From cf3d32b745dd1d9b5720f279a36bd437edf13557 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Fri, 22 May 2026 01:38:53 +0000
Subject: [PATCH] perf: Optimize chained array operations in CSV export
 rendering

Replaced `.map().join()` and `.filter().map().join()` chains with
single-pass `for...of` loops in `src/csv.ts`. This avoids unnecessary
array allocations and reduces Garbage Collection pressure on the hot
rendering path when generating datasets.

Co-authored-by: schmug <38227427+schmug@users.noreply.github.com>
---
 src/csv.ts       | 31 +++++++++++++++++++++++--------
 test/mcp.test.ts |  2 +-
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/src/csv.ts b/src/csv.ts
index f16257f..fc832ad 100644
--- a/src/csv.ts
+++ b/src/csv.ts
@@ -41,8 +41,15 @@ export function escapeCsvField(value: string): string {
 function formatFindings(
   validations: Array<{ status: string; message: string }>,
 ): string {
+  // ⚡ Bolt Optimization: Use for...of loop instead of .map().join("")
+  // Avoids intermediate array allocations for the hot rendering path.
   if (validations.length === 0) return "";
-  return validations.map((v) => `[${v.status}] ${v.message}`).join("; ");
+  let result = "";
+  for (const v of validations) {
+    if (result.length > 0) result += "; ";
+    result += `[${v.status}] ${v.message}`;
+  }
+  return result;
 }
 
 function dkimRawSummary(
@@ -79,16 +86,24 @@ export function generateCsv(result: ScanResult): string {
 
   for (const key of protocols) {
     const proto = result.protocols[key];
-    const recs = result.breakdown.recommendations
-      .filter((r) => r.protocol === key)
-      .map((r) => `[P${r.priority}] ${r.title}`)
-      .join("; ");
+
+    // ⚡ Bolt Optimization: Use a single-pass loop instead of .filter().map().join("")
+    let recs = "";
+    for (const r of result.breakdown.recommendations) {
+      if (r.protocol === key) {
+        if (recs.length > 0) recs += "; ";
+        recs += `[P${r.priority}] ${r.title}`;
+      }
+    }
 
     let rawRecord: string;
     if (key === "mx") {
-      rawRecord = result.protocols.mx.records
-        .map((r) => `${r.priority} ${r.exchange}`)
-        .join("; ");
+      // ⚡ Bolt Optimization: Use a single-pass loop instead of .map().join("")
+      rawRecord = "";
+      for (const r of result.protocols.mx.records) {
+        if (rawRecord.length > 0) rawRecord += "; ";
+        rawRecord += `${r.priority} ${r.exchange}`;
+      }
     } else if (key === "dkim") {
       rawRecord = dkimRawSummary(result.protocols.dkim.selectors);
     } else if (key === "mta_sts") {
diff --git a/test/mcp.test.ts b/test/mcp.test.ts
index 25f6ad7..7f21296 100644
--- a/test/mcp.test.ts
+++ b/test/mcp.test.ts
@@ -1,4 +1,4 @@
-import { beforeEach, describe, expect, it, vi } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import {
   handleMcpRequest,
   MCP_PROTOCOL_VERSION,