diff --git a/AI_INIT.md b/AI_INIT.md
index 09d6df3..1afc5bc 100644
--- a/AI_INIT.md
+++ b/AI_INIT.md
@@ -3,85 +3,57 @@
Welcome to the KoalaSync project. This file is the primary entry point for any developer or AI agent working on this codebase. It defines the architecture, non-negotiables, and workflows required to maintain the stability and security of the system.
> [!IMPORTANT]
-> **Privacy & Data Sovereignty**: KoalaSync follows a strict **Zero-External-Requests Policy**: The extension and website must not make requests to any third-party domains (Google Fonts, CDNs, etc.). All assets (fonts, icons, scripts) must be self-hosted or use system defaults.
-> - **Font Stack**: Use a modern system font stack (e.g., -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif) to maintain a premium look without external dependencies. Prohibit the use of `@import` or ` ` for external font services.
+> **Privacy & Data Sovereignty**: KoalaSync follows a strict **Zero-External-Requests Policy**: The extension and website must not make requests to any third-party domains. All assets must be self-hosted.
+> - **Font Stack**: Use a modern system font stack to maintain a premium look without external dependencies.
---
## 1. Project Overview
-KoalaSync is a specialized tool for **synchronized video playback** across multiple remote peers. It supports YouTube, Twitch, and native HTML5 video elements.
-- **Users**: Friends or groups wanting to watch synchronized content together.
-- **Workflow**: A user creates a room, shares an invite link (RoomID#Password), and all peers in that room are synchronized via a Node.js relay server.
+KoalaSync is a specialized tool for **synchronized video playback** across multiple remote peers.
+- **Workflow**: A user creates a room, shares an invitation link, and all peers are synchronized via a Node.js relay server.
+- **Identity**: Users are identified by a unique hex `peerId` combined with a customizable `username`.
## 2. Repository Structure
-- `extension/`: Chrome Extension (Manifest V3). Contains background service worker, content scripts, and popup UI.
+- `extension/`: Chrome Extension (Manifest V3).
- `server/`: Node.js Relay Server using Socket.IO (WebSocket-only).
-- `website/`: **Landing Page** (Marketing, Tutorials, and Downloads).
-- `shared/`: **Single Source of Truth** for protocol constants and event names.
-- `scripts/`: Utility scripts (e.g., `sync-constants.sh`).
-- `docker-compose.yml`: Root-level orchestration for the relay server.
-
-> [!IMPORTANT]
-> `shared/constants.js` and `shared/blacklist.js` must be synchronized to the `extension/shared/` directory after every modification by running `./scripts/sync-constants.sh`.
+- `website/`: Landing Page & Invitation Bridge.
+- `shared/`: Single Source of Truth for protocol constants and event names.
## 3. Mandatory Reading
-Before touching any code, you MUST read the following documents in order:
-1. [ARCHITECTURE.md](ARCHITECTURE.md) – Detailed communication flows and two-phase sync protocol.
-2. [shared/README.md](shared/README.md) – Protocol constants and synchronization requirements.
-3. [extension/README.md](extension/README.md) – Extension components and loading process.
-4. [server/README.md](server/README.md) – Server setup, Docker configuration, and security.
+1. [ARCHITECTURE.md](ARCHITECTURE.md) – Communication flows and Dual Heartbeat protocol.
+2. [extension/README.md](extension/README.md) – UI structure and component overview.
## 4. Design Guidelines
-The popup UI follows a strict design system. Do not modify these variables or the layout structure without explicit approval.
-- **Font**: System font stack (e.g., `-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif`). **MANDATORY**: No external CDNs or Google Fonts to ensure 100% privacy.
- **Popup Width**: Fixed at `320px`.
-- **Tab Structure**: Must maintain the **Room**, **Sync**, and **Dev** tabs.
-- **CSS Variables**:
- | Variable | Value | Purpose |
- | :--- | :--- | :--- |
- | `--bg` | `#0f172a` | Main background |
- | `--card` | `#1e293b` | Form and info cards |
- | `--accent` | `#6366f1` | Primary actions and branding |
- | `--success` | `#22c55e` | Success states / Online dot |
- | `--error` | `#ef4444` | Errors / Offline dot |
+- **Tab Structure**: **Room**, **Sync**, **Settings**, and **Dev**.
