improvise/src/command/cmd.rs

use std::collections::HashMap;
use std::fmt::Debug;

use crossterm::event::KeyCode;

use crate::model::cell::{CellKey, CellValue};
use crate::model::Model;
use crate::ui::app::AppMode;
use crate::ui::effect::{self, Effect, Panel};
use crate::view::{Axis, AxisEntry, GridLayout};

/// Read-only context available to commands for decision-making.
pub struct CmdContext<'a> {
    pub model: &'a Model,
    pub mode: &'a AppMode,
    pub selected: (usize, usize),
    pub row_offset: usize,
    pub col_offset: usize,
    pub search_query: &'a str,
    pub yanked: &'a Option<CellValue>,
    pub dirty: bool,
    pub search_mode: bool,
    pub formula_panel_open: bool,
    pub category_panel_open: bool,
    pub view_panel_open: bool,
    /// Panel cursors
    pub formula_cursor: usize,
    pub cat_panel_cursor: usize,
    pub view_panel_cursor: usize,
    /// Tile select cursor (which category is selected)
    pub tile_cat_idx: usize,
    /// Named text buffers
    pub buffers: &'a HashMap<String, String>,
    /// Pre-resolved cell key at the cursor position (None if out of bounds)
    pub cell_key: Option<crate::model::cell::CellKey>,
    /// Grid dimensions (so commands don't need GridLayout)
    pub row_count: usize,
    pub col_count: usize,
    /// Categories on Axis::None — aggregated away in the current view
    pub none_cats: Vec<String>,
    /// View navigation stacks (for drill back/forward)
    pub view_back_stack: Vec<String>,
    pub view_forward_stack: Vec<String>,
    /// The key that triggered this command
    pub key_code: KeyCode,
}

/// A command that reads state and produces effects.
pub trait Cmd: Debug + Send + Sync {
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>>;
    /// The canonical name of this command (matches its registry key).
    /// Used by the parser tests and for introspection.
    #[allow(dead_code)]
    fn name(&self) -> &'static str;
}

/// Factory that constructs a Cmd from text arguments (headless/script).
pub type ParseFn = fn(&[String]) -> Result<Box<dyn Cmd>, String>;

/// Factory that constructs a Cmd from the interactive context (keymap dispatch).
/// Receives both the keymap args and the interactive context so commands can
/// combine text arguments (e.g. panel name) with runtime state (e.g. whether
/// the panel is currently open).
pub type InteractiveFn = fn(&[String], &CmdContext) -> Result<Box<dyn Cmd>, String>;

type BoxParseFn = Box<dyn Fn(&[String]) -> Result<Box<dyn Cmd>, String>>;
type BoxInteractiveFn = Box<dyn Fn(&[String], &CmdContext) -> Result<Box<dyn Cmd>, String>>;

/// A registered command entry with both text and interactive constructors.
struct CmdEntry {
    name: &'static str,
    parse: BoxParseFn,
    interactive: BoxInteractiveFn,
}

/// Registry of commands constructible from text or from interactive context.
#[derive(Default)]
pub struct CmdRegistry {
    entries: Vec<CmdEntry>,
}

impl CmdRegistry {
    pub fn new() -> Self {
        Self {
            entries: Vec::new(),
        }
    }

    /// Register a command with both a text parser and an interactive constructor.
    /// The name is derived from a prototype command instance.
    pub fn register(
        &mut self,
        prototype: &dyn Cmd,
        parse: ParseFn,
        interactive: InteractiveFn,
    ) {
        self.entries.push(CmdEntry {
            name: prototype.name(),
            parse: Box::new(parse),
            interactive: Box::new(interactive),
        });
    }

    /// Register a command that doesn't need interactive context.
    /// When called interactively with args, delegates to parse.
    /// When called interactively without args, returns an error.
    pub fn register_pure(&mut self, prototype: &dyn Cmd, parse: ParseFn) {
        self.entries.push(CmdEntry {
            name: prototype.name(),
            parse: Box::new(parse),
            interactive: Box::new(move |args, _ctx| {
                if args.is_empty() {
                    Err("this command requires arguments".into())
                } else {
                    parse(args)
                }
            }),
        });
    }

