Reclaim hidden terminal renderers on memory pressure

.github/swift-file-length-budget.tsv

@@ -2,7 +2,7 @@
 # Format: max_lines<TAB>relative path
 # Reduce counts as files shrink. CI fails if tracked files exceed this budget.
 34658	CLI/cmux.swift
-17907	Sources/AppDelegate.swift
+17908	Sources/AppDelegate.swift
 16491	Sources/ContentView.swift
 14239	Sources/TerminalController.swift
 12921	Sources/Workspace.swift

Sources/App/RendererRealizationController.swift

@@ -17,6 +17,7 @@ final class RendererRealizationController {
     static let shared = RendererRealizationController()
 
     private let timerQueue = DispatchQueue(label: "com.cmux.renderer-realization", qos: .utility)
+    private let systemMemoryPressureRetryPasses = 2
     private var timer: DispatchSourceTimer?
     private var settingsObserver: NSObjectProtocol?
 
@@ -82,9 +83,25 @@ final class RendererRealizationController {
         }
     }
 
+    func reclaimForSystemMemoryPressure(now: Date) {
+        evaluate(
+            now: now,
+            trigger: .systemMemoryPressure,
+            remainingSystemMemoryPressureRetries: systemMemoryPressureRetryPasses
+        )
+    }
+
     /// Run one reclamation pass. Internal so a unit/integration test can drive it
     /// deterministically without the timer.
     func evaluate(now: Date) {
+        evaluate(now: now, trigger: .scheduled)
+    }
+
+    private func evaluate(
+        now: Date,
+        trigger: RendererRealizationReclaimTrigger,
+        remainingSystemMemoryPressureRetries: Int = 0
+    ) {
         let settings = RendererRealizationSettings.values()
         guard settings.enabled else { return }
 
@@ -120,11 +137,31 @@ final class RendererRealizationController {
         let selected = RendererRealizationPlanner.selectedSurfaceIds(
             inputs: inputs,
             settings: settings,
-            now: now.timeIntervalSince1970
+            now: now.timeIntervalSince1970,
+            trigger: trigger
         )
         guard !selected.isEmpty else { return }
+        var needsSystemMemoryPressureRetry = false
         for surface in surfaces where selected.contains(surface.id) {
             surface.releaseRenderer()
+            // A dropped Ghostty mailbox enqueue leaves the renderer realized.
+            // Retry with the pressure policy; scheduled policy may keep recent
+            // hidden surfaces warm and skip the exact surface pressure selected.
+            if trigger == .systemMemoryPressure,
+               !surface.isRendererPortalVisible,
+               surface.isRendererRealized {
+                needsSystemMemoryPressureRetry = true
+            }
+        }
+
+        if needsSystemMemoryPressureRetry, remainingSystemMemoryPressureRetries > 0 {
+            Task { @MainActor in
+                RendererRealizationController.shared.evaluate(
+                    now: Date(),
+                    trigger: .systemMemoryPressure,
+                    remainingSystemMemoryPressureRetries: remainingSystemMemoryPressureRetries - 1
+                )
+            }
         }
     }
 }

Sources/App/RendererRealizationPlanner.swift

@@ -17,10 +17,19 @@ enum RendererRealizationPlanner {
     static func selectedSurfaceIds(
         inputs: [RendererRealizationPlannerInput],
         settings: RendererRealizationSettings.Values,
-        now: TimeInterval
+        now: TimeInterval,
+        trigger: RendererRealizationReclaimTrigger = .scheduled
     ) -> Set<UUID> {
         guard settings.enabled else { return [] }
 
+        if trigger == .systemMemoryPressure {
+            return Set(
+                inputs.lazy
+                    .filter { $0.isRealized && !$0.isVisible }
+                    .map(\.surfaceId)
+            )
+        }
+
         // Only realized surfaces hold releasable GPU resources. Rank by recency
         // (most-recent first); visible surfaces are stamped ~now so they sort to
         // the top and land inside the warm set.

Sources/App/RendererRealizationReclaimTrigger.swift

@@ -0,0 +1,7 @@
+import Foundation
+
+/// Reason a renderer realization pass is selecting surfaces to reclaim.
+enum RendererRealizationReclaimTrigger: Equatable, Sendable {
+    case scheduled
+    case systemMemoryPressure
+}

Sources/AppDelegate.swift

@@ -2108,6 +2108,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
             self?.paneMemoryGuardrailDescriptors() ?? []
         }
         guardrail.onSystemMemoryPressure = { [weak self] in
+            RendererRealizationController.shared.reclaimForSystemMemoryPressure(now: Date())
             self?.discardHiddenBrowserWebViewsForSystemMemoryPressure()
         }
         guardrail.start()

