From cb86316506a8fdd26698dbca6559e9c82fb9ff93 Mon Sep 17 00:00:00 2001
From: rzen <rzenetl@gmail.com>
Date: Sun, 26 Jul 2026 19:48:12 -0400
Subject: [PATCH] =?UTF-8?q?Selection=20liveness=20is=20effective=20?=
 =?UTF-8?q?=E2=80=94=20ancestor-walked=20(ratified)?=
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The parallel design session settled the tombstoned-ancestor question:
a card counts as trashed if its own flag or its lane's says so, so
tombstoning a lane ejects its cards from a live selection — they render
nowhere once the lane collapses to a single trash entry, and nothing
invisible may stay selected, drag-included, or pending-cut. One-line
predicate change in Selection.resolved(against:), plus the test.

Full BoardStore suite green (15 tests).

Claude-Session: https://claude.ai/code/session_018BjQRYBR6jQja3jCRi5S3A
---
 Kanban/LiveStore/BoardStore.swift | 10 ++++++----
 KanbanTests/BoardStoreTests.swift | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/Kanban/LiveStore/BoardStore.swift b/Kanban/LiveStore/BoardStore.swift
index 7b72e4d..d7d50cf 100644
--- a/Kanban/LiveStore/BoardStore.swift
+++ b/Kanban/LiveStore/BoardStore.swift
@@ -100,9 +100,11 @@ public struct Selection: Sendable, Equatable {
     ///   homogeneous-by-liveness invariant true across reloads so menu validation never sees a
     ///   mixed selection.
     ///
-    /// The match is on the item's *own* tombstone flag. A live card sitting under a tombstoned lane
-    /// therefore survives re-resolution even though the board does not render it — the loader keeps
-    /// it in the snapshot, and "still present, same side" is the rule as written.
+    /// The liveness that is matched is **effective — ancestor-walked** (settled): a card counts as
+    /// trashed if its own flag *or its lane's* says so. Tombstoning a lane therefore ejects its
+    /// cards from a live selection even though their own flags never changed — the card renders
+    /// nowhere once 03-board-ui.md collapses the lane to a single trash entry, and nothing
+    /// invisible may stay selected, drag-included, or pending-cut.
     public func resolved(against snapshot: BoardModel) -> Selection {
         guard !ids.isEmpty else { return self }
 
@@ -113,7 +115,7 @@ public struct Selection: Sendable, Equatable {
                 survivors.insert(lane.id)
             }
             for card in lane.cards where ids.contains(card.id) {
-                if Liveness(isDeleted: card.isDeleted) == liveness {
+                if Liveness(isDeleted: lane.isDeleted || card.isDeleted) == liveness {
                     survivors.insert(card.id)
                 }
             }
diff --git a/KanbanTests/BoardStoreTests.swift b/KanbanTests/BoardStoreTests.swift
index 9ffa7f4..8d97fad 100644
--- a/KanbanTests/BoardStoreTests.swift
+++ b/KanbanTests/BoardStoreTests.swift
@@ -393,6 +393,25 @@ struct BoardStoreTests {
         #expect(store.selection.ids == [ItemID(rawValue: Ident.card2)])
     }
 
+    @Test("Tombstoning a lane ejects its cards from a live selection — liveness is effective")
+    func selectionEjectsCardsUnderATombstonedLane() async throws {
+        let fixture = try makeBoard()
+        defer { fixture.tearDown() }
+        let store = try BoardStore(rootURL: fixture.root)
+        store.select([ItemID(rawValue: Ident.card1), ItemID(rawValue: Ident.card2)], liveness: .live)
+
+        try fixture.item(Ident.lane1, tombstoned(order: "1024", title: "Lane one"))
+        store.handleWatcherEvent(.treeChanged(.foreign))
+        await store.awaitQuiescence()
+
+        // The cards' own flags never changed, but their lane's did — and liveness is
+        // ancestor-walked (02, settled): the cards render nowhere once 03 collapses the lane to
+        // a single trash entry, and nothing invisible may stay selected.
+        let survivor = lane(Ident.lane1, in: store.snapshot)?.cards.first { $0.id.rawValue == Ident.card1 }
+        #expect(survivor?.isDeleted == false, "the card's own flag is untouched")
+        #expect(store.selection.ids.isEmpty)
+    }
+
     @Test("A selection can resolve to nothing, and nothing is invented to replace it")
     func selectionCanResolveToNothing() async throws {
         let fixture = try makeBoard()