Claude Session URL appended to commit messages and PR descriptions by default

Claude Code automatically appends a session URL (e.g., "https://claude.ai/code/session _...") to every commit message and PR description. This occurs without an opt-in prompt, warning, or mention during onboarding, leading users to discover it only after it has already affected their git history. While a commit-msg git hook can strip it, this method is not always reliable in remote or cloud environments.