Context
Perplexity described Photon, a Rust-based in-house retrieval and ranking engine, replacing an adapted open-source system and introducing a fast Search API preset.
What changed
Perplexity moved its retrieval/ranking infrastructure to a proprietary engine with compact indexes, separate index building and serving, and multi-stage ranking.
Why it matters
The architecture shows how index representation, candidate retrieval, ranking and latency affect the source-discovery pipeline before an answer is generated.
Visibility OS interpretation
Retrieval capacity and latency should be measured separately from citations and publisher referrals; faster search is not evidence that any particular domain will be cited more often.
What remains uncertain
How does Photon affect index coverage, candidate diversity, citation selection and live referrals? First-party latency benchmarks have not been independently audited.