Fix stale surface-to-panel rebinding

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

@@ -5,7 +5,7 @@
 17717	Sources/AppDelegate.swift
 16112	Sources/ContentView.swift
 13950	Sources/TerminalController.swift
-12758	Sources/Workspace.swift
+12772	Sources/Workspace.swift
 12144	cmuxTests/AppDelegateShortcutRoutingTests.swift
 11924	Sources/Panels/BrowserPanel.swift
 11867	Sources/GhosttyTerminalView.swift
@@ -20,7 +20,7 @@
 6084	Sources/TextBoxInput.swift
 5915	cmuxTests/TerminalAndGhosttyTests.swift
 5573	cmuxTests/BrowserConfigTests.swift
-5566	Packages/iOS/CmuxMobileShell/Sources/CmuxMobileShell/MobileShellComposite.swift
+5507	Packages/iOS/CmuxMobileShell/Sources/CmuxMobileShell/MobileShellComposite.swift
 4487	Sources/Panels/FilePreviewPanel.swift
 4478	Sources/cmuxApp.swift
 4401	cmuxTests/BrowserPanelTests.swift
@@ -123,9 +123,9 @@
 754	Sources/TerminalController+ControlWorkspaceContext.swift
 752	cmuxUITests/CloseWorkspaceCmdDUITests.swift
 738	Packages/macOS/CMUXProjectModel/Sources/CMUXProjectModel/XcodeProjectAdapter.swift
-736	Packages/Shared/CmuxAuthRuntime/Sources/CmuxAuthRuntime/Coordinator/AuthCoordinator.swift
 726	cmuxTests/CLICodexHookTimeoutRegressionTests.swift
 722	Packages/Shared/CmuxAgentChat/Sources/CmuxAgentChat/Store/ChatConversationStore.swift
+718	Packages/Shared/CmuxAuthRuntime/Sources/CmuxAuthRuntime/Coordinator/AuthCoordinator.swift
 716	Sources/TaskManagerSnapshot.swift
 715	Sources/AppleScriptSupport.swift
 710	Sources/TerminalSSHSessionDetector.swift

Packages/macOS/CmuxPanes/Sources/CmuxPanes/Model/PaneTreeModel.swift

@@ -34,13 +34,22 @@ public final class PaneTreeModel<Panel> {
 
     /// Mapping from bonsplit `TabID` (surface id) to the owning panel id
     /// (legacy `Workspace.surfaceIdToPanelId`).
-    public var surfaceIdToPanelId: [TabID: UUID] = [:]
+    ///
+    /// A panel can be mounted under only one bonsplit surface at a time.
+    /// Rebinding the same panel id to a new surface id removes any stale
+    /// surface entries for that panel so focus and input never resolve two
+    /// tabs to one live PTY.
+    public private(set) var surfaceIdToPanelId: [TabID: UUID] = [:]
 
     /// Snapshot of the spatially ordered panel ids from the last geometry
     /// notification, used to gate `paneLayoutVersion` bumps to genuine
     /// reorder events (legacy `Workspace.lastOrderedPanelIds`).
     public var lastOrderedPanelIds: [UUID] = []
 
+    /// Reverse index for targeted panel lookups and stale-surface removal.
+    @ObservationIgnored
+    private var panelIdToSurfaceId: [UUID: TabID] = [:]
+
     @ObservationIgnored
     private weak var host: (any PaneTreeHosting<Panel>)?
 
@@ -55,17 +64,50 @@ public final class PaneTreeModel<Panel> {
         self.host = host
     }
 
