Crawshaw Argues Agents Make Closed Devtools Untenable

Agents erased the return-on-investment problem that used to make forking a closed-source devtool a bad bet, David Crawshaw wrote on exe.dev. That math flips who holds the advantage: teams building on agents can maintain their own fork instead of waiting on a vendor's roadmap.

Plugin systems and giant configuration files, Crawshaw argues, were workarounds for how expensive it used to be to modify a tool by hand. Closed tools that force users through predetermined hooks now compete against open ones users can rewrite themselves.

Crawshaw names Claude Code as one of the tools facing that pressure. His demo: prompting his agent to fold meat.dev, a personal diff-cleaning tool, straight into Shelley, his own harness.

Simon Willison's follow-up sharpens the practical read: weight source availability higher than API quality when picking a dependency, he argues. Crawshaw's original post has drawn 634 points and 211 comments, a sign the tradeoff is landing with developers who've hit the same wall.

If Crawshaw's right, closed-source devtool vendors, including Claude Code, start losing users to agent-built open forks. The post doesn't say which vendors are already seeing that defection, only that the incentive has flipped.