The most clarifying moment in a debate is often a mind that changed. A developer posted this week that their long-standing skepticism about AI productivity gains traced directly to ChatGPT — and that switching to Claude Code reversed that skepticism completely [20]. The post is brief and unambiguous: "The models and tool use matters" . What makes it useful is not the conclusion but the mechanism: the prior skepticism was not wrong for its context. ChatGPT as a conversational interface is genuinely inadequate as an explanation for 2x developer productivity.…