fix: transpile private class methods in the starter build by hellofanny · Pull Request #3452 · vtex/faststore

hellofanny · 2026-08-15T01:54:30Z

Problem

Every PR targeting 3.x has been failing the Build starter job since Aug 3 with:

../node_modules/jose/dist/webapi/jwks/remote.js
SyntaxError: Class private methods are not enabled. Please add `@babel/plugin-proposal-private-methods` to your configuration.
  96 |     #validFor(duration) {

The last green run on 3.x was Jul 27. #3404 is not a counterexample: its checks ran Jun 23 and it was merged Jun 30 without re-running them.

Root cause

Two independent dependency drifts had to line up, and neither is in anyone's diff:

jose@6.2.8 (published Aug 3) introduced the package's first private class method. dist/webapi/jwks/remote.js in 6.2.4 — the newest version on Jul 27 — has 10 private fields and zero private methods. 6.2.8 added #validFor(duration) at line 96, which is exactly the line the error points at. The starter installs with no lockfile, so jose: ^6.2.3 resolves to whatever is latest.
next/babel only adds the private-methods transform when the resolved browserslist targets lack native support. @faststore/core declares browserslist: "supports es6-module and not dead"; as caniuse-lite drops dead browsers, that query collapses to targets which do support private methods, so the transform is skipped — while Next still applies class-properties unconditionally, and that plugin throws on #method().

Two more preconditions explain why this surfaces here at all. jose reaches Babel because password-protection-service.ts is used by middleware.ts, and Next bundles dependencies for the edge runtime instead of skipping node_modules. And Babel runs at all because this config exists: loading babelOptimizerPlugin disables SWC, which would have handled private methods natively.

Only 3.x is affected. dev has the same jose range and the same .babelrc.js, but resolves a newer Next whose Babel handles private methods natively.

Fix

Enable @babel/plugin-transform-private-methods unconditionally, so the build no longer depends on caniuse-lite vintage. Version 7.25.9 is the one already resolved in the monorepo tree; it is a dependencies entry because the config is evaluated from the consumer's .faststore directory, the same reason the codegen packages live there.
Pin jose exactly, removing silent drift on every lockfile-less install. Pinned to 6.2.8 rather than the last working 6.2.4 so its fixes are kept (rejecting a non-string alg in EmbeddedJWK, enforcing a single recipient for dir and ECDH-ES).

pnpm-lock.yaml is intentionally untouched: regenerating it with pnpm 9.15.5 today rewrites ~7.4k lines through a repo-wide dedupe, which does not belong in a CI fix. The Install dependencies step runs pnpm i unfrozen, and the starter resolves core's dependencies with its own yarn install.

Verification

Reproduced the failure and the fix against Next's own bundled Babel (7.18.0), the same one in the CI stack trace, using the class shape from jose@6.2.8:

targets	plugin	result
`supports es6-module and not dead`	off	transpiles
modern (chrome 110 / safari 16)	off	fails with the exact CI error
modern (chrome 110 / safari 16)	on	transpiles

The middle row is the CI condition; the last row is this PR. The Build starter job on this PR is the end-to-end check.

Made with Cursor

Summary by CodeRabbit

Bug Fixes
- Improved compatibility for middleware and dependencies using private class methods.
- Stabilized authentication-related behavior by locking a compatible dependency version.

Second, unrelated CI bug found along the way

The first push here surfaced a separate pre-existing failure in the Test step:

FAIL test/server/index.test.ts
  ● Test suite failed to run
    src/server/index.ts:28:23 - error TS2307: Cannot find module '@generated/persisted-documents.json'

prebuild writes @generated/ (schema, persisted documents, generated types), but the build task only declared dist/** as its output, which core does not produce. So @faststore/core:build: cache hit, replaying logs restored nothing and left the workspace without those files, while test depends on ^build rather than on its own package's build.

It stayed hidden because core#test was itself being served from cache. It surfaces as soon as a change invalidates the test hash but not the build hash — which is what happened here, since Packages Preview runs on the same commit and populated the build cache first. Declaring @generated/** as a build output is the one-line fix; a cache hit now restores the artifacts.

This means the failure is not specific to this PR: any change that invalidates core#test while the build cache hits will hit it.

The starter build has been failing on `jose/dist/webapi/jwks/remote.js` since two independent dependency drifts lined up. `jose@6.2.8` (Aug 3) introduced the package's first private class method, and the starter installs without a lockfile, so `jose: ^6.2.3` resolves to it. At the same time, `next/babel` only adds the private-methods transform when the resolved browserslist targets lack native support; as caniuse-lite drops dead browsers, `supports es6-module and not dead` collapses to targets that support it, so the transform is skipped while class-properties is still applied, and that combination throws on `#method()`. Enabling the transform unconditionally makes the build independent of caniuse-lite drift, and pinning `jose` exactly removes the silent version drift on every lockfile-less install. Pinning to 6.2.8 rather than the last working 6.2.4 keeps its fixes (rejecting a non-string `alg` in EmbeddedJWK, enforcing a single recipient for `dir` and ECDH-ES). The v4 line is not affected: it resolves a newer Next whose Babel handles private methods natively. Co-authored-by: Cursor <cursoragent@cursor.com>

coderabbitai · 2026-08-15T01:54:50Z

Walkthrough

The core package now transforms private methods through Babel and declares the required plugin. The jose dependency is pinned to version 6.2.8.