+- **CSS Variables**: Uses the CSS variables defined in `popup.html` for a consistent Dark Mode / Glassmorphic look.
## 5. Non-Negotiables (Core Logic)
-The following features are critical and must not be removed or fundamentally altered:
-- **Two-Phase Force Sync**: The `Prepare` → `ACK` → `Execute` flow ensures all peers are buffered before playback resumes.
-- **Platform Specifics**: Specialized click-logic for YouTube (`.ytp-play-button`) and Twitch play/pause buttons in `content.js`.
-- **pollSeekReady()**: The polling mechanism that checks `video.readyState` and `currentTime` offset before acknowledging a sync command.
-- **SW Keep-alive**: Use of `chrome.alarms` to prevent the Manifest V3 Service Worker from suspending.
-- **Exponential Backoff**: Reconnection logic in `background.js` (1s → 30s max).
-- **Rate Limiting**: IP-based connection limits (10/min) and socket-based event limits (30/10s) on the server.
-- **Security**: Token validation during the initial WebSocket handshake.
-- **Persistence**: `peerId` must be stored in `chrome.storage.local` to remain stable across sessions.
+- **Two-Phase Force Sync**: `Prepare` → `ACK` → `Execute` flow for frame-perfect sync.
+- **Dual Heartbeat**:
+ - **Background Heartbeat (30s)**: Keeps the session alive even without a video.
+ - **Content Heartbeat (15s)**: Transmits current video metadata (title, time).
+- **Dead Peer Pruning**: Server automatically disconnects peers after 5 minutes of total silence.
+- **Deduplication**: Server kills old sockets if a user re-joins with the same `peerId`.
+- **Diagnostics**: The "Dev" tab provides real-time access to the underlying `` state for troubleshooting.
## 6. Technical Constraints
-- **No Bundler**: The extension uses plain ES Modules. Do not introduce build steps or npm packages into the `extension/` folder.
-- **Manual Protocol**: `background.js` implements a subset of the Socket.IO wire protocol (e.g., `42[...]` framing) to work with native WebSockets.
-- **Server Transport**: Restricted to `websocket` only. Polling is disabled.
-- **Docker Context**: The Docker build must run from the **Repo Root**, as it needs access to the `shared/` directory.
-- **Manifest Settings**: `run_at` must remain `document_idle`, and `all_frames` must remain `false`.
+- **No Bundler**: Plain ES Modules only.
+- **Socket.IO Protocol**: Manual implementation of the wire protocol in `background.js`.
+- **Docker Context**: Must build from the **Repo Root**.
## 7. Security & Deployment
-- **Tokens**: `OFFICIAL_SERVER_TOKEN` and `OFFICIAL_SERVER_URL` are intentionally hardcoded in `constants.js` by design.
-- **Environment**: `.env` is excluded via `.gitignore`. Only `.env.example` should be committed.
-- **Revocation**: `MIN_VERSION` in the server configuration is the only way to deprecate old extension versions.
-- **Token Rotation**: Requires updating `shared/constants.js`, running the sync script, incrementing the extension version, and re-deploying the server.
+- **Invitation Links**: Correctly propagate server URLs and room credentials via the URL hash.
+- **Rate Limiting**: IP and socket-based limits are enforced server-side.
+- **Persistence**: `peerId` and `username` must persist across browser sessions.
## 8. Common Workflows
-### Adding a Protocol Event
-1. Add the event name to `shared/constants.js`.
-2. Run `./scripts/sync-constants.sh`.
-3. Implement the handler in `server/index.js` and `background.js`.
+### Modifying the Protocol
+1. Edit `shared/constants.js`.
+2. Run `scripts/sync-constants.bat` (Windows) or `scripts/sync-constants.sh` (POSIX).
+3. Restart the server and reload the extension.
-### Testing Locally
-1. Load `extension/` as an "Unpacked Extension" in Chrome.
-2. Start the server from the root: `docker-compose up --build`.
-3. Select "Custom" server in the popup and enter `ws://localhost:3000`.
-
-### Locking Old Versions
-1. Increase `APP_VERSION` in `shared/constants.js`.
-2. Update `MIN_VERSION` in the server's `.env` file.
-3. Restart the server.
+### Testing
+- Use **different browser profiles** or vendors to test multi-peer logic locally.
