How can I tell which repository and branch a shard is using?

Open the shard’s three-dot menu and choose details, or inspect it from the CLI with crystl shards --gem <gem>. Inside the shard, ordinary Git commands are authoritative:

pwd
git rev-parse --show-toplevel
git branch --show-current

A shared shard normally reports the gem’s checkout and current branch. An isolated shard reports its .crystl/worktrees/{name} checkout and crystl/{name} branch.