Hacker News Summarizer

A Google Apps Script application that fetches top Hacker News articles, generates AI summaries, and posts them to Slack.

Features

• 🔥 Hacker News Integration: Fetches top stories from Hacker News API
• 🤖 AI Summarization: Uses Gemini AI to generate concise Japanese summaries
• 💬 Slack Integration: Posts formatted summaries with article titles and discussion links

Setup

1. Development Environment

Prerequisites

• Node.js (managed via Nix)
• TypeScript (included in dev dependencies)
• Google Apps Script CLI (clasp)
• Google Cloud Project with Gemini API access
• Slack workspace with bot permissions

Environment Setup

# Using Nix (recommended)
nix develop

# Install dependencies
npm install

# Setup Google Apps Script CLI (first time only)
npx clasp login
npx clasp create --type standalone --title "Hacker News Summarizer"

# Clone existing project (optional)
npx clasp clone <PROJECT_ID>
npx clasp pull

clasp.json Configuration

Note: clasp.json is excluded from git as it contains project-specific settings.

After setting up your Google Apps Script project, create a clasp.json file in the project root:

{
  "scriptId": "your-google-apps-script-project-id",
  "rootDir": "./dist"
}

How to find your Script ID:

1. Open your Google Apps Script project in the web editor
2. Click ⚙️ Project Settings in the left sidebar
3. Copy the Script ID from the IDs section
4. Paste it into your clasp.json file

Alternative: Use npx clasp create or npx clasp clone <PROJECT_ID> to automatically generate this file.

2. Google Apps Script Configuration

Script Properties

Configure the following properties in Google Apps Script:

Property	Description	Required	Default
GEMINI_API_KEY	Gemini AI API authentication key	✅	-
SLACK_BOT_TOKEN	Slack Bot User OAuth Token	✅	-
SLACK_CHANNEL_ID	Target Slack channel ID	✅	-
ARTICLE_COUNT	Number of articles to process	❌	3

Triggers Setup

Set up automated execution:

1. Function to run: main (for both time-driven and manual execution)
2. Deployment: Head
3. Event source: Time-driven
4. Trigger type:
   • Hour timer (recommended for production)
   • Minute timer (for testing only)
5. Interval: Every 6 hours (recommended)
6. Failure notifications: Daily

API Permissions

Required OAuth scopes (automatically configured):

• https://www.googleapis.com/auth/script.external_request
• https://www.googleapis.com/auth/script.scriptapp

3. Build and Deploy

# Build the project (type check + compile + bundle for Google Apps Script)
npm run build

# Deploy to Google Apps Script
npx clasp push

# Create a new deployment (optional)
npx clasp deploy --description "Hacker News Summarizer v1.0"

Usage

Manual Execution

// In Google Apps Script editor
main()  // Returns: "X summaries posted."

Automated Execution

Set up time-driven triggers in the Google Apps Script editor:

1. Go to Triggers (⏰) in the left sidebar
2. Click + Add Trigger
3. Choose function: main
4. Choose event source: Time-driven
5. Choose type: Hour timer or Day timer
6. Choose interval as needed (e.g., Every 6 hours)

Entry Points

• main(): Main processing function (synchronous)
  • Returns: String with number of summaries posted
  • Usage: Direct execution in GAS editor or via triggers

Configuration

Rate Limiting

• Gemini API: 1000ms delay between requests
• Slack API: 2000ms delay between posts
• Configurable via withRateLimit() higher-order function

Article Processing

• Default count: 3 articles (configurable via ARTICLE_COUNT)
• Source: Top 30 Hacker News stories
• Filtering: Auto-filters deleted/dead articles
• Comments: Up to 10 comments per article

AI Prompts

Prompts are externalized in src/prompts.yaml:

• Japanese output format
• Structured summary format
• Configurable without code changes

Development

Build Process

1. YAML Processing: Converts prompts.yaml to TypeScript with strict type definitions
2. TypeScript Type Checking: Validates all code with strict compiler settings
3. esbuild Bundling: Single file output for Google Apps Script
4. Manifest Copy: Copies Apps Script manifest to dist

Generated files:

• src/loadedPrompts.ts: Auto-generated from YAML with typed interfaces

API Integrations

Hacker News API

• Endpoint: https://hacker-news.firebaseio.com/v0/
• Rate Limit: No official limit (built-in delays for safety)
• Data: Top stories, article details, comments

Gemini AI

• Model: gemini-1.5-pro
• Rate Limit: ~15 RPM (Free tier)
• Input: Article content + comments
• Output: Japanese summary

Slack API

• Method: chat.postMessage
• Format: Rich attachments with titles and links
• Rate Limit: ~1 message per second

References

• Nix Package Manager
• Google Apps Script
• esbuild
• Hacker News API
• Gemini AI API
• Slack API