+- Use the **Dev tab** to verify that the extension is correctly detecting the video state.
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 2ffdb22..3e30270 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -3,54 +3,40 @@
This document describes the communication flows and internal logic of the KoalaSync system.
## 1. Extension Startup & Connection
-- **Initialization**: On startup, `background.js` reads settings (Server URL, Last Room) from `chrome.storage.sync`.
+- **Initialization**: On startup, `background.js` reads settings (Server URL, Username, Last Room) from `chrome.storage.sync`.
- **WebSocket Handshake**:
- 1. Background creates a `new WebSocket` to `/socket.io/?EIO=4&transport=websocket&version=1.0.0&token=...`.
+ 1. Background creates a `new WebSocket` to `/socket.io/?EIO=4&transport=websocket&version=1.0.0`.
2. Server performs security checks:
- - **IP Rate Limit**: Checks if the IP has exceeded 10 connections/min.
- - **Auth Token**: If a server token is required, it must match.
- - **Version Check**: Client version must be `>= MIN_VERSION`.
- 3. Server responds with an Engine.IO handshake (packet type `0`).
- 4. Background sends `40` to join the default Socket.IO namespace.
- 5. Server responds with `40`.
-- **Room Join**: If a Room ID is stored, Background emits `42["join_room", {...}]`.
-- **Reconnect Logic**: If the connection drops, Background uses an exponential backoff (1s, 2s, 4s... max 30s) to reconnect.
+ - **IP Rate Limit**: Checks if the IP has exceeded connection limits.
+ - **Protocol Version**: Client must match the server's protocol (currently `1.0.0`).
+ 3. Server responds with Engine.IO handshake (`0`) and the client joins the namespace (`40`).
+- **Room Join**: Background emits `JOIN_ROOM` containing `roomId`, `password`, `peerId`, and `username`.
+- **Deduplication**: If a user joins with a `peerId` that already has an active socket, the server kills the old socket to prevent "Ghost Peers".
## 2. Media Event Synchronization
-When a user presses Play/Pause in a synchronized tab:
-1. **Detection**: `content.js` listens to native `play`/`pause` events on the `` element.
-2. **Reporting**: `content.js` sends a `CONTENT_EVENT` message to `background.js`.
-3. **Emission**: `background.js` emits `42["play"|"pause", {...}]` to the server.
-4. **Relay**: The Server forwards the event to all other sockets in the same room.
-5. **Reception**: Other Extensions receive the event via WebSocket.
-6. **Execution**: `background.js` sends a `SERVER_COMMAND` to its `content.js`.
-7. **Control**: `content.js` calls `video.play()` or `video.pause()`.
- - *Note*: It uses `isProcessingCommand` to prevent feedback loops.
+When a user interacts with a video:
+1. **Detection**: `content.js` listens to native events (`play`, `pause`, `seeked`) on the `` element.
+2. **Prevention of Loops**: Uses `lastTargetState` to distinguish between user actions and programmatic actions triggered by the extension.
+3. **Reporting**: `content.js` sends a `CONTENT_EVENT` to `background.js`.
+4. **Relay**: The Server forwards the event to all other peers in the room.
+5. **Execution**: Remote peers receive the command and call `video.play()`, `video.pause()`, or `video.currentTime = targetTime`.
## 3. Two-Phase Force Sync
-This protocol ensures all peers are paused and buffered at the exact same timestamp before resuming playback.
-1. **Initiation**: User clicks "Force Sync" in the popup.
-2. **Preparation**:
- - Popup asks Content Script for the current time.
- - Background emits `FORCE_SYNC_PREPARE` with `targetTime`.
-3. **Coordination**:
- - Peers receive `PREPARE`, `content.js` pauses and seeks.
- - Once `video.readyState >= 3` (buffered), `content.js` sends `FORCE_SYNC_ACK`.
- - Background forwards ACK to the Initiator via Server.
-4. **Execution**:
- - Initiator collects ACKs. Once all peers have responded (or 5s timeout), Initiator emits `FORCE_SYNC_EXECUTE`.
- - All peers receive `EXECUTE` and call `video.play()`.
+Ensures all peers are frame-perfect and buffered before resuming:
+1. **Prepare**: Initiator sends `FORCE_SYNC_PREPARE` with the target timestamp.
