pg 8.22.0 CJS entry can resolve pg-protocol as ESM under Cloudflare/Vite worker tests

pg/lib/connection.js から始め、CommonJS エントリが pg-protocol、pg-pool、pg-connection-string のエントリポイントをどのように解決するかを調べます。@cloudflare/vitest-pool-workers と Vite の worker-test パイプラインで障害を再現し、その後、CommonJS エントリが pnpm のレイアウトに依存せずに互換性のある依存ファイルを読み込むことを確認します。

Summary

When pg@8.22.0 is bundled by the @cloudflare/vitest-pool-workers / Vite worker-test pipeline in a pnpm workspace, the CommonJS entry can fail while loading pg-protocol from pg/lib/connection.js:

SyntaxError: Cannot use import statement outside a module
  at node_modules/.pnpm/pg@8.22.0/node_modules/pg/lib/connection.js?mf_vitest_no_cjs_esm_shim:5:30
  at node_modules/.pnpm/pg@8.22.0/node_modules/pg/lib/client.js?mf_vitest_no_cjs_esm_shim:10:20
  at node_modules/.pnpm/pg@8.22.0/node_modules/pg/lib/index.js

The failing line is the CommonJS package-name require:

const { parse, serialize } = require("pg-protocol")

In this environment, that dependency can be resolved/transformed as an ES module, then loaded from a CJS wrapper.

Environment

• pg: 8.22.0
• pg-protocol: 1.15.0
• package manager: pnpm
• test/bundler stack: @cloudflare/vitest-pool-workers + Vite + Miniflare/workerd
• worker compatibility flag: nodejs_compat

Local workaround

We currently patch pg to force the CJS files to load the CJS dependency files directly from pnpm's sibling layout:

-const { parse, serialize } = require("pg-protocol")
+const { parse, serialize } = require("../../pg-protocol/dist/index.js")

-const Pool = require("pg-pool")
+const Pool = require("../../pg-pool/index.js")

-const parse = require("pg-connection-string").parse
+const parse = require("../../pg-connection-string/index.js").parse

That patch is not a good general solution because it depends on pnpm's installed package layout.

Ask

Would pg consider an upstream change that makes the CommonJS entry robust in bundler/worker environments, for example by ensuring the CJS entry always resolves CJS-compatible dependency entrypoints for pg-protocol, pg-pool, and pg-connection-string?

Happy to provide more details or test a candidate fix.