⚡ Bolt: Use for-where loops to eliminate intermediate array allocations during recommendation generation (#407)

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: acebytes <2820910+acebytes@users.noreply.github.com>

Author: acebytes

.jules/bolt.md

@@ -32,3 +32,6 @@
 ## 2024-05-30 - SwiftUI ForEach and Lazy Collections
 **Learning:** In SwiftUI, avoid using `.lazy.filter` directly inside a `ForEach` loop, as `ForEach` requires the data to conform to `RandomAccessCollection`, which `LazyFilterSequence` does not. Eagerly compute the filtered array before passing it to the `ForEach` view builder.
 **Action:** When optimizing SwiftUI views, only apply `.lazy.filter` to properties where you immediately consume the sequence (e.g., calling `.count`, `.reduce`, or `.sorted()`). For data bound to a `ForEach` list, continue using standard eager `.filter`.
+## 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.

Sources/Cacheout/Memory/RecommendationEngine.swift

@@ -205,10 +205,7 @@ struct RecommendationEngine {
         }
 
         // rosetta_detected
-        let rosettaProcesses = scanResult.processes.filter {
-            $0.isRosetta && $0.physFootprint >= Self.rosettaMinFootprint
-        }
-        for proc in rosettaProcesses {
+        for proc in scanResult.processes where proc.isRosetta && proc.physFootprint >= Self.rosettaMinFootprint {
             let footprintGB = Double(proc.physFootprint) / (1024 * 1024 * 1024)
             recommendations.append(Recommendation(
                 type: .rosettaDetected,
@@ -223,8 +220,7 @@ struct RecommendationEngine {
         }
 
         // agent_memory_pressure
-        let agents = AgentDetector.agentProcesses(from: scanResult.processes)
-        for agent in agents where agent.physFootprint >= Self.agentMinFootprint {
+        for agent in scanResult.processes where AgentDetector.isAgent(agent) && agent.physFootprint >= Self.agentMinFootprint {
             let footprintGB = Double(agent.physFootprint) / (1024 * 1024 * 1024)
             recommendations.append(Recommendation(
                 type: .agentMemoryPressure,