+2. **Buffer**: Peers seek and pause. Once buffered (`readyState >= 3`), they send a `FORCE_SYNC_ACK`.
+3. **Execute**: Once the Initiator collects ACKs (or after a 5s timeout), they send `FORCE_SYNC_EXECUTE`.
+4. **Resume**: All peers call `play()` simultaneously.
-## 4. Peer Lifecycle
-- **Join**: Server sends `ROOM_DATA` to the joiner and `PEER_STATUS (joined)` to others.
-- **Leave**:
- - **Manual**: User clicks "Leave". Popup sends `LEAVE_ROOM` to Background -> Server.
- - **Pruning**: If a socket disconnects, the Server automatically broadcasts `PEER_STATUS (left)` and deletes the room if empty.
-- **Heartbeat**: `content.js` sends a status heartbeat every 15s to keep the peer list updated with current playback states.
+## 4. Peer Lifecycle & Dual Heartbeat
+To maintain a clean room state and eliminate "Ghost Peers":
+- **Session Heartbeat (Background)**: Every 30 seconds, `background.js` sends an "I'm alive" signal to the server. This keeps you in the room even if no video is playing.
+- **Video Heartbeat (Content)**: Every 15 seconds, `content.js` sends current playback metadata (time, title, state) if a video is found.
+- **Server Pruning**: The server runs a "Reaper" every 2 minutes. If a peer has sent **zero** activity (no events and no heartbeats) for 5 minutes, they are forcefully disconnected.
+- **Immediate Cleanup**: Rooms are deleted instantly when the last peer leaves or disconnects.
-## 5. Service Worker Keep-alive
-Manifest V3 Service Workers are ephemeral. To keep the connection alive:
-1. `chrome.alarms` triggers every 15 seconds.
-2. The alarm listener checks the WebSocket `readyState`.
-3. If not `OPEN`, it triggers a `connect()` attempt.
-4. This keeps the background process "awake" enough to handle incoming WebSocket messages.
+## 5. Security & Stability
+- **Service Worker Lifecycle**: Uses `chrome.alarms` to prevent the Manifest V3 service worker from suspending while in an active room.
+- **Rate Limiting**: Server-side per-socket and per-IP rate limits to prevent sync-spamming or DoS.
+- **Noise Filtering**: Uses a curated blacklist of domains (Search Engines, Social Media) to declutter the "Target Tab" selector in the popup.
+- **Diagnostics**: A "Dev" tab provides real-time access to the underlying `` state (`readyState`, `paused`, `currentTime`) for easier troubleshooting.
diff --git a/README.md b/README.md
index f2f3bf9..86eb93b 100644
--- a/README.md
+++ b/README.md
@@ -1,20 +1,28 @@
# KoalaSync
-KoalaSync is a Chrome Extension and Relay Server for synchronized video playback (YouTube, Twitch, HTML5).
+KoalaSync is a premium, lightweight Chrome Extension and Relay Server for synchronized video playback across any website (YouTube, Twitch, Netflix, and custom HTML5 players).
> [!TIP]
> **New Developers & AI Agents**: Please read [AI_INIT.md](AI_INIT.md) before starting work.
## Repository Structure
-- `extension/`: Chrome Extension (Manifest V3).
-- `server/`: Node.js + Socket.IO Relay Server.
+- `extension/`: Chrome Extension (Manifest V3, Vanilla JS).
+- `server/`: Node.js + Socket.IO Relay Server (Containerized).
- `website/`: Static marketing landing page & tutorials.
- `shared/`: Shared protocol constants.
+## Key Features
+- **Global Synchronization**: Synchronize Play, Pause, and Seeking on any website with a `` tag.
+- **Smart Identity**: Customizable usernames combined with unique hexadecimal peer IDs.
+- **Dual Heartbeat Architecture**: Robust session tracking that prevents ghost rooms and stale connections.
+- **Zero-Latency Relay**: Custom Socket.IO wire protocol implementation for maximum performance.
+- **Integrated Diagnostics**: A dedicated "Dev" tab for real-time video state debugging.
+- **Seamless Invitations**: Smart invitation links that automatically configure the server and room credentials for your friends.
+
## Setup Instructions
### 1. Relay Server (Docker)
-The server runs on Node.js using Socket.IO but is restricted to WebSocket transport for compatibility with native clients.
