[gx1400]

Stacked on #354. Closes #355. Spec: docs/features/F4.16-device-list.md. The decisions were agreed 2026-10-19; what this build settled is under Built in the spec.

Engine (Engine.DeviceList.cs)

• On start, the engine loads the kept tocalls.json if it reads and is newer than APRS.NET's built-in list. Otherwise it deletes the file and uses the built-in list.

• Schedule: the first check is 3 minutes after start, or one interval after the last check if that's later. Then it checks weekly by default (or daily, or never). The engine checks nothing while the Internet switch is off or the address is empty.

• Update now runs a check at once.

• A check sends the kept copy's ETag with AprsDeviceListSource. If the server has a newer list that reads:

  • it's written as published (to a temporary file, then moved into place);
  • it's used at once;
  • StationStore.UseDeviceList names every station already heard again.

  Otherwise the check reports devicelist.not-newer, unreadable, unexpected-answer or unreachable.

• The last-check time and the ETag are kept with the settings. A client's save never overwrites them, and only the desktop may change the address.

• Options: Engine:DeviceList:Url (empty turns downloading off), Folder (defaults to deviceid in the data folder) and Timeout. The desktop sets UrlIsSetting.

• The new devicelist HTTP client sends the same User-Agent as address lookup.

• EngineStatus.DeviceList, GetDeviceListAsync (everyone) and UpdateDeviceListAsync (operator-only on a gateway) are added, through the hub and the remote client.

UI

• Settings › Data › Device list shows:
  • which list is in use, from what date;
  • the last check and its result, in the warning colour if it failed;
  • Update now and Check automatically (Weekly/Daily/Off), for whoever may change the station;
  • an Advanced expander on the desktop for the address, with Save and Reset to the default;
  • the list's credit.
• About credits the list (OH7LZB and contributors, CC BY-SA 2.0), links to it, and says which list is in use.

Tests

• Core (DeviceListTests):
  • the built-in list by default;
  • a newer list is kept as published and used, and a station already heard is named at once;
  • the second check sends If-None-Match and gets a 304;
  • not-newer, unreadable JSON and an unknown device class are thrown away with their reasons;
  • a 404 and an unreachable server;
  • a kept list is loaded on start, and an older one is deleted;
  • the schedule over 7 days: weekly checks 2 times, daily 8, off never, and nothing with the Internet off;
  • an empty address never downloads.
• Gateway: a viewer sees the list but is refused Update now. A browser save keeps the schedule but can't change the address.
• UI: the texts, Update now, saving the schedule, viewer vs operator, no address, and address validation, empty and reset.
• Release build, then 563 Core, 653 UI, 172 Gateway and 17 Tiles tests: all pass. The user's data folder isn't touched.