From 9fe40042dae896a24299ee871d716d4eeb94275d Mon Sep 17 00:00:00 2001
From: Anders Olsson <anders.e.olsson@gmail.com>
Date: Fri, 24 Apr 2026 13:35:15 +0200
Subject: [PATCH] feat(cargo): add rayon as optional dependency
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Opt-in feature flag — users who want parallel paths build with
--features rayon. Default build remains single-threaded.

Spec Section 6 calls for default-on; we defer that flip until the
feature is stable under field use.

Part of T3 of docs/superpowers/specs/2026-04-23-trueskill-engine-redesign-design.md.
---
 Cargo.toml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index f0307df..6704f73 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,8 +16,13 @@ harness = false
 
 [dependencies]
 approx = { version = "0.5.1", optional = true }
+rayon = { version = "1", optional = true }
 smallvec = "1"
 
+[features]
+approx = ["dep:approx"]
+rayon = ["dep:rayon"]
+
 [dev-dependencies]
 criterion = "0.5"
 plotters = { version = "0.3", default-features = false, features = ["svg_backend", "all_elements", "all_series"] }