    /// Register a zero-arg command (same instance for parse and interactive).
    /// The name is derived by calling `f()` once.
    pub fn register_nullary(&mut self, f: fn() -> Box<dyn Cmd>) {
        let name = f().name();
        self.entries.push(CmdEntry {
            name,
            parse: Box::new(move |_| Ok(f())),
            interactive: Box::new(move |_, _| Ok(f())),
        });
    }

    /// Construct a command from text arguments (script/headless).
    pub fn parse(&self, name: &str, args: &[String]) -> Result<Box<dyn Cmd>, String> {
        for e in &self.entries {
            if e.name == name {
                return (e.parse)(args);
            }
        }
        Err(format!("Unknown command: {name}"))
    }

    /// Construct a command from interactive context (keymap dispatch).
    /// Always calls the interactive constructor with both args and ctx,
    /// so commands can combine text arguments with runtime state.
    pub fn interactive(
        &self,
        name: &str,
        args: &[String],
        ctx: &CmdContext,
    ) -> Result<Box<dyn Cmd>, String> {
        for e in &self.entries {
            if e.name == name {
                return (e.interactive)(args, ctx);
            }
        }
        Err(format!("Unknown command: {name}"))
    }

    #[allow(dead_code)]
    pub fn names(&self) -> impl Iterator<Item = &'static str> + '_ {
        self.entries.iter().map(|e| e.name)
    }
}

/// Dummy prototype used only for name extraction in registry calls
/// where the real command struct is built by a closure.
#[derive(Debug)]
struct NamedCmd(&'static str);
impl Cmd for NamedCmd {
    fn name(&self) -> &'static str {
        self.0
    }
    fn execute(&self, _: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![]
    }
}

fn require_args(word: &str, args: &[String], n: usize) -> Result<(), String> {
    if args.len() < n {
        Err(format!(
            "{word} requires {n} argument(s), got {}",
            args.len()
        ))
    } else {
        Ok(())
    }
}

/// Parse Cat/Item coordinate args into a CellKey.
fn parse_cell_key_from_args(args: &[String]) -> crate::model::cell::CellKey {
    let coords: Vec<(String, String)> = args
        .iter()
        .filter_map(|s| {
            let (cat, item) = s.split_once('/')?;
            Some((cat.to_string(), item.to_string()))
        })
        .collect();
    crate::model::cell::CellKey::new(coords)
}

// ── Navigation commands ──────────────────────────────────────────────────────
// All navigation commands take explicit cursor state. The interactive spec
// fills position/bounds from context; the parser accepts them as args.

/// Shared viewport state for navigation commands.
#[derive(Debug, Clone, Default)]
pub struct CursorState {
    pub row: usize,
    pub col: usize,
    pub row_count: usize,
    pub col_count: usize,
    pub row_offset: usize,
    pub col_offset: usize,
}

impl CursorState {
    pub fn from_ctx(ctx: &CmdContext) -> Self {
        Self {
            row: ctx.selected.0,
            col: ctx.selected.1,
            row_count: ctx.row_count,
            col_count: ctx.col_count,
            row_offset: ctx.row_offset,
            col_offset: ctx.col_offset,
        }
    }
}

/// Compute viewport-tracking effects for a new row/col position.
fn viewport_effects(
    nr: usize,
    nc: usize,
    old_row_offset: usize,
    old_col_offset: usize,
) -> Vec<Box<dyn Effect>> {
    let mut effects: Vec<Box<dyn Effect>> = vec![effect::set_selected(nr, nc)];
    let mut row_offset = old_row_offset;
    let mut col_offset = old_col_offset;
    if nr < row_offset {
        row_offset = nr;
    }
    if nr >= row_offset + 20 {
        row_offset = nr.saturating_sub(19);
    }
    if nc < col_offset {
        col_offset = nc;
    }
    if nc >= col_offset + 8 {
        col_offset = nc.saturating_sub(7);
    }
    if row_offset != old_row_offset {
        effects.push(Box::new(effect::SetRowOffset(row_offset)));
    }
    if col_offset != old_col_offset {
        effects.push(Box::new(effect::SetColOffset(col_offset)));
    }
    effects
}

