From 4a4bcd6ca8dc9435c3586af06dcb6cd61229395b Mon Sep 17 00:00:00 2001
From: Arkadiusz Fal <arek@arekf.net>
Date: Sun, 4 Oct 2026 23:32:44 +0200
Subject: [PATCH] Keep a section's stack when the sidebar selection changes

In the split-view sidebar layout (macOS, and now iPad and the iPhone
Duo), the detail NavigationStack that a selection change replaces
writes an empty path through its binding on the way out, so going to
another section and back always landed on the section's root. macOS
already behaved this way before the router.

Only the selected section's stack is on screen and can pop, so path
writes for any other section are ignored.
---
 .../Navigation/NavigationRouter.swift         | 10 ++++++++-
 YatteeTests/NavigationTests.swift             | 22 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/Yattee/Services/Navigation/NavigationRouter.swift b/Yattee/Services/Navigation/NavigationRouter.swift
index 6f97a337..299b0bb1 100644
--- a/Yattee/Services/Navigation/NavigationRouter.swift
+++ b/Yattee/Services/Navigation/NavigationRouter.swift
@@ -44,7 +44,15 @@ final class NavigationRouter {
         let key = item.id
         return Binding(
             get: { self.stacks[key] ?? [] },
-            set: { self.stacks[key] = $0 }
+            set: {
+                // Only the selected section's stack is on screen, so only it
+                // edits its path (Back, swipe back). A NavigationSplitView
+                // detail stack that is being replaced on a selection change
+                // writes an empty path on its way out, which would throw
+                // away what the section had pushed.
+                guard key == self.selection.id else { return }
+                self.stacks[key] = $0
+            }
         )
     }
 
diff --git a/YatteeTests/NavigationTests.swift b/YatteeTests/NavigationTests.swift
index 054ae909..5b125655 100644
--- a/YatteeTests/NavigationTests.swift
+++ b/YatteeTests/NavigationTests.swift
@@ -677,6 +677,28 @@ struct NavigationCoordinatorTests {
         #expect(router.selection == .bookmarks)
     }
 
+    @Test("A stack that is no longer selected can't clear itself")
+    func offscreenStackWriteIgnored() {
+        let router = NavigationRouter()
+        router.push(.history)
+        let homePath = router.path(for: .home)
+
+        router.select(.bookmarks)
+        homePath.wrappedValue = []
+
+        #expect(router.stack(for: .home) == [.history])
+    }
+
+    @Test("The selected stack still pops")
+    func selectedStackPops() {
+        let router = NavigationRouter()
+        router.push(.history)
+
+        router.path(for: .home).wrappedValue = []
+
+        #expect(router.stack(for: .home).isEmpty)
+    }
+
     @Test("A destination pushed before startup keeps its section")
     func deepLinkBeforeStartup() {
         let coordinator = NavigationCoordinator()