One day not long ago, a founder texted his investor with an update: he was replacing his entire customer service team with Claude Code, an AI tool that can write and deploy software on its own. To Lex Zhao, an investor at One Way Ventures, the message indicated something bigger — the moment when companies like Salesforce stopped being the automatic default. “The barriers to entry for creating software are so low now thanks to coding agents, that the build versus buy decision is shifting toward build in so many cases,” Zhao told TechCrunch.  The build versus buy shift is only part of the problem. The whole idea of using AI agents instead of people to perform work throws into question the SaaS business model itself. SaaS companies currently price their software per seat — meaning by how many employees log in to use it.…