# Design Offline Sync

> Design an offline sync and conflict protocol that preserves user intent across retries, multi-device edits, deletion, and partial failure. Use when offline is a declared product capability. Do not use for ordinary online CRUD or for a live incident.

- Skill: `sylphxai/design-offline-sync` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add sylphxai/design-offline-sync`
- Raw SKILL.md: https://api.skillmd.com/api/skills/sylphxai/design-offline-sync/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: SylphxAI (https://skillmd.com/u/sylphxai)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/sylphxai/design-offline-sync

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# Design Offline Sync

Last-write-wins needs explicit bounded-harm acceptance. A disabled sync domain queues nothing and starts no background or network work. Money, permissions, legal records, inventory, and deletion use an explicit conflict protocol, not silent merge. A CRDT name is not a merge proof.

Open [offline sync patterns](references/offline-sync-conflict-patterns.md) when classifying operations or choosing a merge. Open [CRDT convergence](references/crdt-convergence.md) only when a CRDT is a candidate, and prove the merge algebra rather than selecting it by name.