Reply Collision Detector
Build an internal tool that shows when a teammate already has a thread open or is drafting a reply, and warns the next person before they double-answer the same customer.
A login-protected presence and soft-lock board where opening a thread claims it, teammates are warned before they reply to a claimed thread, locks auto-expire, and every claim, release, and override is audited.
Before you start
- A free Supabase account
- A free Vercel account
- A free Resend account (for optional email alerts)
- A list of your shared threads/tickets (or a spreadsheet you can paste in)
The problem this kills
You share an inbox or a support queue. A customer writes in. Two agents open the same thread within seconds of each other, both type a thoughtful reply, and both hit send. Now the customer has two answers - sometimes contradicting each other - and your team looks disorganized. The "wait, did you already get this one?" Slack message is a daily tax on a busy queue.
Most shared inboxes have no real collision detection. You're flying blind on who is looking at what right now. The result is wasted effort, duplicate replies, awkward customer experiences, and threads that quietly get ignored because everyone assumed someone else "had it."
What you'll build
A simple, login-protected web app that sits alongside your queue and answers one question at a glance: who is on which thread right now?
- Open a thread and it shows a live presence indicator to everyone else on your team.
- Take a soft-lock to claim a thread - a gentle "I've got this" that others can see.
- When a second agent opens a claimed thread, they get a clear warning (or a block) before they can reply.
- Locks auto-expire after an idle timeout, so a thread never gets stuck owned by someone who wandered off.
- Releasing happens automatically on send or timeout, or anyone can override a stale lock - and every override is logged.
What's inside the Implementation Plan
The plan opens by interviewing you about your business - your queue, your tools, your team size, your busiest hours, and the exact way you work - so the tool is tailored to you, not a generic template. It reflects a short spec back to you for a thumbs-up before a single line is built.
From there it walks you, step by step, through building the whole thing by pasting ready-made prompts into an AI coding agent. You'll set up the database, the login, the live presence board, the soft-lock and warning logic, the auto-expiry, the audit trail, and optional email alerts. Each step ends with a copy-paste prompt. No prior coding required.
The governance it includes (this is the point)
This isn't a toy. The plan builds in the controls that make an internal tool safe to actually use:
- Login so only your team can see and use the board.
- Row-level security so each organization only ever sees its own threads and activity.
- A complete audit trail - every claim, release, override, and expiry is recorded with who and when.
- A human-in-the-loop claim gate - a lock is only taken when an agent explicitly claims a thread, never silently.
- Duplicate guards - the unique key is thread + active lock, so the same thread can't be double-claimed and the same input can't be processed twice.
Who it's for
Teams sharing an inbox, help desk, or chat queue that has no built-in collision detection - support, success, operations, dispatch, or any group where two people answering the same message is a real and recurring problem.
You've got this - paste the first prompt and let the agent interview you.