vercel__chat/packages/adapter-gchat

@chat-adapter/gchat

Google Chat adapter for the chat SDK.

Installation

npm install chat @chat-adapter/gchat

Usage

import { Chat } from "chat";
import { createGoogleChatAdapter } from "@chat-adapter/gchat";

const chat = new Chat({
  userName: "mybot",
  adapters: {
    gchat: createGoogleChatAdapter({
      credentials: JSON.parse(process.env.GOOGLE_CHAT_CREDENTIALS!),
    }),
  },
});

// Handle @mentions
chat.onNewMention(async (thread, message) => {
  await thread.post("Hello from Google Chat!");
});

Configuration

Option	Required	Description
credentials	Yes*	Service account credentials JSON
useADC	No	Use Application Default Credentials instead
pubsubTopic	No	Pub/Sub topic for Workspace Events
impersonateUser	No	User email for domain-wide delegation

*Either credentials or useADC: true is required.

Environment Variables

GOOGLE_CHAT_CREDENTIALS={"type":"service_account",...}

# Optional: for receiving ALL messages, not just @mentions
GOOGLE_CHAT_PUBSUB_TOPIC=projects/your-project/topics/chat-events
GOOGLE_CHAT_IMPERSONATE_USER=admin@yourdomain.com

Google Chat Setup

1. Create a GCP Project

1. Go to console.cloud.google.com
2. Click the project dropdown → New Project
3. Enter project name and click Create

2. Enable Required APIs

1. Go to APIs & Services → Library
2. Search and enable:
   • Google Chat API
   • Google Workspace Events API (for receiving all messages)
   • Cloud Pub/Sub API (for receiving all messages)

3. Create a Service Account

1. Go to IAM & Admin → Service Accounts
2. Click Create Service Account
3. Enter name and description
4. Click Create and Continue
5. Skip the optional steps, click Done

4. Create Service Account Key

Note

: If your organization has the iam.disableServiceAccountKeyCreation constraint enabled, you'll need to:

1. Go to IAM & Admin → Organization Policies
2. Find iam.disableServiceAccountKeyCreation
3. Click Manage Policy → Override parent's policy
4. Set to Not enforced (or add an exception for your project)

1. Click on your service account
2. Go to Keys tab
3. Click Add Key → Create new key
4. Select JSON and click Create
5. Save the downloaded file
6. Copy the entire JSON content → GOOGLE_CHAT_CREDENTIALS (as a single line)

5. Configure Google Chat App

1. Go to console.cloud.google.com/apis/api/chat.googleapis.com/hangouts-chat
2. Click Configuration
3. Fill in:
   • App name: Your bot's display name
   • Avatar URL: URL to your bot's avatar image
   • Description: What your bot does
   • Interactive features:
     • Enable Receive 1:1 messages
     • Enable Join spaces and group conversations
   • Connection settings: Select App URL
   • App URL: https://your-domain.com/api/webhooks/gchat
   • Visibility: Choose who can discover and install your app
4. Click Save

Important for button clicks: The same App URL receives both message events and interactive events (card button clicks). Google Chat sends CARD_CLICKED events to this URL when users click buttons in cards.

6. Add Bot to a Space

1. Open Google Chat
2. Create or open a Space
3. Click the space name → Manage apps & integrations (or Apps & integrations)
4. Click Add apps
5. Search for your app name
6. Click Add

(Optional) Pub/Sub for All Messages

By default, Google Chat only sends webhooks for @mentions. To receive ALL messages in a space (for conversation context), you need to set up Workspace Events with Pub/Sub.

1. Create Pub/Sub Topic

1. Go to Pub/Sub → Topics
2. Click Create Topic
3. Enter topic ID (e.g., chat-events)
4. Uncheck Add a default subscription
5. Click Create
6. Copy the full topic name → GOOGLE_CHAT_PUBSUB_TOPIC
   • Format: projects/your-project-id/topics/chat-events

2. Grant Chat Service Account Access

Note

: If your organization has the iam.allowedPolicyMemberDomains constraint, you may need to temporarily relax it or use the console workaround below.

