Functional Requirements
Audio, video, notifications, and other functional behavior requirements.
Audio
Playback Initialization
| Requirement |
Specification |
| Response time |
< 1 second |
| If delayed |
Show visual progress indicator |
| User feedback |
Immediate acknowledgment of action |
Audio Focus Rules
| Event |
Required Action |
| Another app requests focus |
Pause or reduce volume |
| Focus regained |
Resume or restore volume |
| Playback stops |
Abandon focus |
Audio Focus Handling
| Focus Change |
Action |
| AUDIOFOCUS_LOSS |
Stop playback |
| AUDIOFOCUS_LOSS_TRANSIENT |
Pause playback |
| AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK |
Reduce volume |
| AUDIOFOCUS_GAIN |
Resume playback |
Background Playback
| Requirement |
Implementation |
| Continue when backgrounded |
Use Foreground Service |
| Notification |
MediaStyle notification required |
| Media controls |
System media controls integration |
| Session |
MediaSession for system integration |
Video
Picture-in-Picture (PiP)
| Requirement |
Specification |
| Video apps |
Should support PiP |
| Aspect ratio |
16:9 to 2.39:1 |
| Auto-enter |
When user navigates away during playback |
Video Encoding
| Standard |
Requirement |
| Compression |
HEVC (H.265) recommended |
| Fallback |
H.264 for compatibility |
| Quality |
Adaptive based on network |
Video Player Requirements
| Feature |
Implementation |
| Fullscreen |
Support landscape |
| Controls |
Play, pause, seek, volume |
| Captions |
Support closed captions |
| Resume |
Remember playback position |
Notifications
Channel Best Practices
| Practice |
Reason |
| Multiple channels |
User can control each type |
| Descriptive names |
User understands purpose |
| Appropriate importance |
Match user expectation |
| Don't share channels |
Different content = different channel |
Notification Priority
| Importance |
Usage |
| HIGH |
Time-sensitive (messages, calls) |
| DEFAULT |
Normal notifications |
| LOW |
Background info |
| MIN |
Minimal interruption |
Notification Content Rules
| Do |
Don't |
| Relevant information |
Cross-promotion |
| Clear, concise text |
Advertising other products |
| Actionable content |
Unnecessary interruptions |
| Set timeouts |
Persistent non-ongoing notifications |
Messaging Apps Requirements
| Feature |
Description |
| MessagingStyle |
Use for conversation notifications |
| Direct reply |
Support inline reply action |
| Conversation shortcuts |
Enable direct share |
| Bubbles |
Support floating conversations |
Notification Grouping
Group related notifications together with a summary notification. Set appropriate group keys and summary flags.
Sharing
Android Sharesheet
Use the system sharesheet for sharing content. Create an ACTION_SEND intent with appropriate type and extras, then use createChooser().
Direct Share
Provide conversation shortcuts for Direct Share ranking:
- Create ShortcutInfo for each conversation
- Set appropriate categories
- Push dynamic shortcuts
Background Services
Service Restrictions
| Rule |
Implementation |
| Avoid long-running services |
Use WorkManager |
| No background starts (API 26+) |
Use foreground service or JobScheduler |
| Battery-efficient |
Batch work, respect Doze |
Poor Background Service Uses
| Don't Use For |
Alternative |
| Maintaining network connection |
FCM (push notifications) |
| Persistent Bluetooth |
Companion device manager |
| Keeping GPS on |
Geofencing, fused location |
| Polling server |
FCM or WorkManager |
State Management
State Preservation Requirements
| Scenario |
Required Behavior |
| App switcher return |
Exact previous state |
| Device wake |
Exact previous state |
| Process death |
Restore critical state |
| Configuration change |
Seamless transition |
State Categories
| State Type |
Storage |
| UI state (scroll, selection) |
ViewModel + SavedState |
| User input (forms) |
SavedState |
| Navigation |
NavController state |
| Persistent data |
Room database |
Navigation
Back Button/Gesture
| Requirement |
Implementation |
| System back |
Navigate to previous screen |
| Gesture navigation |
Support back gesture |
| No custom back buttons |
Use system navigation |
| Predictable |
User knows what back does |
Gestures
Gesture Navigation Support
| Gesture |
Default Action |
| Swipe from left edge |
Back |
| Swipe up from bottom |
Home |
| Swipe up and hold |
Recent apps |
Custom Gestures
| Practice |
Reason |
| Avoid edge swipes |
Conflicts with navigation |
| Provide alternatives |
Not all users gesture-capable |
| Test with gesture nav |
Ensure no conflicts |
Handle system gesture insets to avoid conflicts with edge gestures.
Functional Checklist
Audio
Video
Notifications
Messaging (if applicable)
Background
Navigation
