Extract shared footer hint wrapping in the TUI (#44354)

## What changed

Replace duplicated footer wrapping in the MCP elicitation and request-user-input overlays with `wrap_hint_rows`. Preserve whole-hint grouping, display-width and separator accounting, oversized hints, and the single empty row for empty input.

## Testing

Add unit tests for Unicode display widths, whole-hint wrapping, oversized hints at zero width, and empty input.

GitOrigin-RevId: 4d8ead0acbfa3bf9241baedb86d2476566d26ebc

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

@@ -1716,44 +1716,12 @@ impl BottomPaneView for McpServerElicitationOverlay {
 }
 
 fn wrap_footer_tips(width: u16, tips: Vec<FooterTip>) -> Vec<Vec<FooterTip>> {
-    let max_width = width.max(1) as usize;
-    let separator_width = UnicodeWidthStr::width(FOOTER_SEPARATOR);
-    if tips.is_empty() {
-        return vec![Vec::new()];
-    }
-
-    let mut lines = Vec::new();
-    let mut current = Vec::new();
-    let mut used = 0usize;
-
-    for tip in tips {
-        let tip_width = UnicodeWidthStr::width(tip.text.as_str()).min(max_width);
-        let extra = if current.is_empty() {
-            tip_width
-        } else {
-            separator_width.saturating_add(tip_width)
-        };
-        if !current.is_empty() && used.saturating_add(extra) > max_width {
-            lines.push(current);
-            current = Vec::new();
-            used = 0;
-        }
-        if current.is_empty() {
-            used = tip_width;
-        } else {
-            used = used
-                .saturating_add(separator_width)
-                .saturating_add(tip_width);
-        }
-        current.push(tip);
-    }
-
-    if current.is_empty() {
-        lines.push(Vec::new());
-    } else {
-        lines.push(current);
-    }
-    lines
+    crate::footer_hint::wrap_hint_rows(
+        tips,
+        width,
+        UnicodeWidthStr::width(FOOTER_SEPARATOR),
+        |tip| UnicodeWidthStr::width(tip.text.as_str()),
+    )
 }
 
 #[cfg(test)]

codex-rs/tui/src/bottom_pane/request_user_input/mod.rs

@@ -655,44 +655,12 @@ impl RequestUserInputOverlay {
     }
 
     fn wrap_footer_tips(&self, width: u16, tips: Vec<FooterTip>) -> Vec<Vec<FooterTip>> {
-        let max_width = width.max(1) as usize;
-        let separator_width = UnicodeWidthStr::width(TIP_SEPARATOR);
-        if tips.is_empty() {
-            return vec![Vec::new()];
-        }
-
-        let mut lines: Vec<Vec<FooterTip>> = Vec::new();
-        let mut current: Vec<FooterTip> = Vec::new();
-        let mut used = 0usize;
-
-        for tip in tips {
-            let tip_width = UnicodeWidthStr::width(tip.text.as_str()).min(max_width);
-            let extra = if current.is_empty() {
-                tip_width
-            } else {
-                separator_width.saturating_add(tip_width)
-            };
-            if !current.is_empty() && used.saturating_add(extra) > max_width {
-                lines.push(current);
-                current = Vec::new();
-                used = 0;
-            }
-            if current.is_empty() {
-                used = tip_width;
-            } else {
-                used = used
-                    .saturating_add(separator_width)
-                    .saturating_add(tip_width);
-            }
-            current.push(tip);
-        }
-
-        if current.is_empty() {
-            lines.push(Vec::new());
-        } else {
-            lines.push(current);
-        }
-        lines
+        crate::footer_hint::wrap_hint_rows(
+            tips,
+            width,
+            UnicodeWidthStr::width(TIP_SEPARATOR),
+            |tip| UnicodeWidthStr::width(tip.text.as_str()),
+        )
     }
 
     pub(super) fn footer_required_height(&self, width: u16) -> u16 {

codex-rs/tui/src/footer_hint.rs

@@ -0,0 +1,40 @@
+//! Packs footer hints into rows without separating a shortcut from its label.
+//! Callers retain ownership of styling and of clipping or wrapping oversized hints.
+
+pub(crate) fn wrap_hint_rows<T>(
+    hints: impl IntoIterator<Item = T>,
+    width: u16,
+    separator_width: usize,
+    hint_width: impl Fn(&T) -> usize,
+) -> Vec<Vec<T>> {
+    let width = usize::from(width.max(1));
+    let mut rows = Vec::new();
+    let mut row = Vec::new();
+    let mut used = 0usize;
+    for hint in hints {
+        let hint_width = hint_width(&hint).min(width);
+        let extra = if row.is_empty() {
+            hint_width
+        } else {
+            separator_width.saturating_add(hint_width)
+        };
+        if !row.is_empty() && used.saturating_add(extra) > width {
+            rows.push(std::mem::take(&mut row));
+            used = 0;
+        }
+        if row.is_empty() {
+            used = hint_width;
+        } else {
+            used = used
+                .saturating_add(separator_width)
+                .saturating_add(hint_width);
+        }
+        row.push(hint);
+    }
+    rows.push(row);
+    rows
+}
+
+#[cfg(test)]
+#[path = "footer_hint_tests.rs"]
+mod tests;

codex-rs/tui/src/footer_hint_tests.rs

@@ -0,0 +1,39 @@
+use super::wrap_hint_rows;
+use pretty_assertions::assert_eq;
+use unicode_width::UnicodeWidthStr;
+
+#[test]
+fn wraps_whole_hints_using_display_width() {
+    let hints = ["↑ 上", "↓ 下", "enter select"];
+    assert_eq!(
+        wrap_hint_rows(
+            hints,
+            /*width*/ 9,
+            /*separator_width*/ 1,
+            |hint| { UnicodeWidthStr::width(*hint) }
+        ),
+        vec![vec!["↑ 上", "↓ 下"], vec!["enter select"]]
+    );
+}
+
+#[test]
+fn retains_oversized_hints_and_an_empty_row() {
+    assert_eq!(
+        wrap_hint_rows(
+            ["ctrl+x stop", "esc back"],
+            /*width*/ 0,
+            /*separator_width*/ 3,
+            |hint| hint.len()
+        ),
+        vec![vec!["ctrl+x stop"], vec!["esc back"]]
+    );
+    assert_eq!(
+        wrap_hint_rows(
+            Vec::<String>::new(),
+            /*width*/ 40,
+            /*separator_width*/ 3,
+            String::len
+        ),
+        vec![Vec::<String>::new()]
+    );
+}

codex-rs/tui/src/lib.rs

@@ -155,6 +155,7 @@ mod ide_context;
 mod inline_visualization;
 pub(crate) mod insert_history;
 pub use insert_history::insert_history_lines;
+mod footer_hint;
 mod key_hint;
 mod keymap;
 mod keymap_setup;