`@turbo/gen` 2.8.8+ breaks generator configs using Node.js APIs not implemented in Bun

[lfantone]

Verify canary release

• I verified that the issue exists in the latest Turborepo canary release.

Link to code that reproduces this issue

https://github.com/lfantone/turborepo-gen-bun-compat-repro

Which canary version will you have in your reproduction?

turbo 2.8.12-canary.2

Environment information

CLI:
   Version: 2.8.12-canary.2
   Path to executable: /Users/lfantone/Workspace/sas/adg-octopus-main/node_modules/turbo-darwin-arm64/bin/turbo
   Daemon status: Not running
   Package manager: berry

Platform:
   Architecture: aarch64
   Operating system: macos
   WSL: false
   Available memory (MB): 6392
   Available CPU cores: 12

Environment:
   CI: None
   Terminal (TERM): xterm-256color
   Terminal program (TERM_PROGRAM): zed
   Terminal program version (TERM_PROGRAM_VERSION): 0.226.1+preview.185.548dbdcb52a7e1b0d6969225e7f475b4fa965aef
   Shell (SHELL): /bin/zsh
   stdin: false

Expected behavior

Generator configs using standard Node.js APIs (e.g., findPackageJSON from node:module) should continue to work across patch releases of @turbo/gen, since patch versions must not introduce breaking changes per semver.

Actual behavior

Starting in 2.8.8, @turbo/gen switched its runtime from Node.js to an embedded Bun v1.3.9 binary (PR #11825, commit 4f5632c). This was released as a patch bump (2.8.7 → 2.8.8), but Bun does not fully implement the Node.js API surface.

Generator configs that worked under 2.8.7 now fail with errors like:

TypeError: import_node_module.findPackageJSON is not a function

module.findPackageJSON is a stable Node.js API (available since v22.8.0), but Bun has not implemented it — there's an open bug for it: oven-sh/bun#23898.

This is not limited to findPackageJSON. Any Node.js API that Bun hasn't implemented will break in the same way, making this a potentially wide-reaching issue for existing generator configs.

To Reproduce

1. Create a turbo generator config that uses findPackageJSON from node:module:

// turbo/generators/config.js
import { findPackageJSON } from 'node:module';

const pkgPath = findPackageJSON('some-package', import.meta.url);

export default function generator(plop) {
  // ...
}

2. With turbo@2.8.7: turbo gen works fine (runs under Node.js)
3. Upgrade to turbo@2.8.8 or later: turbo gen fails with `TypeError: import_node_module.findPackageJSON is not a function

Additional context

The commit message for the Bun migration uses the feat: conventional commit prefix, but it was released as a patch version (2.8.7 → 2.8.8). A runtime swap that changes API compatibility should arguably be at least a minor bump, if not a major one, since it silently breaks existing generator configs.

• Verified the issue still exists in canary (2.8.12-canary.2) — the Bun binary approach is unchanged.
• This is particularly subtle because findPackageJSON appears in Bun's own documentation as if it's supported, but the implementation doesn't exist in any released version.

[lfantone]

Additionally it is not possible to use a specific version of @turbo/gen package. Even when setting a resolution or installing it as a dependency, turbo totally ignores this and always try to fetch the latest binary:

2026-02-27T20:49:29.783+0100 [DEBUG] turborepo_lib::commands::generate: Running @turbo/gen@latest with command run and args "{"generator_name":null,"config":null,"root":null,"args":[]}"

Doesn't respect your local turbo version, if you are using turbo@2.6.3 it will use latest 😢

[anthonyshew]

@lfantone I also wasn't happy when I learned. I don't know why it was ever that way, and its fixed to your turbo's version in recent releases. You can use turbo gen --tag <your-tag> to specify a specific version if needed for older releases.