Watch: show subagent requests on the parent's card, and settle threads by swipe, Settle all and the thread screen

watch/WristCode/AppModel.swift

@@ -26,6 +26,10 @@ final class AppModel {
     var path: [Route] = []
     private(set) var feed: Feed?
     private(set) var feedError: String?
+    /// Ids of feed items whose settle call is still out. The feed hides them meanwhile.
+    private(set) var settling: Set<String> = []
+    /// Why settling an item failed, by item id. Its row shows the message.
+    private(set) var settleErrors: [String: String] = [:]
     private var apnsToken: String?
     private var refreshing = false
     /// The counts the complication was last told about.
@@ -151,6 +155,38 @@ final class AppModel {
         }
     }
 
+    /// Settles items concurrently. Each one leaves the feed at once and comes back with its error
+    /// if its call fails. Refreshes once every call has answered.
+    func settle(_ items: [FeedItem]) async {
+        let ids = Set(items.map(\.id))
+        settling.formUnion(ids)
+        for id in ids { settleErrors[id] = nil }
+        let api = api
+        let failures = await withTaskGroup(of: (String, (any Error)?).self) { group in
+            for item in items {
+                group.addTask {
+                    do {
+                        try await api.settle(hostId: item.hostId, threadId: item.threadId)
+                        return (item.id, nil)
+                    } catch {
+                        return (item.id, error)
+                    }
+                }
+            }
+            var failures: [String: any Error] = [:]
+            for await (id, error) in group {
+                if let error { failures[id] = error }
+            }
+            return failures
+        }
+        for (id, error) in failures {
+            settleErrors[id] = message(for: error)
+        }
+        feed?.recent.removeAll { ids.contains($0.id) && failures[$0.id] == nil }
+        settling.subtract(ids)
+        await refreshFeed()
+    }
+
     func open(_ route: Route) {
         path = [route]
     }