Independent review pass: utils.base_url_host_matches already owns the
exact-or-dot-suffix hostname contract (userinfo/port stripped, lowercased,
trailing dot removed), so the predicate delegates instead of hand-rolling
a second suffix match to keep in sync. Also locks in the normalization
behavior the review verified empirically: uppercase+port, trailing-dot,
userinfo-stripped, and IPv6-literal cases added to the contract tests.
Pointing openai-api at OpenAI's documented regional hosts
(us.api.openai.com / eu.api.openai.com, mandatory for customers with
data-residency obligations) silently degraded Hermes because three
subsystems tested 'is this OpenAI' with exact-hostname equality against
api.openai.com.
Adds providers.is_official_openai_host(): canonical host plus dot-suffix
subdomains of api.openai.com, hostname-parsed only. Lookalike hosts
(api.openai.com.attacker.test) and path spoofs (proxy.test/api.openai.com/v1)
stay rejected, preserving the #32243 hardening: a genuine *.api.openai.com
subdomain requires control of openai.com DNS.
host_mandated_api_mode() now routes through the predicate, so regional
hosts mandate codex_responses exactly like the canonical host.
Victor Kyriazakos