Prevent multiple script initializations across SPA navigations

[cagandhi]

Description

The mainScript can be executed multiple times due to:

• webNavigation triggers
• GitHub SPA navigation
• manual reinjection

Issues caused

• Duplicate polling loops (setInterval)
• Multiple requestAnimationFrame loops
• Re-attached event listeners
• Unpredictable behavior and performance degradation

Expected Behavior

Script should initialize only once per page lifecycle.

Proposed Fix

Add a global guard at the top of the script:

if (window.__ghSingleFileInitialized) return;
window.__ghSingleFileInitialized = true;

Why this matters

• Prevents memory leaks
• Ensures deterministic behavior
• Required for Chrome Web Store quality standards