Stale HTML breaks app

After a frontend deploy, a fraction of users keep getting the old JavaScript bundle and the app breaks for them with console errors about a missing API the new bundle expects, while other users are fine. The CDN dashboard shows high hit ratio (good) but you notice the deploy changed the cache-control on HTML from 'no-cache' to a 24h max-age 'to improve performance', while the JS bundles use content-hashed filenames. Some POPs and browsers are serving cached HTML that references old, now-deleted hashed bundles. How do you triage this partial breakage and fix the caching correctly?