How I Review Claude Code's Output Before I Ship It

Here is the whole review pass in one breath: read the diff before you read the agent's summary, run the code before you believe it works, and specifically hunt for the three things Claude Code gets wrong most often - scope it quietly expanded, logic it deleted because it judged it unused, and confident-looking code for a case it never actually ran. That is what I do on every single build before it goes near a client. Everything below is how each step works and why skipping it is how you ship a bug with your name on it.

Yes, and it is the step people skip first. The agent writes code that answers the prompt you gave it, not the intent behind it. If you asked it to make a form submit and you forgot to mention what happens when the network drops, it will happily ship a version that assumes the network never drops. The code runs, the demo works, and the bug lives in the case you never spoke out loud. Reading the output is how you find the assumptions the agent made on your behalf. If you ship without reading, you are not shipping your judgment, you are shipping its guess.

Claude Code gives you a tidy summary of what it did. The summary is honest, but it is a summary - it tells you the intent, not the exact lines. I read the actual diff first, then the summary, in that order. When you read the summary first, your brain nods along and then skims the diff looking for confirmation. When you read the diff first, you see what really changed, including the small edits the summary rounded off. The summary says 'updated the form'. The diff shows it also changed a shared helper that three other screens use. Guess which one matters.

After enough builds you learn where the agent drifts, and it is the same three places. First, silent scope creep: you asked for one thing and it also refactored something nearby because it looked improvable. Sometimes helpful, sometimes it just broke a working thing you did not ask it to touch. Second, deletions: it removes code it decided was unused, and it is usually right, until the one time that 'unused' function was called somewhere it did not check. Third, untested confidence: it writes clean, sure-looking code for an edge case it never ran, because you never gave it a way to run that case. Those three are 90% of what I catch in review.

Reading catches intent bugs. Running catches reality bugs. Before I approve anything, I actually execute the path that changed - click the button, hit the endpoint, run the flow with a weird input on purpose. The agent will tell you the code is complete and correct, and it believes that, because from inside its turn it has no way to run your app the way a user will. You do. Two minutes of actually using the thing beats twenty minutes of re-reading it. If it changed data, I check the data. If it changed a UI, I break the UI on purpose. Trust is earned by the code running, not by the agent sounding sure.

The fastest way to review is to review reasoning, not just lines. Before I approve a bigger change, I ask the agent to tell me what it changed, why, and what it chose not to do. When it has to explain itself, two things happen: it often catches its own shaky decision mid-explanation, and I get a map of where to look instead of reading everything with equal attention. This is the CCC read-back review - you do not read faster by reading less, you read faster by making the agent point you at the risky parts first. That single habit cut my review time more than any tool did.

A good review pass is the difference between an AI builder who ships fast and one who ships fast and gets paid again. Read the diff, hunt the three drift spots, run the path, and make the agent show its work. Inside the CCC community we keep a shared review checklist that members actually use before client handoff, with the exact prompts for the read-back step, so you can copy a pass that already works instead of learning the hard way on a live project. Come grab it and add the bug that bit you to the list.