docs: add configuration architecture research
Explore static/dynamic config split, hot-reloadable auth via ArcSwap,
forwarding policy, multi-transport listeners, and config file format.
Documents three problems: no auth hot-reload, no forwarding access control,
no structured config beyond CLI flags.
Key findings:
- Static config (transport, TLS, host key) loaded once at startup
- Dynamic config (auth, forwarding, rate limits) reloadable via ArcSwap
- ForwardingPolicy with rule-based allow/deny, first-match evaluation
- Multi-transport: Server spawns Vec<ListenerConfig> sharing auth config
- WebTransport out of scope for now (requires separate auth model)
- Proposes ADR-020 (static/dynamic split), ADR-021 (forwarding policy),
ADR-022 (multi-transport listeners)
Adds OQ-12 through OQ-17 to open-questions.md.
glm-5.1
41062d810e