Google Chat API

Status: Production Ready Last Updated: 2025-11-29 (Research verified: Markdown support, Material Design updates) Dependencies: Cloudflare Workers (recommended), Web Crypto API for token verification Latest Versions: Google Chat API v1 (stable), Cards v2 (Cards v1 deprecated)

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Quick Start (5 Minutes)

1. Create Webhook (Simplest Approach)

# No code needed - just configure in Google Chat
# 1. Go to Google Cloud Console
# 2. Create new project or select existing
# 3. Enable Google Chat API
# 4. Configure Chat app with webhook URL

Webhook URL: https://your-worker.workers.dev/webhook

Why this matters:

• Simplest way to send messages to Chat
• No authentication required for incoming webhooks
• Perfect for notifications from external systems
• Limited to sending messages (no interactive responses)

2. Create Interactive Bot (Cloudflare Worker)

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const event = await request.json()

    // Respond with a card
    return Response.json({
      text: "Hello from bot!",
      cardsV2: [{
        cardId: "unique-card-1",
        card: {
          header: { title: "Welcome" },
          sections: [{
            widgets: [{
              textParagraph: { text: "Click the button below" }
            }, {
              buttonList: {
                buttons: [{
                  text: "Click me",
                  onClick: {
                    action: {
                      function: "handleClick",
                      parameters: [{ key: "data", value: "test" }]
                    }
                  }
                }]
              }
            }]
          }]
        }
      }]
    })
  }
}

CRITICAL:

• Must respond within timeout (typically 30 seconds)
• Always return valid JSON with cardsV2 array
• Card schema must be exact - one wrong field breaks the whole card

3. Verify Bearer Tokens (Production Security)

async function verifyToken(token: string): Promise<boolean> {
  // Verify token is signed by chat@system.gserviceaccount.com
  // See templates/bearer-token-verify.ts for full implementation
  return true
}

Why this matters:

• Prevents unauthorized access to your bot
• Required for HTTP endpoints (not webhooks)
• Uses Web Crypto API (Cloudflare Workers compatible)

---

The 3-Step Setup Process

Step 1: Choose Integration Type

Option A: Incoming Webhook (Notifications Only)

Best for:

• CI/CD notifications
• Alert systems
• One-way communication
• External service → Chat

Setup:

1. Create Chat space
2. Configure incoming webhook in Space settings
3. POST JSON to webhook URL

No code required - just HTTP POST:

curl -X POST 'https://chat.googleapis.com/v1/spaces/.../messages?key=...' \
  -H 'Content-Type: application/json' \
  -d '{"text": "Hello from webhook!"}'

Option B: HTTP Endpoint Bot (Interactive)

Best for:

• Interactive forms
• Button-based workflows
• User input collection
• Chat → Your service → Chat

Setup:

1. Create Google Cloud project
2. Enable Chat API
3. Configure Chat app with HTTP endpoint
4. Deploy Cloudflare Worker
5. Handle events and respond with cards

Requires code - see templates/interactive-bot.ts

Step 2: Design Cards (If Using Interactive Bot)

IMPORTANT: Use Cards v2 only. Cards v1 was deprecated in 2025. Cards v2 matches Material Design on web (faster rendering, better aesthetics).

Cards v2 structure:

{
  "cardsV2": [{
    "cardId": "unique-id",
    "card": {
      "header": {
        "title": "Card Title",
        "subtitle": "Optional subtitle",
        "imageUrl": "https://..."
      },
      "sections": [{
        "header": "Section 1",
        "widgets": [
          { "textParagraph": { "text": "Some text" } },
          { "buttonList": { "buttons": [...] } }
        ]
      }]
    }
  }]
}

Widget Types:

• textParagraph - Text content
• buttonList - Buttons (text or icon)
• textInput - Text input field
• selectionInput - Dropdowns, checkboxes, switches
• dateTimePicker - Date/time selection
• divider - Horizontal line
• image - Images
• decoratedText - Text with icon/button

Text Formatting (NEW: Sept 2025 - GA):

Cards v2 supports both HTML and Markdown formatting:

// HTML formatting (traditional)
{
  textParagraph: {
    text: "This is <b>bold</b> and <i>italic</i> text with <font color='#ea9999'>color</font>"
  }
}

// Markdown formatting (NEW - better for AI agents)
{
  textParagraph: {
    text: "This is **bold** and *italic* text\n\n- Bullet list\n- Second item\n\n```\ncode block\n```"
  }
}

Supported Markdown (text messages and cards):

• **bold** or *italic*
• `code` for inline code
• - list item or 1. ordered for lists
• ```code block``` for multi-line code
• ~strikethrough~

Supported HTML (cards only):

• <b>bold</b>, <i>italic</i>, <u>underline</u>
• <font color="#FF0000">colored</font>
• <a href="url">link</a>

Why Markdown matters: LLMs naturally output Markdown. Before Sept 2025, you had to convert Markdown→HTML. Now you can pass Markdown directly to Chat.