Changes

Core package transpilation

Layer / File(s)	Summary
Babel configuration and dependency alignment `packages/core/.babelrc.js`, `packages/core/package.json`	The Babel configuration enables `@babel/plugin-transform-private-methods`. The package adds version `7.25.9` of the plugin and pins `jose` to `6.2.8`.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: 🟡 Moderate · up to a09fb

The dependency changes are not reflected in pnpm-lock.yaml, so frozen installs fail before the build can run. Merge should wait for a focused lockfile update recording jose 6.2.8 and @babel/plugin-transform-private-methods 7.25.9.

Suggested reviewers: eduardoformiga, renatomaurovtex

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: transpiling private class methods to fix the starter build.

✨ Finishing Touches

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch fix/starter-build-babel-private-methods

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Actionable comments posted: 1

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Inline comments:
In `@packages/core/package.json`:
- Line 49: Update the packages/core importer entry in pnpm-lock.yaml to include
`@babel/plugin-transform-private-methods` at 7.25.9 and record jose with the
package manifest’s current version range instead of ^6.2.3. Keep the lockfile
change focused on these dependency metadata updates.

Apply the same fix in `@packages/core/package.json` at line 49.

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Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

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Review profile: CHILL

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Run ID: 76c96fd0-7495-4ee1-adb1-5e82fdbbec6d

📥 Commits

Reviewing files that changed from the base of the PR and between bf4812f and a09fb6b.

📒 Files selected for processing (2)

packages/core/.babelrc.js
packages/core/package.json

Edited in place rather than regenerated: pnpm 9.15.5 rewrites the whole file today (~7.4k lines) because the committed lockfile is prettier formatted and a fresh resolve dedupes repo-wide, neither of which belongs in this fix. Co-authored-by: Cursor <cursoragent@cursor.com>

The previous commit accidentally shipped a full pnpm rewrite: running `pnpm install --lockfile-only` to validate the edit also reformatted the file, since the committed lockfile is prettier formatted and a fresh resolve dedupes repo-wide. Restores the three-entry edit. Co-authored-by: Cursor <cursoragent@cursor.com>

pkg-pr-new · 2026-08-15T02:04:32Z

Open in StackBlitz

@faststore/api

yarn add https://pkg.pr.new/vtex/faststore/@faststore/api@0b4a2a9.tgz

@faststore/cli

yarn add https://pkg.pr.new/vtex/faststore/@faststore/cli@0b4a2a9.tgz

@faststore/components

yarn add https://pkg.pr.new/vtex/faststore/@faststore/components@0b4a2a9.tgz

@faststore/core

yarn add https://pkg.pr.new/vtex/faststore/@faststore/core@0b4a2a9.tgz

@faststore/graphql-utils

yarn add https://pkg.pr.new/vtex/faststore/@faststore/graphql-utils@0b4a2a9.tgz

@faststore/lighthouse

yarn add https://pkg.pr.new/vtex/faststore/@faststore/lighthouse@0b4a2a9.tgz

@faststore/sdk

yarn add https://pkg.pr.new/vtex/faststore/@faststore/sdk@0b4a2a9.tgz

@faststore/ui

yarn add https://pkg.pr.new/vtex/faststore/@faststore/ui@0b4a2a9.tgz

commit: 0b4a2a9

codesandbox-ci · 2026-08-15T02:05:45Z

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

`prebuild` writes `@generated/` (the GraphQL schema, persisted documents and generated types), but `build` only declared `dist/**` as its output, which core does not produce. A build cache hit therefore restored nothing and left the workspace without those files, so `core#test` — which depends on `^build`, not on its own package's build — failed to compile with `Cannot find module '@generated/persisted-documents.json'`. This stayed hidden while `core#test` was itself served from cache. It surfaces as soon as a change invalidates the test hash but not the build hash, which is what happens when a second workflow on the same commit populates the build cache first. Co-authored-by: Cursor <cursoragent@cursor.com>

hellofanny requested a review from a team as a code owner August 15, 2026 01:54

hellofanny requested review from eduardoformiga and renatomaurovtex and removed request for a team August 15, 2026 01:54

coderabbitai Bot reviewed Aug 15, 2026

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Comment thread packages/core/package.json

hellofanny and others added 2 commits August 14, 2026 23:02

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fix: transpile private class methods in the starter build - #3452

fix: transpile private class methods in the starter build#3452
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