git:20261017.1753942 to git:20261017.bb68e19

+ - **The noise trim runs on relevance, and decay is a switch, not a curve.** Both engines trim at 10% of the top RRF × salience score *before* any age weighting. Run after decay, as the API did until 2026-10-16, the trim cut old records for their age: 55 of 240 known items were absent from the pool, not merely ranked low. The CLI had no trim, so the engines also disagreed about the pool. Fusion is rank-based: rank 1 scores 1/61, rank 10 scores 1/70, and a rank-1 partial match in another ladder also scores 1/61. An old known item therefore survives the page only if its age factor stays within a few percent of 1. Measured on 204k events (240 known items, 40 recency cases, semantic off), known-item S@10 by age <7d/7-30d/30-90d/90d+ was exp λ=0.001 0.98/0.85/0.62/0.15; power-law t^-0.5 0.98/0.77/0.62/0.30; ACT-R base-level d=0.05 0.80/0.53/0.60/0.72, trading the week for the archive. So when ≤ `CARTOGRAPHER_DECAY_LOOKUP_MAX` (10) candidates hold every query token, those candidates skip decay: 0.98/1.00/0.98/1.00 on the API, with recency unchanged. On the CLI, measured on paired cases, past 90 days went 0.23 → 1.00. Everything else decays as before. Skipping decay keeps a named record on the page, not first: a recent 0.7–0.8-salience record sharing part of the query outranks a 0.25–0.5 one holding all of it. So the named candidates are also multiplied by `CARTOGRAPHER_DECAY_LOOKUP_LIFT` (3) after decay, as a score change so `--min-score` still cuts a sorted list. Live known S@1 went 148 → 221 of 240, S@10 234 → 240, no case lower, recency and topical identical (docs/SCORING.md, "Lifting named records"). "Holds every token" is presence-only (`full` on `scoreBM25` results, column 10 of `bm25-search.awk`), so the engines agree although their idf differs. `tests/unit/age-curve-gate.test.js` proves its fixture reproduces the loss before gating, and `scripts/age-curve.js` runs the same curve on the live corpus. Change λ, the trim, salience, the exemption or the lift only with both. A different browse curve also has to pass the topical kind (`age-curve.js --truth`, on the live corpus and `--as-of` the labels' date), because both gate metrics reward steeper decay. On 2026-10-17 every power-law form tested, ACT-R base-level included, lost topical P@10 there (0.40-0.42 against exp's 0.48), so exp stays (docs/SCORING.md). The truth scorer is `scripts/truth-score.js`, shared with `eval-search.js`; its word-overlap match needs two shared words, because at one it credited any recent row sharing a word with a short label, which is exactly what a steeper curve puts on the page.