# Records & provenance

Interpret IDs, nulls, source evidence and verification times.

## Canonical identity

`id` is the canonical opportunity UUID. Several source manifestations may resolve to one opportunity. `title` and `normalized_title` serve different purposes. `employer` and `intermediary` are distinct; a staffing company is not automatically the hiring employer. `organizations` includes role labels when known.

## Evidence and nulls

`sources` describes record provenance, not a guarantee of a citation for every field. `evidence` may contain structured excerpts when available. Preview redaction can omit source details. Null and unknown values mean no supported value is available. Do not manufacture missing source text.

## Time and liveness

`published_at` describes publication with `published_precision`. `first_seen` is Radar observation time, `changed_at` reflects a recorded change, and `last_verified_live_at` records a successful liveness verification when available. `liveness_status` is separate from a customer's application workflow. Retrieval now does not mean verification now.

## History and deduplication

The public contract exposes current canonical data and observation/change timestamps. It does not promise a complete historical event feed. Deduplication reduces repeated manifestations; it is not a claim of perfect duplicate detection. No full-export endpoint or guaranteed incremental-sync protocol is documented.