#[derive(Debug)]
pub struct MoveSelection {
    pub dr: i32,
    pub dc: i32,
    pub cursor: CursorState,
}

impl Cmd for MoveSelection {
    fn name(&self) -> &'static str {
        "move-selection"
    }

    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let row_max = self.cursor.row_count.saturating_sub(1);
        let col_max = self.cursor.col_count.saturating_sub(1);
        let nr = (self.cursor.row as i32 + self.dr).clamp(0, row_max as i32) as usize;
        let nc = (self.cursor.col as i32 + self.dc).clamp(0, col_max as i32) as usize;
        viewport_effects(nr, nc, self.cursor.row_offset, self.cursor.col_offset)
    }
}

#[derive(Debug)]
pub struct JumpToFirstRow {
    pub col: usize,
}
impl Cmd for JumpToFirstRow {
    fn name(&self) -> &'static str {
        "jump-first-row"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![
            Box::new(effect::SetSelected(0, self.col)),
            Box::new(effect::SetRowOffset(0)),
        ]
    }
}

#[derive(Debug)]
pub struct JumpToLastRow {
    pub col: usize,
    pub row_count: usize,
    pub row_offset: usize,
}
impl Cmd for JumpToLastRow {
    fn name(&self) -> &'static str {
        "jump-last-row"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let last = self.row_count.saturating_sub(1);
        let mut effects: Vec<Box<dyn Effect>> = vec![Box::new(effect::SetSelected(last, self.col))];
        if last >= self.row_offset + 20 {
            effects.push(Box::new(effect::SetRowOffset(last.saturating_sub(19))));
        }
        effects
    }
}

#[derive(Debug)]
pub struct JumpToFirstCol {
    pub row: usize,
}
impl Cmd for JumpToFirstCol {
    fn name(&self) -> &'static str {
        "jump-first-col"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![
            Box::new(effect::SetSelected(self.row, 0)),
            Box::new(effect::SetColOffset(0)),
        ]
    }
}

#[derive(Debug)]
pub struct JumpToLastCol {
    pub row: usize,
    pub col_count: usize,
    pub col_offset: usize,
}
impl Cmd for JumpToLastCol {
    fn name(&self) -> &'static str {
        "jump-last-col"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let last = self.col_count.saturating_sub(1);
        let mut effects: Vec<Box<dyn Effect>> = vec![Box::new(effect::SetSelected(self.row, last))];
        if last >= self.col_offset + 8 {
            effects.push(Box::new(effect::SetColOffset(last.saturating_sub(7))));
        }
        effects
    }
}

#[derive(Debug)]
pub struct ScrollRows {
    pub delta: i32,
    pub cursor: CursorState,
}
impl Cmd for ScrollRows {
    fn name(&self) -> &'static str {
        "scroll-rows"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let row_max = self.cursor.row_count.saturating_sub(1) as i32;
        let nr = (self.cursor.row as i32 + self.delta).clamp(0, row_max) as usize;
        let mut effects: Vec<Box<dyn Effect>> =
            vec![Box::new(effect::SetSelected(nr, self.cursor.col))];
        let mut row_offset = self.cursor.row_offset;
        if nr < row_offset {
            row_offset = nr;
        }
        if nr >= row_offset + 20 {
            row_offset = nr.saturating_sub(19);
        }
        if row_offset != self.cursor.row_offset {
            effects.push(Box::new(effect::SetRowOffset(row_offset)));
        }
        effects
    }
}

// ── Mode change commands ─────────────────────────────────────────────────────

#[derive(Debug)]
pub struct EnterMode(pub AppMode);
impl Cmd for EnterMode {
    fn name(&self) -> &'static str {
        "enter-mode"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();
        // Clear the corresponding buffer when entering a text-entry mode
        let buffer_name = match &self.0 {
            AppMode::CommandMode { .. } => Some("command"),
            AppMode::Editing { .. } => Some("edit"),
            AppMode::FormulaEdit { .. } => Some("formula"),
            AppMode::CategoryAdd { .. } => Some("category"),
            AppMode::ExportPrompt { .. } => Some("export"),
            _ => None,
        };
        if let Some(name) = buffer_name {
            effects.push(Box::new(effect::SetBuffer {
                name: name.to_string(),
                value: String::new(),
            }));
        }
        effects.push(effect::change_mode(self.0.clone()));
        effects
    }
}

