Mod Welcome Bot

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  Devvit code structure and successful cloud upload confirmation via CLI.

## Inspiration

Managing a growing community on Reddit is hard work, and one of the biggest pain points for moderators is getting new members to understand and respect community guidelines from day one. Often, users ignore the sidebar rules, leading to formatting issues, spam, and an overloaded moderation queue. I wanted to build a seamless tool that bridges this gap right at the moment of entry.

## What it does

Mod Welcome Bot is a lightweight background application designed specifically for subreddit onboarding. The moment a user clicks "Join", the application catches the background event and automatically dispatches a personalized private message to that newcomer. This message contains a warm welcome alongside direct, clean access to the subreddit's specific rules and posting requirements.

## How we built it

The app is built entirely using TypeScript and the Reddit Developer Platform (Devvit). By leveraging Devvit's native event triggers (SubredditJoin) and the automated Reddit API services, the bot runs completely serverless and independent of any external databases, ensuring it can scale effortlessly to handle large waves of community joins.

## Challenges we ran into

Building the application under a tight deadline came with environment configuration hurdles. Locally, Devvit's testing framework defaults to port 5678, which caused direct conflicts with my existing self-hosted infrastructure tools like n8n. Because the local CLI port configuration was rigid, I overcame this blocker by bypassing local playtesting altogether and deploying/uploading the builds directly onto Reddit's developer cloud infrastructure. This adaptation allowed me to successfully test the bot live on a private test community.

## Accomplishments that we're proud of

I am proud of creating a highly practical, "one-feature MVP" that works perfectly without any performance bloat. The onboarding experience for a subreddit moderator is entirely seamless: they simply click "Add to community" on the portal, and the bot handles everything else in the background.

## What we learned

During this quick sprint, I deep-dived into Reddit's new Devvit framework and learned how effectively it handles serverless background triggers. I also realized that when local environments present stubborn port blockages, pivoting quickly to direct cloud deployment (devvit upload) is a powerful way to keep moving forward and hit tight deadlines.

## What's next for Mod Welcome Bot

The next step is to introduce customizable welcome text directly through a Devvit UI custom post component. This will allow subreddit moderators to dynamically change the welcome message template directly within Reddit without modifying a single line of code.

Built With

• devvit
• node.js
• typescript