+The server runs on Node.js using Socket.IO, containerized for easy deployment.
```bash
# From the root directory
@@ -29,35 +37,23 @@ The server will be available at `ws://localhost:3000`.
4. Select the `extension/` folder.
## Usage
-1. Open the extension popup.
-2. Enter the Server URL (default: `ws://localhost:3000`).
-3. Click **Join / Create Room**.
-4. In the **Sync** tab, select the tab containing the video you want to sync.
-5. Share the **Invite Link** (RoomID#Password) with your friends.
-6. When they join, your play/pause/seek actions will be synchronized.
-7. Use **Force Sync** to align everyone to your current timestamp.
+1. Open the extension and go to the **Settings** tab to set your **Username**.
+2. Go to the **Room** tab, enter your Server URL (default: `ws://localhost:3000`), and click **Join / Create Room**.
+3. In the **Sync** tab, select the tab containing the video you want to sync.
+4. Share the **Invite Link** from the Room tab. When your friends click it, they will automatically join your room and server.
+5. Use **Force Sync** to perfectly align everyone to your current timestamp.
## Technical Details
-- **Manifest V3**: Uses a Service Worker for background tasks.
-- **Native WebSockets**: The extension uses the native `WebSocket` API.
- - > [!IMPORTANT]
- - > **Socket.IO Compatibility**: The server must use **Socket.IO v4**. The extension implements a subset of the Engine.IO/Socket.IO wire protocol.
-- **Keep-Alive**: A `chrome.alarms` mechanism keeps the Service Worker active.
-- **Two-Phase Force Sync**: Uses `pollSeekReady` to ensure all peers are synchronized before resuming.
+- **Manifest V3**: Uses a persistent Service Worker with Alarm-based keep-alive.
+- **Manual Socket.IO Protocol**: The extension implements the Socket.IO v4 wire protocol natively for extreme performance and zero dependencies.
+- **Dead Peer Pruning**: The server automatically prunes peers after 5 minutes of total inactivity (detected via dual heartbeats).
+- **Two-Phase Sync**: Ensures all peers are buffered (`readyState >= 3`) before resuming playback.
## Security & Privacy
-
> [!IMPORTANT]
-> **Privacy by Design**: KoalaSync is built with extreme data parsimony in mind.
-> - **No Databases**: The server stores absolutely nothing on disk. All room states and peer mappings exist only in RAM and are destroyed as soon as a room is empty or inactive.
-> - **No Tracking**: There is zero telemetry, analytics, or user tracking in both the extension and the server.
-> - **Minimal Logging**: The server logs only technical events (connections, errors, rate-limiting) with no personally identifiable information (PII).
-> - **Extension Permissions**: The `` permission is required solely to detect and synchronize HTML5 video elements on any website you visit. No browsing history is ever transmitted or stored.
-
-- > [!WARNING]
- > **Invite Links**: Passwords in invite links (e.g., `RoomID#Password`) are shared in plaintext. This is a trade-off for convenience. For higher security, share the password via a secure channel.
+> **Privacy First**: KoalaSync stores no data on disk. All room states exist only in RAM and are purged immediately when empty. There is zero telemetry, tracking, or analytics.
## Troubleshooting
-- **Logs**: Check the **Dev** tab in the extension popup for detailed connection logs.
-- **Handshake**: Look for `Socket.IO Handshake: 0{...}` in the logs to verify successful connection.
-- **Permissions**: Ensure you have granted the extension permission to access the video site's tab.
+- **Logs**: Check the **Dev** tab in the extension popup for live connection logs and video state diagnostics.
+- **Handshake**: Verify you see `Joined Namespace /` in the logs.
+- **Permissions**: Ensure the target site hasn't blocked script injection (rare for most video sites).
diff --git a/SYNC_GUIDE.md b/SYNC_GUIDE.md
index dad511e..1cb42fa 100644
--- a/SYNC_GUIDE.md
+++ b/SYNC_GUIDE.md
@@ -1,9 +1,9 @@
-# KoalaSync Protocol Synchronization Guide (SYNC_GUIDE.md)
+# KoalaSync Protocol Synchronization Guide
## Why do we need to sync?
-KoalaSync uses a "Single Source of Truth" for its communication protocol constants located in the `shared/` directory. However, Chrome Extensions (Manifest V3) are strictly sandboxed and **cannot load or import files from outside their root directory**.
