Coalesce session refreshes during event bursts

mac/Sources/Byre/Store.swift

@@ -98,6 +98,8 @@ final class Store {
     @ObservationIgnored private var requestSeqs: [String: Int] = [:]
     @ObservationIgnored private var taskReloads: Set<String> = []
     @ObservationIgnored private var listReloads: Set<String> = []
+    @ObservationIgnored private var sessionReloads: Set<String> = []
+    @ObservationIgnored private var sessionRefetches: Set<String> = []
     @ObservationIgnored private var taskRefetches: [String: Set<String>] = [:]
     @ObservationIgnored private var terminalChanges = 0
     @ObservationIgnored private var streamOpens = 0
@@ -854,13 +856,9 @@ final class Store {
             reloadTask(ev)
         case "session.created", "session.state", "session.subagents", "session.model":
             if ev.owner != nil {
-                spawn("load lead sessions") {
+                reloadSessions(nil)
-                    try await self.loadLeadSessions()
-                }
             } else if let taskId = ev.taskId {
-                spawn("load sessions") {
+                reloadSessions(taskId)
-                    try await self.loadSessions(taskId)
-                }
             }
         case "inbox.created":
             if let taskId = ev.taskId {
@@ -917,6 +915,34 @@ final class Store {
         events.send(ev)
     }
 
+    private func reloadSessions(_ taskId: String?) {
+        let key = taskId ?? "lead"
+        sessionRefetches.insert(key)
+        guard sessionReloads.insert(key).inserted else {
+            return
+        }
+        spawn("load sessions") {
+            defer {
+                self.sessionReloads.remove(key)
+            }
+            var failure: (any Error)?
+            while self.sessionRefetches.remove(key) != nil {
+                do {
+                    if let taskId {
+                        try await self.loadSessions(taskId)
+                    } else {
+                        try await self.loadLeadSessions()
+                    }
+                } catch {
+                    failure = error
+                }
+            }
+            if let failure {
+                throw failure
+            }
+        }
+    }
+
     private func reloadTask(_ ev: ByreEvent) {
         guard let projectId = ev.projectId, let taskId = ev.taskId else {
             return