Class MemoryStore

Shallow-merge chat onto the stored record. An own field set to undefined UNSETS that field, so a partial upsert must omit what it does not know (the Bot does).

Shallow-merge contact onto the stored record; same undefined = unset rule as upsertChat.

Delivery cursor for long-poll/webhook transports (Telegram update_id).

Compare-and-set (see IStore.setCheckpointIf): one synchronous step, so concurrent callers see one winner.

Conditional delete: true when the row is absent, or its revision (0 without one) matched expectedRevision and it was deleted; false when a different revision is stored (the row is left untouched). Same atomicity rule as setCheckpointIf.

Read one entry. MUST return undefined when the entry is missing OR its expiresAt is <= Date.now() (lazy expiry — expired rows may still exist physically until purged).

Upsert one entry as a SINGLE atomic write that replaces both value and expiresAt (no read-modify-write inside the store). An entry whose expiresAt is already in the past may be dropped instead of written.

Delete one key (namespace + key), one whole namespace (key omitted) or every namespace of the user (namespace omitted; key is then ignored). Deleting missing data is a no-op.

Live (non-expired) entries of a user — all namespaces, or just namespace. Order unspecified.

Physically remove entries whose expiresAt <= now (default Date.now()) across the whole store; resolves with how many were removed. Stores with native expiry (Redis) resolve 0.

true when this store mirrors itself to a JSON file, so its data (including persistent() flow checkpoints) survives a process restart. false = RAM only.