ISessionService.fromHeaders(headers: Headers): Promise<SessionView | null>
Opens a session from a Headers object alone — the headers-only read for
non-HTTP entry points that have no request context to commit onto (a
WebSocket onOpen handler, an auth strategy reading a cookie).
This is READ-ONLY: it never commits, never advances the session's seen
stamp, and never writes to the store or the cookie. It runs the same
envelope-open, snapshot-parse, and store-read path as the load behind
ISessionService.from, so it inherits real revocation on the
store strategy.
headers: Headers
The request headers to read the session cookie from
Promise<SessionView | null>
A read-only SessionView, or null when there is no
usable session — the cookie is absent, the envelope cannot be opened, the
snapshot cannot be parsed, the absolute expiry or idle timeout has passed,
or the stored entry is gone (revoked)