Recsys Pipeline Architect

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name: recsys-pipeline-architect
description: Design composable recommendation, ranking, and feed pipelines using the six-stage Source→Hydrator→Filter→Scorer→Selector→SideEffect framework popularized by xAI's open-sourced X For You algorithm. Use when building any system that picks "the top K items for a (user, context)" — content feeds, search ranking, RAG rerankers, task prioritizers, notification triage, ad selection.
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# Recsys Pipeline Architect

A spec-and-scaffold skill for building composable recommendation, ranking, and feed pipelines. Encodes the six-stage pattern popularized by xAI's open-sourced [For You algorithm](https://github.com/xai-org/x-algorithm) (Apache 2.0) and applies it to any "top K for (user, context)" problem.

## Overview

Most "recommendation systems" in production aren't exotic ML — they're *pipelines*: fetch candidates from one or more sources, enrich them with metadata, drop the ineligible, score the rest, sort and pick the top K, then fire async side effects. The pattern is universal. The scoring function and the items change; the pipeline shape doesn't.

This skill is an independent reimplementation of the pattern (MIT) — no code copied from the original.

## When to Use This Skill

- Building any system that returns "the top K items for a user/context"
- Designing or refactoring a personalized feed (content, search results, notifications)
- Wrapping an LLM/ML scorer in proper pipeline plumbing (sources, hydration, filters, side effects)
- Adding multi-action prediction with tunable weights (instead of a single relevance score)
- Building a RAG retrieval reranker (cheap retrieval → expensive rerank)
- Designing a task prioritizer or alert triage system

## The Six-Stage Framework… load the full skill through Skill Me