+    /// Binds a bonsplit surface id to a panel id.
+    ///
+    /// The binding is exclusive by panel id: a live panel can be represented by
+    /// only one surface at a time, so rebinding the panel removes stale surface
+    /// entries before installing the new owner.
+    public func bindSurface(_ surfaceId: TabID, toPanelId panelId: UUID) {
+        if let previousSurfaceId = panelIdToSurfaceId[panelId],
+           previousSurfaceId != surfaceId {
+            surfaceIdToPanelId.removeValue(forKey: previousSurfaceId)
+        }
+        if let previousPanelId = surfaceIdToPanelId[surfaceId],
+           previousPanelId != panelId,
+           panelIdToSurfaceId[previousPanelId] == surfaceId {
+            panelIdToSurfaceId.removeValue(forKey: previousPanelId)
+        }
+
+        surfaceIdToPanelId[surfaceId] = panelId
+        panelIdToSurfaceId[panelId] = surfaceId
+    }
+
+    /// Removes the mapping for one bonsplit surface id.
+    public func removeSurfaceMapping(forSurfaceId surfaceId: TabID) {
+        if let panelId = surfaceIdToPanelId.removeValue(forKey: surfaceId),
+           panelIdToSurfaceId[panelId] == surfaceId {
+            panelIdToSurfaceId.removeValue(forKey: panelId)
+        }
+    }
+
+    /// Removes every mapping that can still resolve to a closed panel.
+    public func removeSurfaceMappings(forPanelId panelId: UUID) {
+        if let surfaceId = panelIdToSurfaceId.removeValue(forKey: panelId) {
+            surfaceIdToPanelId.removeValue(forKey: surfaceId)
+        }
+    }
+
     /// Resolves the owning panel id for a bonsplit surface id (legacy
     /// `Workspace.panelIdFromSurfaceId`).
     public func panelId(forSurfaceId surfaceId: TabID) -> UUID? {
         surfaceIdToPanelId[surfaceId]
     }
 
     /// Resolves the bonsplit surface id currently mapped to a panel id
-    /// (legacy `Workspace.surfaceIdFromPanelId`). When multiple surfaces map
-    /// to the same panel the match is dictionary-order arbitrary, exactly as
-    /// the legacy `first(where:)` lookup was.
+    /// (legacy `Workspace.surfaceIdFromPanelId`).
     public func surfaceId(forPanelId panelId: UUID) -> TabID? {
-        surfaceIdToPanelId.first { $0.value == panelId }?.key
+        panelIdToSurfaceId[panelId]
     }
 }

Packages/macOS/CmuxPanes/Tests/CmuxPanesTests/PaneTreeModelTests.swift

@@ -81,7 +81,7 @@ struct PaneTreeModelTests {
         let model = PaneTreeModel<String>()
         let tabId = TabID()
         let panelId = UUID()
-        model.surfaceIdToPanelId[tabId] = panelId
+        model.bindSurface(tabId, toPanelId: panelId)
         #expect(model.surfaceIdToPanelId[tabId] == panelId)
         model.lastOrderedPanelIds = [panelId]
         #expect(model.lastOrderedPanelIds == [panelId])
@@ -94,11 +94,74 @@ struct PaneTreeModelTests {
         let model = PaneTreeModel<String>()
         let tabId = TabID()
         let panelId = UUID()
-        model.surfaceIdToPanelId[tabId] = panelId
+        model.bindSurface(tabId, toPanelId: panelId)
 
