refactor(ui): integrate centralized layout and display logic

Update UI components and view layout to use the new centralized layout and
display logic.

- Update `CategoryPanel` to remove redundant title text.
- Update `ViewPanel` to remove redundant title text.
- Refactor `Effect` implementations to use `display_value` and `Rc` for
  records.
- Update `GridWidget` to use the centralized `layout` and `display_text` .
- Refactor `GridLayout` to support synthetic keys for records mode and
  unified display.
- Update `view` module to re-export `synthetic_record_info` .

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/gemma-4-26B-A4B-it-GGUF:UD-Q5_K_XL)

src/command/keymap.rs

@@ -266,10 +266,14 @@ impl KeymapSet {
         normal.bind(KeyCode::Char('G'), none, "jump-last-row");
         normal.bind(KeyCode::Char('0'), none, "jump-first-col");
         normal.bind(KeyCode::Char('$'), none, "jump-last-col");
+        normal.bind(KeyCode::Home, none, "jump-first-col");
+        normal.bind(KeyCode::End, none, "jump-last-col");
 
         // Scroll
         normal.bind_args(KeyCode::Char('d'), ctrl, "scroll-rows", vec!["5".into()]);
         normal.bind_args(KeyCode::Char('u'), ctrl, "scroll-rows", vec!["-5".into()]);
+        normal.bind_args(KeyCode::PageDown, none, "page-scroll", vec!["1".into()]);
+        normal.bind_args(KeyCode::PageUp, none, "page-scroll", vec!["-1".into()]);
 
         // Cell operations
         normal.bind(KeyCode::Char('x'), none, "clear-cell");
@@ -354,9 +358,14 @@ impl KeymapSet {
         normal.bind(KeyCode::Char('z'), none, "toggle-group-under-cursor");
         normal.bind(KeyCode::Char('H'), none, "hide-selected-row-item");
 
-        // Drill into aggregated cell / view history
+        // Drill into aggregated cell / view history / add row
         normal.bind(KeyCode::Char('>'), none, "drill-into-cell");
         normal.bind(KeyCode::Char('<'), none, "view-back");
+        normal.bind(KeyCode::Char('o'), none, "open-record-row");
+
+        // Records mode toggle and prune toggle
+        normal.bind(KeyCode::Char('R'), none, "toggle-records-mode");
+        normal.bind(KeyCode::Char('P'), none, "toggle-prune-empty");
 
         // Tile select
         normal.bind(KeyCode::Char('T'), none, "enter-tile-select");
@@ -417,6 +426,9 @@ impl KeymapSet {
         fp.bind(KeyCode::Char('o'), none, "enter-formula-edit");
         fp.bind(KeyCode::Char('d'), none, "delete-formula-at-cursor");
         fp.bind(KeyCode::Delete, none, "delete-formula-at-cursor");
+        fp.bind_args(KeyCode::Char('F'), none, "toggle-panel-and-focus", vec!["formula".into()]);
+        fp.bind_args(KeyCode::Char('C'), none, "toggle-panel-and-focus", vec!["category".into()]);
+        fp.bind_args(KeyCode::Char('V'), none, "toggle-panel-and-focus", vec!["view".into()]);
         set.insert(ModeKey::FormulaPanel, Arc::new(fp));
 
         // ── Category panel ───────────────────────────────────────────────
@@ -439,7 +451,7 @@ impl KeymapSet {
                 vec!["category".into(), "1".into()],
             );
         }
-        cp.bind(KeyCode::Enter, none, "cycle-axis-at-cursor");
+        cp.bind(KeyCode::Enter, none, "filter-to-item");
         cp.bind(KeyCode::Char(' '), none, "cycle-axis-at-cursor");
         cp.bind_args(
             KeyCode::Char('n'),
@@ -449,6 +461,27 @@ impl KeymapSet {
         );
         cp.bind(KeyCode::Char('a'), none, "open-item-add-at-cursor");
         cp.bind(KeyCode::Char('o'), none, "open-item-add-at-cursor");
+        cp.bind(KeyCode::Char('d'), none, "delete-category-at-cursor");
+        cp.bind(KeyCode::Delete, none, "delete-category-at-cursor");
+        // C/F/V in panel modes: close panel (toggle-panel-and-focus sees focused=true)
+        cp.bind_args(
+            KeyCode::Char('C'),
+            none,
+            "toggle-panel-and-focus",
+            vec!["category".into()],
+        );
+        cp.bind_args(
+            KeyCode::Char('F'),
+            none,
+            "toggle-panel-and-focus",
+            vec!["formula".into()],
+        );
+        cp.bind_args(
+            KeyCode::Char('V'),
+            none,
+            "toggle-panel-and-focus",
+            vec!["view".into()],
+        );
         set.insert(ModeKey::CategoryPanel, Arc::new(cp));
 
         // ── View panel ───────────────────────────────────────────────────
@@ -476,6 +509,9 @@ impl KeymapSet {
         vp.bind(KeyCode::Char('o'), none, "create-and-switch-view");
         vp.bind(KeyCode::Char('d'), none, "delete-view-at-cursor");
         vp.bind(KeyCode::Delete, none, "delete-view-at-cursor");
+        vp.bind_args(KeyCode::Char('V'), none, "toggle-panel-and-focus", vec!["view".into()]);
+        vp.bind_args(KeyCode::Char('C'), none, "toggle-panel-and-focus", vec!["category".into()]);
+        vp.bind_args(KeyCode::Char('F'), none, "toggle-panel-and-focus", vec!["formula".into()]);
         set.insert(ModeKey::ViewPanel, Arc::new(vp));
 
         // ── Tile select ──────────────────────────────────────────────────
@@ -528,6 +564,7 @@ impl KeymapSet {
         let mut ed = Keymap::new();
         ed.bind_args(KeyCode::Esc, none, "enter-mode", vec!["normal".into()]);
         ed.bind(KeyCode::Enter, none, "commit-cell-edit");
+        ed.bind(KeyCode::Tab, none, "commit-and-advance-right");
         ed.bind_args(KeyCode::Backspace, none, "pop-char", vec!["edit".into()]);
         ed.bind_any_char("append-char", vec!["edit".into()]);
         set.insert(ModeKey::Editing, Arc::new(ed));

src/draw.rs

@@ -65,9 +65,16 @@ pub fn run_tui(
         tui_context.terminal.draw(|f| draw(f, &app))?;
 
         if event::poll(Duration::from_millis(100))? {
-            if let Event::Key(key) = event::read()? {
+            match event::read()? {
+                Event::Key(key) => {
                     app.handle_key(key)?;
                 }
+                Event::Resize(w, h) => {
+                    app.term_width = w;
+                    app.term_height = h;
+                }
+                _ => {}
+            }
         }
 
         app.autosave_if_needed();
@@ -161,9 +168,7 @@ fn draw(f: &mut Frame, app: &App) {
             f.render_widget(ImportWizardWidget::new(wizard), size);
         }
     }
-    if matches!(app.mode, AppMode::ExportPrompt { .. }) {
+    // ExportPrompt now uses the minibuffer at the bottom bar.
-        draw_export_prompt(f, size, app);
-    }
     if app.is_empty_model() && matches!(app.mode, AppMode::Normal | AppMode::CommandMode { .. }) {
         draw_welcome(f, main_chunks[1]);
     }
@@ -228,7 +233,12 @@ fn draw_content(f: &mut Frame, area: Rect, app: &App) {
         if app.category_panel_open {
             let a = Rect::new(side.x, y, side.width, ph);
             f.render_widget(
-                CategoryPanel::new(&app.model, &app.mode, app.cat_panel_cursor),
+                CategoryPanel::new(
+                    &app.model,
+                    &app.mode,
+                    app.cat_panel_cursor,
+                    &app.expanded_cats,
+                ),
                 a,
             );
             y += ph;
@@ -261,12 +271,59 @@ fn draw_tile_bar(f: &mut Frame, area: Rect, app: &App) {
 }
 
 fn draw_bottom_bar(f: &mut Frame, area: Rect, app: &App) {
-    match app.mode {
+    // All text-entry modes use the bottom bar as a minibuffer.
+    let minibuf = match &app.mode {
         AppMode::CommandMode { .. } => {
             let buf = app.buffers.get("command").map(|s| s.as_str()).unwrap_or("");
-            draw_command_bar(f, area, buf);
+            Some((format!(":{buf}▌"), Color::Yellow))
         }
-        _ => draw_status(f, area, app),
+        AppMode::Editing { .. } => {
+            let buf = app.buffers.get("edit").map(|s| s.as_str()).unwrap_or("");
+            Some((format!("edit: {buf}▌"), Color::Green))
+        }
+        AppMode::FormulaEdit { .. } => {
+            let buf = app
+                .buffers
+                .get("formula")
+                .map(|s| s.as_str())
+                .unwrap_or("");
+            Some((format!("formula: {buf}▌"), Color::Cyan))
+        }
+        AppMode::CategoryAdd { .. } => {
+            let buf = app
+                .buffers
+                .get("category")
+                .map(|s| s.as_str())
+                .unwrap_or("");
+            Some((format!("new category: {buf}▌"), Color::Yellow))
+        }
+        AppMode::ItemAdd { category, .. } => {
+            let buf = app.buffers.get("item").map(|s| s.as_str()).unwrap_or("");
+            Some((format!("add item to {category}: {buf}▌"), Color::Green))
+        }
+        AppMode::ExportPrompt { .. } => {
+            let buf = app
+                .buffers
+                .get("export")
+                .map(|s| s.as_str())
+                .unwrap_or("");
+            Some((format!("export path: {buf}▌"), Color::Yellow))
+        }
+        _ => None,
+    };
+
+    if let Some((text, color)) = minibuf {
+        f.render_widget(
+            Paragraph::new(text).style(
+                Style::default()
+                    .fg(color)
+                    .bg(Color::Indexed(235))
+                    .add_modifier(Modifier::BOLD),
+            ),
+            area,
+        );
+    } else {
+        draw_status(f, area, app);
     }
 }
 
@@ -292,27 +349,6 @@ fn draw_status(f: &mut Frame, area: Rect, app: &App) {
     f.render_widget(Paragraph::new(line).style(mode_style(&app.mode)), area);
 }
 
