chore:Added AGENTS.md file for ai agents (#872)

Author: pmathew92

.github/copilot-instructions.md

@@ -0,0 +1,253 @@
+# AI Agent Guidelines for Auth0.Android SDK
+
+This document provides context and guidelines for AI coding assistants working with the Auth0.Android SDK codebase.
+
+## Project Overview
+
+**Auth0.Android** is a native Android SDK for integrating Auth0 authentication and authorization into Android applications. The SDK provides a comprehensive solution for:
+
+- Web-based authentication (Universal Login via Custom Tabs)
+- Direct API authentication (database connections, passwordless)
+- Secure credential storage with biometric protection
+- Token management with automatic refresh
+- Modern Android development patterns (Coroutines, AndroidX libraries)
+
+## Repository Structure
+
+```
+Auth0.Android/
+├── auth0/                          # Main SDK library module
+│   ├── src/main/java/com/auth0/android/
+│   │   ├── provider/              # Browser-based auth providers
+│   │   ├── authentication/        # Direct API authentication
+│   │   ├── management/            # Management API client
+│   │   ├── myaccount/             # My Account API client
+│   │   ├── request/               # Network request abstractions
+│   │   ├── result/                # Response/error handling
+│   │   └── Auth0.kt               # Main configuration class
+│   └── src/test/                  # Unit tests
+├── sample/                        # Demo application
+├── .github/                       # CI/CD workflows
+├── gradle/                        # Build configuration
+│   ├── versioning.gradle          # Version management
+│   └── maven-publish.gradle       # Publishing setup
+└── .version                       # Current SDK version
+```
+
+## Key Technical Decisions
+
+### Architecture Patterns
+- **Builder Pattern**: Used extensively for web based authentication flows (e.g., `WebAuthProvider.login()`)
+- **Callback + Coroutines**: Dual API support for both traditional callbacks and modern suspend functions
+- **Provider Architecture**: Pluggable authentication providers with fallback strategies
+
+### Authentication Flow
+1. **WebAuthProvider** (Recommended): Browser-based auth via Custom Tabs
+   - Uses App Links (`https://` schemes) or custom URL schemes
+   - Handles PKCE automatically
+   - Supports DPoP for enhanced security
+   
+2. **AuthenticationAPIClient**: Direct API calls without browser
+   - Database connections (login/signup)
+   - Passwordless (email/SMS)
+   - Token refresh and revocation
+
+### Credential Management Strategy
+- **CredentialsManager**: Basic storage with automatic refresh
+- **SecureCredentialsManager**: Adds biometric/device credential protection with encrypted storage
+- Storage abstraction via `Storage` interface (default: SharedPreferences)
+- Encryption using Android Keystore
+
+## Development Guidelines
+
+### Code Style
+- **Language**: Kotlin (primary), with Java interop support
+- **Minimum SDK**: API 21 (Android 5.0)
+- **Target SDK**: Latest stable Android version
+- **Testing**: Robolectric for Android components, MockWebServer for HTTP
+
+### API Design Principles
+When adding or modifying APIs:
+
+1. **Dual API Support**: Provide both callback and suspend function variants
+   ```kotlin
+   // Callback style
+   fun operation(callback: Callback<Result, Error>)
+   
+   // Coroutine style
+   suspend fun operation(): Result
+   ```
+
+2. **Builder Pattern**: Use for WebAuthProvider operations
+   ```kotlin
+   WebAuthProvider.login(account)
+       .withScheme("https")
+       .withScope("openid profile")
+       .start(context, callback)
+   ```
+
+3. **Error Handling**: Use typed exceptions
+   - `AuthenticationException` for auth failures
+   - `CredentialsManagerException` for storage issues
+   - All inherit from `Auth0Exception`
+
+### Testing Requirements
+- Unit tests for all new functionality
+- Code coverage tracked via JaCoCo (target: >80%)
+- Mock external dependencies (network, Android framework)
+- Test both success and failure scenarios
+
+### Common Tasks
+
+#### Adding a New Authentication Method
+1. Create request class in `auth0/src/main/java/com/auth0/android/request/`
+2. Implement both callback and suspend variants
+3. Add unit tests with mocked responses
+4. Update `EXAMPLES.md` with usage example
+5. Add integration test in sample app
+
+#### Modifying Browser Authentication