         #expect(model.panelId(forSurfaceId: tabId) == panelId)
         #expect(model.surfaceId(forPanelId: panelId) == tabId)
         #expect(model.panelId(forSurfaceId: TabID()) == nil)
         #expect(model.surfaceId(forPanelId: UUID()) == nil)
     }
+
+    /// Rebinding one live panel to a new bonsplit surface must not leave the
+    /// old surface id resolving to the same panel.
+    @Test func rebindingPanelToNewSurfaceInvalidatesOldSurfaceMapping() {
+        let model = PaneTreeModel<String>()
+        let oldTabId = TabID()
+        let newTabId = TabID()
+        let panelId = UUID()
+
+        model.bindSurface(oldTabId, toPanelId: panelId)
+        model.bindSurface(newTabId, toPanelId: panelId)
+
+        #expect(model.panelId(forSurfaceId: oldTabId) == nil)
+        #expect(model.panelId(forSurfaceId: newTabId) == panelId)
+        #expect(model.surfaceId(forPanelId: panelId) == newTabId)
+    }
+
+    /// Reusing one bonsplit surface for a different panel must also clear the
+    /// old panel's reverse lookup.
+    @Test func rebindingSurfaceToNewPanelInvalidatesOldPanelMapping() {
+        let model = PaneTreeModel<String>()
+        let tabId = TabID()
+        let oldPanelId = UUID()
+        let newPanelId = UUID()
+
+        model.bindSurface(tabId, toPanelId: oldPanelId)
+        model.bindSurface(tabId, toPanelId: newPanelId)
+
+        #expect(model.panelId(forSurfaceId: tabId) == newPanelId)
+        #expect(model.surfaceId(forPanelId: oldPanelId) == nil)
+        #expect(model.surfaceId(forPanelId: newPanelId) == tabId)
+    }
+
+    /// Close cleanup removes the surface owned by the closed panel.
+    @Test func closedPanelCleanupRemovesClosedSurfaceMapping() {
+        let model = PaneTreeModel<String>()
+        let closedPanelTabId = TabID()
+        let closedPanelId = UUID()
+
+        model.bindSurface(closedPanelTabId, toPanelId: closedPanelId)
+        model.removeSurfaceMappings(forPanelId: closedPanelId)
+
+        #expect(model.panelId(forSurfaceId: closedPanelTabId) == nil)
+        #expect(model.surfaceId(forPanelId: closedPanelId) == nil)
+    }
+
+    /// Close cleanup removes stale aliases for the closed panel without using
+    /// a stale tab id to drop a surface that has already moved to another panel.
+    @Test func closedPanelCleanupKeepsReboundSurfaceMapping() {
+        let model = PaneTreeModel<String>()
+        let reboundTabId = TabID()
+        let closedPanelId = UUID()
+        let livePanelId = UUID()
+
+        model.bindSurface(reboundTabId, toPanelId: closedPanelId)
+        model.bindSurface(reboundTabId, toPanelId: livePanelId)
+
+        model.removeSurfaceMappings(forPanelId: closedPanelId)
+
+        #expect(model.panelId(forSurfaceId: reboundTabId) == livePanelId)
+        #expect(model.surfaceId(forPanelId: closedPanelId) == nil)
+        #expect(model.surfaceId(forPanelId: livePanelId) == reboundTabId)
+    }
 }

Sources/Workspace+CustomSidebarPane.swift

@@ -100,7 +100,7 @@ extension Workspace {
             return nil
         }
 
-        surfaceIdToPanelId[newTabId] = customPanel.id
+        bindSurface(newTabId, toPanelId: customPanel.id)
         if let targetIndex {
             _ = bonsplitController.reorderTab(newTabId, toIndex: targetIndex)
         }
@@ -149,7 +149,7 @@ extension Workspace {
             isLoading: false,
             isPinned: false
         )
-        surfaceIdToPanelId[newTab.id] = customPanel.id
+        bindSurface(newTab.id, toPanelId: customPanel.id)
         let previousHostedView = focusedTerminalPanel?.hostedView
 
         isProgrammaticSplit = true
@@ -162,7 +162,7 @@ extension Workspace {
         ) else {
             panels.removeValue(forKey: customPanel.id)
             panelTitles.removeValue(forKey: customPanel.id)
-            surfaceIdToPanelId.removeValue(forKey: newTab.id)
+            removeSurfaceMapping(forSurfaceId: newTab.id)
             return nil
         }
 

Sources/Workspace+PanelLifecycle.swift

@@ -335,11 +335,7 @@ extension Workspace {
         panels.removeValue(forKey: panelId)
         untrackRemoteTerminalSurface(panelId)
         pendingRemoteTerminalChildExitSurfaceIds.remove(panelId)
-        if let tabId {
-            surfaceIdToPanelId.removeValue(forKey: tabId)
-        } else {
-            surfaceIdToPanelId = surfaceIdToPanelId.filter { $0.value != panelId }
-        }
+        removeSurfaceMappings(forPanelId: panelId)
 
         panelDirectories.removeValue(forKey: panelId)
         panelGitBranches.removeValue(forKey: panelId)