_resolve_task_provider_model returns early on an explicit provider arg,
which skips the config block that consults auxiliary.<task>.base_url /
api_key. Any caller passing provider explicitly (e.g.
resolve_vision_provider_client(provider="custom", ...)) bypasses the
configured custom endpoint and falls through to main-runtime resolution,
silently routing the task to the wrong backend.
Adopt the task's configured base_url/api_key before the early returns,
but only when no explicit base_url was given and the config targets the
same provider (or names none) — a caller forcing a *different* provider
keeps full explicit-arg priority, and an explicit base_url still wins
over config.
Fixes#58515
falkoro
9ad912a791