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Inspiration
We watched moderators drown in tab switching. One tab for the modqueue, another for user history, another for AutoMod logs, another for third-party ban evasion trackers, and five more for spam pattern detection. By the time a mod stitched together enough context to make a decision, the toxic thread had already hit r/all and the subreddit was trending on Twitter for all the wrong reasons. We wanted one brain that could see the whole picture, score the risk, and hand the mod a verdict — not replace their judgment, just remove the detective work.
What it does
ModSentry is an AI-native moderation intelligence layer for Reddit, built entirely on Devvit. It does not swing ban hammers blindly. It thinks. The Sentry Core ingests every new post and comment in real-time, then fires parallel analysis across behavioral signals: account age velocity, cross-subreddit posting patterns, karma distribution entropy, comment-to-post ratio anomalies, and writing style consistency. Everything distills into a single Risk Score (0–100) — not based on keywords, but on behavior. The Command Dashboard replaces the flat, chronological modqueue with a priority-ranked battlefield view. Viral posts with reports float to the top. Trusted regulars sink to the bottom. Color-coded triage: 🔴 Urgent (behavioral anomaly + high engagement), 🟡 Review (borderline signals), 🟢 Trusted (clean history, approve in bulk). Mods see who handled what — no more accidental double-removals or approval wars. The Autonomous Wing handles the noise so mods handle the community. Bulk actions: one-click "Approve All 🟢" or "Hold All 🔴". Smart alerts: if a post hits >100 upvotes/hour AND accumulates reports, the team gets pinged before it becomes a PR disaster. Ban evasion tracking: flagged accounts that reappear with similar behavioral fingerprints get auto-tagged for review. All of this lives inside Reddit. No external server. No AWS bill that surprises you at 3am. Install from the App Directory, configure thresholds in a GUI, and go live in 60 seconds.
How we built it
We built ModSentry entirely on Reddit's Devvit platform — TypeScript, Redis KV for persistence, and Devvit Custom Posts for the mod dashboard. Architecture: Real-time scoring engine: Hooks into onPostSubmit and onCommentSubmit. Calculates suspicion scores using signals stored in Devvit Redis with 48-hour TTL. Priority queue API: A Custom Post component that reads from Redis and renders the sorted modqueue view directly inside the subreddit's mod tools panel. Alert scheduler: Devvit's cron scheduler checks every 5 minutes for viral posts with report spikes, then fires mod-mail via the native messaging API. Ban evasion tracker: Stores behavioral fingerprints (writing entropy, posting intervals, subreddit overlap) in Redis, then flags matches on new account creation within the community. Config UI: A Devvit Settings page with sliders for risk thresholds, toggle switches for each signal, and a whitelist manager — no YAML, no wiki editing, no PhD required. We used the Mod Tool template from Reddit's template library as our scaffold and extended it with the scheduler and KV store patterns from the Devvit docs.
Challenges we ran into
Our first prototype tried to do everything — AI detection, queue sorting, trust levels, automated responses, and a community leaderboard. It was a digital Swiss Army knife with 47 blades and no handle. Three days in, we realized judges would install it, get confused, and uninstall it before lunch. We killed half the features and focused on the two that actually hurt mods the most: queue overload and context starvation (not knowing if a user is a troll or a newbie). The second fight was Redis TTL management. Devvit's KV store has limits. We originally stored every post forever; the app hit storage caps on high-traffic subreddits within hours. We rebuilt the data layer with tiered expiration: raw signals expire in 6 hours, risk scores in 48 hours, and ban evasion fingerprints in 90 days. Graceful degradation — if Redis is full, the app falls back to real-time scoring without historical comparison. The third challenge was mobile moderation. Reddit's mobile mod tools are limited compared to old Reddit. We had to design all Custom Post components to be thumb-friendly and ensure Menu Actions work natively on the Reddit mobile app, not just desktop.
Accomplishments that we're proud of
The feature massacre. Walking away from our over-engineered prototype and shipping a tool that installs in one click and makes sense in 30 seconds. Scope discipline is a feature. Social-to-action in one breath. Watching a brand-new account post identical comments across three subreddits, seeing ModSentry flag it at 94 risk score, and holding it for review before a human mod even opened the queue. The mobile-native dashboard. Most Devvit apps feel like desktop tools squeezed into a phone. Our Custom Post renders clean, tappable cards that actually work while a mod is on the bus. Zero external dependencies. Everything lives on Reddit's platform. No serverless functions, no API keys to rotate, no downtime because someone's credit card expired.
What we learned
Polish beats features. The hackathon rubric weights "close to launch-ready" heavily. We spent our final 24 hours not adding features, but adding error handling, loading states, empty states, and a README that a non-technical mod could follow. That polish doubled our perceived reliability. Mods are users, not admins. We initially built for power-moderators who live in old Reddit. Then we watched a casual mod try to install it on mobile and get lost. We rebuilt the onboarding flow for someone who moderates 20 minutes a day from their phone. Context is the real moderation bottleneck. It is not that mods are lazy — it is that they lack information. Giving a mod a user's cross-subreddit behavior pattern is more valuable than giving them 50 AutoMod rules. What's next for ModSentry Studio LinkedIn and Instagram intelligence via external APIs so mods can verify if AMA guests are who they claim to be. Real-time voice transcription for subreddits that run Discord or Clubhouse AMAs — transcribe, sentiment-score, and flag toxic turns before they derail the conversation. Collaborative mod rooms: Shared workspaces where mod teams can annotate risk scores, debate borderline cases, and build team consensus without scattered DMs. Community health trends: Weekly automated reports showing subreddit toxicity velocity, trusted user retention, and newcomer conversion rates. Developer Funds 2026 pipeline: If ModSentry reaches 50+ Daily Qualified Engagers in SFW communities of 200+ members, we qualify for Reddit's ongoing payout program — turning a hackathon project into sustainable infrastructure.
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