#[derive(Debug)]
pub struct ForceQuit;
impl Cmd for ForceQuit {
    fn name(&self) -> &'static str {
        "force-quit"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![effect::change_mode(AppMode::Quit)]
    }
}

#[derive(Debug)]
pub struct SaveAndQuit;
impl Cmd for SaveAndQuit {
    fn name(&self) -> &'static str {
        "save-and-quit"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::Save), effect::change_mode(AppMode::Quit)]
    }
}

// ── Cell operations ──────────────────────────────────────────────────────────
// All cell commands take an explicit CellKey. The interactive spec fills it
// from ctx.cell_key; the parser fills it from Cat/Item coordinate args.

/// Clear a cell.
#[derive(Debug)]
pub struct ClearCellCommand {
    pub key: crate::model::cell::CellKey,
}
impl Cmd for ClearCellCommand {
    fn name(&self) -> &'static str {
        "clear-cell"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![
            Box::new(effect::ClearCell(self.key.clone())),
            effect::mark_dirty(),
        ]
    }
}

/// Yank (copy) a cell value.
#[derive(Debug)]
pub struct YankCell {
    pub key: crate::model::cell::CellKey,
}
impl Cmd for YankCell {
    fn name(&self) -> &'static str {
        "yank"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let layout = GridLayout::new(ctx.model, ctx.model.active_view());
        let value = ctx.model.evaluate_aggregated(&self.key, &layout.none_cats);
        vec![
            Box::new(effect::SetYanked(value)),
            effect::set_status("Yanked"),
        ]
    }
}

/// Paste the yanked value into a cell.
#[derive(Debug)]
pub struct PasteCell {
    pub key: crate::model::cell::CellKey,
}
impl Cmd for PasteCell {
    fn name(&self) -> &'static str {
        "paste"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if let Some(value) = ctx.yanked.clone() {
            vec![
                Box::new(effect::SetCell(self.key.clone(), value)),
                effect::mark_dirty(),
            ]
        } else {
            vec![]
        }
    }
}

// ── View commands ────────────────────────────────────────────────────────────

#[derive(Debug)]
pub struct TransposeAxes;
impl Cmd for TransposeAxes {
    fn name(&self) -> &'static str {
        "transpose"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::TransposeAxes), effect::mark_dirty()]
    }
}

#[derive(Debug)]
pub struct SaveCmd;
impl Cmd for SaveCmd {
    fn name(&self) -> &'static str {
        "save"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::Save)]
    }
}

// ── Search ───────────────────────────────────────────────────────────────────

#[derive(Debug)]
pub struct EnterSearchMode;
impl Cmd for EnterSearchMode {
    fn name(&self) -> &'static str {
        "search"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![
            Box::new(effect::SetSearchMode(true)),
            Box::new(effect::SetSearchQuery(String::new())),
        ]
    }
}

// ── Panel commands ──────────────────────────────────────────────────────

/// Toggle a panel's visibility; if it opens, focus it (enter its mode).
#[derive(Debug)]
pub struct TogglePanelAndFocus {
    pub panel: Panel,
    pub currently_open: bool,
}
impl Cmd for TogglePanelAndFocus {
    fn name(&self) -> &'static str {
        "toggle-panel-and-focus"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let new_open = !self.currently_open;
        let mut effects: Vec<Box<dyn Effect>> = vec![Box::new(effect::SetPanelOpen {
            panel: self.panel,
            open: new_open,
        })];
        if new_open {
            let mode = match self.panel {
                Panel::Formula => AppMode::FormulaPanel,
                Panel::Category => AppMode::CategoryPanel,
                Panel::View => AppMode::ViewPanel,
            };
            effects.push(effect::change_mode(mode));
        }
        effects
    }
}

/// Toggle a panel's visibility without changing mode.
#[derive(Debug)]
pub struct TogglePanelVisibility {
    pub panel: Panel,
    pub currently_open: bool,
}
impl Cmd for TogglePanelVisibility {
    fn name(&self) -> &'static str {
        "toggle-panel-visibility"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::SetPanelOpen {
            panel: self.panel,
            open: !self.currently_open,
        })]
    }
}

