⚡ Bolt: Optimize dictionary initialization in SysctlJournal.swift using reduce(into:)

.jules/bolt.md

@@ -126,3 +126,7 @@ If your candidate site already uses any of these, the issue is fixed.
 ## 2025-04-13 - Loop Filtering and Intermediate Allocations
 **Learning:** In Swift, using `.filter` before a `for` loop eagerly allocates a new intermediate array, causing unnecessary memory churn and processing overhead, especially during frequent operations like system monitoring.
 **Action:** Use `for ... where` clauses instead of eagerly filtering the collection prior to the loop (e.g., `for item in array where condition { ... }`). This prevents the allocation of intermediate arrays and improves efficiency.
+
+## 2025-05-15 - Array Materialization via sorted() on Lazy Sequences
+**Learning:** `LazyFilterSequence` does not have a custom `sorted()` implementation. Calling `sorted()` on a `LazyFilterSequence` relies on the default `Sequence` extension, which completely consumes the sequence and materializes it into an array immediately. While chaining `.lazy.filter` before `.sorted()` avoids allocating a separate intermediate array just for the filtered results, `sorted()` itself forces array materialization regardless. Adding `.lazy` specifically *just* before `.sorted()` creates confusion because it suggests the sort operation itself is lazy (which is impossible, sorting requires the whole collection). The codebase considers `.lazy.filter.sorted` an anti-pattern.
+**Action:** Do not propose adding `.lazy` before `.sorted()`. Ensure `.lazy` is only proposed when preceding operations that natively support lazy consumption like `.reduce`, `.count`, `.first`, `.contains`, or lazy `prefix`.

Sources/CacheoutHelperLib/SysctlJournal.swift

@@ -360,15 +360,13 @@ public final class SysctlJournal {
     /// `rollbackAll()` does not restore an intermediate value.
     private func revertStaleEntries() {
         let now = Date()
-        var firstStaleIndex: [String: Int] = [:]
-
         // Identify stale, un-rolled-back entries.
-        for i in state.entries.indices {
-            guard !state.entries[i].rolledBack else { continue }
+        let firstStaleIndex: [String: Int] = state.entries.indices.reduce(into: [:]) { dict, i in
+            guard !state.entries[i].rolledBack else { return }
             let age = now.timeIntervalSince(state.entries[i].timestamp)
-            guard age > Self.maxEntryAge else { continue }
-            if firstStaleIndex[state.entries[i].name] == nil {
-                firstStaleIndex[state.entries[i].name] = i
+            guard age > Self.maxEntryAge else { return }
+            if dict[state.entries[i].name] == nil {
+                dict[state.entries[i].name] = i
             }
         }
 
@@ -426,11 +424,10 @@ public final class SysctlJournal {
     @discardableResult
     private func performRollback() -> Bool {
         // Collect the first un-rolled-back entry per sysctl name.
-        var firstEntryIndex: [String: Int] = [:]
-        for i in state.entries.indices {
-            guard !state.entries[i].rolledBack else { continue }
-            if firstEntryIndex[state.entries[i].name] == nil {
-                firstEntryIndex[state.entries[i].name] = i
+        let firstEntryIndex: [String: Int] = state.entries.indices.reduce(into: [:]) { dict, i in
+            guard !state.entries[i].rolledBack else { return }
+            if dict[state.entries[i].name] == nil {
+                dict[state.entries[i].name] = i
             }
         }