A shared memory is only trustworthy if people know where the sharing stops. The Vault is that line. It holds the context that belongs to an individual — their drafts, their private notes, the half-formed thinking they haven’t chosen to publish — and it stays sealed.
The default is exclusion, not inclusion. Nothing enters the shared memory because it happened to pass through a personal surface; it enters because its owner meant it to.
The rule in one line
Access is decided before retrieval, never after. If a consumer isn’t entitled to a passage, the passage is never a candidate in the first place — it can’t leak through a ranking quirk or a clever prompt.
// scope is resolved from identity, before any search runs
const scope = resolveScope(identity);
const candidates = index.search(query, { within: scope });That ordering is the whole guarantee: the boundary is structural, not a filter bolted on at the end.