[mathurshubham]

Fixes #1326

Problem

The webpack server runtime loads chunks with installChunk(require("./chunks/" + __webpack_require__.u(chunkId))), which esbuild cannot bundle, so the adapter rewrites it into a switch with one static require per chunk. That rewrite only listed chunks/<digits>.js and switched on the numeric id. Next's server chunkFilename is [name].js, so a chunk named with /* webpackChunkName: "x" */ (from next/dynamic or a dependency) is written as chunks/x.js and reached through the __webpack_require__.u id-to-name map (e.u=a=>""+(522===a?"x":a)+".js"). It had no case, so the page failed with Error: Unknown chunk 522 and a 500.

Fix

patchWebpackRuntime now lists every .js under chunks/ (nested names like dir/name included, symlinks accepted) and the generated code switches on the computed path:

if (SELF_ID == chunkId) {
  installedChunks[chunkId] = 1;
} else {
  switch ("./chunks/" + __webpack_require__.u(chunkId)) {
    case "./chunks/103.js": installChunk(require("./chunks/103.js")); break;
    case "./chunks/named-chunk.js": installChunk(require("./chunks/named-chunk.js")); break;
    default: throw new Error(`Unknown chunk ${chunkId}`);
  }
}

The single-chunk rule uses the same switch so a single named chunk also loads. Chunk names are escaped ($ to \x24) so they can't collide with the $NAME placeholders of the ast-grep fix template. The chunk listing is skipped when no webpack runtime file exists (Turbopack builds).

Testing

• Spec: updated snapshots, plus new cases for pretty and minified __webpack_require__.u maps, nested names, a single named chunk, a $ in the name, an executable test that runs the patched runtime, and applyRule(...).edits.length no-op checks.
• Old vs new rule were run over the production webpack runtimes of Next 15.2, 15.5 and 16.3 (pages and api runtimes): identical match counts, no require("./chunks/"+ left behind.
• New e2e in examples/e2e/pages-router: /named-chunk/ renders a next/dynamic component with webpackChunkName. Built handler.mjs contains case"./chunks/named-chunk.js" for both runtimes; the full pages-router Playwright suite passes (40 passed, 1 skipped).
• pnpm test and pnpm code:checks pass.

Note: examples/e2e/pages-router is periodically synced from opennextjs-aws; the new test may need to be upstreamed there as well.

---

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Latest commit: a8b267d

The changes in this PR will be included in the next version bump.

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Name	Type
@opennextjs/cloudflare	Patch

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[mathurshubham]

Devin Review reports one flag on this PR but it is not posted here (hidden by the org's review settings), so I could not read it. I re-reviewed the diff against the webpack template shipped in Next 15.5.27 and 16.3.8 and the emitted webpack-runtime.js / webpack-api-runtime.js, and added one hardening change in 3859688: when neither rule matches, the patch now logs an error instead of silently leaving the dynamic require("./chunks/" + ...) in place (which would only surface as a runtime failure). Verified on a fresh pages-router worker build: chunks/named-chunk.js is emitted and referenced from the bundle, no dynamic chunk require remains, and the new guard does not fire. If the hidden flag is about something else, please share it and I will address it.

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commit: a8b267d

[vicb]

Thanks for the PR @mathurshubham!

The e2e was super helpful to investigate.

I moved the e2e to the playground16 app because apps under examples/e22 are shared with the aws adapter.

The last commit simplifies the implementation.