Google Chat Messages

Send messages to Google Chat spaces via incoming webhooks. Produces text messages, rich cards (cardsV2), and threaded replies.

What You Produce

• Text messages with Google Chat formatting

• Rich card messages (cardsV2) with headers, sections, widgets

• Threaded conversations

• Reusable webhook sender utility

Workflow

Step 1: Get Webhook URL

In Google Chat:

• Open a Space > click space name > Manage webhooks

• Create webhook (name it, optionally add avatar URL)

• Copy the webhook URL

Store the URL as an environment variable or in your secrets manager — never hardcode.

Step 2: Choose Message Type

Need Type Complexity

Simple notification Text message Low

Structured info (status, digest) Card message (cardsV2) Medium

Ongoing updates Threaded replies Medium

Action buttons (open URL) Card with buttonList Medium

Step 3: Send the Message

Use assets/webhook-sender.ts for the sender utility. Use assets/card-builder.ts for structured card construction.

Text Formatting

Google Chat does NOT use standard Markdown.

Format Syntax Example

Bold text

important

Italic text

emphasis

Strikethrough text

removed

Monospace text

code

Code block text

Multi-line code

Link <url|text>

<https://example.com|Click here>

Mention user <users/USER_ID>

<users/123456>

Mention all <users/all>

<users/all>

Not supported: double asterisks , headings (### ), blockquotes, tables, images inline.

Text Message Example

await sendText(webhookUrl, 'Build Complete\n\nBranch: main\nStatus: Passed\n<https://ci.example.com/123|View Build>');

cardsV2 Structure

Cards use the cardsV2 format (recommended over legacy cards).

const message = { cardsV2: [{ cardId: 'unique-id', card: { header: { title: 'Card Title', subtitle: 'Optional subtitle', imageUrl: 'https://example.com/icon.png', imageType: 'CIRCLE' // or 'SQUARE' }, sections: [{ header: 'Section Title', // optional widgets: [ // widgets go here ] }] } }] };

Widget Types

Text paragraph — formatted text block:

{ textParagraph: { text: 'Bold and italic text' } }

Decorated text — label + value with optional icon:

{ decoratedText: { topLabel: 'Status', text: 'Deployed', startIcon: { knownIcon: 'STAR' } } }

Button list — action buttons:

{ buttonList: { buttons: [{ text: 'View Dashboard', onClick: { openLink: { url: 'https://dashboard.example.com' } } }] } }

Image — standalone image:

{ image: { imageUrl: 'https://example.com/chart.png', altText: 'Usage chart' } }

Divider — horizontal separator:

{ divider: {} }

See references/widget-reference.md for all widget types with full examples. See references/icon-list.md for all available knownIcon values.

Threading

Thread messages together using threadKey :

// First message — creates thread const response = await sendCard(webhookUrl, card, { threadKey: 'deploy-2026-02-16' });

// Reply to thread — append &messageReplyOption=REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD const threadUrl = ${webhookUrl}&messageReplyOption=REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD; await sendCard(threadUrl, replyCard, { threadKey: 'deploy-2026-02-16' });

The threadKey is a client-assigned string. Use consistent keys for related messages (e.g., deploy-{date} , alert-{id} ).

Common Patterns

Notification Card

import { buildCard, sendCard } from './assets/card-builder'; import { sendWebhook } from './assets/webhook-sender';

const card = buildCard({ cardId: 'deploy-notification', title: 'Deployment Complete', subtitle: 'production - v2.1.0', imageUrl: 'https://example.com/your-icon.png', sections: [{ widgets: [ { decoratedText: { topLabel: 'Environment', text: 'Production' } }, { decoratedText: { topLabel: 'Version', text: 'v2.1.0' } }, { decoratedText: { topLabel: 'Status', text: 'Healthy', startIcon: { knownIcon: 'STAR' } } }, { buttonList: { buttons: [{ text: 'View Deployment', onClick: { openLink: { url: 'https://dash.example.com' } } }] } } ] }] });

Digest Card (Weekly Summary)

const digest = buildCard({ cardId: 'weekly-digest', title: 'Weekly Summary', subtitle: ${count} updates this week, sections: [ { header: 'Highlights', widgets: items.map(item => ({ decoratedText: { text: item.title, bottomLabel: item.date } })) }, { widgets: [{ buttonList: { buttons: [{ text: 'View All', onClick: { openLink: { url: dashboardUrl } } }] } }] } ] });

Simple Text Alert

await sendText(webhookUrl, *Alert*: CPU usage above 90% on \worker-prod-1`\n<${alertUrl}|View Alert>`);

Error Prevention

Mistake Fix

bold in text Use bold (single asterisks)

text links Use <url|text> format

Missing cardsV2 wrapper Wrap card in { cardsV2: [{ cardId, card }] }

Thread replies not threading Append &messageReplyOption=REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD to webhook URL

Webhook returns 400 Check JSON structure — common issue is missing text or cardsV2 at top level

Card not showing Ensure sections has at least one widget

Asset Files

File Purpose

assets/types.ts

TypeScript type definitions for cardsV2

assets/card-builder.ts

Utility to build card messages

assets/webhook-sender.ts

POST to webhook with error handling