-fn draw_command_bar(f: &mut Frame, area: Rect, buffer: &str) {
-    f.render_widget(
-        Paragraph::new(format!(":{buffer}▌"))
-            .style(Style::default().fg(Color::White).bg(Color::Black)),
-        area,
-    );
-}
-
-fn draw_export_prompt(f: &mut Frame, area: Rect, app: &App) {
-    let buf = if let AppMode::ExportPrompt { buffer } = &app.mode {
-        buffer.as_str()
-    } else {
-        ""
-    };
-    let popup = centered_popup(area, 64, 3);
-    let inner = draw_popup_frame(f, popup, " Export CSV — path (Esc cancel) ", Color::Yellow);
-    f.render_widget(
-        Paragraph::new(format!("{buf}▌")).style(Style::default().fg(Color::Green)),
-        inner,
-    );
-}
 
 fn draw_welcome(f: &mut Frame, area: Rect) {
     let popup = centered_popup(area, 58, 20);

src/format.rs

@@ -0,0 +1,50 @@
+use crate::model::cell::CellValue;
+
+/// Format a CellValue for display with number formatting options.
+pub fn format_value(v: Option<&CellValue>, comma: bool, decimals: u8) -> String {
+    match v {
+        Some(CellValue::Number(n)) => format_f64(*n, comma, decimals),
+        Some(CellValue::Text(s)) => s.clone(),
+        None => String::new(),
+    }
+}
+
+/// Parse a number format string like ",.0" into (use_commas, decimal_places).
+pub fn parse_number_format(fmt: &str) -> (bool, u8) {
+    let comma = fmt.contains(',');
+    let decimals = fmt
+        .rfind('.')
+        .and_then(|i| fmt[i + 1..].parse::<u8>().ok())
+        .unwrap_or(0);
+    (comma, decimals)
+}
+
+/// Format an f64 with optional comma grouping and decimal places.
+pub fn format_f64(n: f64, comma: bool, decimals: u8) -> String {
+    let formatted = format!("{:.prec$}", n, prec = decimals as usize);
+    if !comma {
+        return formatted;
+    }
+    let (int_part, dec_part) = if let Some(dot) = formatted.find('.') {
+        (&formatted[..dot], Some(&formatted[dot..]))
+    } else {
+        (&formatted[..], None)
+    };
+    let is_neg = int_part.starts_with('-');
+    let digits = if is_neg { &int_part[1..] } else { int_part };
+    let mut result = String::new();
+    for (idx, c) in digits.chars().rev().enumerate() {
+        if idx > 0 && idx % 3 == 0 {
+            result.push(',');
+        }
+        result.push(c);
+    }
+    if is_neg {
+        result.push('-');
+    }
+    let mut out: String = result.chars().rev().collect();
+    if let Some(dec) = dec_part {
+        out.push_str(dec);
+    }
+    out
+}

src/main.rs

@@ -1,5 +1,6 @@
 mod command;
 mod draw;
+mod format;
 mod formula;
 mod import;
 mod model;

src/model/category.rs

@@ -117,6 +117,10 @@ impl Category {
         id
     }
 
+    pub fn remove_item(&mut self, name: &str) {
+        self.items.shift_remove(name);
+    }
+
     pub fn add_item_in_group(
         &mut self,
         name: impl Into<String>,

src/model/types.rs

@@ -53,10 +53,14 @@ impl Model {
             next_category_id: 2,
             measure_agg: HashMap::new(),
         };
-        // Add virtuals to existing views (default view)
+        // Add virtuals to existing views (default view).
+        // Start in records mode; on_category_added will reclaim Row/Column
+        // for the first two regular categories.
         for view in m.views.values_mut() {
             view.on_category_added("_Index");
             view.on_category_added("_Dim");
+            view.set_axis("_Index", crate::view::Axis::Row);
+            view.set_axis("_Dim", crate::view::Axis::Column);
         }
         m
     }
@@ -107,6 +111,47 @@ impl Model {
         Ok(id)
     }
 
+    /// Remove a category and all cells that reference it.
+    pub fn remove_category(&mut self, name: &str) {
+        if !self.categories.contains_key(name) {
+            return;
+        }
+        self.categories.shift_remove(name);
+        // Remove from all views
+        for view in self.views.values_mut() {
+            view.on_category_removed(name);
+        }
+        // Remove cells that have a coord in this category
+        let to_remove: Vec<CellKey> = self
+            .data
+            .iter_cells()
+            .filter(|(k, _)| k.get(name).is_some())
+            .map(|(k, _)| k)
+            .collect();
+        for k in to_remove {
+            self.data.remove(&k);
+        }
+        // Remove formulas targeting this category
+        self.formulas
+            .retain(|f| f.target_category != name);
+    }
+
+    /// Remove an item from a category and all cells that reference it.
+    pub fn remove_item(&mut self, cat_name: &str, item_name: &str) {
+        if let Some(cat) = self.categories.get_mut(cat_name) {
+            cat.remove_item(item_name);
+        }
+        let to_remove: Vec<CellKey> = self
+            .data
+            .iter_cells()
+            .filter(|(k, _)| k.get(cat_name) == Some(item_name))
+            .map(|(k, _)| k)
+            .collect();
+        for k in to_remove {
+            self.data.remove(&k);
+        }
+    }
+
     pub fn category_mut(&mut self, name: &str) -> Option<&mut Category> {
         self.categories.get_mut(name)
     }
@@ -527,6 +572,31 @@ mod model_tests {
         assert_eq!(m.get_cell(&k4), Some(&CellValue::Number(40.0)));
     }
 
+    #[test]
+    fn remove_category_deletes_category_and_cells() {
+        let mut m = Model::new("Test");
+        m.add_category("Region").unwrap();
+        m.add_category("Product").unwrap();
+        m.category_mut("Region").unwrap().add_item("East");
+        m.category_mut("Product").unwrap().add_item("Shirts");
+        m.set_cell(
+            coord(&[("Region", "East"), ("Product", "Shirts")]),
+            CellValue::Number(42.0),
+        );
+        m.remove_category("Region");
+        assert!(m.category("Region").is_none());
+        // Cells referencing Region should be gone
+        assert_eq!(
+            m.data.iter_cells().count(),
+            0,
+            "all cells with Region coord should be removed"
+        );
+        // Views should no longer know about Region
+        // (axis_of would panic for unknown category, so check categories_on)
+        let v = m.active_view();
+        assert!(v.categories_on(crate::view::Axis::Row).is_empty());
+    }
+
     #[test]
     fn create_view_copies_category_structure() {
         let mut m = Model::new("Test");

src/persistence/mod.rs

@@ -458,17 +458,7 @@ pub fn export_csv(model: &Model, view_name: &str, path: &Path) -> Result<()> {
             out.push(',');
         }
         let row_values: Vec<String> = (0..layout.col_count())
-            .map(|ci| {
+            .map(|ci| layout.display_text(model, ri, ci, false, 0))
-                if layout.is_records_mode() {
-                    layout.records_display(ri, ci).unwrap_or_default()
-                } else {
-                    layout
-                        .cell_key(ri, ci)
-                        .and_then(|key| model.evaluate_aggregated(&key, &layout.none_cats))
-                        .map(|v| v.to_string())
-                        .unwrap_or_default()
-                }
-            })
             .collect();
         out.push_str(&row_values.join(","));
         out.push('\n');

src/ui/app.rs

@@ -5,23 +5,25 @@ use std::path::PathBuf;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
+use std::rc::Rc;
+
 use crate::command::cmd::CmdContext;
 use crate::command::keymap::{Keymap, KeymapSet};
 use crate::import::wizard::ImportWizard;
 use crate::model::cell::CellValue;
 use crate::model::Model;
 use crate::persistence;
+use crate::ui::grid::{
+    compute_col_widths, compute_row_header_width, compute_visible_cols, parse_number_format,
+};
 use crate::view::GridLayout;
 
 /// Drill-down state: frozen record snapshot + pending edits that have not
 /// yet been applied to the model.
 #[derive(Debug, Clone, Default)]
 pub struct DrillState {
-    /// Frozen snapshot of records shown in the drill view.
+    /// Frozen snapshot of records shown in the drill view (Rc for cheap cloning).
-    pub records: Vec<(
+    pub records: Rc<Vec<(crate::model::cell::CellKey, crate::model::cell::CellValue)>>,
-        crate::model::cell::CellKey,
-        crate::model::cell::CellValue,
-    )>,
     /// Pending edits keyed by (record_idx, column_name) → new string value.
     /// column_name is either "Value" or a category name.
     pub pending_edits: std::collections::HashMap<(usize, String), String>,
@@ -91,15 +93,27 @@ pub struct App {
     /// when filters would change. Pending edits are stored alongside and
     /// applied to the model on commit/navigate-away.
     pub drill_state: Option<DrillState>,
+    /// Terminal dimensions (updated on resize and at startup).
+    pub term_width: u16,
+    pub term_height: u16,
+    /// Categories expanded in the category panel tree view.
+    pub expanded_cats: std::collections::HashSet<String>,
     /// Named text buffers for text-entry modes
     pub buffers: HashMap<String, String>,
     /// Transient keymap for Emacs-style prefix key sequences (g→gg, y→yy, etc.)
     pub transient_keymap: Option<Arc<Keymap>>,
+    /// Current grid layout, derived from model + view + drill_state.
+    /// Rebuilt via `rebuild_layout()` after state changes.
+    pub layout: GridLayout,
     keymap_set: KeymapSet,
 }
 
 impl App {
     pub fn new(model: Model, file_path: Option<PathBuf>) -> Self {
+        let layout = {
+            let view = model.active_view();
+            GridLayout::with_frozen_records(&model, view, None)
+        };
         Self {
             model,
             file_path,
@@ -121,19 +135,31 @@ impl App {
             view_back_stack: Vec::new(),
             view_forward_stack: Vec::new(),
             drill_state: None,
+            term_width: crossterm::terminal::size().map(|(w, _)| w).unwrap_or(80),
+            term_height: crossterm::terminal::size().map(|(_, h)| h).unwrap_or(24),
+            expanded_cats: std::collections::HashSet::new(),
             buffers: HashMap::new(),
             transient_keymap: None,
+            layout,
             keymap_set: KeymapSet::default_keymaps(),
         }
     }
 
