From 88ce102644d62d71b6658dd1f2986efc509d9289 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Sat, 28 Mar 2026 05:12:10 +0000
Subject: [PATCH] perf: Convert Scanner actors to structs to prevent TaskGroup
 serialization

Converting CacheScanner and NodeModulesScanner from `actor` to `struct`
since they are stateless. Using an actor with `withTaskGroup` inadvertently
serializes all child tasks onto the actor's single-threaded executor,
destroying parallelism.

This change allows true parallel filesystem traversal.

Co-authored-by: acebytes <2820910+acebytes@users.noreply.github.com>
---
 .jules/bolt.md                                    | 3 +++
 Sources/Cacheout/Scanner/CacheScanner.swift       | 4 +++-
 Sources/Cacheout/Scanner/NodeModulesScanner.swift | 4 +++-
 3 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..7cb4036
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-05-24 - Actor Serialization in TaskGroup
+**Learning:** In Swift structured concurrency, using an `actor` to manage a `withTaskGroup` where tasks invoke synchronous, blocking I/O (like `FileManager` operations) directly on the actor inadvertently serializes the tasks, preventing parallelism.
+**Action:** For stateless components interacting with thread-safe dependencies (like `FileManager.default`), use `struct`s or `nonisolated` methods to allow tasks to execute concurrently across threads.
diff --git a/Sources/Cacheout/Scanner/CacheScanner.swift b/Sources/Cacheout/Scanner/CacheScanner.swift
index 3ce3e9c..1ded582 100644
--- a/Sources/Cacheout/Scanner/CacheScanner.swift
+++ b/Sources/Cacheout/Scanner/CacheScanner.swift
@@ -26,7 +26,9 @@
 
 import Foundation
 
-actor CacheScanner {
+// Using struct instead of actor to prevent serialization of parallel tasks.
+// Since this component is stateless, struct allows true concurrency across threads.
+struct CacheScanner {
     private let fileManager = FileManager.default
 
     func scanAll(_ categories: [CacheCategory]) async -> [ScanResult] {
diff --git a/Sources/Cacheout/Scanner/NodeModulesScanner.swift b/Sources/Cacheout/Scanner/NodeModulesScanner.swift
index 3ed4d8c..2a9a5a6 100644
--- a/Sources/Cacheout/Scanner/NodeModulesScanner.swift
+++ b/Sources/Cacheout/Scanner/NodeModulesScanner.swift
@@ -28,7 +28,9 @@
 
 import Foundation
 
-actor NodeModulesScanner {
+// Using struct instead of actor to prevent serialization of parallel tasks.
+// Since this component is stateless, struct allows true concurrency across threads.
+struct NodeModulesScanner {
     private let fileManager = FileManager.default
 
     /// Common directories where developers keep projects