Bug report: microsoft/playwright#41371

Minimal reproduction of a Playwright 1.61.0 regression: the new synchronous ESM loader (module.registerHooks(), PR #40891, commit c758b150) breaks module resolution for pnpm workspace packages.

When an ESM workspace package ("type": "module") does an extensionless subpath import of a sibling workspace package (e.g. import { greet } from '@repro/shared/lib/text.utils'), the sync loader resolves the importing file to its real path (packages/core/lib/conversations.ts) and then hands a file:// URL to Node's native ESM resolver. That resolver only tries .js/.mjs/.cjs — it never adds .ts — so the import fails even though the .ts file plainly exists (Node even prints a "Did you mean…?" hint pointing at it).

The old async loader (module.register(), used in 1.60.0 and still reachable via PLAYWRIGHT_FORCE_ASYNC_LOADER=1) resolved TypeScript subpath imports correctly.

Reproduces on both macOS (arm64) and Linux CI.

Error: Cannot find module '.../packages/core/node_modules/@repro/shared/lib/text.utils'
imported from .../packages/core/lib/conversations.ts
Did you mean to import "file:///.../packages/shared/lib/text.utils.ts"?

All of the following are required — drop any one and the bug disappears:

1. Playwright 1.61.0 on Node 22+ (so module.registerHooks exists and the sync loader activates).
2. Workspace packages marked "type": "module" (forces the strict ESM file:// resolver for sub-imports).
3. Extensionless subpath imports of .ts files (@repro/shared/lib/text.utils, not .../text.utils.ts).
4. No exports / main field — raw .ts source imported directly, no build step.
5. A pnpm workspace, so the imported package is a symlink whose real path differs from the symlink path.

The import chain that breaks: apps/e2e/tests/basic.spec.ts → @repro/core/lib/conversations → @repro/shared/lib/text.utils.

.
├── mise.toml                 # node 24.16.0, pnpm 11.5.3, playwright on PATH via _.path
├── package.json               # workspace root ("type": "module")
├── pnpm-workspace.yaml
├── packages/
│   ├── shared/                # @repro/shared ("type": "module")
│   │   └── lib/text.utils.ts  #   exports greet()
│   └── core/                  # @repro/core   ("type": "module"), dep on @repro/shared
│       └── lib/conversations.ts  # re-exports greet from '@repro/shared/lib/text.utils'
└── apps/
    └── e2e/                   # @repro/e2e (CJS — no "type"), the Playwright test app
        ├── playwright.config.ts
        └── tests/basic.spec.ts   # imports '@repro/core/lib/conversations'

mise install      # node 24.16.0 + pnpm 11.5.3
pnpm install

playwright is on PATH via mise's _.path (see mise.toml), so invoke it directly — do not use pnpm exec, npx, or pnpm run.

playwright test

Fails with Cannot find module …/packages/core/node_modules/@repro/shared/lib/text.utils.

PLAYWRIGHT_FORCE_ASYNC_LOADER=1 playwright test

Passes.

Change @playwright/test to 1.60.0 in apps/e2e/package.json, then:

pnpm install
playwright test     # passes

Restore 1.61.0 to get the failure back.

• Regression commit: c758b150 / PR #40891
• File the upstream issue: https://github.com/microsoft/playwright/issues/new

This reproduction and README were produced by an AI agent.