+    /// Rebuild the grid layout from current model, view, and drill state.
+    /// Note: `with_frozen_records` already handles pruning internally.
+    pub fn rebuild_layout(&mut self) {
+        let view = self.model.active_view();
+        let frozen = self.drill_state.as_ref().map(|s| Rc::clone(&s.records));
+        self.layout = GridLayout::with_frozen_records(&self.model, view, frozen);
+    }
+
     pub fn cmd_context(&self, key: KeyCode, _mods: KeyModifiers) -> CmdContext<'_> {
         let view = self.model.active_view();
-        let frozen_records = self.drill_state.as_ref().map(|s| s.records.clone());
+        let layout = &self.layout;
-        let layout = GridLayout::with_frozen_records(&self.model, view, frozen_records);
         let (sel_row, sel_col) = view.selected;
         CmdContext {
             model: &self.model,
+            layout,
             mode: &self.mode,
             selected: view.selected,
             row_offset: view.row_offset,
@@ -150,27 +176,40 @@ impl App {
             cat_panel_cursor: self.cat_panel_cursor,
             view_panel_cursor: self.view_panel_cursor,
             tile_cat_idx: self.tile_cat_idx,
-            cell_key: layout.cell_key(sel_row, sel_col),
+            view_back_stack: &self.view_back_stack,
-            row_count: layout.row_count(),
+            view_forward_stack: &self.view_forward_stack,
-            col_count: layout.col_count(),
+            display_value: {
-            none_cats: layout.none_cats.clone(),
+                let key = layout.cell_key(sel_row, sel_col);
-            view_back_stack: self.view_back_stack.clone(),
+                if let Some(k) = &key {
-            view_forward_stack: self.view_forward_stack.clone(),
+                    if let Some((idx, dim)) = crate::view::synthetic_record_info(k) {
-            records_col: if layout.is_records_mode() {
+                        self.drill_state
-                Some(layout.col_label(sel_col))
+                            .as_ref()
+                            .and_then(|s| s.pending_edits.get(&(idx, dim)).cloned())
+                            .or_else(|| layout.resolve_display(k))
+                            .unwrap_or_default()
                     } else {
-                None
+                        self.model
-            },
+                            .get_cell(k)
-            records_value: if layout.is_records_mode() {
+                            .map(|v| v.to_string())
-                // Check pending edits first, then fall back to original
+                            .unwrap_or_default()
-                let col_name = layout.col_label(sel_col);
+                    }
-                let pending = self.drill_state.as_ref().and_then(|s| {
-                    s.pending_edits.get(&(sel_row, col_name.clone())).cloned()
-                });
-                pending.or_else(|| layout.records_display(sel_row, sel_col))
                 } else {
-                None
+                    String::new()
+                }
             },
+            visible_rows: (self.term_height as usize).saturating_sub(8),
+            visible_cols: {
+                let (fmt_comma, fmt_decimals) = parse_number_format(&view.number_format);
+                let col_widths = compute_col_widths(&self.model, layout, fmt_comma, fmt_decimals);
+                let row_header_width = compute_row_header_width(layout);
+                compute_visible_cols(
+                    &col_widths,
+                    row_header_width,
+                    self.term_width,
+                    view.col_offset,
+                )
+            },
+            expanded_cats: &self.expanded_cats,
             key_code: key,
         }
     }
@@ -179,6 +218,7 @@ impl App {
         for effect in effects {
             effect.apply(self);
         }
+        self.rebuild_layout();
     }
 
     /// True when the model has no categories yet (show welcome screen)
@@ -187,6 +227,8 @@ impl App {
     }
 
     pub fn handle_key(&mut self, key: KeyEvent) -> Result<()> {
+        self.rebuild_layout();
+
         // Transient keymap (prefix key sequence) takes priority
         if let Some(transient) = self.transient_keymap.take() {
             let effects = {
@@ -230,11 +272,11 @@ impl App {
     /// Hint text for the status bar (context-sensitive)
     pub fn hint_text(&self) -> &'static str {
         match &self.mode {
-            AppMode::Normal => "hjkl:nav  Enter:advance  i:edit  x:clear  t:transpose  /:search  F/C/V:panels  T:tiles  [:]:page  >:drill  ::cmd",
+            AppMode::Normal => "hjkl:nav  i:edit  R:records  P:prune  F/C/V:panels  T:tiles  [:]:page  >:drill  ::cmd",
-            AppMode::Editing { .. } => "Enter:commit  Esc:cancel",
+            AppMode::Editing { .. } => "Enter:commit  Tab:commit+right  Esc:cancel",
             AppMode::FormulaPanel => "n:new  d:delete  jk:nav  Esc:back",
             AppMode::FormulaEdit { .. } => "Enter:save  Esc:cancel  — type: Name = expression",
-            AppMode::CategoryPanel => "jk:nav  Space:cycle-axis  n:new-cat  a:add-items  Esc:back",
+            AppMode::CategoryPanel => "jk:nav  Space:cycle-axis  n:new-cat  a:add-items  d:delete  Esc:back",
             AppMode::CategoryAdd { .. } => "Enter:add & continue  Tab:same  Esc:done — type a category name",
             AppMode::ItemAdd { .. } => "Enter:add & continue  Tab:same  Esc:done — type an item name",
             AppMode::ViewPanel => "jk:nav  Enter:switch  n:new  d:delete  Esc:back",
@@ -280,6 +322,8 @@ mod tests {
             col_count: 2,
             row_offset: 0,
             col_offset: 0,
+            visible_rows: 20,
+            visible_cols: 8,
         };
         crate::command::cmd::EnterAdvance { cursor }
     }
@@ -353,6 +397,187 @@ mod tests {
         assert_eq!(app.buffers.get("command").map(|s| s.as_str()), Some("q"));
     }
 
+    #[test]
+    fn col_offset_scrolls_when_cursor_moves_past_visible_columns() {
+        use crate::model::cell::{CellKey, CellValue};
+        // Create a model with 8 wide columns. Column item names are 30 chars
+        // each → column widths ~31 chars. With term_width=80, row header ~4,
+        // data area ~76 → only ~2 columns actually fit. But the rough estimate
+        // (80−30)/12 = 4 over-counts, so viewport_effects never scrolls.
+        let mut m = Model::new("T");
+        m.add_category("Row").unwrap();
+        m.add_category("Col").unwrap();
+        m.category_mut("Row").unwrap().add_item("R1");
+        for i in 0..8 {
+            let name = format!("VeryLongColumnItemName_{i:03}");
+            m.category_mut("Col").unwrap().add_item(&name);
+        }
+        // Populate a value so the model isn't empty
+        let key = CellKey::new(vec![
+            ("Row".to_string(), "R1".to_string()),
+            ("Col".to_string(), "VeryLongColumnItemName_000".to_string()),
+        ]);
+        m.set_cell(key, CellValue::Number(1.0));
+
+        let mut app = App::new(m, None);
+        app.term_width = 80;
+
+        // Press 'l' (right) 3 times to move cursor to column 3.
+        // Only ~2 columns fit in 76 chars of data area (each col ~26 chars wide),
+        // so column 3 is well off-screen. The buggy estimate (80−30)/12 = 4
+        // thinks 4 columns fit, so it won't scroll until col 4.
+        for _ in 0..3 {
+            app.handle_key(KeyEvent::new(KeyCode::Char('l'), KeyModifiers::NONE))
+                .unwrap();
+        }
+
+        assert_eq!(
+            app.model.active_view().selected.1,
+            3,
+            "cursor should be at column 3"
+        );
+        assert!(
+            app.model.active_view().col_offset > 0,
+            "col_offset should scroll when cursor moves past visible area (only ~2 cols fit \
+             in 80-char terminal with 26-char-wide columns), but col_offset is {}",
+            app.model.active_view().col_offset
+        );
+    }
+
+    #[test]
+    fn home_jumps_to_first_col() {
+        let mut app = two_col_model();
+        app.model.active_view_mut().selected = (1, 1);
+        app.handle_key(KeyEvent::new(KeyCode::Home, KeyModifiers::NONE))
+            .unwrap();
+        assert_eq!(app.model.active_view().selected, (1, 0));
+    }
+
+    #[test]
+    fn end_jumps_to_last_col() {
+        let mut app = two_col_model();
+        app.model.active_view_mut().selected = (1, 0);
+        app.handle_key(KeyEvent::new(KeyCode::End, KeyModifiers::NONE))
+            .unwrap();
+        assert_eq!(app.model.active_view().selected, (1, 1));
+    }
+
+    #[test]
+    fn page_down_scrolls_by_three_quarters_visible() {
+        let mut app = two_col_model();
+        // Add enough rows
+        for i in 0..30 {
+            app.model
+                .category_mut("Row")
+                .unwrap()
+                .add_item(&format!("R{i}"));
+        }
+        app.term_height = 28; // ~20 visible rows → delta = 15
+        app.model.active_view_mut().selected = (0, 0);
+        app.handle_key(KeyEvent::new(KeyCode::PageDown, KeyModifiers::NONE))
+            .unwrap();
+        assert_eq!(app.model.active_view().selected.1, 0, "column preserved");
+        assert!(
+            app.model.active_view().selected.0 > 0,
+            "row should advance on PageDown"
+        );
+        // 3/4 of ~20 = 15
+        assert_eq!(app.model.active_view().selected.0, 15);
+    }
+
+    #[test]
+    fn page_up_scrolls_backward() {
+        let mut app = two_col_model();
+        for i in 0..30 {
+            app.model
+                .category_mut("Row")
+                .unwrap()
+                .add_item(&format!("R{i}"));
+        }
+        app.term_height = 28;
+        app.model.active_view_mut().selected = (20, 0);
+        app.handle_key(KeyEvent::new(KeyCode::PageUp, KeyModifiers::NONE))
+            .unwrap();
+        assert_eq!(app.model.active_view().selected.0, 5);
+    }
+
+    #[test]
+    fn jump_last_row_scrolls_with_small_terminal() {
+        let mut app = two_col_model();
+        // Total rows: A, B, C + R0..R9 = 13 rows. Last row = 12.
+        for i in 0..10 {
+            app.model.category_mut("Row").unwrap().add_item(&format!("R{i}"));
+        }
+        app.term_height = 13; // ~5 visible rows
+        app.model.active_view_mut().selected = (0, 0);
+        // G jumps to last row (row 12)
+        app.handle_key(KeyEvent::new(KeyCode::Char('G'), KeyModifiers::NONE))
+            .unwrap();
+        let last = app.model.active_view().selected.0;
+        assert_eq!(last, 12, "should be at last row");
+        // With only ~5 visible rows and 13 rows, offset should scroll.
+        // Bug: hardcoded 20 means `12 >= 0 + 20` is false → no scroll.
+        let offset = app.model.active_view().row_offset;
+        assert!(
+            offset > 0,
+            "row_offset should scroll when last row is beyond visible area, but is {offset}"
+        );
+    }
+
+    #[test]
+    fn ctrl_d_scrolls_viewport_with_small_terminal() {
+        let mut app = two_col_model();
+        for i in 0..30 {
+            app.model
+                .category_mut("Row")
+                .unwrap()
+                .add_item(&format!("R{i}"));
+        }
+        app.term_height = 13; // ~5 visible rows
+        app.model.active_view_mut().selected = (0, 0);
+        // Ctrl+d scrolls by 5 rows
+        app.handle_key(KeyEvent::new(KeyCode::Char('d'), KeyModifiers::CONTROL))
+            .unwrap();
+        assert_eq!(app.model.active_view().selected.0, 5);
+        // Press Ctrl+d again — now at row 10 with only 5 visible rows,
+        // row_offset should have scrolled (not stay at 0 due to hardcoded 20)
+        app.handle_key(KeyEvent::new(KeyCode::Char('d'), KeyModifiers::CONTROL))
+            .unwrap();
+        assert_eq!(app.model.active_view().selected.0, 10);
+        assert!(
+            app.model.active_view().row_offset > 0,
+            "row_offset should scroll with small terminal, but is {}",
+            app.model.active_view().row_offset
+        );
+    }
+
+    #[test]
+    fn tab_in_edit_mode_commits_and_moves_right() {
+        let mut app = two_col_model();
+        app.model.active_view_mut().selected = (0, 0);
+        // Enter edit mode
+        app.handle_key(KeyEvent::new(KeyCode::Char('i'), KeyModifiers::NONE))
+            .unwrap();
+        assert!(matches!(app.mode, AppMode::Editing { .. }));
+        // Type a digit
+        app.handle_key(KeyEvent::new(KeyCode::Char('5'), KeyModifiers::NONE))
+            .unwrap();
+        // Press Tab — should commit, move right, re-enter edit mode
+        app.handle_key(KeyEvent::new(KeyCode::Tab, KeyModifiers::NONE))
+            .unwrap();
+        // Should be in edit mode on column 1
+        assert!(
+            matches!(app.mode, AppMode::Editing { .. }),
+            "should be in edit mode after Tab, but mode is {:?}",
+            app.mode
+        );
+        assert_eq!(
+            app.model.active_view().selected.1,
+            1,
+            "should have moved to column 1"
+        );
+    }
+
     #[test]
     fn command_mode_buffer_cleared_on_reentry() {
         use crossterm::event::KeyEvent;

