[JS] ERR_UNSUPPORTED_DIR_IMPORT when importing @genkit-ai/google-genai in Firebase Functions (Node 22, ESM)

[janisto]

Describe the bug
Importing @genkit-ai/google-genai in a Firebase Functions project (Node 22, ESM) fails with the following error when deploying:

> npm run deploy

> functions@1.0.1 deploy
> firebase deploy --only functions


=== Deploying to 'undisclosed-name'...

i  deploying functions
Running command: npm --prefix functions run build

> functions@1.0.1 build
> tsc

✔  functions: Finished running predeploy script.
i  functions: preparing codebase default for deployment
i  functions: ensuring required API cloudfunctions.googleapis.com is enabled...
i  functions: ensuring required API cloudbuild.googleapis.com is enabled...
i  artifactregistry: ensuring required API artifactregistry.googleapis.com is enabled...
i  functions: Loading and analyzing source code for codebase default to determine what to deploy
Serving at port 8642

Error [ERR_UNSUPPORTED_DIR_IMPORT]: Directory import '.../functions/node_modules/@genkit-ai/google-genai/lib/googleai' is not supported resolving ES modules imported from .../functions/node_modules/@genkit-ai/google-genai/lib/index.mjs
    at finalizeResolution (node:internal/modules/esm/resolve:262:11)
    at moduleResolve (node:internal/modules/esm/resolve:864:10)
    at defaultResolve (node:internal/modules/esm/resolve:990:11)
    at #cachedDefaultResolve (node:internal/modules/esm/loader:735:20)
    at #resolveAndMaybeBlockOnLoaderThread (node:internal/modules/esm/loader:771:38)
    at ModuleLoader.resolveSync (node:internal/modules/esm/loader:794:52)
    at #cachedResolveSync (node:internal/modules/esm/loader:754:25)
    at ModuleLoader.getModuleJobForRequire (node:internal/modules/esm/loader:466:50)
    at #link (node:internal/modules/esm/module_job:441:34)
    at new ModuleJobSync (node:internal/modules/esm/module_job:414:17) {
  code: 'ERR_UNSUPPORTED_DIR_IMPORT',
  url: 'file:///.../functions/node_modules/@genkit-ai/google-genai/lib/googleai'
}

Error: Functions codebase could not be analyzed successfully. It may have a syntax or runtime error

package.json:

  "type": "module",
  "engines": {
    "node": "22"
  },
  ...

tsconfig.json:

  "compilerOptions": {
    "target": "ES2022",
    "module": "nodenext",
    "moduleResolution": "nodenext",
    ...

To Reproduce
The error occurs when using:

import { vertexAI } from "@genkit-ai/google-genai";

As a workaround, I had to switch to createRequire:

import { createRequire } from "node:module";
const require = createRequire(import.meta.url);
const { vertexAI } = require("@genkit-ai/google-genai");

To Reproduce
1. Create a Firebase Functions project with:
• package.json: "type": "module", "engines": { "node": "22" }
• tsconfig.json: "module": "nodenext", "moduleResolution": "nodenext"
2. Install @genkit-ai/google-genai.
3. Import with:
import { vertexAI } from "@genkit-ai/google-genai";
4. Run firebase deploy --only functions.
5. Observe the ERR_UNSUPPORTED_DIR_IMPORT error.

Expected behavior
The ESM import should work out of the box without requiring createRequire.

Screenshots
N/A

Runtime (please complete the following information):
• OS: MacOS 15.6.1
• Firebase Functions (2nd gen)
• Node.js: v22.18.0

Additional context
This seems related to how the package exposes /lib/googleai through its entry points. Node’s ESM resolver does not allow directory imports. Adding proper "exports" mappings in the package package.json could fix this.