A guide report checks, against the original text, what the official documentation actually guarantees. It is not a product description but an account of what changes when you change a setting, and what you give up. It concentrates on options that look alike but behave differently, limits that are documented but easy to miss, and defaults that change quietly.
What OpenRouter's order, only and allow_fallbacks each prevent, and the availability cost of restricting providers; where the existing API names point after the DeepSeek V4.1 Flash migration; what the read-only default permissions and per-run credit cap of GitHub Agentic Workflows do and do not prevent; what Korea's AI Basic Act makes mandatory and where it attaches administrative fines; and which of 114 developer endpoints an IPv6-only server can reach without an IPv4 path.