Nesting proxy groups: region groups + auto-select combined

A proxy group's members can be not only nodes but other proxy groups. That enables a very practical two-tier layout:

proxy-groups:
  - name: Proxy Select        # tier 1: pick a region
    type: select
    proxies: [HK-Auto, JP-Auto, US-Auto, DIRECT]

  - name: HK-Auto             # tier 2: auto-best within the region
    type: url-test
    proxies: [HK-01, HK-02, HK-03]
    url: http://www.gstatic.com/generate_204
    interval: 300

  - name: JP-Auto
    type: url-test
    proxies: [JP-01, JP-02]
    url: http://www.gstatic.com/generate_204
    interval: 300

Day to day you only choose a region in "Proxy Select"; which server within the region carries traffic is url-test's job. When one server fails it switches to a sibling automatically — your exit region stays stable (many services dislike IPs hopping across countries), with zero manual node-shuffling.

The Proxies page renders nested groups hierarchically. Most subscription profiles are already built this way; if you write your own config, copy the pattern. Just avoid circular references (A contains B, B contains A) — the core rejects them at load time.