ModMutex

ModMutex War Room: Displays queue health status, active locks, average resolution time, and alerts for stale claims in real-time.
Lock Queue: Provides a clear real-time feed of currently checked-out posts, ensuring absolute mutual exclusion for the mod team.
Leaderboard: Gamifies mod coordination by displaying resolved claim counts and average resolution speeds for the entire team.
Configuration: Setup secure BYOK AI triage providers (Gemini/OpenAI) and view the streamlined checkout-to-resolution workflow.

Inspiration

ModMutex was inspired by a small but constant problem in large moderation teams: duplicate review work. When several moderators are clearing the queue at the same time, two people can unknowingly inspect the same post, waste effort, or even take conflicting actions.

This is a coordination problem, not a policy problem. The inspiration was to bring a simple “checkout” model to Reddit moderation, like claiming a task before working on it.

What it does

ModMutex lets moderators claim posts while they review them. When a moderator checks out a post, ModMutex creates an atomic lock, applies a visible “Reviewing” flair, and shows the claim in a War Room dashboard.

ModMutex (LockStep) is a real-time, atomic modqueue coordination tool built natively on Reddit's Devvit platform.

Large subreddits suffer from a major, often invisible inefficiency: moderation race conditions. Multiple moderators reviewing the same flagged post at the same time wastes effort and can result in conflicting actions (one mod approves while another removes minutes later). This inefficiency costs mod teams 30–40% of their review time.

ModMutex solves this by allowing moderators to "Checkout" a post. When a post is claimed:

Atomic Locking: It locks the post using Redis SET NX — guaranteeing exactly one mod wins the lock and preventing race conditions.

Live Flair Badges: It instantly applies a flair badge (🔒 Reviewing – u/ModName) so the entire team can see who is actively reviewing it.

Auto-Release: The moment the reviewing moderator takes action (approves, removes, or spams the post), the onModAction Devvit trigger automatically releases the lock and restores the original flair.

AI Triage Briefing: Optionally, the moment a post is checked out, the mod receives an instant 1-sentence AI briefing summarizing any potential rule violations.

The app prevents duplicate claims, supports manual release, force override, stale lock cleanup, original flair restoration, and auto-release when a moderator approves, removes, or spams the post.

The War Room Dashboard:

ModMutex features a stunning, custom-built "Operations Center" dashboard accessible via the subreddit menu. It provides a real-time view of all active locks, queue health, and a moderator leaderboard showing who has resolved the most claims and their average resolution time.

How we built it

ModMutex was built with Devvit, TypeScript, Hono, Redis, Reddit moderation events, scheduled cleanup jobs, and a custom Devvit Web dashboard.

The core lock uses Redis SET NX, which guarantees that only one moderator can claim a post at a time. Devvit event handlers listen for moderation actions and release the claim automatically. The dashboard shows active locks, queue health, stale lock status, and moderator activity.

Challenges we ran into

The hardest challenge was making locks reliable in real moderation conditions. A moderator might leave, a page might refresh, a post might already have flair, or a moderation action might happen outside the dashboard.

To handle that, ModMutex stores original flair data, detects stale locks, supports force override, and releases claims automatically after real mod actions.

Accomplishments that we're proud of

I’m proud that ModMutex solves a real coordination problem with a simple interaction. Moderators do not need to learn a complicated workflow: check out, review, act, and the app releases the claim.

I’m also proud of the War Room dashboard, which turns hidden queue coordination into a visible team surface.

What we learned

I learned how useful atomic Redis operations are for Devvit apps. SET NX made it possible to build a real concurrency-safe moderation tool. I also learned that good moderation tools should fit naturally into existing habits instead of forcing moderators into a separate system.

What's next for ModMutex

Next, I would add cross-mod notifications, richer queue analytics, per-moderator workload views, configurable stale-lock timing, and deeper integration with Reddit’s modqueue so claims can be created from more review surfaces.