Add expand/collapse all, per-pane key legends

SectionTree:
- 'e': expand all nodes
- 'c': collapse all nodes
- Home/End already wired from previous commit

Key legend shown at bottom border of each focused pane:
- Tree panes: nav, expand/collapse, expand/collapse all, paging
- Agent list: select, tab
- History: scroll, paging

Legend only appears on the focused pane to avoid clutter.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/user/context.rs

@@ -11,7 +11,7 @@ use ratatui::{
 };
 
 use super::{App, ScreenView, screen_legend};
-use super::widgets::{SectionTree, pane_block, render_scrollable};
+use super::widgets::{SectionTree, pane_block, render_scrollable, tree_legend};
 
 pub(crate) struct ConsciousScreen {
     agent: std::sync::Arc<tokio::sync::Mutex<crate::agent::Agent>>,
@@ -94,7 +94,8 @@ impl ScreenView for ConsciousScreen {
         lines.push(Line::raw(format!("  Active tools: {}", app.active_tools.lock().unwrap().len())));
 
         let block = pane_block("context")
-            .title_top(Line::from(screen_legend()).left_aligned());
+            .title_top(Line::from(screen_legend()).left_aligned())
+            .title_bottom(tree_legend());
 
         render_scrollable(frame, area, lines, block, self.tree.scroll);
     }

src/user/subconscious.rs

@@ -15,7 +15,7 @@ use ratatui::{
 };
 
 use super::{App, ScreenView, screen_legend};
-use super::widgets::{SectionTree, pane_block_focused, render_scrollable, format_age, format_ts_age};
+use super::widgets::{SectionTree, pane_block_focused, render_scrollable, tree_legend, format_age, format_ts_age};
 use crate::agent::context::ContextSection;
 
 #[derive(Clone, Copy, PartialEq)]
@@ -185,9 +185,16 @@ impl SubconsciousScreen {
             }
         }).collect();
 
+        let mut block = pane_block_focused("agents", self.focus == Pane::Agents)
+            .title_top(Line::from(screen_legend()).left_aligned());
+        if self.focus == Pane::Agents {
+            block = block.title_bottom(Line::styled(
+                " ↑↓:select  Tab:next pane ",
+                Style::default().fg(Color::DarkGray),
+            ));
+        }
         let list = List::new(items)
-            .block(pane_block_focused("agents", self.focus == Pane::Agents)
-                .title_top(Line::from(screen_legend()).left_aligned()))
+            .block(block)
             .highlight_symbol("▸ ")
             .highlight_style(Style::default().bg(Color::DarkGray));
 
@@ -207,9 +214,9 @@ impl SubconsciousScreen {
             self.output_tree.render_sections(&sections, &mut lines);
         }
 
-        render_scrollable(frame, area, lines,
-            pane_block_focused("state", self.focus == Pane::Outputs),
-            self.output_tree.scroll);
+        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);
     }
 
     fn draw_history(&self, frame: &mut Frame, area: Rect, app: &App) {
@@ -246,9 +253,14 @@ impl SubconsciousScreen {
             }
         }
 
-        render_scrollable(frame, area, lines,
-            pane_block_focused(&title, self.focus == Pane::History),
-            self.history_scroll);
+        let mut block = pane_block_focused(&title, self.focus == Pane::History);
+        if self.focus == Pane::History {
+            block = block.title_bottom(Line::styled(
+                " ↑↓:scroll  PgUp/Dn ",
+                Style::default().fg(Color::DarkGray),
+            ));
+        }
+        render_scrollable(frame, area, lines, block, self.history_scroll);
     }
 
     fn draw_context(
@@ -273,8 +285,8 @@ impl SubconsciousScreen {
             .map(|s| s.name.as_str())
             .unwrap_or("—");
 
-        render_scrollable(frame, area, lines,
-            pane_block_focused(title, self.focus == Pane::Context),
-            self.context_tree.scroll);
+        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);
     }
 }

src/user/widgets.rs

@@ -48,6 +48,14 @@ pub fn format_ts_age(ts: i64) -> String {
     format_age((now - ts).max(0) as f64)
 }
 
+/// Key legend for SectionTree panes.
+pub fn tree_legend() -> Line<'static> {
+    Line::styled(
+        " ↑↓:nav  →/Enter:expand  ←:collapse  e:expand all  c:collapse all  PgUp/Dn  Home/End ",
+        Style::default().fg(Color::DarkGray),
+    )
+}
+
 /// Render a paragraph with a vertical scrollbar.
 pub fn render_scrollable(
     frame: &mut Frame,
@@ -90,6 +98,14 @@ impl SectionTree {
         Self { selected: None, expanded: std::collections::HashSet::new(), scroll: 0 }
     }
 
+    /// Total nodes in the tree (regardless of expand state).
+    fn total_nodes(&self, sections: &[ContextSection]) -> usize {
+        fn count_all(section: &ContextSection) -> usize {
+            1 + section.children.iter().map(|c| count_all(c)).sum::<usize>()
+        }
+        sections.iter().map(|s| count_all(s)).sum()
+    }
+
     pub fn item_count(&self, sections: &[ContextSection]) -> usize {
         fn count(section: &ContextSection, expanded: &std::collections::HashSet<usize>, idx: &mut usize) -> usize {
             let my_idx = *idx;
@@ -146,6 +162,17 @@ impl SectionTree {
                     self.expanded.remove(&sel);
                 }
             }
+            KeyCode::Char('e') => {
+                // Expand all
+                let total = self.total_nodes(sections);
+                for i in 0..total {
+                    self.expanded.insert(i);
+                }
+            }
+            KeyCode::Char('c') => {
+                // Collapse all
+                self.expanded.clear();
+            }
             _ => {}
         }
         self.scroll_to_selected(height);