The existing test_endpoint_resolver.py copies the pure functions to avoid
import side effects, so its assertions can silently drift from the shipped
src/endpoint_resolver.py (the copies already lag: no OpenRouter headers, no
anthropic.com host matching). This adds a sibling module that imports the
REAL resolver and locks in behavior for every provider named in ROADMAP.md's
"Provider setup/probing audit" — Anthropic, Gemini, Groq, xAI, OpenRouter,
OpenAI, DeepSeek — plus Ollama (local + cloud) and the Tailscale self-host
fallback in resolve_url.
Covers build_chat_url, build_models_url, build_headers, normalize_base,
_first_chat_model, _anthropic_api_root, _ollama_api_root, and resolve_url.
conftest.py already stubs the heavy deps, so the import is side-effect free.
Test-only; no behavior change. 55 new tests, all passing.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
