diff --git a/supacode/Features/Terminal/Models/WorktreeTerminalState+Surfaces.swift b/supacode/Features/Terminal/Models/WorktreeTerminalState+Surfaces.swift
index a3d96b48..d35aa839 100644
--- a/supacode/Features/Terminal/Models/WorktreeTerminalState+Surfaces.swift
+++ b/supacode/Features/Terminal/Models/WorktreeTerminalState+Surfaces.swift
@@ -653,9 +653,12 @@ extension WorktreeTerminalState {
   /// is selected, it is the focused pane of the selected tab (`isFocusedSurface`
   /// already implies both), and the app window is key and visible. Unknown window
   /// state (`nil`) is treated as not-viewed so a notification is never silently
-  /// dropped.
+  /// dropped. Canvas mode is also treated as not-viewed: the normal-mode window
+  /// observers are torn down there, so `lastWindowIsKey`/`lastWindowIsVisible`
+  /// freeze at their pre-canvas values and a backgrounded app would keep muting.
   func isViewedSurface(_ surfaceId: UUID) -> Bool {
-    isSelected() && isFocusedSurface(surfaceId) && lastWindowIsKey == true && lastWindowIsVisible == true
+    guard !isCanvasManaged else { return false }
+    return isSelected() && isFocusedSurface(surfaceId) && lastWindowIsKey == true && lastWindowIsVisible == true
   }
 
   func updateRunningState(for tabId: TerminalTabID) {
diff --git a/supacodeTests/WorktreeTerminalStateViewedSurfaceTests.swift b/supacodeTests/WorktreeTerminalStateViewedSurfaceTests.swift
new file mode 100644
index 00000000..65c29d1c
--- /dev/null
+++ b/supacodeTests/WorktreeTerminalStateViewedSurfaceTests.swift
@@ -0,0 +1,65 @@
+import Foundation
+import Testing
+
+@testable import supacode
+
+@MainActor
+struct WorktreeTerminalStateViewedSurfaceTests {
+  @Test func surfaceIsViewedWhenSelectedFocusedAndWindowActive() {
+    let (state, surfaceId) = makeViewedState()
+
+    #expect(state.isViewedSurface(surfaceId))
+  }
+
+  @Test func surfaceIsNotViewedWhenWindowStateIsUnknown() {
+    let (state, surfaceId) = makeViewedState()
+    state.lastWindowIsKey = nil
+    state.lastWindowIsVisible = nil
+
+    #expect(!state.isViewedSurface(surfaceId))
+  }
+
+  @Test func surfaceIsNotViewedWhenWindowIsNotKey() {
+    let (state, surfaceId) = makeViewedState()
+    state.lastWindowIsKey = false
+
+    #expect(!state.isViewedSurface(surfaceId))
+  }
+
+  @Test func surfaceIsNotViewedWhenCanvasManaged() {
+    // Canvas mode tears down the normal-mode window observers, so the window
+    // flags freeze at their pre-canvas values; a stale `true` must not mute
+    // notifications while the app is in the background.
+    let (state, surfaceId) = makeViewedState()
+    state.isCanvasManaged = true
+
+    #expect(!state.isViewedSurface(surfaceId))
+  }
+
+  @Test func differentSurfaceIsNotViewed() {
+    let (state, _) = makeViewedState()
+
+    #expect(!state.isViewedSurface(UUID()))
+  }
+
+  private func makeViewedState() -> (WorktreeTerminalState, UUID) {
+    let state = WorktreeTerminalState(
+      runtime: GhosttyRuntime(),
+      worktree: Worktree(
+        id: "/tmp/repo/wt-1",
+        name: "wt-1",
+        detail: "",
+        workingDirectory: URL(fileURLWithPath: "/tmp/repo/wt-1"),
+        repositoryRootURL: URL(fileURLWithPath: "/tmp/repo")
+      )
+    )
+    let tabId = state.tabManager.createTab(title: "tab", icon: nil)
+    state.tabManager.selectTab(tabId)
+    let surfaceId = UUID()
+    state.focusedSurfaceIdByTab[tabId] = surfaceId
+    state.isSelected = { true }
+    state.lastWindowIsKey = true
+    state.lastWindowIsVisible = true
+    return (state, surfaceId)
+  }
+}