Google's transition to Manifest V3 represents the biggest architectural shift in browser extension history. By replacing long-running background pages with short-lived service workers, MV3 has forced developers to rewrite extensions.
This transition has introduced significant constraints for download interceptors that hook into native browser download managers.
Service Worker Lifecycles
Because Manifest V3 background service workers terminate after a few seconds of inactivity, extensions can no longer store state in memory. Interceptors must persist active session tokens inside local Storage APIs.
Declarative Net Request API
Dynamic script interception has been restricted in favor of declarative rules. NextGen DLM leverages custom native messaging sync hosts to pass intercepted headers directly to the local Rust core instantly.