+Key files:
+- `WebAuthProvider.kt`: Main entry point
+- `AuthenticationActivity.kt`: Handles redirects
+- `OAuthManager.kt`: OAuth2 flow logic
+- `PKCE.kt`: PKCE implementation
+
+#### Updating Credential Storage
+Key files:
+- `CredentialsManager.kt`: Basic implementation
+- `SecureCredentialsManager.kt`: Biometric support
+- `SharedPreferencesStorage.kt`: Persistence layer
+
+## Build & Testing Commands
+
+```bash
+# Full build with tests and coverage
+./gradlew clean test jacocoTestReport
+
+# Run lint checks
+./gradlew lint
+
+# Build sample app
+./gradlew sample:assembleDebug
+
+# CI simulation (matches GitHub Actions)
+./gradlew clean test jacocoTestReport lint --continue --console=plain --max-workers=1 --no-daemon
+```
+
+## Configuration Files
+
+### Version Management
+- **`.version`**: Single source of truth for SDK version
+- Read by `gradle/versioning.gradle` and injected into BuildConfig
+
+### Required Manifest Placeholders
+```gradle
+android {
+    defaultConfig {
+        manifestPlaceholders = [
+            auth0Domain: "YOUR_DOMAIN",
+            auth0Scheme: "https" // or custom scheme
+        ]
+    }
+}
+```
+
+### String Resources Pattern
+```xml
+<string name="com_auth0_client_id">YOUR_CLIENT_ID</string>
+<string name="com_auth0_domain">YOUR_DOMAIN</string>
+```
+
+## Dependencies
+
+### Core Libraries
+- **AndroidX**: Activity, Browser, Biometric, Lifecycle
+- **Kotlin Coroutines**: For async operations
+- **OkHttp**: HTTP client
+- **Gson**: JSON serialization
+- **JWT**: Token parsing and validation
+
+### Testing Libraries
+- **JUnit 4**: Test framework
+- **Robolectric**: Android unit testing
+- **Mockito/PowerMock**: Mocking
+- **MockWebServer**: HTTP testing
+- **Hamcrest**: Assertions
+
+## Security Considerations
+
+1. **PKCE**: Enabled by default for all OAuth flows
+2. **DPoP**: Optional enhanced token security
+3. **Keystore**: All credentials encrypted using Android Keystore
+4. **Biometric**: LocalAuthentication for secure access
+5. **Certificate Pinning**: Configurable via OkHttp interceptors
+
+## Documentation
+
+- **README.md**: Getting started and installation
+- **EXAMPLES.md**: Detailed usage examples
+- **API docs**: Generated via Dokka (KDoc comments)
+- **CHANGELOG.md**: Release notes and breaking changes
+- **MIGRATION.md**: Upgrade guides between major versions
+
+## Release Process
+
+1. Update `.version` file
+2. Update `CHANGELOG.md`
+3. Create release branch
+4. CI runs full test suite
+5. Manual approval for publication
+6. Maven Central publication via `gradle/maven-publish.gradle`
+
+## Common Pitfalls
+
+- **Redirect URIs**: Must match exactly between Auth0 dashboard and app configuration
+- **Custom Tabs**: Require Chrome or Chrome Custom Tabs provider installed
+- **Biometric**: Requires device credential fallback configuration
+- **Coroutines**: Must use appropriate dispatcher for Android operations
+- **Proguard**: Keep rules defined in `consumer-rules.pro`
+
+## Getting Help
+
+- **Issues**: GitHub Issues for bugs and feature requests
+- **Discussions**: GitHub Discussions for questions
+- **Auth0 Community**: https://community.auth0.com/
+- **Auth0 Support**: For Auth0 account/dashboard issues
+
+## AI Agent Best Practices
+
+When assisting with this codebase:
+
+1. **Preserve patterns**: Follow existing Builder and callback/coroutine patterns
+2. **Test coverage**: Always include tests for new functionality
+3. **Backward compatibility**: Consider impact on existing users
+4. **Documentation**: Update relevant docs when changing public APIs
+5. **Security**: Never compromise security features (PKCE, encryption, etc.)
+6. **Android compatibility**: Test across Android versions (API 21+)
+7. **Error handling**: Provide clear, actionable error messages
+
+## Example Workflows
+
+### Web Authentication
+```kotlin
+val account = Auth0(clientId, domain)
+WebAuthProvider.login(account)
+    .withScheme("https")
+    .withScope("openid profile email")
+    .start(context, object : Callback<Credentials, AuthenticationException> {
+        override fun onSuccess(result: Credentials) { /* ... */ }
+        override fun onFailure(error: AuthenticationException) { /* ... */ }
+    })
+```
+
+
+### Direct API Authentication
+```kotlin
+val authClient = AuthenticationAPIClient(account)
+authClient.login(email, password, "Username-Password-Authentication")
+    .start(callback)
+```
+
+---
+