## Summary
The original goal of this whole migration: **cross-deployment skew is
now handled by OpenNext's per-version routing instead of by users having
to refresh.**
A client holding a stale tab from deployment X requests assets with
`?dpl=X` — the Worker compares X to the current `DEPLOYMENT_ID`, looks
it up in `CF_DEPLOYMENT_MAPPING`, and routes to the matching old Worker
version via its per-version preview URL
(`<old-version>-twenty-website-<env>.twentyhq.workers.dev`). The old
version serves the old assets / RSC payloads / Server Actions
consistently.
**Verified end-to-end on dev**:
| | Marker in HTML |
|---|---|
| Current Worker (`twenty-main.com/`) | `9npeiytir8EPOtW71cqDZ` |
| Stale request (`twenty-main.com/?dpl=<previous-deploy-id>`) |
`B9OC_TNl1vaGcJ5oUUty6` |
| Direct hit on old preview URL | `B9OC_TNl1vaGcJ5oUUty6` ← matches the
skew-routed response |
## Changes
**`open-next.config.ts`** — enable skew protection
```ts
const baseConfig = defineCloudflareConfig({ incrementalCache: r2IncrementalCache });
export default {
...baseConfig,
cloudflare: {
...baseConfig.cloudflare,
skewProtection: {
enabled: true,
maxNumberOfVersions: 10,
maxVersionAgeDays: 14,
},
},
};
```
(`defineCloudflareConfig` doesn't accept `skewProtection` directly — has
to be merged in)
**`next.config.ts`** — `deploymentId: process.env.DEPLOYMENT_ID`. CI
sets `DEPLOYMENT_ID` per-build; Next bakes it into prerendered HTML,
`?dpl=…` on asset URLs, Server Actions, and RSC fetch headers.
**`wrangler.jsonc`**:
- `compatibility_date: 2026-04-15` (was `2025-01-15`; build was warning)
- `assets.run_worker_first: true` — Worker must intercept asset requests
so the skew handler can route stale `/_next/static/*` to the old
version. CF edge cache absorbs hot paths so this isn't a 5×
billable-invocation tax
- `preview_urls: true` — required; skew routes via the per-version
preview URL which only exists when previews are enabled
- Per-env `services: [{ binding: WORKER_SELF_REFERENCE, service:
twenty-website-<env> }]` — OpenNext's recommended setup for
fire-and-forget ISR revalidation
- Per-env `vars`: `CF_WORKER_NAME` + `CF_PREVIEW_DOMAIN` (bare
`twentyhq`, *not* `twentyhq.workers.dev` — OpenNext appends
`.workers.dev` itself, see
[opennextjs-cloudflare#811](https://github.com/opennextjs/opennextjs-cloudflare/issues/811))
- Kept `global_fetch_strictly_public` in compat flags — without it, CF's
optimised intra-account routing self-loops the cross-version fetch and
522s out. With it, the fetch takes the public-Internet path which routes
correctly.
**`public/_headers`** — deleted (with `run_worker_first: true` the
assets pipeline doesn't process it; Next sets the same `Cache-Control:
immutable` on `/_next/static/*` anyway).
## Companion infra PR
https://github.com/twentyhq/twenty-infra/pull/__ — wires the four CF env
vars (`DEPLOYMENT_ID`, `CF_WORKER_NAME`, `CF_PREVIEW_DOMAIN`,
`CF_ACCOUNT_ID`, `CF_WORKERS_SCRIPTS_API_TOKEN`) into the deploy
workflow.
## Known limitation
Skew routing only works for Worker versions deployed AFTER this PR
(older versions don't have `preview_urls: true` and don't have
`DEPLOYMENT_ID` bindings OpenNext can read). Users on tabs older than
the first post-merge deploy still fall through to the current Worker
(same behaviour as today).
OpenNext marks `skewProtection` as **experimental** in their type docs
("might break on minor releases") — worth keeping an eye on.
