Telemetry: tag relay fetches with X-Client (app/widget) — app via RelayFuelProvider, widget focused/fuel-only fetches + diag beacon; Siri untouched (cached-only). Purely observational for relay admin /stats.

Shared/FuelPriceProvider.swift

@@ -71,6 +71,19 @@ struct RelayFuelProvider: FuelPriceProviding {
     /// dataset update time). Written by fetchStations, read by the view.
     static var latestMeta: RelayMeta?
 
+    /// Admin telemetry: the relay tags inbound connections by client kind
+    /// (app vs widget) so the developer can monitor the poll model. Siri
+    /// never fetches (cached-data-first). Purely observational — the relay
+    /// ignores the header for responses.
+    static let clientTagHeader = "X-Client"
+
+    static func relayRequest(_ url: URL, client: String, timeout: TimeInterval = 30) -> URLRequest {
+        var request = URLRequest(url: url)
+        request.timeoutInterval = timeout
+        request.setValue(client, forHTTPHeaderField: clientTagHeader)
+        return request
+    }
+
     func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType, radiusKM: Double?) async throws -> [FuelStation] {
         var components = URLComponents(url: baseURL.appendingPathComponent("api/v1/stations"), resolvingAgainstBaseURL: false)!
         var query: [URLQueryItem] = [URLQueryItem(name: "fuel", value: fuel.rawValue)]
@@ -89,7 +102,8 @@ struct RelayFuelProvider: FuelPriceProviding {
         }
         components.queryItems = query
 
-        let (data, response) = try await URLSession.shared.data(from: components.url!)
+        let request = RelayFuelProvider.relayRequest(components.url!, client: "app")
+        let (data, response) = try await URLSession.shared.data(for: request)
         guard let http = response as? HTTPURLResponse, http.statusCode == 200 else {
             throw FuelProviderError.relayUnavailable
         }