60 days with Claude Code on a production ERP: the honest balance (no hype, raw numbers)

The evening Étienne asked to see the numbers Tuesday evening, end of the day, the open space had cleared except for Étienne. Étienne holds sixty percent of the house and spends his working week at a fund that acquires software publishers, and he looks at ERPs all year the way others read balance sheets. He sat on the edge of my desk, a metal water bottle in hand, and said what he always says when he senses someone is telling themselves a story. "What's that based on?" I was about to answer with a narrative. Sixty days of solo production on Rembrandt with Claude Code, learning the doctrine, the in-flight retractions, the incidents that hardened the rules. The declarative form was ready. But Étienne doesn't ask for a narrative, he asks for the material inventory. So I opened a terminal and let wc -l speak. This article is what I should have given him without waiting for him to ask — the dry, numbered balance, what worked, what didn't, what I would do differently. Not a success story, not a cautionary tale . Just the audit nobody runs on DEV.to because we're all too busy publishing the parts that shine. What's at stake behind Étienne's question is less the performance of a device than the possibility of measuring it honestly. Sixty days of practice with an AI assistant on a production project is a rare object at this stage. Most publications circulating on the subject are either brief demos from a hackathon or marketing announcements from vendors. The field return at sixty days, delivered with its numbers and retractions, barely exists. That's the gap I intend to close here, without more pedagogy than is strictly needed. The dry material inventory Sixty calendar days between the first session and today. Fifty-eight active days out of sixty , meaning two days without a commit and explaining why the rest of my life barely held. Over that window, the repo accumulated nine hundred and eighty-four commits bearing my name — an average of sixteen commits per working day, on d