Subreach: Building Two AI Agents for Reddit
Reddit is full of people describing problems out loud. Founders ask what others are building, site owners ask why Google is ignoring their pages, and small business owners ask for help they cannot find elsewhere.
This article describes the development of Subreach, an AI-powered automation system designed to engage with Reddit threads by deploying two distinct AI agents. The system is built to address specific user needs on the platform, promoting a SaaS tool while also providing genuine SEO assistance.
What happened
The author developed Subreach, an AI automation system for Reddit, which uses two agents to engage with users. One agent promotes a SaaS tool, while the other provides SEO assistance. The system is designed to operate independently, with each agent having its own rules, configuration, and workflow.
Why it matters
This project is significant for AI developers and automation enthusiasts as it demonstrates how AI can be used to engage with online communities effectively. It also highlights the importance of separating tasks and intent in AI agent design to ensure quality and relevance.
- Separate agents by intent rather than by task to ensure clarity and quality.
- Use cost-effective models for decision-making and reserve stronger models for output.
- Small constraints can significantly improve the quality of AI-generated content.
- Configuration over code allows for easier adjustments to target audiences and workflows.
- Model routing and cost optimization are essential for scalable AI systems.
The bigger picture
Subreach has the potential to improve user engagement on Reddit by providing timely and relevant responses. It also serves as a model for how AI can be used to automate interactions in online communities, with implications for customer engagement and product promotion.
Subreach is a well-designed AI automation system that effectively engages with Reddit users by deploying two distinct agents. It demonstrates the importance of intent-based design, model optimization, and configuration management in AI development.
Technical details
- Two AI agents operate independently with their own configurations and rules.
- The system uses a pipeline that includes search, filtering, commenting, and tracking.
- Model routing is used to optimize cost and performance, with gpt-5-nano for filtering and gpt-4o-mini for comment generation.
- The system uses Playwright and Chrome DevTools Protocol for comment submission.
- Configuration files are used to manage subreddits, queries, and timing.
FAQ
What are the two agents in Subreach?
Subreach uses two agents: the marketing agent, which promotes the SaaS tool, and the knowledge agent, which provides SEO assistance.
How does the system decide which threads to respond to?
The system uses a filtering step where a language model checks each post against specific rules to determine if it should be approved for a response.
What models are used in Subreach?
The filtering step uses gpt-5-nano for cost efficiency, while comment generation uses gpt-4o-mini for better writing quality.
How are comments submitted on Reddit?
Comments are typed into an already logged-in Chrome tab using Playwright and the Chrome DevTools Protocol, with a small delay between keystrokes.
Where can I find the full code for Subreach?
The full code, including both agents and their configuration, is available on GitHub at github.com/bluntjudg/autopilot.
This summary and analysis were generated with AI from the original article and may contain errors. Read the original for the full story.
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Originally published by Dev.to AI on Oct 4, 2026.
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