claude-code-hooks

How to write, test, register, and debug Claude Code hooks — PreToolUse / PostToolUse / SessionStart / Stop Bash guards that enforce a rule the model would otherwise talk itself past. Use whenever the user wants to create a hook, block/intercept a tool call, turn a repeatedly-violated rule into a hard gate, add a guard rail, debug a hook that misfires or "poisons the session", register a hook across profiles, or mentions hooks / PreToolUse / Stop hook / 拦截 / 守卫 / 钩子 / 拦下. Bakes in the hard-won pitfalls: UserPromptSubmit only ever sees user input, never Claude's own text — a rule about Claude's own output belongs on Stop instead; token-level shlex matching (never awk splitting); bash -n + real-JSON end-to-end testing BEFORE registering (a corrupted PreToolUse hook poisons every Bash call); SSOT + symlink so a ~/.claude reinstall can't lose it; multi-profile convergence; and human-confirmation release gates. Reach for this even for "make it stop doing X" — a durable stop is a hook, not a reminder.