Deep-learning Causal Retrieval Optimization for Efficient e-commerce Distribution in Pinterest

This silver document is an arXiv feed (multiple 2026 papers) focused on retrieval, recommendation, and ranking systems with emphasis on causal decision-making, robustness to coordinated manipulation, and production deployment. Key contributions: CoSimRec — an agent-based offline evaluation and the Algorithmic Penetration Rate (APR) metric showing that coordinated accounts can be amplified by recommenders (popularity- and feedback-sensitive rankers show high APR); Bridge Evidence — a counterfactual trajectory utility showing many “bridge” documents are causally critical to multi-step agentic搜索/