Enrich one OpenRTB bid request in place

The SSP splice path. The body is a standard OpenRTB 2.6 bid request; only the documented input fields are read and everything else is preserved. On a hit, the response is the same bid request with the program-identity fields of app.content — id, title, series, episode, season, genre, cat, len, channel, livestream, contentrating, language — replaced atomically by the single best candidate: each is set to the resolved value or removed when resolved as absent, so no stale program facts from the request survive next to the resolution. Identity-neutral app.content fields and everything outside app.content are preserved untouched, and app.content.ext.openepg.attribution is set. season and cat belong to the replaced cluster but are never populated in v1, so a hit always removes them. Preservation is in meaning, not bytes: re-serialization may change encoding (key order, number formatting), never values — detect misses by reading the X-OpenEPG-Outcome header, not by byte-comparing bodies.

On a miss — and on a degraded resolution where the channel resolved but nothing airs at the lookup instant — the bid request comes back unchanged, HTTP 200. A channel-only splice next to foreign program fields is never produced.

Nothing is ever added to the body: no confidence, reason, notices, or debug — anything in this body must be assumed to enter the bidstream. The outcome and the confidence of the chosen candidate travel in X-OpenEPG-* response headers.

Exactly one candidate is used, always; there are no query parameters on this route. Passing a bid request that carries the needed identifier values (channel id, channel name, or show title) raises the precision of the enrichment — an app-only request on an aggregator app is a structured miss, never a guess. A supplied ext.pixalate.timestamp is honored on this route and on its batch variant: the resolution joins the schedule at that instant instead of at now, under the same window and clamping rules the lookup route applies. An instant outside the servable window is a 400 carrying TIMESTAMP_OUT_OF_WINDOW, never a silent substitution of now.