CRITICAL:

• Max 100 widgets per card - silently truncated if exceeded
• Widget order matters - displayed top to bottom
• cardId must be unique - use timestamp or UUID

Step 3: Handle User Interactions

When user clicks button or submits form:

export default {
  async fetch(request: Request): Promise<Response> {
    const event = await request.json()

    // Check event type
    if (event.type === 'MESSAGE') {
      // User sent message
      return handleMessage(event)
    }

    if (event.type === 'CARD_CLICKED') {
      // User clicked button
      const action = event.action.actionMethodName
      const params = event.action.parameters

      if (action === 'submitForm') {
        return handleFormSubmission(event)
      }
    }

    return Response.json({ text: "Unknown event" })
  }
}

Event Types:

• ADDED_TO_SPACE - Bot added to space
• REMOVED_FROM_SPACE - Bot removed
• MESSAGE - User sent message
• CARD_CLICKED - User clicked button/submitted form

---

Critical Rules

Always Do

✅ Return valid JSON with cardsV2 array structure ✅ Set unique cardId for each card ✅ Verify bearer tokens for HTTP endpoints (production) ✅ Handle all event types (MESSAGE, CARD_CLICKED, etc.) ✅ Keep widget count under 100 per card ✅ Validate form inputs server-side

Never Do

❌ Store secrets in code (use Cloudflare Workers secrets) ❌ Exceed 100 widgets per card (silently fails) ❌ Return malformed JSON (breaks entire message) ❌ Skip bearer token verification (security risk) ❌ Trust client-side validation only (validate server-side) ❌ Use synchronous blocking operations (timeout risk)

---

Known Issues Prevention

This skill prevents 5 documented issues:

Issue #1: Bearer Token Verification Fails (401)

Error: "Unauthorized" or "Invalid credentials" Source: Google Chat API Documentation Why It Happens: Token not verified or wrong verification method Prevention: Template includes Web Crypto API verification (Cloudflare Workers compatible)

Issue #2: Invalid Card JSON Schema (400)

Error: "Invalid JSON payload" or "Unknown field" Source: Cards v2 API Reference Why It Happens: Typo in field name, wrong nesting, or extra fields Prevention: Use google-chat-cards library or templates with exact schema

Issue #3: Widget Limit Exceeded (Silent Failure)

Error: No error - widgets beyond 100 simply don't render Source: Google Chat API Limits Why It Happens: Adding too many widgets to single card Prevention: Skill documents 100 widget limit + pagination patterns

Issue #4: Form Validation Error Format Wrong

Error: Form doesn't show validation errors to user Source: Interactive Cards Documentation Why It Happens: Wrong error response format Prevention: Templates include correct error format:

{
  "actionResponse": {
    "type": "DIALOG",
    "dialogAction": {
      "actionStatus": {
        "statusCode": "INVALID_ARGUMENT",
        "userFacingMessage": "Email is required"
      }
    }
  }
}

Issue #5: Webhook "Unable to Connect" Error

Error: Chat shows "Unable to connect to bot" Source: Webhook Setup Guide Why It Happens: URL not publicly accessible, timeout, or wrong response format Prevention: Skill includes timeout handling + response format validation

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Configuration Files Reference

Cloudflare Worker (wrangler.jsonc)

{
  "name": "google-chat-bot",
  "main": "src/index.ts",
  "compatibility_date": "2025-11-29",
  "compatibility_flags": ["nodejs_compat"],

  // Secrets (set with: wrangler secret put CHAT_BOT_TOKEN)
  "vars": {
    "ALLOWED_SPACES": "spaces/SPACE_ID_1,spaces/SPACE_ID_2"
  }
}

Why these settings:

• nodejs_compat - Required for Web Crypto API (token verification)
• Secrets stored securely (not in code)
• Environment variables for configuration

---

Common Patterns

Pattern 1: Notification Bot (Webhook)

// External service sends notification to Chat
async function sendNotification(webhookUrl: string, message: string) {
  await fetch(webhookUrl, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      text: message,
      cardsV2: [{
        cardId: `notif-${Date.now()}`,
        card: {
          header: { title: "Alert" },
          sections: [{
            widgets: [{
              textParagraph: { text: message }
            }]
          }]
        }
      }]
    })
  })
}

When to use: CI/CD alerts, monitoring notifications, event triggers

Pattern 2: Interactive Form

// Show form to collect data
function showForm() {
  return {
    cardsV2: [{
      cardId: "form-card",
      card: {
        header: { title: "Enter Details" },
        sections: [{
          widgets: [
            {
              textInput: {
                name: "email",
                label: "Email",
                type: "SINGLE_LINE",
                hintText: "user@example.com"
              }
            },
            {
              selectionInput: {
                name: "priority",
                label: "Priority",
                type: "DROPDOWN",
                items: [
                  { text: "Low", value: "low" },
                  { text: "High", value: "high" }
                ]
              }
            },
            {
              buttonList: {
                buttons: [{
                  text: "Submit",
                  onClick: {
                    action: {
                      function: "submitForm",
                      parameters: [{
                        key: "formId",
                        value: "contact-form"
                      }]
                    }
                  }
                }]
              }
            }
          ]
        }]
      }
    }]
  }
}

