OIDC login succeeds but lands back on `/login` instead of the home page

I click the OIDC provider button on the Storyteller login page, authenticate with my identity provider, and get handed back to https://<host>/login as if nothing happened; clicking the button again just refreshes the same URL. There is nothing in the container logs even at trace/debug level. If I edit the URL to drop /login I'm actually authenticated. Seen on the v3 beta, including 3.0.0-beta.8.

Resolution: Authentication itself is working -- this is a v3 middleware bug, not an OIDC misconfiguration, which is why nothing shows up in the logs. The v3 beta rewrites /v3/... paths to /... based on a cookie, and that cookie is not set on the request coming back from an external auth provider, so the post-login redirect resolves to the login route while your session is perfectly valid. Workaround on an affected build: after authenticating, navigate to the instance root URL manually. The middleware bug was fixed in a later v3 beta (after 3.0.0-beta.8) and the fix was confirmed by multiple people, so updating is the real solution. The same middleware bug also breaks the first-run setup redirect on fresh installs, where /init has to be visited by hand.