This is a Layer 2 document. See CLAUDE.md for project overview.

Elo Rating System Specification

Superseded (2026-07): folded into Rating System v2 — Specification. Kept for reference.

Status: Superseded

Overview

TwoMore uses an Elo rating system to track player skill levels within clubs. The system is designed for fast convergence in club play, where match frequency is lower than professional settings.

Parameters

Parameter	Value	Notes
Default rating	1200	Assigned to all new players
K-factor	32	High for faster convergence in club play
Doubles weight	0.5	Each player gets half the adjustment in doubles matches

Tiers

Tier	Rating Range	Description
Beginner	900 - 1200	New or developing players
Intermediate	1200 - 1600	Competent club players
Advanced	1600+	Strong competitive players

Rating Flow

1. Initial rating: Players self-rate when joining a club. This sets their starting Elo within the appropriate tier range.
2. Auto-update: After each match, ratings are recalculated automatically based on match results.
3. Doubles adjustment: In doubles matches, each player receives half the standard Elo adjustment (weight = 0.5) to account for shared outcomes.

Implementation

• Core algorithm: domain/rules/elo.rules.ts
• Rating storage: profile.repository.port.ts via updateElo()
• Score submission flow: application/match/submit-score.usecase.ts records the score, calculates Elo changes, updates ratings, and writes history