My Agentic AI Coding Setup with Copilot CLI - Making a Kotlin Multiplatform App for 13 Platforms

Hey everyone, Arnav here! It’s been a while, but I’m incredibly excited to finally share a massive update on my latest side project: 2FAC.

2FAC is an open-source, "bring-your-own-cloud" two-factor authentication app. I wanted a solid alternative to Authy and Google Authenticator that doesn't rely on a centralized server and actually syncs seamlessly across all my devices—including wearables and the terminal.

✨ Features & Where it Runs:

📱 Everywhere you need it: Android, iOS, WearOS, watchOS, Windows, Mac, Linux (Ubuntu), Web (PWA), and browser extensions (Chrome/Firefox).

💻 GUI & CLI: Full graphical apps built with Compose/Kotlin Multiplatform, plus super lightweight (2MB) native CLI apps with animations.

☁️ Bring Your Own Cloud: Back up your secrets locally or directly to your own Google Drive/iCloud (supports both encrypted and plain text backups).

🔒 Secure: Biometric unlock support (Face ID/Touch ID) across devices.

🤖 The "Vibe Coding" Process:
The craziest part? I built almost this entire 100k+ line codebase without typing in an IDE. In the second half of the video, I break down my AI agent workflow (using Copilot, Claude, etc.), how I use custom skills, structured planning, and automated UI testing with Maestro to keep the AI on track.

⚠️ Disclaimer: We are super close to a 1.0 release, but please do not migrate your real, production 2FA secrets to this app just yet!

Want to try it out or contribute?
The code is fully open-source and I would love some help squashing bugs and adding features before the official app store launch.

GitHub Repo: https://github.com/championswimmer/TwoFac

Check the releases tab for unsigned APKs, EXEs, DMGs, and CLI binaries to test out!

Let me know what you think in the comments, or hit me up on Twitter/GitHub. Thanks for watching!

[00:00:00] Project Overview & Motivation - Why build a new 2FA app (replacing Authy) and project goals.
[00:03:31] Android App Demo - Core features, account management, and biometric unlock on Android.
[00:04:19] iOS & watchOS App Demo - Testing the app on Apple devices and Apple Watch.
[00:05:32] Desktop App Demo - Running the Compose multi-platform app natively on desktop.
[00:06:05] System Tray Integration - Using the app directly from the system notification tray.
[00:07:05] Command Line Interface (CLI) Demo - Managing 2FA codes directly from the terminal.
[00:08:44] Browser Extension Demo - Running 2fac as a Firefox developer extension.
[00:10:00] Web App (PWA) Demo - Accessing the fully local web application front-end.
[00:11:40] Secure Unlock & Passkeys - Simulating fingerprint and Face ID authentication across platforms.
[00:16:30] GitHub Repository & 1.0 Release Plans - Current state of the open-source code and upcoming release.
[00:17:30] CI/CD Pipeline Setup - How artifacts (extensions, EXEs, DMGs, APKs) are built and distributed.
[00:19:00] AI Agentic Coding Workflow - Explaining the `agents.md` setup and how AI built the app without an IDE.
[00:23:50] Production Usage Warning - Why you shouldn't use it for production accounts until a stable release.
[00:26:00] Custom AI Agent Skills - Deep dive into the `.agents/skills` folder and how Copilot/Claude consume them.
[00:28:30] Automated Planning & Roadmaps - Prompting the AI to generate phase-wise development plans.
[00:31:14] UI Testing with Maestro - Setting up an AI skill to run automated UI tests and verify app functionality.
[00:35:12] Creating Custom AI Agents - Configuring specific models and instructions for tasks like Git operations.
[00:38:34] Codebase Test Coverage - Reviewing tests for the shared KMP library, backups, and crypto modules.
[00:41:30] AI-Driven Test-Driven Development (TDD) - How AI changes the development loop by focusing on test harnesses.