[JS] Unable to use `jsonSchema` for structured output

[christophe-g]

Describe the bug

I have schemas defined with effect

It seems schema definition using identifiers ("$ref": "#/$defs/ID" -> "$defs": {"ID": {...def}}) is not supported.

To Reproduce

import { gemini20Flash, googleAI } from '@genkit-ai/googleai';
import { genkit } from 'genkit';

const schema = {
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$defs": {
    "Name": {
      "type": "string",
      "description": "a string",
      "title": "string"
    },
    "Age": {
      "type": "number",
      "description": "a number",
      "title": "number"
    }
  },
  "type": "object",
  "required": [
    "name",
    "age"
  ],
  "properties": {
    "name": {
      "$ref": "#/$defs/Name"
    },
    "age": {
      "$ref": "#/$defs/Age"
    }
  },
  "additionalProperties": false
}

// configure a Genkit instance
const ai = genkit({
  plugins: [googleAI({ apiKey: process.env.GEMINI_API_KEY! })],
  model: gemini20Flash, // set default model
});

async function main() {
  // make a generation request
  const { text } = await ai.generate({
    model: gemini20Flash,
    system: `
        You are a Person generator. Person has a name and a age
        `,
    prompt: `Create a new person`,
    output: { jsonSchema: schema },
  });
  console.log(text);
}

main();

results in

genkit start -- pnpx tsx src/ai/generatePerson.ts 
[Telemetry Server] initialized local file trace store at root: /home/christophe/Programming/preignition/app/app-survey/functions/.genkit/traces
Telemetry API running on http://localhost:4033
Error reading tools config Unexpected token 'T', "[Telemetry "... is not valid JSON
Error reading tools config Unexpected token 'T', "[Telemetry "... is not valid JSON
Error reading tools config ENOENT: no such file or directory, open '/home/christophe/Programming/preignition/app/app-survey/functions/.genkit/servers/tools-478984.json'
Project root: /home/christophe/Programming/preignition/app/app-survey/functions
Genkit Developer UI: http://localhost:4000
node:internal/process/promises:394
    triggerUncaughtException(err, true /* fromPromise */);
    ^

GoogleGenerativeAIFetchError: [GoogleGenerativeAI Error]: Error fetching from https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent: [400 Bad Request] Invalid JSON payload received. Unknown name "$defs" at 'generation_config.response_schema': Cannot find field.
Invalid JSON payload received. Unknown name "$ref" at 'generation_config.response_schema.properties[0].value': Cannot find field.
Invalid JSON payload received. Unknown name "$ref" at 'generation_config.response_schema.properties[1].value': Cannot find field. [{"@type":"type.googleapis.com/google.rpc.BadRequest","fieldViolations":[{"field":"generation_config.response_schema","description":"Invalid JSON payload received. Unknown name \"$defs\" at 'generation_config.response_schema': Cannot find field."},{"field":"generation_config.response_schema.properties[0].value","description":"Invalid JSON payload received. Unknown name \"$ref\" at 'generation_config.response_schema.properties[0].value': Cannot find field."},{"field":"generation_config.response_schema.properties[1].value","description":"Invalid JSON payload received. Unknown name \"$ref\" at 'generation_config.response_schema.properties[1].value': Cannot find field."}]}]
    at handleResponseNotOk (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@google+generative-ai@0.24.1/node_modules/@google/generative-ai/dist/index.js:434:11)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async makeRequest (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@google+generative-ai@0.24.1/node_modules/@google/generative-ai/dist/index.js:403:9)
    at async generateContent (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@google+generative-ai@0.24.1/node_modules/@google/generative-ai/dist/index.js:867:22)
    at async ChatSession.sendMessage (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@google+generative-ai@0.24.1/node_modules/@google/generative-ai/dist/index.js:1210:9)
    at async callGemini (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@genkit-ai+googleai@1.7.0_genkit@1.7.0/node_modules/@genkit-ai/googleai/src/gemini.ts:1045:26)
    at async <anonymous> (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@genkit-ai+googleai@1.7.0_genkit@1.7.0/node_modules/@genkit-ai/googleai/src/gemini.ts:1102:11)
    at async <anonymous> (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@genkit-ai+core@1.7.0/node_modules/@genkit-ai/core/src/action.ts:438:14)
    at async <anonymous> (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@genkit-ai+core@1.7.0/node_modules/@genkit-ai/core/src/action.ts:334:26)
    at async <anonymous> (/home/christophe/Programming/preignition/app/app-survey/functions/node_modules/.pnpm/@genkit-ai+core@1.7.0/node_modules/@genkit-ai/core/src/tracing/instrumentation.ts:73:16) {
  status: 400,
  statusText: 'Bad Request',
  errorDetails: [
    {
      '@type': 'type.googleapis.com/google.rpc.BadRequest',
      fieldViolations: [
        {
          field: 'generation_config.response_schema',
          description: `Invalid JSON payload received. Unknown name "$defs" at 'generation_config.response_schema': Cannot find field.`
        },
        {
          field: 'generation_config.response_schema.properties[0].value',
          description: `Invalid JSON payload received. Unknown name "$ref" at 'generation_config.response_schema.properties[0].value': Cannot find field.`
        },
        {
          field: 'generation_config.response_schema.properties[1].value',
          description: `Invalid JSON payload received. Unknown name "$ref" at 'generation_config.response_schema.properties[1].value': Cannot find field.`
        }
      ]
    }
  ],
  traceId: '7cb8aa986000cf63231fa47f234d40c0'
}

Node.js v23.6.1
/home/christophe/.local/share/pnpm/global/5/.pnpm/genkit-cli@1.7.0_encoding@0.1.13/node_modules/genkit-cli/dist/commands/start.js:95
                    reject(new Error(`app process exited with code ${code}`));
                           ^

Error: app process exited with code 1
    at ChildProcess.<anonymous> (/home/christophe/.local/share/pnpm/global/5/.pnpm/genkit-cli@1.7.0_encoding@0.1.13/node_modules/genkit-cli/dist/commands/start.js:95:28)
    at ChildProcess.emit (node:events:507:28)
    at ChildProcess._handle.onexit (node:internal/child_process:294:12)

Node.js v23.6.1

Expected behavior

Valid JSON schemas can be used

Runtime (please complete the following information):

• OS: Linux
• Version: genkit 1.7.0

** Node version

• 23.6.1

Additional context
Add any other context about the problem here.