+KoalaSync uses a "Single Source of Truth" for its communication protocol constants located in the root `shared/` directory. However, Chrome Extensions (Manifest V3) are strictly sandboxed and **cannot load or import files from outside their root directory**.
-To ensure that the extension and the relay server are always using the exact same event names and protocol versions, we must maintain a mirrored copy of the shared files within the extension folder.
+To ensure that the extension and the relay server are always using the exact same event names and protocol versions, we maintain a mirrored copy of the shared files within the `extension/shared/` folder.
## When should you run the sync script?
You MUST run the synchronization script in any of the following scenarios:
@@ -32,5 +32,11 @@ The script performs the following actions:
2. Copies `shared/constants.js` to `extension/shared/constants.js`.
3. Copies `shared/blacklist.js` to `extension/shared/blacklist.js`.
+## Protocol Versioning
+As of v1.0.0-RC5, the system enforces a strict `protocolVersion` check during the `JOIN_ROOM` handshake.
+- The version is defined in `shared/constants.js`.
+- If the extension and server versions mismatch, the server will reject the connection with an `Incompatible protocol version` error.
+- **Always run the sync script** after bumping the version number to ensure both components are updated.
+
> [!CAUTION]
> **NEVER** edit the files inside `extension/shared/` directly. They will be overwritten the next time the sync script is run. Always edit the files in the root `shared/` directory and then run the sync script.
diff --git a/extension/README.md b/extension/README.md
index b49f83a..3f5750c 100644
--- a/extension/README.md
+++ b/extension/README.md
@@ -1,23 +1,32 @@
# KoalaSync Chrome Extension
-A Manifest V3 Chrome Extension for synchronized video playback.
+A Manifest V3 Chrome Extension for synchronized video playback across any website.
## Key Features
-- **Manifest V3**: Using a modern Service Worker architecture.
-- **Native WebSockets**: No heavy libraries, uses the browser's native API.
+- **Manifest V3**: Optimized Service Worker architecture with session persistence.
+- **Pure Vanilla JS**: No external dependencies or heavy libraries.
+- **Smart Peer IDs**: Hexadecimal IDs combined with customizable Usernames for easy identification.
+- **Dual Heartbeat**: Advanced session tracking (Background) and video synchronization (Content) to prevent ghost sessions.
+- **Live Diagnostics**: Built-in "Dev" tab for real-time video state debugging (ReadyState, CurrentTime, etc.).
+
+## Tab Overview
+1. **Room**: Manage connections, view active peers, and share invitation links.
+2. **Sync**: Control video playback (Play/Pause/Force Sync) and view recent activity.
+3. **Settings**: Customize your Username and toggle domain-based Noise Filtering.
+4. **Dev**: Monitor connection status and view real-time video element metadata for debugging.
## Privacy & Permissions
-KoalaSync requires `` permission to detect and interact with video elements (``) on any website.
-- **No Browsing History**: We do not track which sites you visit.
-- **No Telemetry**: There are no analytics or tracking scripts included.
-- **Local State**: Settings (Server URL, Room ID, Password) are stored only locally in your browser using `chrome.storage`.
+KoalaSync requires `` permission to detect and interact with video elements (``) on websites.
+- **No Browsing History**: We do not track or store your browsing history.
+- **State Management**: Sensitive data (Room Passwords) is stored locally using `chrome.storage`.
+- **Zero Telemetry**: No analytics or external tracking scripts.
## Installation
-1. Go to `chrome://extensions/`.
-2. Enable **Developer mode**.
-3. Click **Load unpacked** and select this folder.
+1. Open Chrome and go to `chrome://extensions/`.
+2. Enable **Developer mode** (top right).
+3. Click **Load unpacked** and select the `extension` folder from this repository.
## Development
-If you change `shared/constants.js`, remember to run the synchronization script:
-- Windows: `..\scripts\sync-constants.bat`
-- Linux/macOS: `../scripts/sync-constants.sh`
+If you modify `shared/constants.js`, you must synchronize the changes across the extension and server:
+- **Windows**: Run `scripts\sync-constants.bat`
+- **Linux/macOS**: Run `scripts/sync-constants.sh`