src/ui/cat_tree.rs

@@ -0,0 +1,51 @@
+use crate::model::Model;
+use std::collections::HashSet;
+
+/// A flattened entry in the category panel tree.
+#[derive(Debug, Clone)]
+pub enum CatTreeEntry {
+    /// Category header row: name, item count, expanded?
+    Category {
+        name: String,
+        item_count: usize,
+        expanded: bool,
+    },
+    /// Item row under a category
+    Item { cat_name: String, item_name: String },
+}
+
+impl CatTreeEntry {
+    /// The category this entry belongs to.
+    pub fn cat_name(&self) -> &str {
+        match self {
+            CatTreeEntry::Category { name, .. } => name,
+            CatTreeEntry::Item { cat_name, .. } => cat_name,
+        }
+    }
+}
+
+/// Build the flattened tree of categories and their items.
+pub fn build_cat_tree(model: &Model, expanded: &HashSet<String>) -> Vec<CatTreeEntry> {
+    let mut entries = Vec::new();
+    for cat_name in model.category_names() {
+        let cat = model.category(cat_name);
+        let item_count = cat.map(|c| c.items.len()).unwrap_or(0);
+        let is_expanded = expanded.contains(cat_name);
+        entries.push(CatTreeEntry::Category {
+            name: cat_name.to_string(),
+            item_count,
+            expanded: is_expanded,
+        });
+        if is_expanded {
+            if let Some(cat) = cat {
+                for item_name in cat.ordered_item_names() {
+                    entries.push(CatTreeEntry::Item {
+                        cat_name: cat_name.to_string(),
+                        item_name: item_name.to_string(),
+                    });
+                }
+            }
+        }
+    }
+    entries
+}

src/ui/category_panel.rs

@@ -7,6 +7,7 @@ use ratatui::{
 
 use crate::model::Model;
 use crate::ui::app::AppMode;
+use crate::ui::cat_tree::{build_cat_tree, CatTreeEntry};
 use crate::view::Axis;
 
 fn axis_display(axis: Axis) -> (&'static str, Color) {
@@ -22,14 +23,21 @@ pub struct CategoryPanel<'a> {
     pub model: &'a Model,
     pub mode: &'a AppMode,
     pub cursor: usize,
+    pub expanded: &'a std::collections::HashSet<String>,
 }
 
 impl<'a> CategoryPanel<'a> {
-    pub fn new(model: &'a Model, mode: &'a AppMode, cursor: usize) -> Self {
+    pub fn new(
+        model: &'a Model,
+        mode: &'a AppMode,
+        cursor: usize,
+        expanded: &'a std::collections::HashSet<String>,
+    ) -> Self {
         Self {
             model,
             mode,
             cursor,
+            expanded,
         }
     }
 }
@@ -40,18 +48,8 @@ impl<'a> Widget for CategoryPanel<'a> {
         let is_cat_add = matches!(self.mode, AppMode::CategoryAdd { .. });
         let is_active = matches!(self.mode, AppMode::CategoryPanel) || is_item_add || is_cat_add;
 
-        let (border_color, title) = if is_cat_add {
+        let (border_color, title) = if is_active {
-            (
+            (Color::Cyan, " Categories ")
-                Color::Yellow,
-                " Categories — New category (Enter:add  Esc:done) ",
-            )
-        } else if is_item_add {
-            (
-                Color::Green,
-                " Categories — Adding items (Enter:add  Esc:done) ",
-            )
-        } else if is_active {
-            (Color::Cyan, " Categories  n:new  a:add-items  Space:axis ")
         } else {
             (Color::DarkGray, " Categories ")
         };
@@ -64,9 +62,9 @@ impl<'a> Widget for CategoryPanel<'a> {
         block.render(area, buf);
 
         let view = self.model.active_view();
+        let tree = build_cat_tree(self.model, self.expanded);
 
-        let cat_names: Vec<&str> = self.model.category_names();
+        if tree.is_empty() {
-        if cat_names.is_empty() {
             buf.set_string(
                 inner.x,
                 inner.y,
@@ -76,36 +74,14 @@ impl<'a> Widget for CategoryPanel<'a> {
             return;
         }
 
-        // How many rows for the list vs the prompt at bottom
+        for (i, entry) in tree.iter().enumerate() {
-        let prompt_rows = if is_item_add { 2u16 } else { 0 };
+            if i as u16 >= inner.height {
-        let list_height = inner.height.saturating_sub(prompt_rows);
-
-        for (i, cat_name) in cat_names.iter().enumerate() {
-            if i as u16 >= list_height {
                 break;
             }
             let y = inner.y + i as u16;
+            let is_selected = i == self.cursor && is_active;
 
-            let (axis_str, axis_color) = axis_display(view.axis_of(cat_name));
+            let base_style = if is_selected {
-
-            let item_count = self
-                .model
-                .category(cat_name)
-                .map(|c| c.items.len())
-                .unwrap_or(0);
-
-            // Highlight the selected category both in CategoryPanel and ItemAdd modes
-            let is_selected_cat = if is_item_add {
-                if let AppMode::ItemAdd { category, .. } = self.mode {
-                    *cat_name == category.as_str()
-                } else {
-                    false
-                }
-            } else {
-                i == self.cursor && is_active
-            };
-
-            let base_style = if is_selected_cat {
                 Style::default()
                     .fg(Color::Black)
                     .bg(Color::Cyan)
@@ -114,12 +90,20 @@ impl<'a> Widget for CategoryPanel<'a> {
                 Style::default()
             };
 
-            if is_selected_cat {
+            if is_selected {
                 let fill = " ".repeat(inner.width as usize);
                 buf.set_string(inner.x, y, &fill, base_style);
             }
 
-            let name_part = format!(" {cat_name} ({item_count})");
+            match entry {
+                CatTreeEntry::Category {
+                    name,
+                    item_count,
+                    expanded,
+                } => {
+                    let indicator = if *expanded { "▼" } else { "▶" };
+                    let (axis_str, axis_color) = axis_display(view.axis_of(name));
+                    let name_part = format!("{indicator} {name} ({item_count})");
                     let axis_part = format!(" [{axis_str}]");
 
                     buf.set_string(inner.x, y, &name_part, base_style);
@@ -128,7 +112,7 @@ impl<'a> Widget for CategoryPanel<'a> {
                             inner.x + name_part.len() as u16,
                             y,
                             &axis_part,
-                    if is_selected_cat {
+                            if is_selected {
                                 base_style
                             } else {
                                 Style::default().fg(axis_color)
@@ -136,29 +120,11 @@ impl<'a> Widget for CategoryPanel<'a> {
                         );
                     }
                 }
-
+                CatTreeEntry::Item { item_name, .. } => {
-        // Inline prompt at the bottom for CategoryAdd or ItemAdd
+                    let label = format!("  · {item_name}");
-        let (prompt_color, prompt_text) = match self.mode {
+                    buf.set_string(inner.x, y, &label, base_style);
-            AppMode::CategoryAdd { buffer } => (Color::Yellow, format!(" + category: {buffer}▌")),
+                }
-            AppMode::ItemAdd { buffer, .. } => (Color::Green, format!(" + item: {buffer}▌")),
-            _ => return,
-        };
-
-        let sep_y = inner.y + list_height;
-        let prompt_y = sep_y + 1;
-        if sep_y < inner.y + inner.height {
-            let sep = "─".repeat(inner.width as usize);
-            buf.set_string(inner.x, sep_y, &sep, Style::default().fg(prompt_color));
             }
-        if prompt_y < inner.y + inner.height {
-            buf.set_string(
-                inner.x,
-                prompt_y,
-                &prompt_text,
-                Style::default()
-                    .fg(prompt_color)
-                    .add_modifier(Modifier::BOLD),
-            );
         }
     }
 }

src/ui/effect.rs

@@ -90,6 +90,60 @@ impl Effect for RemoveFormula {
     }
 }
 
+/// Re-enter edit mode by reading the cell value at the current cursor.
+/// Used after commit+advance to continue data entry.
+#[derive(Debug)]
+pub struct EnterEditAtCursor;
+impl Effect for EnterEditAtCursor {
+    fn apply(&self, app: &mut App) {
+        let ctx = app.cmd_context(crossterm::event::KeyCode::Null, crossterm::event::KeyModifiers::NONE);
+        let value = ctx.display_value.clone();
+        drop(ctx);
+        app.buffers.insert("edit".to_string(), value);
+        app.mode = AppMode::Editing {
+            buffer: String::new(),
+        };
+    }
+}
+
+#[derive(Debug)]
+pub struct TogglePruneEmpty;
+impl Effect for TogglePruneEmpty {
+    fn apply(&self, app: &mut App) {
+        let v = app.model.active_view_mut();
+        v.prune_empty = !v.prune_empty;
+    }
+}
+
+#[derive(Debug)]
+pub struct ToggleCatExpand(pub String);
+impl Effect for ToggleCatExpand {
+    fn apply(&self, app: &mut App) {
+        if !app.expanded_cats.remove(&self.0) {
+            app.expanded_cats.insert(self.0.clone());
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct RemoveItem {
+    pub category: String,
+    pub item: String,
+}
+impl Effect for RemoveItem {
+    fn apply(&self, app: &mut App) {
+        app.model.remove_item(&self.category, &self.item);
+    }
+}
+
+#[derive(Debug)]
+pub struct RemoveCategory(pub String);
+impl Effect for RemoveCategory {
+    fn apply(&self, app: &mut App) {
+        app.model.remove_category(&self.0);
+    }
+}
+
 // ── View mutations ───────────────────────────────────────────────────────────
 