/// Tab through open panels, entering the first open panel's mode.
#[derive(Debug)]
pub struct CyclePanelFocus {
    pub formula_open: bool,
    pub category_open: bool,
    pub view_open: bool,
}
impl Cmd for CyclePanelFocus {
    fn name(&self) -> &'static str {
        "cycle-panel-focus"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if self.formula_open {
            vec![effect::change_mode(AppMode::FormulaPanel)]
        } else if self.category_open {
            vec![effect::change_mode(AppMode::CategoryPanel)]
        } else if self.view_open {
            vec![effect::change_mode(AppMode::ViewPanel)]
        } else {
            vec![]
        }
    }
}

// ── Editing entry ───────────────────────────────────────────────────────

/// Enter editing mode with an initial buffer value.
#[derive(Debug)]
pub struct EnterEditMode {
    pub initial_value: String,
}
impl Cmd for EnterEditMode {
    fn name(&self) -> &'static str {
        "enter-edit-mode"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![
            Box::new(effect::SetBuffer {
                name: "edit".to_string(),
                value: self.initial_value.clone(),
            }),
            effect::change_mode(AppMode::Editing {
                buffer: String::new(),
            }),
        ]
    }
}

/// Typewriter-style advance: move down, wrap to top of next column at bottom.
#[derive(Debug)]
pub struct EnterAdvance {
    pub cursor: CursorState,
}
impl Cmd for EnterAdvance {
    fn name(&self) -> &'static str {
        "enter-advance"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let row_max = self.cursor.row_count.saturating_sub(1);
        let col_max = self.cursor.col_count.saturating_sub(1);
        let (r, c) = (self.cursor.row, self.cursor.col);
        let (nr, nc) = if r < row_max {
            (r + 1, c)
        } else if c < col_max {
            (0, c + 1)
        } else {
            (r, c) // already at bottom-right; stay
        };
        viewport_effects(nr, nc, self.cursor.row_offset, self.cursor.col_offset)
    }
}

/// Enter export prompt mode.
#[derive(Debug)]
pub struct EnterExportPrompt;
impl Cmd for EnterExportPrompt {
    fn name(&self) -> &'static str {
        "enter-export-prompt"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![effect::change_mode(AppMode::ExportPrompt {
            buffer: String::new(),
        })]
    }
}

// ── Search / navigation ─────────────────────────────────────────────────

/// Navigate to the next or previous search match.
#[derive(Debug)]
pub struct SearchNavigate(pub bool);
impl Cmd for SearchNavigate {
    fn name(&self) -> &'static str {
        "search-navigate"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let query = ctx.search_query.to_lowercase();
        if query.is_empty() {
            return vec![];
        }

        let layout = GridLayout::new(ctx.model, ctx.model.active_view());
        let (cur_row, cur_col) = ctx.selected;
        let total_rows = layout.row_count().max(1);
        let total_cols = layout.col_count().max(1);
        let total = total_rows * total_cols;
        let cur_flat = cur_row * total_cols + cur_col;

        let matches: Vec<usize> = (0..total)
            .filter(|&flat| {
                let ri = flat / total_cols;
                let ci = flat % total_cols;
                let key = match layout.cell_key(ri, ci) {
                    Some(k) => k,
                    None => return false,
                };
                let s = match ctx.model.evaluate_aggregated(&key, &layout.none_cats) {
                    Some(CellValue::Number(n)) => format!("{n}"),
                    Some(CellValue::Text(t)) => t,
                    None => String::new(),
                };
                s.to_lowercase().contains(&query)
            })
            .collect();

        if matches.is_empty() {
            return vec![effect::set_status(format!(
                "No matches for '{}'",
                ctx.search_query
            ))];
        }

        let target_flat = if self.0 {
            matches
                .iter()
                .find(|&&f| f > cur_flat)
                .or_else(|| matches.first())
                .copied()
        } else {
            matches
                .iter()
                .rev()
                .find(|&&f| f < cur_flat)
                .or_else(|| matches.last())
                .copied()
        };

        if let Some(flat) = target_flat {
            let ri = flat / total_cols;
            let ci = flat % total_cols;
            let mut effects: Vec<Box<dyn Effect>> = vec![effect::set_selected(ri, ci)];
            if ri < ctx.row_offset {
                effects.push(Box::new(effect::SetRowOffset(ri)));
            }
            if ci < ctx.col_offset {
                effects.push(Box::new(effect::SetColOffset(ci)));
            }
            effects.push(effect::set_status(format!(
                "Match {}/{} for '{}'",
                matches.iter().position(|&f| f == flat).unwrap_or(0) + 1,
                matches.len(),
                ctx.search_query,
            )));
            effects
        } else {
            vec![]
        }
    }
}

