Apple data transport

The host writes widget data through one transport you choose in config. You know your signing setup — do not rely on runtime fan-out.

{
  "plugins": {
    "widgets": {
      "appGroup": "group.com.example.myapp",
      "transport": "appGroup",
      "extensionBundleId": "com.example.myapp.widgetkit"
    }
  }
}

Situation	transport
Release / Team ID + App Groups enabled	appGroup
Mac App Store	appGroup
Local ad-hoc signing (no shared App Group container)	widgetContainer
iOS (device and simulator)	appGroup only — other values fail at plugin init
Not sure yet	auto once at startup (dev only) — read the log, then pin the winner in conf

transport	Host write path	Requirements
appGroup	containerURL(group)/widget_data.json	Real Team ID + App Groups on App + Extension
userDefaults	App Group UserDefaults suite	Same as appGroup
widgetContainer	~/Library/Containers/<appex>/Data/widget_data.json	macOS host not sandboxed; works with ad-hoc
auto	One-shot probe, then latch	Development only — never ship this

Wrong transport / missing appGroup fails plugin init with a concrete message (empty widgets from a silent fallback are not a thing).

init-macos / init-ios do not write this block — add plugins.widgets yourself (Install).

Override without editing conf: WIDGET_TRANSPORT=widgetContainer.

The widget extension still reads all channels and picks the freshest map (so it can find data wherever the host wrote). Host-side writes use only the configured driver. Render receipts feed getWidgetDiagnostics, not transport selection.

setItems skips disk I/O when the value is unchanged (no nonce bump).