xAI returns HTTP 403 (not 401) with unauthenticated:bad-credentials
when an OAuth2 access token has expired or is invalid. The existing
_is_auth_error() only checked for 401 status codes, so these tokens
were never refreshed and the 403 propagated as a generic permission
denied error.
Three fixes:
1. _is_auth_error: Recognize xAI's 403+bad-credentials pattern as
an auth failure, triggering token refresh instead of silent failure.
2. _refresh_provider_credentials: Add xai-oauth branch with
pool-level refresh (try_refresh_current with select to ensure
current entry) then fallback to singleton resolver with
force_refresh=True.
3. _recoverable_pool_provider: Map api.x.ai host to xai-oauth
pool for auto-resolved providers, matching existing pattern for
openai-codex/openrouter/nous/anthropic.
Includes 14 tests covering the new detection logic, host mapping,
and graceful fallback behavior.
Signed-off-by: moikapy <moikapy@devmoi.com>
f6a2ba6261