Library Sync Setup (Device Registration & Discovery)

Description

Implement the library sync setup flow that enables paired devices to discover each other's libraries and register for synchronization.

Update (Oct 2025): No longer assigns leader roles (leaderless architecture).

Implementation Notes

• Complete implementation detailed in docs/core/sync-setup.md
• Devices must be paired (NET-002) before library sync setup
• Two-phase process: Discovery → Registration
• Bidirectional device registration in each library's database
• Leader election during setup (No longer needed)
• No actual sync replication in Phase 1 (just registration)

Changes for Leaderless Model

Removed:

• Leader election during setup
• Setting sync_leadership field

Acceptance Criteria

• Paired devices can discover each other's libraries
• Devices can be registered in remote library databases
• Sync leadership assigned during setup (No longer applicable)
• sync_partners records created
• sync_setup.discover query implemented
• sync_setup.input action implemented
• Integration tests validate cross-device setup

References

• docs/core/sync-setup.md - Setup flow
• core/src/infra/sync/NEW_SYNC.md - Leaderless model