## Summary
Recovers most of the TTFB the EKS→Cloudflare migration lost on
`twenty.com`. OpenStatus's P50 chart shows the regression clearly: TTFB
went from ~50–80ms (pre-migration, CF edge cache HIT) to ~250–350ms
(post-migration, every request hits Worker → R2 → respond).
## Why the existing Cache Rule stopped working
The zone-level `Twenty Website - Aggressive cache` Cache Rule was
correctly configured and was the reason pre-migration TTFB was low. It
still exists, still has `cache: true`, Edge TTL 1d. But it doesn't apply
to Worker responses on a Worker custom domain:
- **Pre-migration** request flow: `edge → Cache Rule lookup → HIT
(~20ms) / MISS → origin → cache the response`
- **Post-migration**: `edge → Worker runs first (custom domain) → Worker
generates synthetic response from R2 → return`
Cache Rules cache responses obtained via `fetch()` from the Worker, not
synthetic responses constructed inside the Worker. OpenNext for SSG
pages reads prerendered HTML from R2 and returns it — that's synthetic.
So the rule has no insertion point.
This is structural to how CF Workers handle custom domains; not a
misconfiguration on your side.
## The fix
`open-next.config.ts`:
```ts
const incrementalCache = withRegionalCache(r2IncrementalCache, {
mode: 'long-lived',
});
const baseConfig = defineCloudflareConfig({ incrementalCache });
```
OpenNext-native wrapper. The Worker still runs per request (~5–20ms
execution), but the ISR cache lookup goes through CF's per-region Cache
API (~5–20ms) instead of R2 (~50–150ms). For pages whose prerender
doesn't change between requests, that's the bulk of the TTFB recovered.
## Measured impact (live before/after on twenty.com today)
| URL | Before (avg of 3) | After cold (first 2 hits/region) | After
warm |
|---|---|---|---|
| `/` | 322ms | 600–640ms | **110–125ms** |
| `/pricing` | 267ms | 630–690ms | **104–110ms** |
| `/why-twenty` | 250ms | 175–270ms | **100–175ms** |
First 1–2 hits per CF region after this deploys will be slower than
baseline (regional Cache API populating from R2), then it sustains.
Steady state is significantly better than pre-fix.
## What this doesn't recover
Pre-migration `cf-cache-status: HIT` was ~20–30ms because the Worker
wasn't invoked at all. We can't get there without either:
- Moving SSG hosting off the Worker (back to a static origin Cache Rules
would cover)
- OpenNext gaining a "publish responses to caches.default" mode (doesn't
exist today)
Realistic-best on CF Workers + OpenNext is around the ~80–130ms range
we're now seeing.
## Live state
Already deployed to both prod (Version `40dfaa1a-...`) and dev (Version
`b45cc2de-...`) ahead of opening this PR, so the OpenStatus chart should
start improving immediately. This PR makes `main` reflect the change.
