GitHub Copilot CLI 1.0.49 Adds /rubber-duck and /chronicle for Session Introspection

GitHub shipped Copilot CLI 1.0.49 on May 18, adding a handful of features that lean into session introspection and agent self-awareness. The standout additions are /rubber-duck and /chronicle, two commands that help you understand what the agent has been doing.

/rubber-duck

The name comes from rubber duck debugging, where explaining your problem out loud to an inanimate object often helps you spot the issue yourself. Here, /rubber-duck asks the agent to independently critique its own current work, detached from whatever direction it was heading. The idea is to catch cases where the agent has drifted off course or is confidently pursuing a wrong approach.

It’s a useful escape hatch for long sessions where you’re not sure the agent is still on the right track. Rather than scrolling back through the history to audit what it’s done, you can just ask it to check itself.

/chronicle search

/chronicle is a new subcommand that lets you search all session content by keyword or topic. If you had a session last week where you worked through a particular architecture decision and want to find it, /chronicle search <term> can surface it without you having to remember which session it was.

The release also adds /session id, which displays and copies the current session identifier. Helpful if you’re referencing sessions in notes or external issue trackers.

Persistent memory controls

/memory on|off|show is now available for managing persistent memory status. You can toggle whether the CLI maintains memory across sessions, and show lets you inspect what’s currently stored. This was previously only accessible through configuration; having it as a slash command makes it easier to manage during a session.

Hook fix: postToolUse additionalContext

This one matters if you use hooks. The postToolUse hook’s additionalContext field was previously injected as tool response content, which caused it to be silently discarded. It’s now correctly injected as a system message, so the model actually sees it.

If you’ve written hooks that pass context through additionalContext and wondered why the model wasn’t responding to it, this is why.

Plugin and other additions

copilot plugin update --all is now available, which updates all installed plugins at once instead of requiring individual updates. An experimental MCP server registry search command is also included for finding and installing MCP servers from within the CLI.

Alpine Linux users can now run the CLI natively. The release adds musl libc support, which covers the common setup of running Alpine-based containers in CI or Docker environments.

Auto-linking for GitHub issues and pull requests in assistant responses is also new. When the agent references a PR or issue number, it now renders as a clickable link rather than plain text.

The full release notes are on GitHub.