Note that for Claude Code, it looks like they added a new undocumented command line argument `--thinking-display summarized` to control this parameter, and that

Note that for Claude Code, it looks like they added a new undocumented command line argument `--thinking-display summarized` to control this parameter, and that's the only way to get thinking summaries back there. VS Code users can write a wrapper script which contains `exec "$@" --thinking-display summarized` and set that as their claudeCode.claudeProcessWrapper in VS Code settings in order to get thinking summaries back.