Workspace operators set 'provider: minimax' in /configs/config.yaml
expecting the adapter to route to MiniMax. Pre-fix behavior: adapter
ignored 'provider:' entirely, _resolve_provider model-matched against
_BUILTIN_PROVIDERS (anthropic-oauth + anthropic-api only), no model_prefix
matched 'MiniMax-M2.7-highspeed', silent fallback to providers[0]
(anthropic-oauth) — SDK kept using CLAUDE_CODE_OAUTH_TOKEN, hit OAuth
quota under a name the operator never asked for.
Fix: _resolve_provider now takes an explicit_provider arg. setup() reads
it from runtime_config.provider OR top-level config.yaml provider:.
Explicit name in registry → returned. Not in registry → ValueError with
the two paths to fix (add provider entry, or switch runtime template).
10 new tests cover: explicit-in-registry returns match, case-insensitive,
not-in-registry raises with actionable message, defense-in-depth against
silent fallback regression, custom-registry lookup, empty/None treated as
no-explicit (back-compat).
Closes#180.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>