Real-time engine state is NOT the routing lever. Across 6 policies × es0/es1,
real state reshuffles 44-76% of decisions but never beats the champion
(unified+A+B, p90 7.62s). The effect's SIGN is set by reactivity: one-shot
placement (sticky) HELPS -26%; per-request affinity-dominated is a wash;
per-request pure-load (lmetric +17%, load_only +27%) HURTS via herding (stale
shadow was a dampener). Feed verified fresh (median 25ms, <=92ms during
prefills). Prior shadow-state results stand. ES_ABLATION_RESULTS.md has the
table + mechanism; run_full_ablation.sh / fresh_sampler.py / cmp_es.py are the
harness.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Gahow Wang
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