Subreddit Pulse 🔴

An AI-powered app that turns any subreddit into a structured daily digest — built to show how tool use lets a small model punch above its weight.

🔗 Try the live app on Hugging Face Spaces

What it does

Give it a subreddit and a date, and Subreddit Pulse searches for that day's posts and returns a concise, structured summary: overall themes, notable posts with links, repeated questions and issues, and a takeaway. You can steer the emphasis with free-text preferences (e.g. "focus on performance problems" for r/MicrosoftFabric).

Why this architecture

The interesting design decision is not using a large model. Subreddit Pulse runs on gpt-4o-mini — a small, cheap model — and gets its capability from tooling instead:

• Retrieval does the heavy lifting. A Tavily search tool (domain-restricted to reddit.com, advanced search depth) fetches real, current posts. The model never has to "know" anything about the subreddit — it only has to summarise what's in front of it.
• Grounding rules over model size. The system prompt forbids inventing posts, scores, or trends, and requires the model to be transparent when retrieval is thin. Honest limitations beat confident hallucination.
• Guardrails in code, not prompts. Date normalisation, input validation, and a 30k-character context cap are handled in Python before the model is ever called.

The result: a useful, deployable app for a fraction of the cost of a frontier-model pipeline — retrieval quality, not model size, is what determines output quality.

Architecture

User input (subreddit, date, preferences)
        │
        ▼
normalize_date_for_search()          ← input validation in code
        │
        ▼
Tavily search  ──────────────────────  domain-locked to reddit.com
        │
        ▼
Formatted results (capped at 30k chars)
        │
        ▼
gpt-4o-mini + grounding system prompt
        │
        ▼
Structured digest (Gradio UI)

Stack

Python · OpenAI API (gpt-4o-mini) · Tavily Search · Gradio · Hugging Face Spaces

Run it locally

git clone https://github.com/ailinnesse/subreddit-pulse.git
cd subreddit-pulse
pip install -r requirements.txt

Create a .env file (see .env.example):

OPENAI_API_KEY=your-key
TAVILY_API_KEY=your-key

Then:

python app.py

Known limitations

• Tavily is a web search tool, not the Reddit API — coverage of a given day is good but not exhaustive, and post scores/comment counts aren't always available. The app is explicit about this in its output rather than papering over it.

About

Built by Tatiana Patrusheva (LinkedIn) as part of an agentic AI engineering course, then extracted into a standalone project. The original community contribution lives in the course repo; this is the canonical home.

May 2026