cmux.xcodeproj/project.pbxproj

@@ -801,6 +801,7 @@
 		D36A00040000000000000001 /* RendererRealizationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D36A00040000000000000002 /* RendererRealizationController.swift */; };
 		D36A00060000000000000001 /* RendererRealizationPlanner.swift in Sources */ = {isa = PBXBuildFile; fileRef = D36A00060000000000000002 /* RendererRealizationPlanner.swift */; };
 		D36A00050000000000000001 /* RendererRealizationPlannerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D36A00050000000000000002 /* RendererRealizationPlannerTests.swift */; };
+		D36A00070000000000000001 /* RendererRealizationReclaimTrigger.swift in Sources */ = {isa = PBXBuildFile; fileRef = D36A00070000000000000002 /* RendererRealizationReclaimTrigger.swift */; };
 		F5410004A1B2C3D4E5F60718 /* RestorableAgentHookProviderHermesTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F5410005A1B2C3D4E5F60718 /* RestorableAgentHookProviderHermesTests.swift */; };
 		F5410000A1B2C3D4E5F60718 /* RestorableAgentHookProviderResumeTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F5410001A1B2C3D4E5F60718 /* RestorableAgentHookProviderResumeTests.swift */; };
 		F5410002A1B2C3D4E5F60718 /* RestorableAgentNonInteractiveTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F5410003A1B2C3D4E5F60718 /* RestorableAgentNonInteractiveTests.swift */; };
@@ -1993,6 +1994,7 @@
 		D36A00040000000000000002 /* RendererRealizationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = App/RendererRealizationController.swift; sourceTree = "<group>"; };
 		D36A00060000000000000002 /* RendererRealizationPlanner.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = App/RendererRealizationPlanner.swift; sourceTree = "<group>"; };
 		D36A00050000000000000002 /* RendererRealizationPlannerTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RendererRealizationPlannerTests.swift; sourceTree = "<group>"; };
+		D36A00070000000000000002 /* RendererRealizationReclaimTrigger.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = App/RendererRealizationReclaimTrigger.swift; sourceTree = "<group>"; };
 		F5410005A1B2C3D4E5F60718 /* RestorableAgentHookProviderHermesTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RestorableAgentHookProviderHermesTests.swift; sourceTree = "<group>"; };
 		F5410001A1B2C3D4E5F60718 /* RestorableAgentHookProviderResumeTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RestorableAgentHookProviderResumeTests.swift; sourceTree = "<group>"; };
 		F5410003A1B2C3D4E5F60718 /* RestorableAgentNonInteractiveTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RestorableAgentNonInteractiveTests.swift; sourceTree = "<group>"; };
@@ -2692,6 +2694,7 @@
 				D36A00010000000000000002 /* AgentHibernationController.swift */,
 				D36A00040000000000000002 /* RendererRealizationController.swift */,
 				D36A00060000000000000002 /* RendererRealizationPlanner.swift */,
+				D36A00070000000000000002 /* RendererRealizationReclaimTrigger.swift */,
 				243632BA1DBBA36FD46E0610 /* SidebarAppearanceSupport.swift */,
 				D50D9BCE46701FBA91C2EFB6 /* SidebarWorkspaceSnapshotRefreshPolicy.swift */,
 				D35450020000000000000002 /* SidebarWorkspaceRowHoverTracker.swift */,
@@ -4563,6 +4566,7 @@
 				D5037010000000000000003 /* RenderableSystemSymbol.swift in Sources */,
 				D36A00040000000000000001 /* RendererRealizationController.swift in Sources */,
 				D36A00060000000000000001 /* RendererRealizationPlanner.swift in Sources */,
+				D36A00070000000000000001 /* RendererRealizationReclaimTrigger.swift in Sources */,
 				A5001660 /* RestorableAgentSession.swift in Sources */,
 				C13519000000000000000005 /* RestorableAgentTypes.swift in Sources */,
 				B7F9A600B7F9A600B7F9A600 /* RightSidebarChromeGeometryReporting.swift in Sources */,

cmuxTests/RendererRealizationPlannerTests.swift

@@ -137,4 +137,41 @@ struct RendererRealizationPlannerTests {
         #expect(selected.contains(b))
         #expect(!selected.contains(a))
     }
+
+    @Test func systemMemoryPressureReclaimsAllHiddenRealizedRenderers() {
+        let now: TimeInterval = 1000
+        let visible = UUID()
+        let recentHidden = UUID()
+        let oldHidden = UUID()
+        let alreadyReleased = UUID()
+        let selected = RendererRealizationPlanner.selectedSurfaceIds(
+            inputs: [
+                input(visible, visible: true, lastVisibleAt: now),
+                input(recentHidden, lastVisibleAt: now - 1),
+                input(oldHidden, lastVisibleAt: now - 100),
+                input(alreadyReleased, realized: false, lastVisibleAt: now - 100),
+            ],
+            settings: settings(idle: 600, warm: 12),
+            now: now,
+            trigger: .systemMemoryPressure
+        )
+
+        #expect(!selected.contains(visible))
+        #expect(selected.contains(recentHidden))
+        #expect(selected.contains(oldHidden))
+        #expect(!selected.contains(alreadyReleased))
+    }
+
+    @Test func systemMemoryPressureRespectsDisabledSetting() {
+        let now: TimeInterval = 1000
+        let hidden = UUID()
+        let selected = RendererRealizationPlanner.selectedSurfaceIds(
+            inputs: [input(hidden, lastVisibleAt: now - 1)],
+            settings: settings(enabled: false, idle: 600, warm: 12),
+            now: now,
+            trigger: .systemMemoryPressure
+        )
+
+        #expect(selected.isEmpty)
+    }
 }