Maintainer fixup on the #79787 salvage:
- An explicit fb.api_mode of "chat_completions" was silently overridden
by the codex_responses / bedrock re-detection pass (which only skipped
re-detection when the pre-computed mode was non-default). Track
explicitness in fb_api_mode_explicit and gate the whole re-detection
block on it.
- Replace the locals().get('fb_api_mode') dead-code hack with clean code
(fb_api_mode is always bound at that point).
- Restore the post-resolve /anthropic + api.anthropic.com host check for
named custom providers whose base_url comes from config rather than
the fallback entry (#32243, #49247), which the PR's restructure dropped.
- Add regression tests: explicit api_mode honored (incl. explicit
chat_completions not overridden), /anthropic-hint fallback detected
pre-rewrite, api_mode forwarded to resolve_provider_client, plain
fallback unchanged.
Teknium