for-youlisted

# For You Structured reference for [xai-org/x-algorithm](https://github.com/xai-org/x-algorithm). The upstream repository is the source of truth. This skill maps concepts to paths and defines agent workflows. ## Core mental model Three independent concerns compose every For You response: | Concern | Question | Primary code | |---------|----------|--------------| | **Retrieval** | Which posts enter the candidate pool? | `thunder/`, `phoenix/` retrieval, `simclusters/` | | **Ranking** | In what order? | `home-mixer/scorers/`, `phoenix/` ranking, `vm-ranker/` | | **Visibility** | Can this post be shown to this viewer? | `visibility-filtering/`, labeling path | Ranking and visibility are separate services. A high score does not override a DROP verdict. Visibility filtering runs after top-K selection. ## Request path (Post Pipeline) Execute stages in order. Stage toggles and defaults live in `home-mixer/params/param.rs`. ``` Query Hydration -> Candidate Sources (parallel) -> Candidate Hydration -> Pre-Scoring Filters -> Scoring -> Top-K Selection -> Post-Selection Hydration + Filters -> [Blending Pipeline: ads, Who to Follow, prompts] ``` | Item | Path | |------|------| | Pipeline definition | `home-mixer/candidate_pipeline/phoenix_candidate_pipeline.rs` | | Pipeline framework | `candidate-pipeline/` | Framework stage types: source, hydrator, filter, scorer, selector, side effect. ### 1. Query hydration Loads viewer context before candidates are fetched: