Open slash commands from empty drafts in Vim Normal mode (#50788)

## Why

Pressing `/` in Vim Normal mode starts a composer search, even when the draft is empty. Allow this key to open slash commands directly on an empty draft.

## What changed

When slash commands are enabled, a standalone `/` on an empty draft switches to Insert mode, inserts `/`, and opens command completion. Preserve Vim search behavior for nonempty drafts, `?`, and pending operators.

## Testing

Add a snapshot test for the Insert mode transition and command picker. Exercise Vim slash-command entry in the transcript overlay test across terminal sizes, and extend command sparkle coverage to Vim mode.

GitOrigin-RevId: 806c2f6b841190ccdc1a258f88dfa590773ba33a

codex-rs/tui/src/app/owned_transcript_tests.rs

@@ -1185,10 +1185,30 @@ async fn slash_picker_overlays_history_without_moving_the_transcript_or_composer
     ))];
     let mut tui = crate::tui::test_support::make_test_tui()?;
     tui.set_owned_screen(/*owned*/ true)?;
+    let mut app_server = Box::pin(crate::start_embedded_app_server_for_picker(&app.config)).await?;
     for (width, height) in [(80, 14), (32, 14), (80, 7), (80, 5)] {
         let size = Size::new(width, height);
         tui.terminal.resize(size)?;
-        app.chat_widget.apply_external_edit("/m".to_string());
+        app.chat_widget.apply_external_edit(String::new());
+        app.chat_widget.toggle_vim_mode_and_notify();
+        app.chat_widget.handle_key_event(KeyCode::Esc.into());
+        let slash = KeyEvent::new(KeyCode::Char('/'), KeyModifiers::NONE);
+        assert!(!app.handle_owned_transcript_event(
+            &mut tui,
+            &mut app_server,
+            &TuiEvent::Key(slash),
+        )?);
+        tokio::time::pause();
+        for key in [slash, KeyCode::Char('m').into()] {
+            app.chat_widget.handle_key_event(key);
+            tokio::time::advance(crate::bottom_pane::ChatComposer::recommended_paste_flush_delay())
+                .await;
+            app.chat_widget
+                .handle_paste_burst_tick(tui.frame_requester());
+        }
+        tokio::time::resume();
+        assert_eq!(app.chat_widget.composer_text_with_pending(), "/m");
+        app.chat_widget.toggle_vim_mode_and_notify();
         app.chat_widget
             .handle_key_event(KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE));
         app.render_owned_transcript(&mut tui, size)?;
@@ -1260,6 +1280,7 @@ async fn slash_picker_overlays_history_without_moving_the_transcript_or_composer
         );
     }
     tui.set_owned_screen(/*owned*/ false)?;
+    app_server.shutdown().await?;
     Ok(())
 }
 

codex-rs/tui/src/bottom_pane/chat_composer.rs

@@ -36,6 +36,7 @@
 //! [`ChatComposer::handle_key_event_without_popup`]. After every handled key, we call
 //! [`ChatComposer::sync_popups`] so UI state follows the latest buffer/cursor.
 //! Fresh Vim drafts start in Insert; Normal `/` and `?` search the composer.
+//! On an empty draft, a standalone Normal `/` enters Insert and opens command completion.
 //! Backspace on an empty Vim search query cancels search and any pending operator.
 //!
 //! # Completion and Popup Dismissal
@@ -1915,6 +1916,18 @@ impl ChatComposer {
             return (InputResult::None, false);
         }
 
+        if self.history_search.is_none()
+            && !self.popups.active()
+            && self.config.slash_commands_enabled
+            && self.is_empty()
+            && self.draft.textarea.wants_vim_search_key(key_event)
+            && !self.draft.textarea.is_vim_operator_pending()
+            && key_event.code == KeyCode::Char('/')
+            && key_event.modifiers.is_empty()
+        {
+            self.draft.textarea.enter_vim_insert_mode();
+        }
+
         self.draft.textarea_state.get_mut().follow_cursor();
         let before = self.before_sparkle_key(key_event);
         let result = self.handle_key_event_inner(key_event);

codex-rs/tui/src/bottom_pane/chat_composer/sparkle_tests.rs

@@ -806,8 +806,9 @@ fn fresh_draft_replacement_ends_search_and_dismisses_sparkles() {
 fn arbitrary_commands_preserve_a_never_used_fresh_opportunity() {
     palette(|| {
         let now = Instant::now();
-        for completion in [false, true] {
+        for (completion, vim) in [(false, false), (true, false), (false, true), (true, true)] {
             let mut pane = pane();
+            pane.set_vim_enabled(vim);
             pane.mark_fresh_task_for_sparkle("gpt-5.5", &enabled());
             assert!(dots(&draw(&pane.composer, /*width*/ 80, now).0).is_empty());
             for command in ["/status", "/diff", "/pwd"] {

codex-rs/tui/src/bottom_pane/chat_composer/vim_search_tests.rs

@@ -2,6 +2,7 @@
 
 use super::super::InputResult;
 use super::super::tests::snapshot_composer_state_with_width;
+use super::super::tests::type_chars_humanlike;
 use crate::keymap::KeyChordMatch;
 use crate::keymap::KeyChordMatcher;
 use crate::keymap::RuntimeKeymap;
@@ -48,6 +49,9 @@ fn backspace_cancels_empty_vim_search() {
                 composer.set_vim_enabled(/*enabled*/ true);
                 let cursor = composer.cursor();
                 for prefix in ["/", "?", "d/", "d?", "c/", "c?", "y/", "y?"] {
+                    if text.is_empty() && prefix == "/" {
+                        continue;
+                    }
                     for ch in prefix.chars() {
                         composer
                             .handle_key_event(KeyEvent::new(KeyCode::Char(ch), KeyModifiers::NONE));
@@ -107,3 +111,18 @@ fn vim_search_query_edits_and_paste_preserve_the_draft() {
         },
     );
 }
+
+#[test]
+fn empty_vim_normal_slash_opens_commands() {
+    snapshot_composer_state_with_width(
+        "vim_empty_normal_slash",
+        /*width*/ 60,
+        /*enhanced_keys_supported*/ false,
+        |composer| {
+            composer.set_vim_enabled(/*enabled*/ true);
+            type_chars_humanlike(composer, &['/']);
+            assert_eq!(composer.current_text(), "/");
+            assert_eq!(composer.draft.textarea.vim_mode_label(), Some("Insert"));
+        },
+    );
+}

codex-rs/tui/src/bottom_pane/snapshots/codex_tui__bottom_pane__chat_composer__tests__vim_empty_normal_slash.snap

@@ -0,0 +1,14 @@
+---
+source: tui/src/bottom_pane/chat_composer.rs
+assertion_line: 5217
+expression: terminal.backend()
+---
+"› /model          choose what model and reasoning effort to "
+"                  use                                       "
+"  /ide            include current selection, open files, and"
+"                  other context from your IDE               "
+"  /permissions    choose what Codex is allowed to do        "
+"                                                            "
+"› /                                                         "
+"                                                            "
+"                           100% context left | Vim: Insert  "