/// If search query is active, navigate backward; otherwise open CategoryAdd.
#[derive(Debug)]
pub struct SearchOrCategoryAdd;
impl Cmd for SearchOrCategoryAdd {
    fn name(&self) -> &'static str {
        "search-or-category-add"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if !ctx.search_query.is_empty() {
            SearchNavigate(false).execute(ctx)
        } else {
            vec![
                Box::new(effect::SetPanelOpen {
                    panel: Panel::Category,
                    open: true,
                }),
                effect::change_mode(AppMode::CategoryAdd {
                    buffer: String::new(),
                }),
            ]
        }
    }
}

// ── Page navigation ─────────────────────────────────────────────────────

/// Advance to the next page (odometer-style cycling).
#[derive(Debug)]
pub struct PageNext;
impl Cmd for PageNext {
    fn name(&self) -> &'static str {
        "page-next"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let data = page_cat_data(ctx);
        if data.is_empty() {
            return vec![];
        }
        let mut indices: Vec<usize> = data.iter().map(|(_, _, i)| *i).collect();
        let mut carry = true;
        for i in (0..data.len()).rev() {
            if !carry {
                break;
            }
            indices[i] += 1;
            if indices[i] >= data[i].1.len() {
                indices[i] = 0;
            } else {
                carry = false;
            }
        }
        data.iter()
            .enumerate()
            .map(|(i, (cat, items, _))| {
                Box::new(effect::SetPageSelection {
                    category: cat.clone(),
                    item: items[indices[i]].clone(),
                }) as Box<dyn Effect>
            })
            .collect()
    }
}

/// Go to the previous page (odometer-style cycling).
#[derive(Debug)]
pub struct PagePrev;
impl Cmd for PagePrev {
    fn name(&self) -> &'static str {
        "page-prev"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let data = page_cat_data(ctx);
        if data.is_empty() {
            return vec![];
        }
        let mut indices: Vec<usize> = data.iter().map(|(_, _, i)| *i).collect();
        let mut borrow = true;
        for i in (0..data.len()).rev() {
            if !borrow {
                break;
            }
            if indices[i] == 0 {
                indices[i] = data[i].1.len().saturating_sub(1);
            } else {
                indices[i] -= 1;
                borrow = false;
            }
        }
        data.iter()
            .enumerate()
            .map(|(i, (cat, items, _))| {
                Box::new(effect::SetPageSelection {
                    category: cat.clone(),
                    item: items[indices[i]].clone(),
                }) as Box<dyn Effect>
            })
            .collect()
    }
}

/// Gather (cat_name, items, current_idx) for page-axis categories.
fn page_cat_data(ctx: &CmdContext) -> Vec<(String, Vec<String>, usize)> {
    let view = ctx.model.active_view();
    let page_cats: Vec<String> = view
        .categories_on(Axis::Page)
        .into_iter()
        .map(String::from)
        .collect();
    page_cats
        .into_iter()
        .filter_map(|cat| {
            let items: Vec<String> = ctx
                .model
                .category(&cat)
                .map(|c| {
                    c.ordered_item_names()
                        .into_iter()
                        .map(String::from)
                        .collect()
                })
                .unwrap_or_default();
            if items.is_empty() {
                return None;
            }
            let current = view
                .page_selection(&cat)
                .map(String::from)
                .or_else(|| items.first().cloned())
                .unwrap_or_default();
            let idx = items.iter().position(|i| *i == current).unwrap_or(0);
            Some((cat, items, idx))
        })
        .collect()
}

