Replaces the shared GITEA_MCP_DEFAULT_TOKEN for all callers. When a
request's bearer validates directly against Gitea's own /api/v1/user,
that token is used for every upstream call this request makes instead
of the service PAT, and the caller identity comes from Gitea's own
login rather than the proxy header. Any other bearer (static token,
JWT, none) falls through unchanged to the existing chassis auth.
Prep: Authentik now SSOs into Gitea (infra a32801c), so each real user
can mint their own PAT from their own linked account.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
CallerMiddleware silently preferred X-Auth-Request-User over X-Forwarded-User
with no explanation and no signal when both were set. Documented the precedence
(X-Auth-Request-User is the verified OIDC identity oauth2-proxy sets, so it is
authoritative; X-Forwarded-User is a fallback), and it now takes a *slog.Logger
and warns when both headers are present and disagree, so a proxy
misconfiguration is visible instead of silently resolved. Table-driven tests
cover precedence (both/single/none) and the conflict-warning path.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>