Context

Nexum requires a storage architecture that can store wallet metadata, preferences, and state locally while maintaining forward compatibility with Swarm-based decentralized storage. The design must support encryption, synchronization across devices, and efficient local caching.

Considerations

This specification should address the following considerations:

• Swarm-based content addressing and chunking strategy
• Local storage format and file structure
• Encryption scheme for sensitive data (keys, metadata, preferences)
• Key derivation for storage encryption (integration with docs: define derivation path standards #86 / NXP-1)
• Synchronization protocol for multi-device scenarios
• Conflict resolution for concurrent modifications
• Cache invalidation and refresh strategies
• Storage abstraction layer API
• Migration path from local-only to Swarm-backed storage
• Backup and restore mechanisms
• Storage quota management and pruning
• Performance requirements for read/write operations

Solution

Draft specification: NXP-2: Storage Architecture (draft)

This document defines:

• System key allocations for storage operations (registered in NXP-1 registry)
• Swarm primitives (CAC, SOC, feeds, batches)
• Encryption scheme using EIP-1581 derived keys
• Feed structure for profile metadata
• Local caching strategy

Dependencies

Depends on (Phase 3):

• docs: define derivation path standards #86 (Derivation standards for encryption keys) ✅ NXP-1 complete
• docs: design metadata schema #88 (Metadata schema defines what gets stored)

Out of Scope

• Full Swarm implementation in Q4 2025 (deferred per epic notes)
• Blockchain-based storage
• Centralized cloud storage backends
• Real-time sync (eventual consistency is acceptable)

References

• NXP-1: Derivation Path Standards (system key registry)
• Swarm documentation: https://docs.ethswarm.org/
• Related: docs: define derivation path standards #86 (Derivation standards), docs: design metadata schema #88 (Metadata schema)
• Implementation: feat: implement storage abstraction layer #90 (Storage abstraction layer)
• Epic: [EPIC 0.0] Foundation - Identity & Account Architecture pm#3 (Foundation)