Discord and custom webhook URLs are checked when saved and before every call: https only, Discord URLs must point to discord.com. A guarded HTTP client resolves hosts itself and connects only to allowed IPs; localhost, link-local and cloud metadata are always blocked, LAN ranges (incl. Tailscale CGNAT) and plain http only with the new admin switch. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>