The dashboard, Insights, the workouts list, the medications list and the
Coach server-prefetch their data and serialise one account's health record
into the HTML document through a TanStack HydrationBoundary. Those pages
are dynamic today only as a side effect of reading the session cookie —
a property of the page code, not a guarantee. A stray revalidate export, a
force-static segment, or a caching proxy in front of the app would be
enough to retain one account's record and hand it to the next caller.
Stamp `Cache-Control: private, no-store` at the edge instead, driven by the
same predicate that governs the auth redirect, so a page cannot be
session-gated without also being uncacheable. Public legal, auth and
locale-catalog surfaces keep their cacheable posture; API routes keep
managing their own caching.
Two guards: the proxy test pins the header on gated pages and its absence
on the public ones, and a structural test walks the app tree and refuses a
prefetching page that sits on a public path or opts into static /
revalidated rendering.
