Implements issue #71 with ADR-0020 (supersedes ADR-0019's endpoint-signature
cleanup, startup cleanup, and health-gate cleanup).
- New ShadowsocksX-NG2SystemProxyHelper target: app-bundled root LaunchDaemon
(SMAppService.daemon, on-demand via MachServices) that mechanically applies
a closed typed configuration or executes an unconditional clear. Clients are
accepted by code-signing bundle identifier only; requests run serially on a
shared queue (last-writer-wins).
- SystemProxyConfiguration is now the closed typed apply payload (Codable over
JSON XPC): explicit SOCKS/HTTP/HTTPS enable + endpoints, PAC and
auto-discovery disabled with URL/JS removed, explicit simple-hostname
exclusion, complete ExceptionsList. Unmodeled Proxies keys are preserved and
equivalent values skip the commit.
- Cleanup is a side effect of a persisted system-proxy intent on-to-off
transition only: the switch itself, or the agent-off cascade (persist both
intents off, clear, then stop listeners; failed cascade persistence records
no transition and clears nothing). Launch with the switch off, health-gate
closure, invalid targets, and passive events never clear. Failed clears are
surfaced without deferred retry.
- Endpoint-signature store, ownership migration, and direct Authorization
Services writes are removed; old signature files stay inert. Helper
unavailability or pending approval keeps an enabled intent pending and
surfaces the Login Items approval path (HomeView button + menu label).
Qiu Yuzhou