fallbackAccountId
fallbackAccountId(
userId):string
Build the fallback account key for a user id — FALLBACK_ACCOUNT_ID_PREFIX followed by the id verbatim.
The id is used exactly as given: redaction and trimming belong to the caller,
which already resolved the user_id it is about to put on the same wire row.
Deriving the key here from a different normalization is how the two lanes
would stop joining.
Parameters
Section titled “Parameters”userId
Section titled “userId”string
The user id (or anonymous id) the event is attributed to,
already normalized/redacted exactly as it will appear in user_id.
Returns
Section titled “Returns”string
The prefixed fallback account key.