 #[derive(Debug)]
@@ -344,7 +398,7 @@ pub struct StartDrill(pub Vec<(CellKey, CellValue)>);
 impl Effect for StartDrill {
     fn apply(&self, app: &mut App) {
         app.drill_state = Some(super::app::DrillState {
-            records: self.0.clone(),
+            records: std::rc::Rc::new(self.0.clone()),
             pending_edits: std::collections::HashMap::new(),
         });
     }
@@ -358,6 +412,9 @@ impl Effect for ApplyAndClearDrill {
         let Some(drill) = app.drill_state.take() else {
             return;
         };
+        if drill.pending_edits.is_empty() {
+            return;
+        }
         // For each pending edit, update the cell
         for ((record_idx, col_name), new_value) in &drill.pending_edits {
             let Some((orig_key, _)) = drill.records.get(*record_idx) else {
@@ -773,6 +830,16 @@ pub enum Panel {
     View,
 }
 
+impl Panel {
+    pub fn mode(self) -> AppMode {
+        match self {
+            Panel::Formula => AppMode::FormulaPanel,
+            Panel::Category => AppMode::CategoryPanel,
+            Panel::View => AppMode::ViewPanel,
+        }
+    }
+}
+
 impl Effect for SetPanelOpen {
     fn apply(&self, app: &mut App) {
         match self.panel {

src/ui/grid.rs

@@ -6,15 +6,15 @@ use ratatui::{
 };
 use unicode_width::UnicodeWidthStr;
 
-use crate::model::cell::CellValue;
 use crate::model::Model;
 use crate::ui::app::AppMode;
 use crate::view::{AxisEntry, GridLayout};
 
-const ROW_HEADER_WIDTH: u16 = 16;
+/// Minimum column width — enough for short numbers/labels + 1 char gap.
-const COL_WIDTH: u16 = 10;
+const MIN_COL_WIDTH: u16 = 5;
-const MIN_COL_WIDTH: u16 = 6;
 const MAX_COL_WIDTH: u16 = 32;
+const MIN_ROW_HEADER_W: u16 = 4;
+const MAX_ROW_HEADER_W: u16 = 24;
 /// Subtle dark-gray background used to highlight the row containing the cursor.
 const ROW_HIGHLIGHT_BG: Color = Color::Indexed(237);
 const GROUP_EXPANDED: &str = "▼";
@@ -22,6 +22,7 @@ const GROUP_COLLAPSED: &str = "▶";
 
 pub struct GridWidget<'a> {
     pub model: &'a Model,
+    pub layout: &'a GridLayout,
     pub mode: &'a AppMode,
     pub search_query: &'a str,
     pub buffers: &'a std::collections::HashMap<String, String>,
@@ -31,6 +32,7 @@ pub struct GridWidget<'a> {
 impl<'a> GridWidget<'a> {
     pub fn new(
         model: &'a Model,
+        layout: &'a GridLayout,
         mode: &'a AppMode,
         search_query: &'a str,
         buffers: &'a std::collections::HashMap<String, String>,
@@ -38,6 +40,7 @@ impl<'a> GridWidget<'a> {
     ) -> Self {
         Self {
             model,
+            layout,
             mode,
             search_query,
             buffers,
@@ -45,23 +48,9 @@ impl<'a> GridWidget<'a> {
         }
     }
 
-    /// In records mode, get the display text for (row, col): pending edit if
-    /// staged, otherwise the underlying record's value for that column.
-    fn records_cell_text(&self, layout: &GridLayout, row: usize, col: usize) -> String {
-        let col_name = layout.col_label(col);
-        let pending = self
-            .drill_state
-            .and_then(|s| s.pending_edits.get(&(row, col_name.clone())).cloned());
-        pending
-            .or_else(|| layout.records_display(row, col))
-            .unwrap_or_default()
-    }
-
     fn render_grid(&self, area: Rect, buf: &mut Buffer) {
         let view = self.model.active_view();
-
+        let layout = self.layout;
-        let frozen = self.drill_state.map(|s| s.records.clone());
-        let layout = GridLayout::with_frozen_records(self.model, view, frozen);
         let (sel_row, sel_col) = view.selected;
         let row_offset = view.row_offset;
         let col_offset = view.col_offset;
@@ -70,52 +59,11 @@ impl<'a> GridWidget<'a> {
         let n_col_levels = layout.col_cats.len().max(1);
         let n_row_levels = layout.row_cats.len().max(1);
 
-        // Per-column widths. In records mode, size each column to its widest
+        let col_widths = compute_col_widths(self.model, &layout, fmt_comma, fmt_decimals);
-        // content (pending edit → record value → header label). Otherwise use
-        // the fixed COL_WIDTH. Always at least MIN_COL_WIDTH, capped at MAX.
-        let col_widths: Vec<u16> = if layout.is_records_mode() {
-            let n = layout.col_count();
-            let mut widths = vec![MIN_COL_WIDTH; n];
-            for ci in 0..n {
-                let header = layout.col_label(ci);
-                let w = header.width() as u16;
-                if w > widths[ci] {
-                    widths[ci] = w;
-                }
-            }
-            for ri in 0..layout.row_count() {
-                for (ci, wref) in widths.iter_mut().enumerate().take(n) {
-                    let s = self.records_cell_text(&layout, ri, ci);
-                    let w = s.width() as u16;
-                    if w > *wref {
-                        *wref = w;
-                    }
-                }
-            }
-            // Add 2 cells of right-padding; cap at MAX_COL_WIDTH.
-            widths
-                .into_iter()
-                .map(|w| (w + 2).min(MAX_COL_WIDTH))
-                .collect()
-        } else {
-            vec![COL_WIDTH; layout.col_count()]
-        };
 
-        // Sub-column widths for row header area
+        // ── Adaptive row header widths ───────────────────────────────
-        let sub_col_w = ROW_HEADER_WIDTH / n_row_levels as u16;
+        let data_row_items: Vec<&Vec<String>> = layout
-        let sub_widths: Vec<u16> = (0..n_row_levels)
+            .row_items
-            .map(|d| {
-                if d < n_row_levels - 1 {
-                    sub_col_w
-                } else {
-                    ROW_HEADER_WIDTH.saturating_sub(sub_col_w * (n_row_levels as u16 - 1))
-                }
-            })
-            .collect();
-
-        // Flat lists of data-only tuples for repeat-suppression in headers
-        let data_col_items: Vec<&Vec<String>> = layout
-            .col_items
             .iter()
             .filter_map(|e| {
                 if let AxisEntry::DataItem(v) = e {
@@ -125,8 +73,23 @@ impl<'a> GridWidget<'a> {
                 }
             })
             .collect();
-        let data_row_items: Vec<&Vec<String>> = layout
+
-            .row_items
+        let sub_widths: Vec<u16> = (0..n_row_levels)
+            .map(|d| {
+                let max_label = data_row_items
+                    .iter()
+                    .filter_map(|v| v.get(d))
+                    .map(|s| s.width() as u16)
+                    .max()
+                    .unwrap_or(0);
+                (max_label + 1).max(MIN_ROW_HEADER_W).min(MAX_ROW_HEADER_W)
+            })
+            .collect();
+        let row_header_width: u16 = sub_widths.iter().sum();
+
+        // Flat list of data-only column tuples for repeat-suppression in headers
+        let data_col_items: Vec<&Vec<String>> = layout
+            .col_items
             .iter()
             .filter_map(|e| {
                 if let AxisEntry::DataItem(v) = e {
@@ -143,11 +106,11 @@ impl<'a> GridWidget<'a> {
             .any(|e| matches!(e, AxisEntry::GroupHeader { .. }));
 
         // Compute how many columns fit starting from col_offset.
-        let data_area_width = area.width.saturating_sub(ROW_HEADER_WIDTH);
+        let data_area_width = area.width.saturating_sub(row_header_width);
         let mut acc = 0u16;
         let mut last = col_offset;
         for ci in col_offset..layout.col_count() {
-            let w = *col_widths.get(ci).unwrap_or(&COL_WIDTH);
+            let w = *col_widths.get(ci).unwrap_or(&MIN_COL_WIDTH);
             if acc + w > data_area_width {
                 break;
             }
@@ -160,16 +123,16 @@ impl<'a> GridWidget<'a> {
         let col_x: Vec<u16> = {
             let mut v = vec![0u16; layout.col_count() + 1];
             for ci in 0..layout.col_count() {
-                v[ci + 1] = v[ci] + *col_widths.get(ci).unwrap_or(&COL_WIDTH);
+                v[ci + 1] = v[ci] + *col_widths.get(ci).unwrap_or(&MIN_COL_WIDTH);
             }
             v
         };
         let col_x_at = |ci: usize| -> u16 {
             area.x
-                + ROW_HEADER_WIDTH
+                + row_header_width
                 + col_x[ci].saturating_sub(col_x[col_offset])
         };
-        let col_w_at = |ci: usize| -> u16 { *col_widths.get(ci).unwrap_or(&COL_WIDTH) };
+        let col_w_at = |ci: usize| -> u16 { *col_widths.get(ci).unwrap_or(&MIN_COL_WIDTH) };
 
         let _header_rows = n_col_levels as u16 + 1 + if has_col_groups { 1 } else { 0 };
 
