Function shared_client 

pub fn shared_client() -> &'static Client

Return the process-wide shared [reqwest::blocking::Client]. First call constructs it via Client::builder() with SHARED_CLIENT_CONNECT_TIMEOUT applied; every subsequent call returns a reference to the same instance. This helper is for top-level CLI entries that want the default client.

Tests that need to verify a network round-trip (rather than a cache hit) must NOT pass shared_client() to a cache-routed helper (cached_releases, cached_releases_with, fetch_latest_stable_version, fetch_version_for_prefix) — RELEASES_CACHE may already be populated by a peer test, in which case the helper returns cached data and the network is never touched. Construct a local Client and pass it to the cache-routed helper to skip the cache; the pointer-equality gate in cached_releases_with routes a non-singleton client to a direct fetch_releases call against RELEASES_URL (the production URL — the bypass skips the cache, NOT the URL). For full URL injection (e.g. localhost mock server testing), call either fetch_releases directly with the mock URL — see fetch_releases_against_localhost_mock_returns_parsed — or use the cache-aware seam cached_releases_with_url, which routes the non-singleton bypass branch through the supplied URL while preserving the singleton/cache routing identical to cached_releases_with.

Panics

Panics on the first call if Client::builder().build() fails to construct a client. Documented failure modes include TLS backend initialization (e.g. rustls/native-tls subsystem unreachable) and system-resolver config load failure; both are treated as setup bugs rather than runtime errors. The expect here, rather than propagating the error, mirrors the inherited behavior of reqwest::blocking::Client::new() (which is itself an infallible wrapper around builder().build().expect).