From 007204bbc28638d8327c69e0bc72eba59b620238 Mon Sep 17 00:00:00 2001
From: Hector Hernandez <39923391+hectorhdzg@users.noreply.github.com>
Date: Tue, 8 Sep 2026 13:45:57 -0700
Subject: [PATCH] Fix ESM XHR instrumentation tree shaking

Remove the no-side-effects annotation from isXhrSupported so Rollup preserves capability checks that install XHR instrumentation.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
---
 shared/AppInsightsCore/src/utils/EnvUtils.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/shared/AppInsightsCore/src/utils/EnvUtils.ts b/shared/AppInsightsCore/src/utils/EnvUtils.ts
index b8209b2b1..67a16a25e 100644
--- a/shared/AppInsightsCore/src/utils/EnvUtils.ts
+++ b/shared/AppInsightsCore/src/utils/EnvUtils.ts
@@ -290,7 +290,8 @@ export function useXDomainRequest(): boolean | undefined {
  * Checks if XMLHttpRequest is supported
  * @returns True if supported, otherwise false
  */
-/*#__NO_SIDE_EFFECTS__*/
+// Do not mark this function as side-effect-free. Rollup can remove capability checks
+// guarded by this return value, which prevents XHR instrumentation from being installed.
 export function isXhrSupported(): boolean {
     let isSupported = false;
     try {