K9 trend lines (OWNER industry-page design handoff 2026-10-05): ONE metric's quarterly history for every company in a KPI tab, in ONE request -- the expanded ranked view's trend, which would otherwise cost one ?period= request per quarter. Built by ssr_operating_kpis_history.build_metric_history from one store read through the same gated collector the peer table uses (default confidence/scope untouched).

Ungated like the 23 tab routes (public SEC data, OWNER decision 2). Answered for EVERY caller since OWNER 2026-10-10, which superseded the 2026-10-05 anonymous refusal (the old 200 / available False / reason 'sign_in'). 404 not_found for an unknown or flag-dark tab; 503 build_failed when the store could not be read.