📋⚡ Clipy — Cross-Device Universal Clipboard (Android + Desktop)

TL;DR: Copy on one device, paste on another. Clipy syncs clipboard text across devices using Firebase and lightweight clients for Android and desktop.

Overview • Features • Architecture • Data Model & Security • Usage • Roadmap • Notes

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Overview

Clipy is a universal clipboard that lets you copy text on one device and paste it on another with minimal friction.
The current repo includes:

• A desktop client (Python) that pushes/pulls clipboard text.
• An Android client (Java/Android Studio) prototype for mobile sync.
• A Firebase Realtime Database backend for transport and state.

Optional enhancement: FCM push to wake clients for near real-time sync without polling.

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Features

• One-tap copy/paste across devices
• Channel-based sync (link specific devices to a channel key)
• Stateless transport via Firebase Realtime Database
• Lightweight clients (Python desktop + Android)
• Graceful fallbacks (polling) with optional push (FCM) integration

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Architecture

1) High-Level Map

flowchart LR
  subgraph Clients
    D["Desktop Client<br/>(Python + pyperclip)"]
    A["Android App<br/>(Java/Android)"]
  end

  subgraph Firebase["Firebase Backend"]
    RTDB["Realtime Database<br/>(/clipboards/<channelId>)"]
    FCM["Optional: FCM Push<br/>notify device to pull"]
  end

  D <--> RTDB
  A <--> RTDB
  FCM --> D
  FCM --> A

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2) Copy → Transport → Paste

sequenceDiagram
  autonumber
  participant User as User
  participant D as Desktop
  participant A as Android
  participant RT as RTDB
  participant P as (Optional) FCM

  User->>D: Copy text (OS clipboard)
  D->>RT: Write {text, ts, from, channelId}
  Note right of RT: onDataChange triggers on clients
  RT-->>A: onDataChange delivers payload
  A->>A: Validate channel + freshness
  A-->>User: Paste into focused input (UX flow)
  alt optional push
    RT->>P: Emit notification
    P->>A: Wake / fetch latest
  end

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Data Model & Security

RTDB Paths

/clipboards/<channelId>/messages/<pushId> = {
  "text": "<string>",
  "from": "<deviceId>",
  "ts":  "<epochMillis>"
}

Transport & Privacy

• Use channel IDs (shared secret) to isolate devices.
• Prefer data messages via FCM (optional) to nudge clients, and pull content from RTDB to avoid putting clipboard content in push payloads.
• Consider client-side encryption of text (e.g., AES-GCM) if you want end-to-end protection; store only ciphertext and metadata in RTDB.

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Usage

• Pick a channelId (e.g., family-room, dev-laptop-phone).
• Launch desktop client with that channel; pair Android app with the same channel.
• Copy on one device → paste on another.

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Roadmap

• 🔒 End-to-end encryption with device keys
• 📸 Image/file payloads with temporary object storage (S3/GCS) + signed URLs
• 🔔 Push-first flow (FCM data messages) to reduce polling
• 🧪 Conflict handling & per-message ACKs
• 🖥️ Native desktop tray UI + auto-start
• 📱 Android foreground service + battery-aware backoff

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Notes

• This repository currently focuses on text payloads and a Firebase RTDB transport with Python & Android prototypes.