Fix: boundary fix in help/dict views

src/services/dict_nav.rs

@@ -96,8 +96,9 @@ pub fn prev_category(ui: &mut UiState) {
 }
 
 pub fn scroll_down(ui: &mut UiState, n: usize) {
+    let max = ui.dict_max_scroll.get();
     let s = ui.dict_scroll_mut();
-    *s = s.saturating_add(n);
+    *s = s.saturating_add(n).min(max);
 }
 
 pub fn scroll_up(ui: &mut UiState, n: usize) {

src/services/help_nav.rs

@@ -98,8 +98,9 @@ pub fn prev_topic(ui: &mut UiState, n: usize) {
 }
 
 pub fn scroll_down(ui: &mut UiState, n: usize) {
+    let max = ui.help_max_scroll.get();
     let s = ui.help_scroll_mut();
-    *s = s.saturating_add(n);
+    *s = s.saturating_add(n).min(max);
 }
 
 pub fn scroll_up(ui: &mut UiState, n: usize) {

src/state/ui.rs

@@ -1,4 +1,4 @@
-use std::cell::RefCell;
+use std::cell::{Cell, RefCell};
 use std::time::{Duration, Instant};
 
 use cagire_markdown::ParsedMarkdown;
@@ -57,6 +57,8 @@ pub struct UiState {
     pub dict_scrolls: Vec<usize>,
     pub dict_search_query: String,
     pub dict_search_active: bool,
+    pub help_max_scroll: Cell<usize>,
+    pub dict_max_scroll: Cell<usize>,
     pub help_collapsed: Vec<bool>,
     pub help_on_section: Option<usize>,
     pub dict_collapsed: Vec<bool>,
@@ -107,6 +109,8 @@ impl Default for UiState {
             dict_scrolls: vec![0; crate::model::categories::category_count()],
             dict_search_query: String::new(),
             dict_search_active: false,
+            help_max_scroll: Cell::new(usize::MAX),
+            dict_max_scroll: Cell::new(usize::MAX),
             help_collapsed: vec![false; crate::model::docs::section_count()],
             help_on_section: None,
             dict_collapsed: vec![false; crate::model::categories::section_count()],

src/views/dict_view.rs

@@ -160,6 +160,7 @@ fn render_words(frame: &mut Frame, app: &App, area: Rect, is_searching: bool) {
     let visible_height = content_area.height.saturating_sub(2) as usize;
     let total_lines = lines.len();
     let max_scroll = total_lines.saturating_sub(visible_height);
+    app.ui.dict_max_scroll.set(max_scroll);
     let scroll = app.ui.dict_scroll().min(max_scroll);
 
     let title = if is_searching {

src/views/help_view.rs

@@ -223,6 +223,7 @@ fn render_content(frame: &mut Frame, app: &App, area: Rect) {
         .map(|l| wrapped_line_count(l, content_width))
         .sum();
     let max_scroll = total_wrapped.saturating_sub(visible_height);
+    app.ui.help_max_scroll.set(max_scroll);
     let scroll = app.ui.help_scroll().min(max_scroll);
 
     let mut lines = parsed.lines.clone();