Session ID
Domain: Sessions & Persistence
Motivation
The session id addresses a single session everywhere it is stored or queried: persistence handles, query reads, titles, and export all key on it. create on an occupied id rejects with SessionAlreadyExistsError, and open(id, 'write') while an owner is active rejects with SessionAlreadyOwnedError. It is the stable handle that lets a session be found and resumed later.
Concrete Example
ctx.sessions.get(id), ctx.sessionPersistence.open(id, 'write'), and ctx.sessionQuery.readSession(id) all take the same id; the export ZIP is named dsh-session-<id>.zip.
Analogy
The primary key of a row in a database.