Product Context

Meta operates a large fleet of connected devices across homes, offices, and edge deployments. Design an end-to-end ML system that decides which devices should receive an over-the-air firmware update, in what order, and how to minimize bricking risk from power failures while enforcing strong security guarantees.

Scale

Task

1. Clarify the product goals and define functional and non-functional requirements for an ML-assisted OTA system.
2. Design a multi-stage decision pipeline for update eligibility, candidate retrieval, risk ranking, and final rollout policy.
3. Propose how the system handles interrupted updates, especially power loss during download, install, and reboot.
4. Define the security architecture: authenticity, integrity, anti-rollback, key management, and secure recovery.
5. Describe the offline and online data pipelines, model training cadence, and how you prevent training-serving skew.
6. Define evaluation, monitoring, rollback strategy, and top failure modes at fleet scale.

Constraints

• Devices are heterogeneous: battery-powered and mains-powered, with intermittent connectivity and limited flash/storage.
• Some devices check in only a few times per day; others stream telemetry continuously.
• The online service must make rollout decisions within 150ms p99 and remain available during regional outages.
• Regulatory/compliance constraints require signed firmware, auditable rollout decisions, and region-specific update policies.
• Cost matters: avoid shipping large updates to devices unlikely to succeed on the first attempt.
• The system must prefer safe degradation: if ML is unavailable, updates should fall back to deterministic policy rather than block critical security patches.