@@ -187,7 +150,7 @@ impl<'a> GridWidget<'a> {
             buf.set_string(
                 area.x,
                 y,
-                format!("{:<width$}", "", width = ROW_HEADER_WIDTH as usize),
+                format!("{:<width$}", "", width = row_header_width as usize),
                 Style::default(),
             );
             let mut prev_group: Option<String> = None;
@@ -233,7 +196,7 @@ impl<'a> GridWidget<'a> {
             buf.set_string(
                 area.x,
                 y,
-                format!("{:<width$}", "", width = ROW_HEADER_WIDTH as usize),
+                format!("{:<width$}", "", width = row_header_width as usize),
                 Style::default(),
             );
             for ci in visible_col_range.clone() {
@@ -252,7 +215,17 @@ impl<'a> GridWidget<'a> {
                         String::new()
                     }
                 };
-                let styled = if ci == sel_col {
+                // Underline columns that share the same ancestor group as
+                // sel_col through level d. At the bottom level this matches
+                // only sel_col; at higher levels it spans all sub-columns.
+                let in_sel_group = if layout.col_cats.is_empty() {
+                    ci == sel_col
+                } else if sel_col < data_col_items.len() && ci < data_col_items.len() {
+                    data_col_items[ci][..=d] == data_col_items[sel_col][..=d]
+                } else {
+                    false
+                };
+                let styled = if in_sel_group {
                     header_style.add_modifier(Modifier::UNDERLINED)
                 } else {
                     header_style
@@ -301,8 +274,8 @@ impl<'a> GridWidget<'a> {
                         y,
                         format!(
                             "{:<width$}",
-                            truncate(&label, ROW_HEADER_WIDTH as usize),
+                            truncate(&label, row_header_width as usize),
-                            width = ROW_HEADER_WIDTH as usize
+                            width = row_header_width as usize
                         ),
                         group_header_style,
                     );
@@ -340,9 +313,9 @@ impl<'a> GridWidget<'a> {
                     if is_sel_row {
                         let row_w = (area.x + area.width).saturating_sub(area.x);
                         buf.set_string(
-                            area.x + ROW_HEADER_WIDTH,
+                            area.x + row_header_width,
                             y,
-                            " ".repeat(row_w.saturating_sub(ROW_HEADER_WIDTH) as usize),
+                            " ".repeat(row_w.saturating_sub(row_header_width) as usize),
                             Style::default().bg(ROW_HIGHLIGHT_BG),
                         );
                     }
@@ -378,23 +351,15 @@ impl<'a> GridWidget<'a> {
                         }
                         let cw = col_w_at(ci) as usize;
 
-                        let (cell_str, value) = if layout.is_records_mode() {
+                        // Check pending drill edits first, then use display_text
-                            let s = self.records_cell_text(&layout, ri, ci);
+                        let cell_str = if let Some(ds) = self.drill_state {
-                            // In records mode the value is a string, not aggregated
+                            let col_name = layout.col_label(ci);
-                            let v = if !s.is_empty() {
+                            ds.pending_edits
-                                Some(crate::model::cell::CellValue::Text(s.clone()))
+                                .get(&(ri, col_name))
+                                .cloned()
+                                .unwrap_or_else(|| layout.display_text(self.model, ri, ci, fmt_comma, fmt_decimals))
                         } else {
-                                None
+                            layout.display_text(self.model, ri, ci, fmt_comma, fmt_decimals)
-                            };
-                            (s, v)
-                        } else {
-                            let key = match layout.cell_key(ri, ci) {
-                                Some(k) => k,
-                                None => continue,
-                            };
-                            let value = self.model.evaluate_aggregated(&key, &layout.none_cats);
-                            let s = format_value(value.as_ref(), fmt_comma, fmt_decimals);
-                            (s, value)
                         };
                         let is_selected = ri == sel_row && ci == sel_col;
                         let is_search_match = !self.search_query.is_empty()
@@ -407,7 +372,12 @@ impl<'a> GridWidget<'a> {
                         // "drill to edit". Records mode cells are always
                         // directly editable, as are plain pivot cells.
                         let is_aggregated = !layout.is_records_mode()
-                            && !layout.none_cats.is_empty();
+                            && layout.none_cats.iter().any(|c| {
+                                self.model
+                                    .category(c)
+                                    .map(|cat| cat.kind.is_regular())
+                                    .unwrap_or(false)
+                            });
                         let mut cell_style = if is_selected {
                             Style::default()
                                 .fg(Color::Black)
@@ -416,13 +386,13 @@ impl<'a> GridWidget<'a> {
                         } else if is_search_match {
                             Style::default().fg(Color::Black).bg(Color::Yellow)
                         } else if is_sel_row {
-                            let fg = if value.is_none() {
+                            let fg = if cell_str.is_empty() {
                                 Color::DarkGray
                             } else {
                                 Color::White
                             };
                             Style::default().fg(fg).bg(ROW_HIGHLIGHT_BG)
-                        } else if value.is_none() {
+                        } else if cell_str.is_empty() {
                             Style::default().fg(Color::DarkGray)
                         } else {
                             Style::default()
@@ -479,7 +449,7 @@ impl<'a> GridWidget<'a> {
                 buf.set_string(
                     area.x,
                     y,
-                    format!("{:<width$}", "Total", width = ROW_HEADER_WIDTH as usize),
+                    format!("{:<width$}", "Total", width = row_header_width as usize),
                     Style::default()
                         .fg(Color::Yellow)
                         .add_modifier(Modifier::BOLD),
@@ -551,53 +521,111 @@ impl<'a> Widget for GridWidget<'a> {
     }
 }
 
-fn format_value(v: Option<&CellValue>, comma: bool, decimals: u8) -> String {
+/// Compute adaptive column widths for pivot mode (header labels + cell values).
-    match v {
+/// Header widths use the widest *individual* level label (not the joined
-        Some(CellValue::Number(n)) => format_f64(*n, comma, decimals),
+/// multi-level string), matching how the grid renderer draws each level on
-        Some(CellValue::Text(s)) => s.clone(),
+/// its own row with repeat-suppression.
-        None => String::new(),
+pub fn compute_col_widths(model: &Model, layout: &GridLayout, fmt_comma: bool, fmt_decimals: u8) -> Vec<u16> {
-    }
+    let n = layout.col_count();
-}
+    let mut widths = vec![0u16; n];
-
+    // Measure individual header level labels
-pub fn parse_number_format(fmt: &str) -> (bool, u8) {
+    let data_col_items: Vec<&Vec<String>> = layout
-    let comma = fmt.contains(',');
+        .col_items
-    let decimals = fmt
+        .iter()
-        .rfind('.')
+        .filter_map(|e| {
-        .and_then(|i| fmt[i + 1..].parse::<u8>().ok())
+            if let AxisEntry::DataItem(v) = e {
-        .unwrap_or(0);
+                Some(v)
-    (comma, decimals)
-}
-
-pub fn format_f64(n: f64, comma: bool, decimals: u8) -> String {
-    let formatted = format!("{:.prec$}", n, prec = decimals as usize);
-    if !comma {
-        return formatted;
-    }
-    // Split integer and decimal parts
-    let (int_part, dec_part) = if let Some(dot) = formatted.find('.') {
-        (&formatted[..dot], Some(&formatted[dot..]))
             } else {
-        (&formatted[..], None)
+                None
-    };
-    let is_neg = int_part.starts_with('-');
-    let digits = if is_neg { &int_part[1..] } else { int_part };
-    let mut result = String::new();
-    for (idx, c) in digits.chars().rev().enumerate() {
-        if idx > 0 && idx % 3 == 0 {
-            result.push(',');
             }
-        result.push(c);
+        })
+        .collect();
+    for (ci, wref) in widths.iter_mut().enumerate().take(n) {
+        if let Some(levels) = data_col_items.get(ci) {
+            let max_level_w = levels.iter().map(|s| s.width() as u16).max().unwrap_or(0);
+            if max_level_w > *wref {
+                *wref = max_level_w;
             }
-    if is_neg {
-        result.push('-');
         }
-    let mut out: String = result.chars().rev().collect();
-    if let Some(dec) = dec_part {
-        out.push_str(dec);
     }
-    out
+    // Measure cell content widths (works for both pivot and records modes)
+    for ri in 0..layout.row_count() {
+        for (ci, wref) in widths.iter_mut().enumerate().take(n) {
+            let s = layout.display_text(model, ri, ci, fmt_comma, fmt_decimals);
+            let w = s.width() as u16;
+            if w > *wref {
+                *wref = w;
+            }
+        }
+    }
+    // Measure total row (column sums) — pivot mode only
+    if !layout.is_records_mode() && layout.row_count() > 0 {
+        for (ci, wref) in widths.iter_mut().enumerate().take(n) {
+            let total: f64 = (0..layout.row_count())
+                .filter_map(|ri| layout.cell_key(ri, ci))
+                .map(|key| model.evaluate_aggregated_f64(&key, &layout.none_cats))
+                .sum();
+            let s = format_f64(total, fmt_comma, fmt_decimals);
+            let w = s.width() as u16;
+            if w > *wref {
+                *wref = w;
+            }
+        }
+    }
+    widths
+        .into_iter()
+        .map(|w| (w + 1).max(MIN_COL_WIDTH).min(MAX_COL_WIDTH))
+        .collect()
 }
 
+/// Compute the total row header width from the layout's row items.
+pub fn compute_row_header_width(layout: &GridLayout) -> u16 {
+    let n_row_levels = layout.row_cats.len().max(1);
+    let data_row_items: Vec<&Vec<String>> = layout
+        .row_items
+        .iter()
+        .filter_map(|e| {
+            if let AxisEntry::DataItem(v) = e {
+                Some(v)
+            } else {
+                None
+            }
+        })
+        .collect();
+    let sub_widths: Vec<u16> = (0..n_row_levels)
+        .map(|d| {
+            let max_label = data_row_items
+                .iter()
+                .filter_map(|v| v.get(d))
+                .map(|s| s.width() as u16)
+                .max()
+                .unwrap_or(0);
+            (max_label + 1).max(MIN_ROW_HEADER_W).min(MAX_ROW_HEADER_W)
+        })
+        .collect();
+    sub_widths.iter().sum()
+}
+
+/// Count how many columns fit starting from `col_offset` given the available width.
+pub fn compute_visible_cols(col_widths: &[u16], row_header_width: u16, term_width: u16, col_offset: usize) -> usize {
+    // Account for grid border (2 chars)
+    let data_area_width = term_width.saturating_sub(2).saturating_sub(row_header_width);
+    let mut acc = 0u16;
+    let mut count = 0usize;
+    for ci in col_offset..col_widths.len() {
+        let w = col_widths[ci];
+        if acc + w > data_area_width {
+            break;
+        }
+        acc += w;
+        count += 1;
+    }
+    count.max(1)
+}
+
+// Re-export shared formatting functions
+pub use crate::format::{format_f64, parse_number_format};
+
 fn truncate(s: &str, max_width: usize) -> String {
     let w = s.width();
     if w <= max_width {
@@ -637,7 +665,8 @@ mod tests {
         let area = Rect::new(0, 0, width, height);
         let mut buf = Buffer::empty(area);
         let bufs = std::collections::HashMap::new();
-        GridWidget::new(model, &AppMode::Normal, "", &bufs, None).render(area, &mut buf);
+        let layout = GridLayout::new(model, model.active_view());
+        GridWidget::new(model, &layout, &AppMode::Normal, "", &bufs, None).render(area, &mut buf);
         buf
     }
 
