Restored from the pre-rewrite branch head 342d44efe (backed up as
backup/event-token-lazy-resolution-pre-rewrite); the auth-layer changes
apply verbatim on the rebased branch.
- Add ClassifyRefreshFailure with structured HTTPStatusError so refresh
failures split into transient (network, timeout, 408/429/5xx) and
terminal (400/401/403) classes; unknown errors stay fatal.
- GetTokenSnapshot no longer marks a profile expired on transient
refresh failures, so long-running sources can retry after backoff.
- postJSON returns HTTPStatusError keeping the response body out of the
error string; the OAuth callback page HTML-escapes the sanitized
exchange error instead of echoing raw server output.
- isInvalidGrantError also matches the preserved response body.
上官玄