1. Go to your Pub/Sub topic
2. Click Permissions tab (or Show Info Panel → Permissions)
3. Click Add Principal
4. Enter: chat-api-push@system.gserviceaccount.com
5. Select role: Pub/Sub Publisher
6. Click Save

If you get a policy error, try via Cloud Console:

1. Go to Pub/Sub → Topics
2. Check the box next to your topic
3. Click Permissions in the info panel
4. Click Add Principal
5. Add chat-api-push@system.gserviceaccount.com with Pub/Sub Publisher role

3. Create Push Subscription

1. Go to Pub/Sub → Subscriptions
2. Click Create Subscription
3. Enter subscription ID (e.g., chat-messages-push)
4. Select your topic
5. Delivery type: Push
6. Endpoint URL: https://your-domain.com/api/webhooks/gchat
7. Click Create

4. Enable Domain-Wide Delegation

To create Workspace Events subscriptions and initiate DMs, you need domain-wide delegation:

Step 1: Enable delegation on the Service Account (GCP Console)

1. Go to IAM & Admin → Service Accounts
2. Click on your service account
3. Go to Details tab
4. Check Enable Google Workspace Domain-wide Delegation
5. Click Save
6. Go to Advanced settings (or click on the service account again)
7. Copy the Client ID - this is a numeric ID (e.g., 123456789012345678901), NOT the email address

Step 2: Authorize the Client ID (Google Admin Console)

1. Go to Google Admin Console
2. Go to Security → Access and data control → API controls
3. Click Manage Domain Wide Delegation
4. Click Add new
5. Enter:
   • Client ID: The numeric ID from Step 1 (e.g., 123456789012345678901)
   • OAuth Scopes (all on one line, comma-separated):

     https://www.googleapis.com/auth/chat.spaces.readonly,https://www.googleapis.com/auth/chat.messages.readonly,https://www.googleapis.com/auth/chat.spaces,https://www.googleapis.com/auth/chat.spaces.create
     

6. Click Authorize

Step 3: Set environment variable

Set GOOGLE_CHAT_IMPERSONATE_USER to an admin user email in your domain (e.g., admin@yourdomain.com). This user will be impersonated when creating DM spaces and Workspace Events subscriptions.

Features

• Message posting and editing
• Thread subscriptions
• Reaction events (via Workspace Events)
• File attachments
• Rich cards (Google Chat Cards)
• Action callbacks (card buttons)
• Direct messages
• Space management

Limitations

• Typing indicators: Not supported by Google Chat API
• Adding reactions: Requires domain-wide delegation (appears from impersonated user, not bot)

Troubleshooting

No webhook received

• Verify the App URL is correct in Google Chat configuration
• Check that the Chat API is enabled
• Ensure the service account has the necessary permissions

Pub/Sub not working

• Verify chat-api-push@system.gserviceaccount.com has Pub/Sub Publisher role
• Check that the push subscription URL is correct
• Verify domain-wide delegation is configured with correct scopes
• Check GOOGLE_CHAT_IMPERSONATE_USER is a valid admin email

"Permission denied" for Workspace Events

• Ensure domain-wide delegation is configured
• Verify the OAuth scopes are exactly as specified
• Check that the impersonated user has access to the spaces

"Insufficient Permission" for DMs (openDM)

• DMs require domain-wide delegation with chat.spaces and chat.spaces.create scopes
• Add these scopes to your domain-wide delegation configuration in Google Admin Console
• Set GOOGLE_CHAT_IMPERSONATE_USER to an admin email in your domain
• Scope changes can take up to 24 hours to propagate

"unauthorized_client" error

• The Client ID is not registered in Google Admin Console
• Or domain-wide delegation is not enabled on the service account

Button clicks (CARD_CLICKED) not received

• Verify "Interactive features" is enabled in the Google Chat app configuration
• Check that the App URL is correctly set and accessible
• Button clicks go to the same webhook URL as messages
• Ensure your button elements have valid id attributes (these become the actionId)

License

MIT