From 0b7ab5a1b5f8ede944aaadb4a3351c85a1001fd8 Mon Sep 17 00:00:00 2001
From: kerty <g.kabakov@inbox.ru>
Date: Sun, 19 Oct 2025 17:09:00 +0300
Subject: [PATCH] Fix not preserving empty last line in multiline prompts

Reproduction:
fish -C '
    function fish_prompt
        echo left-prompt\n
    end
    function fish_right_prompt
        echo right-prompt
    end
'
and pressing Enter would not preserve the line with right prompt.

This occurred because Screen::cursor_is_wrapped_to_own_line assumed
the last prompt line always had index 0. However, commit 606802daa (Make
ScreenData track multiline prompt, 2025-10-15) changed this so the last
prompt line's index is now `Screen.actual.visible_prompt_lines - 1`.

Screen::cursor_is_wrapped_to_own_line also didn't account for situations
where commandline indentation was 0.

Fix Screen::cursor_is_wrapped_to_own_line and add tests for prompts with
empty last lines.
---
 src/screen.rs                       |  3 +-
 tests/checks/tmux-empty-prompt.fish | 80 +++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 tests/checks/tmux-empty-prompt.fish

diff --git a/src/screen.rs b/src/screen.rs
index 56aa23e2d..8ad70b4b8 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -753,8 +753,9 @@ pub fn save_status(&mut self) {
     pub fn cursor_is_wrapped_to_own_line(&self) -> bool {
         // Don't consider dumb terminals to have wrapping for the purposes of this function.
         self.actual.cursor.x == 0
-            && self.actual.cursor.y != 0
+            && self.actual.cursor.y + 1 != self.actual.visible_prompt_lines
             && self.actual.cursor.y + 1 == self.actual.line_count()
+            && self.actual.line(self.actual.cursor.y - 1).is_soft_wrapped
             && !is_dumb()
     }
 
diff --git a/tests/checks/tmux-empty-prompt.fish b/tests/checks/tmux-empty-prompt.fish
new file mode 100644
index 000000000..508f7ea61
--- /dev/null
+++ b/tests/checks/tmux-empty-prompt.fish
@@ -0,0 +1,80 @@
+#RUN: %fish %s
+#REQUIRES: command -v tmux
+
+isolated-tmux-start
+isolated-tmux send-keys '
+    function fish_prompt; end
+    function fish_right_prompt
+        set -q right_prompt
+        and echo right-prompt
+    end
+    set right_prompt 1
+    bind ctrl-g "set right_prompt 1" repaint
+    bind alt-g "set -e right_prompt" repaint
+' 
+tmux-sleep
+isolated-tmux send-keys M-g C-l Enter  
+tmux-sleep
+isolated-tmux send-keys C-g Enter
+tmux-sleep
+isolated-tmux capture-pane -p | string replace -r '$' '+'
+#CHECK: +
+#CHECK: right-prompt+
+#CHECK: right-prompt+
+#CHECK: +
+#CHECK: +
+#CHECK: +
+#CHECK: +
+#CHECK: +
+#CHECK: +
+#CHECK: +
+
+isolated-tmux send-keys M-g Tab Tab
+tmux-sleep
+isolated-tmux capture-pane -p | string replace -r '$' '+'
+#CHECK: +
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+
+isolated-tmux send-keys '
+    function fish_prompt
+        echo left-prompt\n
+    end
+'  
+tmux-sleep
+isolated-tmux send-keys C-l Enter  
+tmux-sleep
+isolated-tmux send-keys C-g Enter
+tmux-sleep
+isolated-tmux capture-pane -p | string replace -r '$' '+'
+#CHECK: left-prompt+
+#CHECK: +
+#CHECK: left-prompt+
+#CHECK: right-prompt+
+#CHECK: left-prompt+
+#CHECK: right-prompt+
+#CHECK: +
+#CHECK: +
+#CHECK: +
+#CHECK: +
+
+isolated-tmux send-keys M-g Tab Tab
+tmux-sleep
+isolated-tmux capture-pane -p | string replace -r '$' '+'
+#CHECK: left-prompt+
+#CHECK: +
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+
+#CHECK: {{.*}}+