chore(ui): debt cleanup — input, dialogs, viewer, render

src/input/command_line.rs

@@ -96,7 +96,6 @@ pub(crate) fn handle_command_line(state: &mut AppState, key: KeyEvent) {
         KeyCode::Up if !state.input.command_history.is_empty() => {
             if state.input.history_index.is_none() {
                 state.input.command_draft = state.input.command_line.text().to_owned();
-                state.input.command_line.set_text(String::new());
             }
             let idx = match state.input.history_index {
                 Some(i) if i > 0 => i - 1,

src/render.rs

@@ -1,9 +1,15 @@
 use crate::render_dialog_map;
+use lc::{app, ui};
 use ratatui::{
     layout::{Constraint, Direction, Layout},
     prelude::*,
 };
 
+use app::types::{ActivePanel, AppMode, AppState, PickerKind, ViewMode};
+use std::borrow::Cow;
+use ui::theme::{ColorPalette, Theme};
+use ui::{dialogs, panels, viewer};
+
 fn safe_split_at(s: &str, mut byte_idx: usize) -> (&str, &str) {
     byte_idx = byte_idx.min(s.len());
     while byte_idx > 0 && !s.is_char_boundary(byte_idx) {
@@ -19,13 +25,6 @@ fn cursor_line(prefix: &str, text: &str, byte_pos: usize) -> String {
     format!("{prefix}{before}_{after}")
 }
 
-use lc::{app, ui};
-
-use app::types::{ActivePanel, AppMode, AppState, PickerKind, ViewMode};
-use std::borrow::Cow;
-use ui::theme::{ColorPalette, Theme};
-use ui::{dialogs, panels, viewer};
-
 pub(crate) fn render_ui(
     f: &mut Frame,
     state: &AppState,

src/ui/mod.rs

@@ -5,11 +5,6 @@ pub mod panels;
 pub mod theme;
 pub mod viewer;
 
-// Top-level re-exports of the cross-cutting theming API, mirroring the way
-// `dialogs::mod` re-exports its public surface, so callers can reach the common
-// types via `ui::Theme` rather than the full module path.
-pub use theme::{ColorPalette, IconTheme, Theme};
-
 /// Number of rows reserved for UI elements outside the main panels.
 /// Accounts for: top menu bar (1), status bar (1), command line (1),
 /// function key bar (1), and borders (2). Used to calculate available

src/ui/panels/tests.rs

@@ -1,5 +1,3 @@
-#![allow(clippy::expect_used)]
-
 use super::*;
 use crate::app::types::{format_size, format_time, sanitize_for_display};
 use crate::ui::theme::{DEFAULT_COLORS, IconTheme};

src/ui/theme.rs

@@ -1,5 +1,4 @@
-use ratatui::style::Modifier;
-use ratatui::style::{Color, Style};
+use ratatui::style::{Color, Modifier, Style};
 use serde::Deserialize;
 
 use crate::app::types::FileCategory;
@@ -53,11 +52,10 @@ macro_rules! define_theme_colors {
         pub struct ThemeConfig {
             $(pub $field: Option<String>,)*
             pub preset: Option<String>,
-            #[serde(default)]
             pub icon_theme: IconTheme,
         }
 
-        #[derive(Copy, Clone, Debug, PartialEq)]
+        #[derive(Copy, Clone, Debug, PartialEq, Eq)]
         pub struct ColorPalette {
             $(pub $field: Color,)*
             icon_theme: IconTheme,
@@ -220,16 +218,21 @@ fn parse_color(s: &str) -> Option<Color> {
 }
 
