For example I have a Stop hook that scans my messages to see which files we've worked on. It'll check to see if the changes to those files have been committed and, if not, it will prevent Claude from stopping and send it a message to commit the specific files in a specific style that includes the id of the current session. The same script also cleans up all previous instances of the same message in the conversation, saving like 5k tokens per session.

I have a lot of PreToolUse hooks that injects guideline messages whenever certain tools are called or bash commands run. My hooks also prune older versions of those out of context. All of the transcripts are in ~/.claude/projects/ in jsonl format and are hot-editable.