"hooks": {
    "PreToolUse": [
      {
        "matcher": "Edit|Write",
        "hooks": [
          {
            "type": "command",
            "command": "if command -v jj >/dev/null && jj root >/dev/null 2>&1; then if ! jj status >/dev/null 2>&1; then echo 'WARNING: failed to snapshot jj repository, tell user to fix'; fi; fi"
          }
        ]
      }
    ],
    "PostToolUse": [
      {
        "matcher": "Edit|Write",
        "hooks": [
          {
            "type": "command",
            "command": "if command -v jj >/dev/null && jj root >/dev/null 2>&1; then if ! jj status >/dev/null 2>&1; then echo 'WARNING: failed to snapshot jj repository, tell user to fix'; fi; fi"
          }
        ]
      },

In newer jj there’s a dedicated snapshot command but I’ve not updated yet. Pop this in your Claude Code settings.json. It will snapshot the repository, thus recording any changes. Explore with jj evolog.