@@ -667,6 +696,7 @@ mod tests {
     }
 
     /// Minimal model: Type on Row, Month on Column.
+    /// Every cell has a value so rows/cols survive pruning.
     fn two_cat_model() -> Model {
         let mut m = Model::new("Test");
         m.add_category("Type").unwrap(); // → Row
@@ -679,6 +709,15 @@ mod tests {
             c.add_item("Jan");
             c.add_item("Feb");
         }
+        // Fill every cell so nothing is pruned as empty.
+        for t in ["Food", "Clothing"] {
+            for mo in ["Jan", "Feb"] {
+                m.set_cell(
+                    coord(&[("Type", t), ("Month", mo)]),
+                    CellValue::Number(1.0),
+                );
+            }
+        }
         m
     }
 
@@ -738,10 +777,19 @@ mod tests {
 
     #[test]
     fn unset_cells_show_no_value() {
-        let m = two_cat_model();
+        // Build a model without the two_cat_model helper (which fills every cell).
+        let mut m = Model::new("Test");
+        m.add_category("Type").unwrap();
+        m.add_category("Month").unwrap();
+        m.category_mut("Type").unwrap().add_item("Food");
+        m.category_mut("Month").unwrap().add_item("Jan");
+        // Set one cell so the row/col isn't pruned
+        m.set_cell(
+            coord(&[("Type", "Food"), ("Month", "Jan")]),
+            CellValue::Number(1.0),
+        );
         let text = buf_text(&render(&m, 80, 24));
-        // No digits should appear in the data area if nothing is set
+        // Should not contain large numbers that weren't set
-        // (Total row shows "0" — exclude that from this check by looking for non-zero)
         assert!(!text.contains("100"), "unexpected '100' in:\n{text}");
     }
 
@@ -873,6 +921,15 @@ mod tests {
         }
         m.active_view_mut()
             .set_axis("Recipient", crate::view::Axis::Row);
+        // Populate cells so rows/cols survive pruning
+        for t in ["Food", "Clothing"] {
+            for r in ["Alice", "Bob"] {
+                m.set_cell(
+                    coord(&[("Type", t), ("Month", "Jan"), ("Recipient", r)]),
+                    CellValue::Number(1.0),
+                );
+            }
+        }
 
         let text = buf_text(&render(&m, 80, 24));
         // Multi-level row headers: category values shown separately, not joined with /
@@ -936,6 +993,13 @@ mod tests {
         }
         m.active_view_mut()
             .set_axis("Year", crate::view::Axis::Column);
+        // Populate cells so cols survive pruning
+        for y in ["2024", "2025"] {
+            m.set_cell(
+                coord(&[("Type", "Food"), ("Month", "Jan"), ("Year", y)]),
+                CellValue::Number(1.0),
+            );
+        }
 
         let text = buf_text(&render(&m, 80, 24));
         // Multi-level column headers: category values shown separately, not joined with /

src/ui/mod.rs

@@ -1,4 +1,5 @@
 pub mod app;
+pub mod cat_tree;
 pub mod category_panel;
 pub mod effect;
 pub mod formula_panel;

src/ui/view_panel.rs

@@ -36,7 +36,7 @@ impl<'a> Widget for ViewPanel<'a> {
         let block = Block::default()
             .borders(Borders::ALL)
             .border_style(border_style)
-            .title(" Views [Enter] switch [n]ew [d]elete ");
+            .title(" Views ");
         let inner = block.inner(area);
         block.render(area, buf);
 

src/view/layout.rs

@@ -1,7 +1,17 @@
+use std::rc::Rc;
+
 use crate::model::cell::{CellKey, CellValue};
 use crate::model::Model;
 use crate::view::{Axis, View};
 
+/// Extract (record_index, dim_name) from a synthetic records-mode CellKey.
+/// Returns None for normal pivot-mode keys.
+pub fn synthetic_record_info(key: &CellKey) -> Option<(usize, String)> {
+    let idx: usize = key.get("_Index")?.parse().ok()?;
+    let dim = key.get("_Dim")?.to_string();
+    Some((idx, dim))
+}
+
 /// One entry on a grid axis: either a visual group header or a data-item tuple.
 ///
 /// `GroupHeader` entries are always visible so the user can see the group label
@@ -30,8 +40,8 @@ pub struct GridLayout {
     /// Categories on `Axis::None` — hidden, implicitly aggregated.
     pub none_cats: Vec<String>,
     /// In records mode: the filtered cell list, one per row.
-    /// None for normal pivot views.
+    /// None for normal pivot views. Rc for cheap sharing.
-    pub records: Option<Vec<(CellKey, CellValue)>>,
+    pub records: Option<Rc<Vec<(CellKey, CellValue)>>>,
 }
 
 impl GridLayout {
@@ -40,12 +50,11 @@ impl GridLayout {
     pub fn with_frozen_records(
         model: &Model,
         view: &View,
-        frozen_records: Option<Vec<(CellKey, CellValue)>>,
+        frozen_records: Option<Rc<Vec<(CellKey, CellValue)>>>,
     ) -> Self {
         let mut layout = Self::new(model, view);
         if layout.is_records_mode() {
             if let Some(records) = frozen_records {
-                // Re-build with the frozen records instead
                 let row_items: Vec<AxisEntry> = (0..records.len())
                     .map(|i| AxisEntry::DataItem(vec![i.to_string()]))
                     .collect();
@@ -53,6 +62,9 @@ impl GridLayout {
                 layout.records = Some(records);
             }
         }
+        if view.prune_empty {
+            layout.prune_empty(model);
+        }
         layout
     }
 
@@ -152,10 +164,11 @@ impl GridLayout {
             .map(|i| AxisEntry::DataItem(vec![i.to_string()]))
             .collect();
 
-        // Synthesize col items: one per category + "Value"
+        // Synthesize col items: one per non-virtual category + "Value"
         let cat_names: Vec<String> = model
             .category_names()
             .into_iter()
+            .filter(|c| !c.starts_with('_'))
             .map(String::from)
             .collect();
         let mut col_items: Vec<AxisEntry> = cat_names
@@ -171,7 +184,7 @@ impl GridLayout {
             row_items,
             col_items,
             none_cats,
-            records: Some(records),
+            records: Some(Rc::new(records)),
         }
     }
 
@@ -195,6 +208,104 @@ impl GridLayout {
         }
     }
 
+    /// Remove data rows where every column is empty and data columns
+    /// where every row is empty. Group headers are kept if at least one
+    /// of their data items survives.
+    ///
+    /// In records mode every column is shown (the user drilled in to see
+    /// all the raw data). In pivot mode, rows and columns where every
+    /// cell is empty are hidden to reduce clutter.
+    pub fn prune_empty(&mut self, model: &Model) {
+        if self.is_records_mode() {
+            return;
+        }
+        let rc = self.row_count();
+        let cc = self.col_count();
+        if rc == 0 || cc == 0 {
+            return;
+        }
+
+        // Build a row×col grid of "has content?"
+        let mut has_value = vec![vec![false; cc]; rc];
+        for ri in 0..rc {
+            for ci in 0..cc {
+                has_value[ri][ci] = self
+                    .cell_key(ri, ci)
+                    .and_then(|k| model.evaluate_aggregated(&k, &self.none_cats))
+                    .is_some();
+            }
+        }
+
+        // Which data-row indices are non-empty?
+        let keep_row: Vec<bool> = (0..rc)
+            .map(|ri| (0..cc).any(|ci| has_value[ri][ci]))
+            .collect();
+        // Which data-col indices are non-empty?
+        let keep_col: Vec<bool> = (0..cc)
+            .map(|ci| (0..rc).any(|ri| has_value[ri][ci]))
+            .collect();
+
+        // Filter row_items, preserving group headers when at least one
+        // subsequent data item survives.
+        let mut new_rows = Vec::new();
+        let mut pending_header: Option<AxisEntry> = None;
+        let mut data_idx = 0usize;
+        for entry in self.row_items.drain(..) {
+            match &entry {
+                AxisEntry::GroupHeader { .. } => {
+                    pending_header = Some(entry);
+                }
+                AxisEntry::DataItem(_) => {
+                    if data_idx < rc && keep_row[data_idx] {
+                        if let Some(h) = pending_header.take() {
+                            new_rows.push(h);
+                        }
+                        new_rows.push(entry);
+                    }
+                    data_idx += 1;
+                }
+            }
+        }
+        self.row_items = new_rows;
+
+        // Filter col_items (same logic)
+        let mut new_cols = Vec::new();
+        let mut pending_header: Option<AxisEntry> = None;
+        let mut data_idx = 0usize;
+        for entry in self.col_items.drain(..) {
+            match &entry {
+                AxisEntry::GroupHeader { .. } => {
+                    pending_header = Some(entry);
+                }
+                AxisEntry::DataItem(_) => {
+                    if data_idx < cc && keep_col[data_idx] {
+                        if let Some(h) = pending_header.take() {
+                            new_cols.push(h);
+                        }
+                        new_cols.push(entry);
+                    }
+                    data_idx += 1;
+                }
+            }
+        }
+        self.col_items = new_cols;
+
+        // If records mode, also prune the records vec and re-index row_items
+        if let Some(records) = &self.records {
+            let new_records: Vec<_> = keep_row
+                .iter()
+                .enumerate()
+                .filter(|(_, keep)| **keep)
+                .map(|(i, _)| records[i].clone())
+                .collect();
+            let new_row_items: Vec<AxisEntry> = (0..new_records.len())
+                .map(|i| AxisEntry::DataItem(vec![i.to_string()]))
+                .collect();
+            self.row_items = new_row_items;
+            self.records = Some(Rc::new(new_records));
+        }
+    }
+
     /// Whether this layout is in records mode.
     pub fn is_records_mode(&self) -> bool {
         self.records.is_some()
@@ -246,18 +357,57 @@ impl GridLayout {
             .unwrap_or_default()
     }
 
