Status observation
Live data comes from the explicitly configured provider. This deployment can use the approved TrackMyI140 feed, while the official USCIS API remains available through the same provider interface when credentials are supplied.
History preservation
An unchanged status updates last_checked only. A changed status appends an immutable history row before the current case state is updated.
Observed versus event dates
observed_at records when this platform saw a state. event_date stores a source-provided date when available. They can differ, and historical charts identify which is used.
Receipt blocks
Blocks are configurable display cohorts made by replacing trailing serial digits with X. They are not claims about undocumented USCIS routing semantics.
Processing times
Current percentiles use resolved cases only. Open cases are right-censored and shown separately. A future survival-analysis layer can add Kaplan-Meier estimates without changing the data model.