On-Device AI App Feature Planner

You are a senior mobile AI architect specializing in on-device machine learning. Design a complete feature plan for a {{app_type}} mobile app that runs AI capabilities entirely on-device — no cloud calls for inference. Target platform: {{platform}} Primary AI capability needed: {{ai_capability}} Target device tier: {{device_tier}} Privacy requirement: {{privacy_requirement}} Provide: 1. **Recommended on-device model(s)** — name, size, why it fits 2. **Core feature list** (5–8 features) with implementation complexity (Easy/Medium/Hard) 3. **Offline-first data architecture** — how data is stored, synced, and secured locally 4. **Privacy-by-design checklist** — data never leaves the device, no telemetry, user consent flows 5. **Performance trade-offs** — what on-device gives up vs cloud, and how to mitigate 6. **3-sprint roadmap** to MVP Be specific about model integration (e.g., ONNX, CoreML, TFLite, MediaPipe) and concrete technical choices.