Start with the interrupted task
“Works offline” is too broad to guide a useful implementation. Start with the person and the task: what information do they need, what can they change, and what would happen if that change conflicts with another one?
A read-only catalogue and a financial settlement operation have very different requirements. Listing them together under an offline feature hides the decisions that matter. Build a workflow inventory and give each operation a clear boundary.
Separate local evidence from shared truth
A local save means the device retained information. It does not necessarily mean the server accepted it, another device can see it, or the action passed the latest authorization rules.
Use specific states in the interface and in the data model. Queued, syncing, accepted, and needs review are more useful than a single generic success flag. Tell the person what they can safely do next.
Choose the conflict policy deliberately
The latest write is not always the right write. A changed address, a collected quantity, and a closed settlement cycle may need different correction rules. Decide which changes can merge and which require a person to review them.
Dairify’s documented direction includes an offline-first owner/staff application and an append-only ledger with immutable closed cycles. Those are design intentions for an early-stage product, not a claim of production-validated synchronization. They illustrate why offline behavior and financial history must be considered together.
Treat connection signals as hints
A device can have a network connection while the required service remains unreachable. Browser connectivity indicators do not prove that a particular API is available.
The application should handle the result of the actual operation. Plan for slow responses, interrupted requests, retries, and a user leaving the screen. Keep the recovery path visible without filling every view with technical diagnostics.
Write the acceptance scenario first
A useful test might begin with a disconnected device, a locally saved action, and a later server rejection. The expected outcome should include the preserved data, the message shown, and the person responsible for resolving the issue.
That scenario is a product decision as much as a technical one. Once it is clear, a synchronization tool can be evaluated against the behavior the product actually needs.
Reference: MDN: Navigator.onLine and its limitations. This note offers a design approach; it is not a claim of a measured client outcome.