Automate Daily Hacker News Digest with LangChain
A step-by-step guide to building a daily news digest agent with LangChain. The agent fetches, summarizes, and ranks Hacker News stories by your interests, then emails you a clean digest every morning.
Build an agent that scrapes the top 10 Hacker News stories every morning, summarizes each article using GPT-4, scores them by relevance to your interests, and delivers a formatted digest to your email inbox via Resend.
LangChain, OpenAI GPT-4, Node.js, Cheerio, Resend API, node-cron
Fetch top stories
Use the HN API (/v0/topstories.json) to get the current top 10 story IDs, then fetch each story's title, URL, and score.
Scrape article content
For each URL, use Cheerio to extract the main article text (skipping paywalled sites gracefully).
Summarize with GPT-4
Pass each article's text to a LangChain LLM chain with the prompt: "Summarize this article in 2-3 sentences. Highlight why a developer would care."
Score relevance
Use a second chain to rate each summary 1-10 against a user-defined interest profile (e.g. "AI, distributed systems, startups") stored in a .env variable.
Format and send email
Compile the ranked summaries into an HTML email template and send via Resend API at 8am using a cron trigger.
Daily HN Digest — Feb 15, 2026 1. [9/10] Show HN: I built a local-first database in Rust A developer built a SQLite alternative optimized for edge computing with CRDT-based sync. Relevant because it combines distributed systems and Rust — two of your top interests. 2. [8/10] OpenAI announces GPT-5 reasoning benchmarks New benchmark results show 40% improvement on multi-step math and coding tasks. Directly relevant to AI engineering workflows. 3. [7/10] Why we moved from Kubernetes to plain VMs A startup shares their journey back to simplicity after K8s operational overhead exceeded their team's capacity. 4. [6/10] PostgreSQL 18 beta adds native JSON schema validation The upcoming release includes JSON Schema support directly in CHECK constraints. Useful for teams validating API payloads at the database layer. 5. [5/10] The state of WebAssembly in 2026 A comprehensive overview of WASM adoption in production. Covers edge computing, plugin systems, and browser-based IDEs. ... (5 more stories) Delivered to: james@example.com at 8:00 AM PST
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