Add basic copilot-instructions.md

Author: alex-friedl

.github/copilot-instructions.md

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+# Copilot Instructions for AI Agents
+
+## Project Overview
+This repository implements a Node.js module for sending push notifications across multiple platforms: Apple (APN), Google (GCM/FCM), Windows (WNS), Amazon (ADM), and Web-Push. The core logic is in `lib/` and `src/`, with each platform handled by a dedicated file (e.g., `sendAPN.js`, `sendFCM.js`).
+
+## Architecture & Data Flow
+- **Entry Point:** Use `PushNotifications` from `lib/index.js` or `src/index.js`.
+- **Settings:** Each platform's credentials/config are passed to the constructor. See the example in `README.md`.
+- **Sending:** The main method is `push.send(registrationIds, data, callback)` or as a Promise. It auto-detects device type and routes to the correct sender.
+- **Platform Senders:** Each sender (e.g., `sendAPN.js`, `sendFCM.js`) implements the logic for its platform. Shared utilities are in `lib/utils/` and `src/utils/`.
+- **RegId Detection:** Device type is inferred from the registration ID structure. See `PN.getPushMethodByRegId` for details.
+
+## Developer Workflows
+- **Install:** `npm install`
+- **Test:** Run all tests with `npm test`. Tests are in `test/` and cover basic flows and platform-specific cases.
+- **Debug:** Use the callback or Promise error/result from `push.send`. Each result object includes method, success/failure counts, and error details per device.
+- **Build:** No build step required for basic usage. ES6 is used, but compatible with ES5 via Babel if needed.
+
+## Conventions & Patterns
+- **Platform-specific files:** Each push service has its own file for isolation and clarity.
+- **Unified Data Model:** The `data` object for notifications is normalized across platforms. See `README.md` for all supported fields.
+- **Error Handling:** Errors are unified and returned in the result array from `push.send`.
+- **RegId Format:** Prefer object format for registration IDs (`{id, type}`), but string format is supported for legacy reasons.
+- **Chunking:** Android tokens are chunked in batches of 1,000 automatically.
+- **Constants:** Use constants from `constants.js` for platform types.
+
+## Integration Points
+- **External Libraries:**
+  - APN: `node-apn`
+  - FCM: `firebase-admin`
+  - GCM: `node-gcm`
+  - ADM: `node-adm`
+  - WNS: `wns`
+  - Web-Push: `web-push`
+- **Credentials:** Place service account keys and certificates in appropriate locations (see `README.md` for examples).
+
+## Key Files & Directories
+- `lib/` and `src/`: Main implementation (mirrored structure)
+- `test/`: Test cases and sample credentials
+- `README.md`: Usage, configuration, and data model reference
+
+## Example Usage
+See `README.md` for a full example of settings, registration ID formats, and sending notifications.
+
+---
+For unclear or incomplete sections, please provide feedback or specify which workflows, patterns, or integrations need further documentation.