[SandObserver]

Summary

• U4-3: writeItems posts a copy of the list it records as sent (JSON.parse(sent)) instead of the live state.items. apiPost serialises the body again when it retries after sign-in, so a list change made while the first POST was in flight reached the server unrecorded, and a later failed save restored the list without it so the next save deleted it.

Testing
All green, including the Docker build and e2e suite. Added an assertion that the list save posts the list it records as sent.

Changelog

Fixed

• Stop a later list save from silently deleting a change sent during a sign-in retry.

Checklist

• Stays within the project constraints: one container, no runtime dependencies, no build step (see CONTRIBUTING.md).
• Tests added or updated for new logic, and the full suite, lint, and typechecks pass.
• Docs updated if behavior or configuration changed.