Colours show what the commit history discloses: an AI co-author or Assisted-by trailer, an AI agent's own account, or a bot-named account. Uncoloured wood means no signal, not "written by a human". Disclosure is not usage: tool settings, squash merges and agents committing under their own accounts add or remove these signals. Non-merge commits on the default branch, grouped by author date (UTC). 1 commit with an out-of-range date (2001-01-25) is not drawn.