perf(cmux-next): hidden agent chat pages freeze like browser tabs; background-opened tabs start their hidden clock

Packages/macOS/CmuxNext/Sources/CmuxNextAgentPane/AgentPaneTransport.swift

@@ -30,6 +30,11 @@ import CmuxNextCompat
     /// Gets each push for the page (the view sends it through the bridge) and a completion to call
     /// once the page has run it (it paces the next push).
     public var deliver: (@MainActor (AgentPaneTransportEvent, _ done: @escaping @MainActor @Sendable () -> Void) -> Void)?
+    /// Runs right before anything reaches the page: a push here, a script call or a picture
+    /// (``AgentPaneView/callPageScript(_:arguments:)``, ``AgentPaneView/pageSnapshot()``). A hidden page
+    /// that froze (the app's hibernation) thaws first, so the work runs now instead of waiting on a
+    /// page that runs no script (a push's completion paces the next one).
+    public var beforePageWork: (@MainActor () -> Void)?
     /// Counts pushes, so a late completion of a previous connection's push is ignored.
     private var deliveries = 0
     private var pacerStorage: any AgentPaneTransportPacer
@@ -406,6 +411,7 @@ import CmuxNextCompat
         guard let deliver else { return AgentPaneFlush(delivered: false, more: more) }
         deliveries += 1
         let delivery = deliveries
+        beforePageWork?()
         deliver(event) { [weak self] in
             guard let self, self.deliveries == delivery else { return }
             self.pacer.delivered()

Packages/macOS/CmuxNext/Sources/CmuxNextAgentPane/AgentPaneView+Engine.swift

@@ -10,8 +10,15 @@ extension AgentPaneView {
     /// The Chromium page that shows the chat now; nil on WebKit.
     public var chromiumPage: (any PageChromiumPage)? { page?.chromiumPage }
 
+    /// The page shows in Chromium once its browser is made (``chromiumPage`` is nil until then).
+    public var waitsForChromium: Bool {
+        guard let page else { return false }
+        return page.engineDecision.engine == .cef && !page.showsChromium
+    }
+
     /// A picture of the page as it draws now; nil when there is none.
     public func pageSnapshot() async -> NSImage? {
+        model.transport.beforePageWork?()
         if let page { return await page.snapshot() }
         return try? await webView.takeSnapshot(configuration: nil)
     }

Packages/macOS/CmuxNext/Sources/CmuxNextAgentPane/AgentPaneView+PageHost.swift

@@ -64,6 +64,7 @@ extension AgentPaneView {
     /// Runs `body` as an async function body in the chat's page, in whichever engine shows it
     /// (``PageWebView/callPageScript(_:arguments:)``).
     public func callPageScript(_ body: String, arguments: [String: Any] = [:]) async throws -> Any? {
+        model.transport.beforePageWork?()
         if let page { return try await page.callPageScript(body, arguments: arguments) }
         return try await webView.callAsyncJavaScript(body, arguments: arguments, in: nil, contentWorld: .page)
     }

Packages/macOS/CmuxNext/Sources/CmuxNextApp/AgentTabs+Wiring.swift

@@ -427,6 +427,8 @@ extension AgentTabStore {
             tabs?.localHostName = name
             return AgentPaneModel.rememberLocalMachineName(AgentTabStore.displayName(name) ?? name)
         }
+        tabs.onPageBuilt = { [weak services] key in services?.cache.hibernation?.agentPages?.pageBuilt(key) }
+        tabs.onCollectingPages = { [weak services] held in services?.cache.hibernation?.agentPages?.holdAwake(held) }
         services.madeAgentTabs = tabs
         return tabs
     }

Packages/macOS/CmuxNext/Sources/CmuxNextApp/AgentTabs.swift

@@ -126,6 +126,11 @@ final class AgentTabStore {
     var recycle: ((AgentPaneView) -> Bool)?
     /// The prewarmed New Tab page, for a first page that has no view yet (NewTabSparePool).
     var takeSpare: (() -> AgentPaneView?)?
+    /// Tab `key` got a page (built or adopted from the spare), drawn or not: a page built while its
+    /// tab does not draw starts its hidden clock (`AgentPageHibernation.pageBuilt`).
+    var onPageBuilt: ((String) -> Void)?
+    /// Every page is asked what it holds now (true), or that ended (false) (`AgentPageHibernation.holdAwake`).
+    var onCollectingPages: ((Bool) -> Void)?
     /// Closed pages leave the view tree at once; their teardown waits (R81).
     let retirer = AgentPageRetirer()
     /// The session each tab's page reported, ahead of the store's echo of the bind and across a
@@ -215,8 +220,13 @@ final class AgentTabStore {
     var wakeStates: [String: AgentPaneWakeState] = [:]
     /// What the chat pages held at the last quit, for each tab's first page at launch (``AgentPaneRelaunchWake``).
     var relaunchWake = AgentPaneRelaunchWake(file: nil)
-    /// What every chat holds for the next launch (the quit's window step).
-    func relaunchWakeStates() async -> [String: AgentPaneWakeState] { await relaunchWake.collect(held: wakeStates, pages: views.map { (resolve($0.key), $0.value) }, live: isAgentTab) }
+    /// What every chat holds for the next launch (the quit's window step). Pages that froze while
+    /// hidden thaw first and stay awake until it is collected: a frozen page answers nothing.
+    func relaunchWakeStates() async -> [String: AgentPaneWakeState] {
+        onCollectingPages?(true)
+        defer { onCollectingPages?(false) }
+        return await relaunchWake.collect(held: wakeStates, pages: views.map { (resolve($0.key), $0.value) }, live: isAgentTab)
+    }
     /// The git link of tab `key`: the session host of the tab's own machine (AgentPaneGitReads.swift),
     /// so a Cloud or SSH chat reads its folder there; nil answers the page `native.not_connected`. Move to Floating Chat puts a session in Start Agent's panel.
     /// The upload for a chat tab's dropped or pasted files, nil when it takes none (``CloudUploads``).
@@ -389,6 +399,7 @@ final class AgentTabStore {
            seed?.holdsOnlyFolder ?? true, wakeStates[key] == nil, !relaunchWake.mayHold(key), let spare = takeSpare?() {
             adoptSpare(spare, key: key, page: newTab.page)
             track(key, in: store)
+            onPageBuilt?(key)
             return spare
         }
         let model = AgentPaneModel(
@@ -421,6 +432,7 @@ final class AgentTabStore {
         }
         views[key] = view
         track(key, in: store)
+        onPageBuilt?(key)
         return view
     }