This is a great point, although I would add that Anthropic has a possible slight advantage, as they can RLVR the Claude LLMs themselves on Claude Code tool calls and Claude Code tasks. Having said that, it's not clear how much that really matters at all for making the Claude Code CLI specifically better-performing than other coding agents using the same LLM (the tool calls are fairly generic and the LLMs are good at plenty of tool calls they weren't RLVRed on too).

The other advantage Anthropic have is just that they can sell CC subscriptions at lower cost because they own the models. But that's a separate set of questions that don't really relate to technical capabilities.

Anyhow, to follow up on your point, I do find it surprising that Claude Code is still (it seems?) definitively leading the pack in terms of coding agents. I've tried Gemini CLI and Codex and they feel distinctly less good, but I'm surprised we haven't seen too many alternatives from small startups or open source projects rise to the top as well. After all, they can build on all the lessons learned from previous agents (UX, context management, features people like such as Skills etc.). Maybe we will see more of this in 2026.