Action on Google working, but with a Dialogflow agent broken - actions-on-google

Question

I have a project with Actions on Google, Dialogflow & an AWS Lambda to manage the fulfilment. On the backend (NodeJs) I use actions-on-google (v2)
const {dialogflow} = require('actions-on-google');
const app = dialogflow({debug: true});
app.intent('StartIntent', (conv) => {
console.log('Hello AWS');
conv.ask('Hello AWS');
});
exports.handler = app
Dialogflow is configured with one Intent StartIntent & with webhook fulfilment.
Everything seems to work fine when I test with the Actions on Google simulator. I got the expected answer 'Hello AWS'.
However, it doesn't work with the dialogflow simulator. There is no answer, although I can read "Webhook execution successful" in the Diagnostic Info, with the correct fulfilment response:
{
"payload": {
"google": {
"expectUserResponse": true,
"richResponse": {
"items": [
{
"simpleResponse": {
"textToSpeech": "Hello AWS"
}
}
]
},
"userStorage": "{\"data\":{}}"
}
},
"outputContexts": [
{
"name": "projects..../_actions_on_google",
"lifespanCount": 99,
"parameters": {
"data": "{}"
}
}
]
}
This seems really strange to me, as the Actions on Google just make a call to dialogflow and that return a good response. Whereas testing dialogflow alone doesn't work.
Any idea ?

Answer 1

This is expected. The actions-on-google library has its output tuned for the Google Assistant integration. It doesn't try to include output that would be used by generic Dialogflow agents, which is what the Dialogflow test field uses.
If it works in the Assistant Simulator - you should be good.
Update
To be specific, the actions-on-google library sets values in payload.google.richResponse in the JSON response which set the messages that are displayed by the Google Assistant. As the name suggests, this is Google-specific output, so the Dialogflow test side-bar (as well as other agents that work with Dialogflow) ignore this section.
Dialogflow has generic ways of sending messages back including the fulfillmentText and fulfillmentMessages fields in the JSON response. The Dialogflow test side-bar uses these fields to display results. The actions-on-google library does not set, or use, these fields, so results aren't available.