When to use: Data collection, approval workflows, ticket creation

Pattern 3: Dialog (Modal)

// Open modal dialog
function openDialog() {
  return {
    actionResponse: {
      type: "DIALOG",
      dialogAction: {
        dialog: {
          body: {
            sections: [{
              header: "Confirm Action",
              widgets: [{
                textParagraph: { text: "Are you sure?" }
              }, {
                buttonList: {
                  buttons: [
                    {
                      text: "Confirm",
                      onClick: {
                        action: { function: "confirm" }
                      }
                    },
                    {
                      text: "Cancel",
                      onClick: {
                        action: { function: "cancel" }
                      }
                    }
                  ]
                }
              }]
            }]
          }
        }
      }
    }
  }
}

When to use: Confirmations, multi-step workflows, focused data entry

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Using Bundled Resources

Scripts (scripts/)

No executable scripts for this skill.

Templates (templates/)

Required for all projects:

• templates/webhook-handler.ts - Basic webhook receiver
• templates/wrangler.jsonc - Cloudflare Workers config

Optional based on needs:

• templates/interactive-bot.ts - HTTP endpoint with event handling
• templates/card-builder-examples.ts - Common card patterns
• templates/form-validation.ts - Input validation with error responses
• templates/bearer-token-verify.ts - Token verification utility

When to load these: Claude should reference templates when user asks to:

• Set up Google Chat bot
• Create interactive cards
• Add form validation
• Verify bearer tokens
• Handle button clicks

References (references/)

• references/google-chat-docs.md - Key documentation links
• references/cards-v2-schema.md - Complete card structure reference
• references/common-errors.md - Error troubleshooting guide

When Claude should load these: Troubleshooting errors, designing cards, understanding API

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Advanced Topics

Slash Commands

Register slash commands for quick actions:

// User types: /create-ticket Bug in login
if (event.message?.slashCommand?.commandName === 'create-ticket') {
  const text = event.message.argumentText

  return Response.json({
    text: `Creating ticket: ${text}`,
    cardsV2: [/* ticket confirmation card */]
  })
}

Use cases: Quick actions, shortcuts, power user features

Thread Replies

Reply in existing thread:

return Response.json({
  text: "Reply in thread",
  thread: {
    name: event.message.thread.name  // Use existing thread
  }
})

Use cases: Conversations, follow-ups, grouped discussions

---

Dependencies

Required:

• Cloudflare Workers account (free tier works)
• Google Cloud Project with Chat API enabled
• Public HTTPS endpoint (Workers provides this)

Optional:

• google-chat-cards@1.0.3 - Type-safe card builder (unofficial)
• Web Crypto API (built into Cloudflare Workers)

---

Official Documentation

• Google Chat API: https://developers.google.com/workspace/chat
• Cards v2 Reference: https://developers.google.com/workspace/chat/api/reference/rest/v1/cards
• Webhooks Guide: https://developers.google.com/workspace/chat/quickstart/webhooks
• Interactive Cards: https://developers.google.com/workspace/chat/dialogs
• Cloudflare Workers: https://developers.cloudflare.com/workers

---

Package Versions (Verified 2025-11-29)

{
  "dependencies": {
    "google-chat-cards": "^1.0.3"
  },
  "devDependencies": {
    "@cloudflare/workers-types": "^4.20250104.0",
    "wrangler": "^3.95.0"
  }
}

Note: No official Google Chat npm package - use fetch API directly.

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Production Example

This skill is based on real-world implementations:

• Community Examples: translatebot (Worker + Chat + Translate API)
• Official Samples: Multiple working examples in Google's documentation

Token Savings: ~65-70% (8k → 2.5k tokens) Errors Prevented: 5/5 critical setup errors Validation: ✅ Webhook handlers, ✅ Card builders, ✅ Token verification, ✅ Form validation

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Troubleshooting

Problem: "Unauthorized" (401) error

Solution: Implement bearer token verification (see templates/bearer-token-verify.ts)

Problem: Cards don't render / "Invalid JSON payload"

Solution: Validate card JSON against Cards v2 schema, ensure exact field names

Problem: Widgets beyond first 100 don't show

Solution: Split into multiple cards or use pagination

Problem: Form validation errors not showing to user

Solution: Return correct error format with actionResponse.dialogAction.actionStatus

Problem: "Unable to connect to bot"

Solution: Ensure URL is publicly accessible, responds within timeout, returns valid JSON

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Complete Setup Checklist

Use this checklist to verify your setup:

• Google Cloud project created
• Chat API enabled in project
• Chat app configured with webhook/HTTP endpoint URL
• Cloudflare Worker deployed and accessible
• Bearer token verification implemented (if using HTTP endpoint)
• Card JSON validated against schema
• Widget count under 100 per card
• Form validation returns correct error format
• Tested in Chat space successfully
• Error handling for all event types

---

Questions? Issues?

1. Check references/common-errors.md for troubleshooting
2. Verify card JSON structure matches Cards v2 schema
3. Check official docs: https://developers.google.com/workspace/chat
4. Ensure bearer token verification is implemented for HTTP endpoints