Convert SectionTree and all remaining callers to ScrollPane

SectionTree.scroll is now a ScrollPaneState. All callers of
render_scrollable replaced with ScrollPane::render_stateful_widget.

Deleted render_scrollable and its imports — no hand-rolled scroll
rendering remains outside of scroll_pane.rs.

Co-Authored-By: Kent Overstreet <kent.overstreet@gmail.com>

src/user/context.rs

@@ -6,7 +6,7 @@ use ratatui::{
 };
 
 use super::{App, ScreenView, screen_legend};
-use super::widgets::{SectionTree, SectionView, section_to_view, pane_block, render_scrollable, tree_legend};
+use super::widgets::{SectionTree, SectionView, section_to_view, pane_block, tree_legend};
 use crate::agent::context::{AstNode, NodeBody, Ast};
 
 pub(crate) struct ConsciousScreen {
@@ -177,6 +177,7 @@ impl ScreenView for ConsciousScreen {
             .title_top(Line::from(screen_legend()).left_aligned())
             .title_bottom(tree_legend());
 
-        render_scrollable(frame, area, lines, block, self.tree.scroll);
+        let widget = super::scroll_pane::ScrollPane::new(&lines).block(block);
+        frame.render_stateful_widget(widget, area, &mut self.tree.scroll);
     }
 }

src/user/subconscious.rs

@@ -15,7 +15,7 @@ use ratatui::{
 };
 
 use super::{App, ScreenView, screen_legend};
-use super::widgets::{SectionTree, SectionView, section_to_view, pane_block_focused, render_scrollable, tree_legend, format_age, format_ts_age};
+use super::widgets::{SectionTree, SectionView, section_to_view, pane_block_focused, tree_legend, format_age, format_ts_age};
 
 #[derive(Clone, Copy, PartialEq)]
 enum Pane { Agents, Outputs, History, Context }
@@ -282,7 +282,7 @@ impl SubconsciousScreen {
         frame.render_stateful_widget(list, area, &mut self.list_state);
     }
 
-    fn draw_outputs(&self, frame: &mut Frame, area: Rect, app: &App) {
+    fn draw_outputs(&mut self, frame: &mut Frame, area: Rect, app: &App) {
         let sections = self.output_sections(app);
         let mut lines: Vec<Line> = Vec::new();
 
@@ -297,7 +297,8 @@ impl SubconsciousScreen {
 
         let mut block = pane_block_focused("state", self.focus == Pane::Outputs);
         if self.focus == Pane::Outputs { block = block.title_bottom(tree_legend()); }
-        render_scrollable(frame, area, lines, block, self.output_tree.scroll);
+        let widget = super::scroll_pane::ScrollPane::new(&lines).block(block);
+        frame.render_stateful_widget(widget, area, &mut self.output_tree.scroll);
     }
 
     fn draw_history(&mut self, frame: &mut Frame, area: Rect, app: &App) {
@@ -351,7 +352,7 @@ impl SubconsciousScreen {
     }
 
     fn draw_context(
-        &self,
+        &mut self,
         frame: &mut Frame,
         area: Rect,
         sections: &[SectionView],
@@ -374,6 +375,7 @@ impl SubconsciousScreen {
 
         let mut block = pane_block_focused(title, self.focus == Pane::Context);
         if self.focus == Pane::Context { block = block.title_bottom(tree_legend()); }
-        render_scrollable(frame, area, lines, block, self.context_tree.scroll);
+        let widget = super::scroll_pane::ScrollPane::new(&lines).block(block);
+        frame.render_stateful_widget(widget, area, &mut self.context_tree.scroll);
     }
 }

src/user/widgets.rs

@@ -1,11 +1,9 @@
 // widgets.rs — Shared TUI helpers and reusable components
 
 use ratatui::{
-    layout::{Margin, Rect},
     style::{Color, Modifier, Style},
     text::Line,
-    widgets::{Block, Borders, Paragraph, Scrollbar, ScrollbarOrientation, ScrollbarState, Wrap},
-    Frame,
+    widgets::{Block, Borders},
     crossterm::event::KeyCode,
 };
 use crate::agent::context::{AstNode, Ast};
@@ -102,35 +100,6 @@ pub fn tree_legend() -> Line<'static> {
     )
 }
 
-/// Render a scrollable paragraph with a vertical scrollbar.
-///
-/// Legacy wrapper — callers that manage their own `u16` scroll offset
-/// use this. For new code, prefer ScrollPane + ScrollPaneState.
-pub fn render_scrollable(
-    frame: &mut Frame,
-    area: Rect,
-    lines: Vec<Line<'_>>,
-    block: Block<'_>,
-    scroll: u16,
-) {
-    let content_len = lines.len();
-    let para = Paragraph::new(lines)
-        .block(block)
-        .wrap(Wrap { trim: false })
-        .scroll((scroll, 0));
-    frame.render_widget(para, area);
-
-    let visible = area.height.saturating_sub(2) as usize;
-    if content_len > visible {
-        let mut sb_state = ScrollbarState::new(content_len)
-            .position(scroll as usize);
-        frame.render_stateful_widget(
-            Scrollbar::new(ScrollbarOrientation::VerticalRight),
-            area.inner(Margin { vertical: 1, horizontal: 0 }),
-            &mut sb_state,
-        );
-    }
-}
 
 // ---------------------------------------------------------------------------
 // SectionTree — expand/collapse tree renderer for ContextSection
@@ -139,12 +108,12 @@ pub fn render_scrollable(
 pub struct SectionTree {
     pub selected: Option<usize>,
     pub expanded: std::collections::HashSet<usize>,
-    pub scroll: u16,
+    pub scroll: super::scroll_pane::ScrollPaneState,
 }
 
 impl SectionTree {
     pub fn new() -> Self {
-        Self { selected: None, expanded: std::collections::HashSet::new(), scroll: 0 }
+        Self { selected: None, expanded: std::collections::HashSet::new(), scroll: super::scroll_pane::ScrollPaneState::new() }
     }
 
     fn total_nodes(&self, sections: &[SectionView]) -> usize {
@@ -184,14 +153,14 @@ impl SectionTree {
             KeyCode::PageUp => {
                 let sel = self.selected.unwrap_or(0);
                 self.selected = Some(sel.saturating_sub(page));
-                self.scroll = self.scroll.saturating_sub(page as u16);
+                self.scroll.scroll_up(page as u16);
                 return;
             }
             KeyCode::PageDown => {
                 let max = item_count.saturating_sub(1);
                 let sel = self.selected.map_or(0, |s| (s + page).min(max));
                 self.selected = Some(sel);
-                self.scroll += page as u16;
+                self.scroll.scroll_down(page as u16);
                 return;
             }
             KeyCode::Home => {
@@ -228,10 +197,10 @@ impl SectionTree {
         if let Some(sel) = self.selected {
             let sel_line = sel as u16;
             let visible = height.saturating_sub(2);
-            if sel_line < self.scroll {
-                self.scroll = sel_line;
-            } else if sel_line >= self.scroll + visible {
-                self.scroll = sel_line.saturating_sub(visible.saturating_sub(1));
+            if sel_line < self.scroll.offset {
+                self.scroll.offset = sel_line;
+            } else if sel_line >= self.scroll.offset + visible {
+                self.scroll.offset = sel_line.saturating_sub(visible.saturating_sub(1));
             }
         }
     }