fix(tui): suppress inline skill completions in slash command args

Prevent inline skill slash completions from opening while editing arguments for an existing slash command.

  This keeps `/attach /path/to/image.png` usable without showing skill entries after the path slash, while
  preserving inline skill completions in normal message text.

  Adds a regression test for `/attach /`.

crates/tui/src/tui/slash_menu.rs

@@ -87,6 +87,10 @@ pub(crate) fn partial_inline_skill_mention_at_cursor(
     input: &str,
     cursor_chars: usize,
 ) -> Option<(usize, String)> {
+    if looks_like_slash_command_input(input) {
+        return None;
+    }
+
     let chars: Vec<char> = input.chars().collect();
     if cursor_chars > chars.len() {
         return None;

crates/tui/src/tui/ui/tests.rs

@@ -3323,6 +3323,28 @@ fn inline_skill_slash_popup_filters_partial_without_leaking_to_command_position(
     );
 }
 
+#[test]
+fn inline_skill_slash_popup_does_not_open_inside_command_arguments() {
+    let mut app = create_test_app();
+    app.cached_skills = vec![
+        (
+            "config-doctor".to_string(),
+            "Diagnose configuration".to_string(),
+        ),
+        ("cargo-ci-fixer".to_string(), "Fix CI failures".to_string()),
+    ];
+    app.input = "/attach /".to_string();
+    app.cursor_position = app.input.chars().count();
+
+    let entries = visible_slash_menu_entries(&app, 128);
+
+    assert!(
+        entries.is_empty(),
+        "command argument paths should not show inline skill entries: {:?}",
+        entries.iter().map(|entry| &entry.name).collect::<Vec<_>>()
+    );
+}
+
 #[test]
 fn apply_slash_menu_selection_splices_inline_skill_mention() {
     let mut app = create_test_app();