+    /// Resolve the display string for a synthetic records-mode CellKey.
+    /// Returns None for non-synthetic (pivot) keys.
+    pub fn resolve_display(&self, key: &CellKey) -> Option<String> {
+        let (idx, dim) = synthetic_record_info(key)?;
+        let records = self.records.as_ref()?;
+        let (orig_key, value) = records.get(idx)?;
+        if dim == "Value" {
+            Some(value.to_string())
+        } else {
+            Some(orig_key.get(&dim).unwrap_or("").to_string())
+        }
+    }
+
+    /// Unified display text for a cell at (row, col). Handles both pivot and
+    /// records modes. In pivot mode, evaluates and formats the cell value.
+    /// In records mode, resolves via the frozen records snapshot.
+    pub fn display_text(
+        &self,
+        model: &Model,
+        row: usize,
+        col: usize,
+        fmt_comma: bool,
+        fmt_decimals: u8,
+    ) -> String {
+        if self.is_records_mode() {
+            self.records_display(row, col).unwrap_or_default()
+        } else {
+            self.cell_key(row, col)
+                .and_then(|key| model.evaluate_aggregated(&key, &self.none_cats))
+                .map(|v| crate::format::format_value(Some(&v), fmt_comma, fmt_decimals))
+                .unwrap_or_default()
+        }
+    }
+
     /// Build the CellKey for the data cell at (row, col), including the active
     /// page-axis filter. Returns None if row or col is out of bounds.
-    /// In records mode: returns the real underlying CellKey when the column
+    /// In records mode: returns a synthetic `(_Index, _Dim)` key for every column.
-    /// is "Value" (editable); returns None for coord columns (read-only).
     pub fn cell_key(&self, row: usize, col: usize) -> Option<CellKey> {
-        if let Some(records) = &self.records {
+        if self.records.is_some() {
-            // Records mode: only the Value column maps to a real, editable cell.
+            let records = self.records.as_ref().unwrap();
-            if self.col_label(col) == "Value" {
+            if row >= records.len() {
-                return records.get(row).map(|(k, _)| k.clone());
-            } else {
                 return None;
             }
+            let col_label = self.col_label(col);
+            if col_label.is_empty() {
+                return None;
+            }
+            return Some(CellKey::new(vec![
+                ("_Index".to_string(), row.to_string()),
+                ("_Dim".to_string(), col_label),
+            ]));
         }
         let row_item = self
             .row_items
@@ -421,7 +571,7 @@ fn cross_product(model: &Model, view: &View, cats: &[String]) -> Vec<AxisEntry>
 
 #[cfg(test)]
 mod tests {
-    use super::{AxisEntry, GridLayout};
+    use super::{synthetic_record_info, AxisEntry, GridLayout};
     use crate::model::cell::{CellKey, CellValue};
     use crate::model::Model;
     use crate::view::Axis;
@@ -450,6 +600,30 @@ mod tests {
         m
     }
 
+    #[test]
+    fn prune_empty_removes_all_empty_columns_in_pivot_mode() {
+        let mut m = Model::new("T");
+        m.add_category("Row").unwrap();
+        m.add_category("Col").unwrap();
+        m.category_mut("Row").unwrap().add_item("A");
+        m.category_mut("Col").unwrap().add_item("X");
+        m.category_mut("Col").unwrap().add_item("Y");
+        // Only X has data; Y is entirely empty
+        m.set_cell(
+            CellKey::new(vec![
+                ("Row".into(), "A".into()),
+                ("Col".into(), "X".into()),
+            ]),
+            CellValue::Number(1.0),
+        );
+
+        let mut layout = GridLayout::new(&m, m.active_view());
+        assert_eq!(layout.col_count(), 2); // X and Y before pruning
+        layout.prune_empty(&m);
+        assert_eq!(layout.col_count(), 1); // only X after pruning
+        assert_eq!(layout.col_label(0), "X");
+    }
+
     #[test]
     fn records_mode_activated_when_index_and_dim_on_axes() {
         let mut m = records_model();
@@ -462,40 +636,66 @@ mod tests {
     }
 
     #[test]
-    fn records_mode_cell_key_editable_for_value_column() {
+    fn records_mode_cell_key_returns_synthetic_for_all_columns() {
         let mut m = records_model();
         let v = m.active_view_mut();
         v.set_axis("_Index", Axis::Row);
         v.set_axis("_Dim", Axis::Column);
         let layout = GridLayout::new(&m, m.active_view());
         assert!(layout.is_records_mode());
-        // Find the "Value" column index
         let cols: Vec<String> = (0..layout.col_count()).map(|i| layout.col_label(i)).collect();
+        // All columns return synthetic keys
         let value_col = cols.iter().position(|c| c == "Value").unwrap();
-        // cell_key should be Some for Value column
+        let key = layout.cell_key(0, value_col).unwrap();
-        let key = layout.cell_key(0, value_col);
+        assert_eq!(key.get("_Index"), Some("0"));
-        assert!(key.is_some(), "Value column should be editable");
+        assert_eq!(key.get("_Dim"), Some("Value"));
-        // cell_key should be None for coord columns
+
         let region_col = cols.iter().position(|c| c == "Region").unwrap();
-        assert!(
+        let key = layout.cell_key(0, region_col).unwrap();
-            layout.cell_key(0, region_col).is_none(),
+        assert_eq!(key.get("_Index"), Some("0"));
-            "Region column should not be editable"
+        assert_eq!(key.get("_Dim"), Some("Region"));
-        );
     }
 
     #[test]
-    fn records_mode_cell_key_maps_to_real_cell() {
+    fn records_mode_resolve_display_returns_values() {
         let mut m = records_model();
         let v = m.active_view_mut();
         v.set_axis("_Index", Axis::Row);
         v.set_axis("_Dim", Axis::Column);
         let layout = GridLayout::new(&m, m.active_view());
         let cols: Vec<String> = (0..layout.col_count()).map(|i| layout.col_label(i)).collect();
+
+        // Value column resolves to the cell value
         let value_col = cols.iter().position(|c| c == "Value").unwrap();
-        // The CellKey at (0, Value) should look up a real cell value
         let key = layout.cell_key(0, value_col).unwrap();
-        let val = m.evaluate(&key);
+        let display = layout.resolve_display(&key);
-        assert!(val.is_some(), "cell_key should resolve to a real cell");
+        assert!(display.is_some(), "Value column should resolve");
+
+        // Category column resolves to the coordinate value
+        let region_col = cols.iter().position(|c| c == "Region").unwrap();
+        let key = layout.cell_key(0, region_col).unwrap();
+        let display = layout.resolve_display(&key).unwrap();
+        assert!(!display.is_empty(), "Region column should resolve to a value");
+    }
+
+    #[test]
+    fn synthetic_record_info_returns_none_for_pivot_keys() {
+        let key = CellKey::new(vec![
+            ("Region".to_string(), "East".to_string()),
+            ("Product".to_string(), "Shoes".to_string()),
+        ]);
+        assert!(synthetic_record_info(&key).is_none());
+    }
+
+    #[test]
+    fn synthetic_record_info_extracts_index_and_dim() {
+        let key = CellKey::new(vec![
+            ("_Index".to_string(), "3".to_string()),
+            ("_Dim".to_string(), "Region".to_string()),
+        ]);
+        let (idx, dim) = synthetic_record_info(&key).unwrap();
+        assert_eq!(idx, 3);
+        assert_eq!(dim, "Region");
     }
 
     fn coord(pairs: &[(&str, &str)]) -> CellKey {

src/view/mod.rs

@@ -3,5 +3,5 @@ pub mod layout;
 pub mod types;
 
 pub use axis::Axis;
-pub use layout::{AxisEntry, GridLayout};
+pub use layout::{synthetic_record_info, AxisEntry, GridLayout};
 pub use types::View;

src/view/types.rs

@@ -4,6 +4,10 @@ use std::collections::{HashMap, HashSet};
 
 use super::axis::Axis;
 
+fn default_prune() -> bool {
+    true
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct View {
     pub name: String,
@@ -17,6 +21,9 @@ pub struct View {
     pub collapsed_groups: HashMap<String, HashSet<String>>,
     /// Number format string (e.g. ",.0f" for comma-separated integer)
     pub number_format: String,
+    /// When true, empty rows/columns are pruned from the display.
+    #[serde(default = "default_prune")]
+    pub prune_empty: bool,
     /// Scroll offset for grid
     pub row_offset: usize,
     pub col_offset: usize,
@@ -33,6 +40,7 @@ impl View {
             hidden_items: HashMap::new(),
             collapsed_groups: HashMap::new(),
             number_format: ",.0".to_string(),
+            prune_empty: false,
             row_offset: 0,
             col_offset: 0,
             selected: (0, 0),
@@ -41,16 +49,47 @@ impl View {
 
     pub fn on_category_added(&mut self, cat_name: &str) {
         if !self.category_axes.contains_key(cat_name) {
-            // Virtual categories (names starting with `_`) default to Axis::None.
+            // Virtual/underscore categories default to Axis::None.
             // Regular categories auto-assign: first → Row, second → Column, rest → Page.
+            // If a virtual currently holds Row or Column and a regular category needs
+            // the slot, bump the virtual to None.
             let axis = if cat_name.starts_with('_') {
                 Axis::None
             } else {
-                let rows = self.categories_on(Axis::Row).len();
+                let regular_rows: Vec<String> = self
-                let cols = self.categories_on(Axis::Column).len();
+                    .categories_on(Axis::Row)
-                if rows == 0 {
+                    .into_iter()
+                    .filter(|c| !c.starts_with('_'))
+                    .map(String::from)
+                    .collect();
+                let regular_cols: Vec<String> = self
+                    .categories_on(Axis::Column)
+                    .into_iter()
+                    .filter(|c| !c.starts_with('_'))
+                    .map(String::from)
+                    .collect();
+                if regular_rows.is_empty() {
+                    // Bump any virtual on Row to None
+                    let bump: Vec<String> = self
+                        .categories_on(Axis::Row)
+                        .into_iter()
+                        .filter(|c| c.starts_with('_'))
+                        .map(String::from)
+                        .collect();
+                    for c in bump {
+                        self.category_axes.insert(c, Axis::None);
+                    }
                     Axis::Row
-                } else if cols == 0 {
+                } else if regular_cols.is_empty() {
+                    let bump: Vec<String> = self
+                        .categories_on(Axis::Column)
+                        .into_iter()
+                        .filter(|c| c.starts_with('_'))
+                        .map(String::from)
+                        .collect();
+                    for c in bump {
+                        self.category_axes.insert(c, Axis::None);
+                    }
                     Axis::Column
                 } else {
                     Axis::Page
@@ -60,6 +99,12 @@ impl View {
         }
     }
 
+    pub fn on_category_removed(&mut self, cat_name: &str) {
+        self.category_axes.shift_remove(cat_name);
+        self.page_selections.remove(cat_name);
+        self.hidden_items.remove(cat_name);
+    }
+
     pub fn set_axis(&mut self, cat_name: &str, axis: Axis) {
         if let Some(a) = self.category_axes.get_mut(cat_name) {
             *a = axis;