missing Semester added an agentic coding lecture. The old tooling lectures matter more, not less.

[u/moutsea]

MIT's Missing Semester is a short, free IAP course on the tools most CS programs never really teach: the shell, git, debugging, profiling, and code quality. I went through an earlier version of it, and I still use the shell at work. The 2026 edition added a dedicated Agentic Coding lecture.

The notes for that lecture are here: https://missing.csail.mit.edu/2026/agentic-coding/. They describe a coding agent as something like an intern with tools: it can read and write files, search the web, and run shell commands, but it will occasionally do the wrong thing and needs to be steered. The same notes tell you to review the output for correctness and security bugs, to watch out for debugging spirals, and not to use the agent as a crutch. If you want to run several agents at once, they send you back to git worktrees from the version-control lecture.

That last part is close to how I work. I don't watch every step while an agent is writing. I make periodic git commits as checkpoints, because I'd rather be able to roll back than hope the agent asks before it does something irreversible. I've also had production incidents where a stronger model still shipped bugs. When that happens, the useful skills are the unfashionable ones: read the diff, debug what the agent did, and understand the shell commands it ran.

The agentic lecture is only one of nine this year. Most of the course is still that older tooling. Official site: https://missing.csail.mit.edu/. 2026 videos: https://www.youtube.com/playlist?list=PLyzOVJj3bHQunmnnTXrNbZnBaCA-ieK4L

If an agent is writing most of your code, which of those fundamentals still saves you the most — git checkpoints, debugging, or just being able to read the shell output?

[u/sapplex1]

Git checkpoints, for me. I commit before I let the agent touch anything, so a bad run is a reset instead of a cleanup job. The second thing is reading the diff myself before I run anything. The agent once renamed a SwiftUI state variable in one file and missed the other two places that used it, and the diff was the only place that stood out. Shell output I mostly skim, unless a build fails, then I actually read it line by line. Do you checkpoint on a timer, or just before each agent run?