Creating a VS Code agent hook to respond to file changes

Visual Studio Code recently shipped [agent hooks]1 as a way to customize your agent experience. Unlike other enhancements such as skills, agent hooks are deterministic. Instead of relying on the agent to call a tool or use a skill, an agent hook sits in the middle of the agent loop and listens for specific events. You can use those events to trigger an action. That means no more pleading with the agent to always follow one action with another. Just define a hook that makes it happen 100% of the time. For example, I recently set up an agent hook to regenerate TypeScript types whenever a wrangler.jsonc file is edited. These files specify bindings for Cloudflare Workers, and the wrangler types command reads wrangler.jsonc and outputs TypeScript type definitions. I had been struggling to get agents to regenerate types whenever they edited a wrangler.jsonc file. I begged, pleaded, and strongly cautioned the agent, and nothing worked. Now it happens automatically with an agent hook, and I…