Tracking - Record Impression

Called by the SPA when a job card CLEARS THE VIEWPORT THRESHOLD (IAB standard: 50% pixels visible for ≥1s). Distinct from /tracking/page-view — one impression per JOB seen on a page.

─── The click_token is the identifier ──────────────────── Send the exact token from the job's click_url field (the string after /jobs/click/). The server decodes it to recover solr_id, publisher_account_id, and served_id in one step — the SPA does not need to plumb those separately.

─── Response ───────────────────────────────────────────── Returns impression_id when the row was written. Attach it as ?imp={impression_id} on the click_url when rendering the <a href>, e.g.:

<a href="{click_url}?imp={impression_id}">Apply</a>

A click that lands on the server WITH the ?imp parameter will attribute back to this specific impression row, closing the served → impression → click chain.

─── Failure semantics ──────────────────────────────────── Always 200 unless the request body is malformed. recorded: false means the token was bad, referred to a served row we no longer have, or the write failed — SPA should proceed with an un-attributed click URL. Never gate rendering on this endpoint.