 fn parse_hex_color(hex: &str) -> Option<Color> {
-    if hex.len() == 6 {
-        let r = u8::from_str_radix(&hex[0..2], 16).ok()?;
-        let g = u8::from_str_radix(&hex[2..4], 16).ok()?;
-        let b = u8::from_str_radix(&hex[4..6], 16).ok()?;
+    // Operate on bytes and require a pure-ASCII digit string. Slicing `&hex[n..m]`
+    // on a multi-byte UTF-8 config value can split a codepoint and panic at
+    // runtime ("byte index is not a char boundary"). `is_ascii()` rejects any
+    // such input before we index; `as_bytes()` is safe once that holds.
+    let bytes = hex.as_bytes();
+    if bytes.len() == 6 && hex.is_ascii() {
+        let r = u8::from_str_radix(std::str::from_utf8(&bytes[0..2]).ok()?, 16).ok()?;
+        let g = u8::from_str_radix(std::str::from_utf8(&bytes[2..4]).ok()?, 16).ok()?;
+        let b = u8::from_str_radix(std::str::from_utf8(&bytes[4..6]).ok()?, 16).ok()?;
         return Some(Color::Rgb(r, g, b));
     }
-    if hex.len() == 3 {
-        let r = u8::from_str_radix(&hex[0..1], 16).ok()? * 17;
-        let g = u8::from_str_radix(&hex[1..2], 16).ok()? * 17;
-        let b = u8::from_str_radix(&hex[2..3], 16).ok()? * 17;
+    if bytes.len() == 3 && hex.is_ascii() {
+        let r = u8::from_str_radix(std::str::from_utf8(&bytes[0..1]).ok()?, 16).ok()? * 17;
+        let g = u8::from_str_radix(std::str::from_utf8(&bytes[1..2]).ok()?, 16).ok()? * 17;
+        let b = u8::from_str_radix(std::str::from_utf8(&bytes[2..3]).ok()?, 16).ok()? * 17;
         return Some(Color::Rgb(r, g, b));
     }
     None
@@ -470,6 +473,17 @@ mod tests {
         assert_eq!(parse_color("#12345"), None);
     }
 
+    #[test]
+    fn parse_hex_color_non_ascii_does_not_panic() {
+        // Regression: a 6-byte slice that is not char-boundary aligned (e.g. a
+        // multi-byte UTF-8 codepoint sitting where a hex digit is expected)
+        // must return None, not panic on `&hex[n..m]`. Reachable from user
+        // config via parse_color -> parse_hex_color.
+        assert_eq!(parse_hex_color("a\u{4e2d}cd"), None);
+        assert_eq!(parse_hex_color("\u{4e2d}ab"), None);
+        assert_eq!(parse_hex_color("\u{4e2d}"), None);
+    }
+
     #[test]
     fn defaults_match_when_no_config() {
         let c = &DEFAULT_COLORS;

src/ui/viewer/hex.rs

@@ -90,7 +90,7 @@ pub(crate) fn format_hex_line_to_buffer(offset: usize, bytes: &[u8], buf: &mut S
 }
 
 pub(crate) fn find_bytes(haystack: &[u8], needle: &[u8]) -> Option<usize> {
-    if needle.is_empty() || needle.len() > haystack.len() {
+    if needle.is_empty() {
         return None;
     }
     if needle.len() == 1 {

src/ui/viewer/render.rs

@@ -451,10 +451,11 @@ fn render_viewer_status(
     let status_text = format!(
         " {mode_label}  {mime_label}  {size_label}  {position_text}{utf8_warning}{binary_warning}{truncated_warning}",
     );
+    let status_style = Theme::status_bar_with_colors(colors);
     let status_style = if has_warning {
-        Theme::status_bar_with_colors(colors).fg(colors.warning)
+        status_style.fg(colors.warning)
     } else {
-        Theme::status_bar_with_colors(colors)
+        status_style
     };
     let status_paragraph = Paragraph::new(status_text).style(status_style);
     f.render_widget(status_paragraph, status_area);

src/ui/viewer/tests.rs

@@ -743,7 +743,7 @@ fn test_hex_mode_search() {
         "hex search for '01 02' should find matches in hex data section"
     );
     assert_eq!(state.current_match, Some(0));
-    assert!(state.search_matches[0].line == 0);
+    assert_eq!(state.search_matches[0].line, 0);
 }
 
 #[test]

src/ui/viewer/toggle.rs

@@ -42,8 +42,7 @@ impl ViewerState {
         // Reset horizontal scroll on every toggle, both directions. Wrap-mode
         // rendering ignores `horizontal_offset`, but `scroll_right` keeps
         // growing it while wrapped; without this reset the view would jump by
-        // that stale offset the moment wrap is turned back off. (Pairs with the
-        // `mode_dispatch` `scroll_right` wrap-guard tracked in PR8.)
+        // that stale offset the moment wrap is turned back off.
         self.horizontal_offset = 0;
         self.invalidate_visual_cache();
     }