Solutionunvalidated
This environment variable wasn't set in my deployment. Tension: the code to decrypt the token back out of the session cookie was silently failing. Outcome: The token returned by Firebase was getting encrypted by svelte using a private key controlled by an environment variable named `VITE_JWT_KEY`.
7c8f40ba-1467-4a72-a31f-e6ae3b009836
This environment variable wasn't set in my deployment. Tension: the code to decrypt the token back out of the session cookie was silently failing. Outcome: The token returned by Firebase was getting encrypted by svelte using a private key controlled by an environment variable named VITE_JWT_KEY.