This response sends a Link header with three preloads:
Becuase Cloudflare caches Early Hints on the edge node, timestamp parameters should make it obvious which files were Early Hinted (stale) and which were preloaded by the `Link` header in the main response.
Both the script tag and stylesheet tag in the HTML include SRI/integrity.
The final response is delayed by 500ms so it is easier to see whether each file was loaded from Early Hints or from the main response.
When Chrome sees a preload with integrity in Early Hints, it bails from preloading any file from them, while it still does preload from the Link header in the main response.
Caveat: this may be an issue with how Cloudflare does not wrap the integrity attribute with quotes in Early Hints, but the preload from the main response still works, so...
If integrity is omitted from the Early Hints preload, Chrome may fetch the file early, but the preload cannot be reused by the HTML request that has integrity.
DevTools reports this as: "A preload is found, but is not used due to an integrity mismatch."
This means there is no good option for SRI-protected resources: adding integrity prevents Early Hints preloading, while omitting integrity causes the preload to be discarded for the final SRI request.
Early-Hinted files that aren't reused are not visible in Chrome DevTools Network waterfall or resource timings.
The only signal they happened is the console warning that they were preloaded but not actually used.
In Chrome, Axios can be loaded by Early Hints, which is visible in DevTools and Resource Timing.
However, the Resource Timing request timings reflect the later cache read, not the actual time when the file was downloaded by Early Hints.
This makes the timing data misleading: it confirms the resource came from Early Hints, but does not expose when the Early Hints download actually happened.
Waiting for timing data...