From ca5867345d88084d60c7c4ff91465d5bcbf73b82 Mon Sep 17 00:00:00 2001
From: onevcat <onevcat@gmail.com>
Date: Wed, 29 Apr 2026 22:59:25 +0900
Subject: [PATCH] Fix Shelf empty state fallback

---
 .../Features/Shelf/Models/ShelfBook.swift     | 11 ++++++++
 supacode/Features/Shelf/Views/ShelfView.swift |  9 ++++---
 supacodeTests/ShelfBookOrderingTests.swift    | 27 +++++++++++++++++++
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/supacode/Features/Shelf/Models/ShelfBook.swift b/supacode/Features/Shelf/Models/ShelfBook.swift
index 672fdab3..79a2d991 100644
--- a/supacode/Features/Shelf/Models/ShelfBook.swift
+++ b/supacode/Features/Shelf/Models/ShelfBook.swift
@@ -115,4 +115,15 @@ extension RepositoriesFeature.State {
   var openShelfBookID: Worktree.ID? {
     selectedTerminalWorktree?.id
   }
+
+  /// The rendered book matching the current Shelf selection, if any.
+  ///
+  /// `openShelfBookID` can briefly point at a worktree/folder that has
+  /// just been retired from `openedWorktreeIDs` after its last tab closes.
+  /// Views should use this lookup rather than assuming a non-nil open ID
+  /// means an open book is still present in `orderedShelfBooks()`.
+  func openShelfBook(in books: [ShelfBook]) -> ShelfBook? {
+    guard let openShelfBookID else { return nil }
+    return books.first(where: { $0.id == openShelfBookID })
+  }
 }
diff --git a/supacode/Features/Shelf/Views/ShelfView.swift b/supacode/Features/Shelf/Views/ShelfView.swift
index a8f4b50b..1aa07110 100644
--- a/supacode/Features/Shelf/Views/ShelfView.swift
+++ b/supacode/Features/Shelf/Views/ShelfView.swift
@@ -32,9 +32,10 @@ struct ShelfView: View {
     let _ = shelfLogger.event("ShelfView.body")
     let state = store.state
     let books = state.orderedShelfBooks(customTitles: state.repositoryCustomTitles)
-    let openBookID = state.openShelfBookID
-    let openIndex = openBookID.flatMap { id in
-      books.firstIndex(where: { $0.id == id })
+    let openBook = state.openShelfBook(in: books)
+    let openBookID = openBook?.id
+    let openIndex = openBook.flatMap { book in
+      books.firstIndex(where: { $0.id == book.id })
     }
 
     HStack(spacing: 0) {
@@ -44,7 +45,7 @@ struct ShelfView: View {
           openBookArea(for: book, state: state)
         }
       }
-      if openBookID == nil {
+      if openBook == nil {
         emptyOpenArea()
       }
     }
diff --git a/supacodeTests/ShelfBookOrderingTests.swift b/supacodeTests/ShelfBookOrderingTests.swift
index a1e919a0..9212eecb 100644
--- a/supacodeTests/ShelfBookOrderingTests.swift
+++ b/supacodeTests/ShelfBookOrderingTests.swift
@@ -182,6 +182,33 @@ struct ShelfBookOrderingTests {
     #expect(state.openShelfBookID == worktree.id)
   }
 
+  @Test func openShelfBookReturnsNilWhenSelectedBookIsNoLongerRendered() {
+    let rootURL = URL(fileURLWithPath: "/tmp/repo")
+    let worktree = Worktree(
+      id: "/tmp/repo",
+      name: "main",
+      detail: "",
+      workingDirectory: rootURL,
+      repositoryRootURL: rootURL
+    )
+    let repository = Repository(
+      id: rootURL.path(percentEncoded: false),
+      rootURL: rootURL,
+      name: "repo",
+      worktrees: IdentifiedArray(uniqueElements: [worktree])
+    )
+    var state = RepositoriesFeature.State(repositories: [repository])
+    state.repositoryRoots = [rootURL]
+    state.repositoryOrderIDs = [repository.id]
+    state.selection = .worktree(worktree.id)
+    state.openedWorktreeIDs = []
+
+    let books = state.orderedShelfBooks()
+    #expect(books.isEmpty)
+    #expect(state.openShelfBookID == worktree.id)
+    #expect(state.openShelfBook(in: books) == nil)
+  }
+
   @Test func openShelfBookIDResolvesPlainFolderViaRepositoryID() {
     let rootURL = URL(fileURLWithPath: "/tmp/plain")
     let repository = Repository(
-- 
2.51.2