Gemini CLI v0.26.0+ introduces hooks, a middleware-like system that lets developers customize the AI agent's behavior at specific lifecycle points. Hooks enable injecting custom context, enforcing security policies (like blocking secrets from being written to files), and automating workflows through scripts that run synchronously within the agent loop. The feature supports extensions, allowing bundled hooks to be installed with a single command. Examples include security scanners that prevent API keys from being committed and the "Ralph loop" extension that forces continuous iteration on difficult tasks.