Claude Code hooks guide: making rules actually run

On October 8, 2026, DEV Community published two tutorials on Claude Code hooks. The first, posted around midday, walks through three complete hooks: one that blocks dangerous commands such as git push --force at the PreToolUse stage, one that scans writes for AWS, Anthropic, and GitHub keys and asks the developer to switch to environment variables, and one that runs the project's Prettier or Biome automatically after PostToolUse. According to the post, hooks are configured in .claude/settings.json and matched by event and tool; a hook receives the event as JSON over stdin, and exiting with code 2 blocks the action, so the behavior does not depend on the model remembering a rule.

The second post, published that evening, explains the mechanism in more detail. Hooks are commands that run at fixed points in a session: before a tool runs, after a file is edited, when a prompt is submitted, and when Claude stops. Unlike a line in CLAUDE.md, a hook is not advice — it always runs, and a PreToolUse hook can block an action outright by exiting with code 2. The article says its content was checked against the hooks guide and reference on 2026-10-05, corresponding to Claude Code 2.1.289, and that the event list has grown to 33. It also notes three recent changes: sessions now start in auto mode by default, mods can override hooks, and Cursor can run Claude Code hooks as well. Neither report specifies when those changes took effect or provides further detail on them.