From a4fd6e342057ad9876d512f260ec6e0873bb3524 Mon Sep 17 00:00:00 2001
From: Ahmed Ibrahim <aibrahim@openai.com>
Date: Thu, 15 Jan 2026 00:02:35 -0800
Subject: [PATCH] fix

---
 codex-rs/tui/src/bottom_pane/chat_composer.rs | 40 ++++++++++++++++++-
 .../tui2/src/bottom_pane/chat_composer.rs     | 40 ++++++++++++++++++-
 2 files changed, 76 insertions(+), 4 deletions(-)

diff --git a/codex-rs/tui/src/bottom_pane/chat_composer.rs b/codex-rs/tui/src/bottom_pane/chat_composer.rs
index 0e6c887523..387450c904 100644
--- a/codex-rs/tui/src/bottom_pane/chat_composer.rs
+++ b/codex-rs/tui/src/bottom_pane/chat_composer.rs
@@ -124,11 +124,25 @@ impl SlashPopupContext {
 
     /// Return the prefix used to filter slash commands.
     fn popup_prefix(&self) -> &str {
-        let prefix_end = if self.cursor_on_first_line() {
-            self.cursor.max(1).min(self.first_line_end)
+        let mut prefix_end = if self.cursor_on_first_line() {
+            let cursor = if self.cursor == 0 && self.text.starts_with('/') {
+                1
+            } else {
+                self.cursor
+            };
+            cursor.min(self.first_line_end)
         } else {
             self.first_line_end
         };
+        if prefix_end < self.text.len() && !self.text.is_char_boundary(prefix_end) {
+            prefix_end = self
+                .text
+                .char_indices()
+                .map(|(i, _)| i)
+                .take_while(|&i| i <= prefix_end)
+                .last()
+                .unwrap_or(0);
+        }
         &self.text[..prefix_end]
     }
 }
@@ -4535,6 +4549,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn slash_popup_ignores_non_ascii_prefix_at_start() {
+        use tokio::sync::mpsc::unbounded_channel;
+
+        let (tx, _rx) = unbounded_channel::<AppEvent>();
+        let sender = AppEventSender::new(tx);
+        let mut composer = ChatComposer::new(
+            true,
+            sender,
+            false,
+            "Ask Codex to do anything".to_string(),
+            false,
+        );
+
+        composer.set_text_content("あ".to_string());
+
+        assert!(
+            matches!(composer.active_popup, ActivePopup::None),
+            "non-ASCII prefix should not activate slash popup"
+        );
+    }
+
     #[test]
     fn slash_popup_activated_for_prefix_with_args() {
         let (tx, _rx) = unbounded_channel::<AppEvent>();
diff --git a/codex-rs/tui2/src/bottom_pane/chat_composer.rs b/codex-rs/tui2/src/bottom_pane/chat_composer.rs
index c76fabb21b..f32a4327b3 100644
--- a/codex-rs/tui2/src/bottom_pane/chat_composer.rs
+++ b/codex-rs/tui2/src/bottom_pane/chat_composer.rs
@@ -127,11 +127,25 @@ impl SlashPopupContext {
 
     /// Return the prefix used to filter slash commands.
     fn popup_prefix(&self) -> &str {
-        let prefix_end = if self.cursor_on_first_line() {
-            self.cursor.max(1).min(self.first_line_end)
+        let mut prefix_end = if self.cursor_on_first_line() {
+            let cursor = if self.cursor == 0 && self.text.starts_with('/') {
+                1
+            } else {
+                self.cursor
+            };
+            cursor.min(self.first_line_end)
         } else {
             self.first_line_end
         };
+        if prefix_end < self.text.len() && !self.text.is_char_boundary(prefix_end) {
+            prefix_end = self
+                .text
+                .char_indices()
+                .map(|(i, _)| i)
+                .take_while(|&i| i <= prefix_end)
+                .last()
+                .unwrap_or(0);
+        }
         &self.text[..prefix_end]
     }
 }
@@ -4393,6 +4407,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn slash_popup_ignores_non_ascii_prefix_at_start() {
+        use tokio::sync::mpsc::unbounded_channel;
+
+        let (tx, _rx) = unbounded_channel::<AppEvent>();
+        let sender = AppEventSender::new(tx);
+        let mut composer = ChatComposer::new(
+            true,
+            sender,
+            false,
+            "Ask Codex to do anything".to_string(),
+            false,
+        );
+
+        composer.set_text_content("あ".to_string());
+
+        assert!(
+            matches!(composer.active_popup, ActivePopup::None),
+            "non-ASCII prefix should not activate slash popup"
+        );
+    }
+
     #[test]
     fn slash_popup_activated_for_prefix_with_args() {
         use tokio::sync::mpsc::unbounded_channel;