Modern AI coding assistants are great — if you're in a modern editor. But I have a soft spot for old tooling, and I wanted to know: could I bring Claude Code into Visual Studio 2005, a 20-year-old IDE?

The add-in model

VS2005 predates the modern VSIX system. It uses the old COM add-in model — a .AddIn XML manifest pointing at an assembly that implements IDTExtensibility2. The IDE loads your add-in on startup and hands you the DTE automation object: your hook into the editor, the solution, and the output window.

Bridging to Claude Code

From there it's a bridge: capture the current file or selection, shuttle it out to Claude Code, and write the response back into the editor or a tool window. The hard part isn't the AI — it's coaxing a 2005-era extensibility API into doing something it was never designed for.

It's gloriously cursed, and it actually works: AI-assisted coding inside an IDE older than some of my coworkers.

Source is on GitLab if you want to see how the pieces fit together.