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Safari Extension: Cookie Header Missing in Background Fetch from Non-Default User Profile (Works in Default Profile)

When our Safari Web Extension makes a api request from its background script (registered via "scripts" in manifest.json, e.g., "background": { "scripts": ["js/background.bundle.js"] }) to our authenticated API endpoint (https://api-domain/user), the Cookie header is not included in the request. This occurs only when the extension is running within a non-default Safari User Profile. This causes our API to treat the user as unauthenticated. The exact same extension code, manifest, and API call work correctly (Cookie header is present and user is authenticated) when the extension is running in the Default Safari User Profile.

Safari Extension: Cookie Header Missing in Background Fetch from Non-Default User Profile (Works in Default Profile)
 
 
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