Refreshes the OAuth tokens using the refresh_token grant. Concurrent
callers share a single in-flight request. An unrecoverable failure (a 4xx
rejecting the refresh token) clears the tokens and transitions to
LOGGED_OUT; transient failures (network, 5xx, rate limits) leave the
session intact and rethrow so the caller can retry. The resolved tokens omit
the refresh token, which core retains internally for subsequent refreshes.
Refreshes the OAuth tokens using the
refresh_tokengrant. Concurrent callers share a single in-flight request. An unrecoverable failure (a 4xx rejecting the refresh token) clears the tokens and transitions toLOGGED_OUT; transient failures (network, 5xx, rate limits) leave the session intact and rethrow so the caller can retry. The resolved tokens omit the refresh token, which core retains internally for subsequent refreshes.