Fallback display names for TUI skill mentions (#18786)

This updates TUI skill mentions to show a fallback label when a skill
does not define a display name, so unnamed skills remain understandable
in the picker without changing behavior for skills that already have
one.

<img width="1028" height="198" alt="Screenshot 2026-04-20 at 6 25 15 PM"
src="https://github.com/user-attachments/assets/84077b85-99d0-4db9-b533-37e1887b4506"
/>

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

@@ -206,6 +206,7 @@ use crate::bottom_pane::textarea::TextAreaState;
 use crate::clipboard_paste::normalize_pasted_path;
 use crate::clipboard_paste::pasted_image_format;
 use crate::history_cell;
+use crate::skills_helpers::skill_display_name;
 use crate::tui::FrameRequester;
 use crate::ui_consts::LIVE_PREFIX_COLS;
 use codex_app_server_protocol::AppInfo;
@@ -3455,7 +3456,7 @@ impl ChatComposer {
         let mut mentions = Vec::new();
         if let Some(skills) = self.skills.as_ref() {
             for skill in skills {
-                let display_name = skill_display_name(skill).to_string();
+                let display_name = skill_display_name(skill);
                 let description = skill_description(skill);
                 let skill_name = skill.name.clone();
                 let search_terms = if display_name == skill.name {
@@ -3659,14 +3660,6 @@ impl ChatComposer {
     }
 }
 
-fn skill_display_name(skill: &SkillMetadata) -> &str {
-    skill
-        .interface
-        .as_ref()
-        .and_then(|interface| interface.display_name.as_deref())
-        .unwrap_or(&skill.name)
-}
-
 fn skill_description(skill: &SkillMetadata) -> Option<String> {
     let description = skill
         .interface

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

@@ -28,7 +28,7 @@ pub(crate) struct MentionItem {
     pub(crate) sort_rank: u8,
 }
 
-const MENTION_NAME_TRUNCATE_LEN: usize = 24;
+const MENTION_NAME_TRUNCATE_LEN: usize = 28;
 
 pub(crate) struct SkillPopup {
     query: String,

codex-rs/tui/src/chatwidget/skills.rs

@@ -75,7 +75,7 @@ impl ChatWidget {
             .iter()
             .map(|skill| {
                 let core_skill = protocol_skill_to_core(skill);
-                let display_name = skill_display_name(&core_skill).to_string();
+                let display_name = skill_display_name(&core_skill);
                 let description = skill_description(&core_skill).to_string();
                 let name = core_skill.name.clone();
                 let path = core_skill.path_to_skills_md;

codex-rs/tui/src/skills_helpers.rs

@@ -5,12 +5,23 @@ use crate::text_formatting::truncate_text;
 
 pub(crate) const SKILL_NAME_TRUNCATE_LEN: usize = 21;
 
-pub(crate) fn skill_display_name(skill: &SkillMetadata) -> &str {
-    skill
+pub(crate) fn skill_display_name(skill: &SkillMetadata) -> String {
+    if let Some(display_name) = skill
         .interface
         .as_ref()
         .and_then(|interface| interface.display_name.as_deref())
-        .unwrap_or(&skill.name)
+    {
+        return display_name.to_string();
+    }
+
+    if let Some((plugin_name, skill_name)) = skill.name.split_once(':')
+        && !plugin_name.is_empty()
+        && !skill_name.is_empty()
+    {
+        return format!("{skill_name} ({plugin_name})");
+    }
+
+    skill.name.clone()
 }
 
 pub(crate) fn skill_description(skill: &SkillMetadata) -> &str {