From aa2f2087f006029959b7eef4021a97dae0d7aa9a Mon Sep 17 00:00:00 2001
From: Junegunn Choi <junegunn.c@gmail.com>
Date: Sat, 28 Feb 2026 13:27:31 +0900
Subject: [PATCH] Fix multi-line scrolling after change-with-nth

Clear numLinesCache when with-nth changes so the constrain/scrolling
logic recalculates item heights instead of using stale cached values.
---
 src/terminal.go   |  1 +
 test/test_core.rb | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/src/terminal.go b/src/terminal.go
index a87064e4..fabb5b43 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -6397,6 +6397,7 @@ func (t *Terminal) Loop() error {
 						t.withNthExpr = withNthExpr
 						t.filterSelection = true
 						changed = true
+						t.clearNumLinesCache()
 						t.forceRerenderList()
 					}
 				})
diff --git a/test/test_core.rb b/test/test_core.rb
index a9f7418f..9eb30f43 100644
--- a/test/test_core.rb
+++ b/test/test_core.rb
@@ -1884,6 +1884,43 @@ class TestCore < TestInteractive
     end
   end
 
+  def test_change_with_nth_multiline
+    # Each item has 3 lines: "N-a\nN-b\nN-c"
+    # --with-nth 1 shows 1 line per item, --with-nth 1..3 shows 3 lines per item
+    tmux.send_keys %(seq 20 | xargs -I{} printf '{}-a\\n{}-b\\n{}-c\\0' | #{FZF} --read0 --delimiter "\n" --with-nth 1 --bind 'space:change-with-nth(1..3|1)' --no-sort), :Enter
+    tmux.until do |lines|
+      assert_equal 20, lines.item_count
+      assert lines.any_include?('1-a')
+      refute lines.any_include?('1-b')
+    end
+    # Expand to 3 lines per item
+    tmux.send_keys :Space
+    tmux.until do |lines|
+      assert lines.any_include?('1-a')
+      assert lines.any_include?('1-b')
+      assert lines.any_include?('1-c')
+    end
+    # Scroll down a few items
+    5.times { tmux.send_keys :Down }
+    tmux.until do |lines|
+      assert lines.any_include?('6-a')
+      assert lines.any_include?('6-b')
+      assert lines.any_include?('6-c')
+    end
+    # Collapse back to 1 line per item
+    tmux.send_keys :Space
+    tmux.until do |lines|
+      assert lines.any_include?('6-a')
+      refute lines.any_include?('6-b')
+    end
+    # Scroll down more after collapse
+    5.times { tmux.send_keys :Down }
+    tmux.until do |lines|
+      assert lines.any_include?('11-a')
+      refute lines.any_include?('11-b')
+    end
+  end
+
   def test_env_vars
     def env_vars
       return {} unless File.exist?(tempname)