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

watch/WristCode/API/Models.swift

@@ -134,6 +134,13 @@ extension PendingRequest.Question {
 }
 
 struct FeedItem: Codable, Hashable, Sendable, Identifiable {
+    /// The subagent a request came from, when a thread delegated work and that work waits on you.
+    struct Via: Codable, Hashable, Sendable {
+        var hostId: String
+        var threadId: String
+        var title: String
+    }
+
     var hostId: String
     var hostLabel: String
     var threadId: String
@@ -144,9 +151,17 @@ struct FeedItem: Codable, Hashable, Sendable, Identifiable {
     var updatedAt: Date
     var lastMessage: String?
     var request: PendingRequest?
+    /// Set when `request` and `phase` belong to a subagent rather than this thread. Older gateways
+    /// leave it out, which decodes as nil.
+    var via: Via? = nil
 
     var id: String { "\(hostId)/\(threadId)" }
     var route: Route { .thread(hostId: hostId, threadId: threadId) }
+
+    /// The thread that answers `request`: the subagent named in `via`, or this thread.
+    var requestThread: (hostId: String, threadId: String) {
+        via.map { ($0.hostId, $0.threadId) } ?? (hostId, threadId)
+    }
 }
 
 struct Feed: Codable, Hashable, Sendable {