SCSV: Substitution-Corrected Supply Valuation for Value-Guided Intervention in Recommender Ecosystems

Recommender platforms continuously invest attention in new items and creators, yet under finite attention the engagement an item attracts may be reallocated from substitutes rather than created. Engagement-based estimators overlook this substitution, while randomized shielding is difficult to scale to item-level valuation. We propose Substitution-Corrected Supply Value (SCSV), which values an item by a shielding estimand, the ecosystem utility lost when it is removed and attention reallocates to substitutes. This value can be settled from production logs, agrees with randomized shielding at shielded-set level, and improves positive supply intervention in production. SCSV uses lagged differencing against exposure leakage and double machine learning against observed confounding. Its settlement is sign-gated and replaceability-discounted, and caps each attribution unit's credit by its realized utility change. The intervention layer distills settled credits into uncertainty-aware priors, ranks candidates by risk-adjusted value density, and allocates exposure only when gains exceed displaced value, with conditional bounds on selection optimality and allocation error. We construct the first industrial-scale benchmark pairing production logs with randomized supply-shielding ground truth. Set-level estimates agree with these shielding losses in sign and ordering, within 0.3 pp on user-initiated content entries (open reasons) and with dose-dependent gaps on watch time. SCSV identifies supply with stronger system-level impact than incumbent metrics, improving selection efficiency by 226%, 90.3%, and 46.9% across cold-start, production, and live-streaming scenarios. In online experiments with at least 20 million daily active users, SCSV improves watch time, open reasons, and long-term retention, while raising open-reason intervention ROI to 3.6 times the baseline. These results support substitution-corrected valuation for directing supply investment toward utility that is created rather than reallocated.