// ── Grid operations ─────────────────────────────────────────────────────

/// Toggle the row group collapse under the cursor.
#[derive(Debug)]
pub struct ToggleGroupUnderCursor;
impl Cmd for ToggleGroupUnderCursor {
    fn name(&self) -> &'static str {
        "toggle-group-under-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let layout = GridLayout::new(ctx.model, ctx.model.active_view());
        let sel_row = ctx.selected.0;
        let Some((cat, group)) = layout.row_group_for(sel_row) else {
            return vec![];
        };
        vec![
            Box::new(effect::ToggleGroup {
                category: cat,
                group,
            }),
            effect::mark_dirty(),
        ]
    }
}

/// Toggle the column group collapse under the cursor.
#[derive(Debug)]
pub struct ToggleColGroupUnderCursor;
impl Cmd for ToggleColGroupUnderCursor {
    fn name(&self) -> &'static str {
        "toggle-col-group-under-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let layout = GridLayout::new(ctx.model, ctx.model.active_view());
        let sel_col = ctx.selected.1;
        let Some((cat, group)) = layout.col_group_for(sel_col) else {
            return vec![];
        };
        // After toggling, col_count may shrink — clamp selection
        // We return ToggleGroup + MarkDirty; selection clamping will need
        // to happen in the effect or in a follow-up pass
        vec![
            Box::new(effect::ToggleGroup {
                category: cat,
                group,
            }),
            effect::mark_dirty(),
        ]
    }
}

/// Hide the row item at the cursor.
#[derive(Debug)]
pub struct HideSelectedRowItem;
impl Cmd for HideSelectedRowItem {
    fn name(&self) -> &'static str {
        "hide-selected-row-item"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let layout = GridLayout::new(ctx.model, ctx.model.active_view());
        let Some(cat_name) = layout.row_cats.first().cloned() else {
            return vec![];
        };
        let sel_row = ctx.selected.0;
        let Some(items) = layout
            .row_items
            .iter()
            .filter_map(|e| {
                if let AxisEntry::DataItem(v) = e {
                    Some(v)
                } else {
                    None
                }
            })
            .nth(sel_row)
        else {
            return vec![];
        };
        let item_name = items[0].clone();
        vec![
            Box::new(effect::HideItem {
                category: cat_name,
                item: item_name,
            }),
            effect::mark_dirty(),
        ]
    }
}

/// Navigate back in view history.
#[derive(Debug)]
pub struct ViewBackCmd;
impl Cmd for ViewBackCmd {
    fn name(&self) -> &'static str {
        "view-back"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if ctx.view_back_stack.is_empty() {
            vec![effect::set_status("No previous view")]
        } else {
            vec![Box::new(effect::ViewBack)]
        }
    }
}

/// Navigate forward in view history.
#[derive(Debug)]
pub struct ViewForwardCmd;
impl Cmd for ViewForwardCmd {
    fn name(&self) -> &'static str {
        "view-forward"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if ctx.view_forward_stack.is_empty() {
            vec![effect::set_status("No forward view")]
        } else {
            vec![Box::new(effect::ViewForward)]
        }
    }
}

/// Drill down into an aggregated cell: create a _Drill view that shows the
/// raw (un-aggregated) data for this cell. Categories on Axis::None in the
/// current view become visible (Row + Column) in the drill view; the cell's
/// fixed coordinates become page filters.
#[derive(Debug)]
pub struct DrillIntoCell {
    pub key: crate::model::cell::CellKey,
}
impl Cmd for DrillIntoCell {
    fn name(&self) -> &'static str {
        "drill-into-cell"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let drill_name = "_Drill".to_string();
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();

        // Create (or replace) the drill view
        effects.push(Box::new(effect::CreateView(drill_name.clone())));
        effects.push(Box::new(effect::SwitchView(drill_name)));

        // All categories currently exist. Set axes:
        // - none_cats → Row (first) and Column (rest) to expand them
        // - cell_key cats → Page with their specific items (filter)
        // - other cats (not in cell_key or none_cats) → Page as well
        let none_cats = &ctx.none_cats;
        let fixed_cats: std::collections::HashSet<String> =
            self.key.0.iter().map(|(c, _)| c.clone()).collect();

        for (i, cat) in none_cats.iter().enumerate() {
            let axis = if i == 0 {
                crate::view::Axis::Row
            } else {
                crate::view::Axis::Column
            };
            effects.push(Box::new(effect::SetAxis {
                category: cat.clone(),
                axis,
            }));
        }

        // All other categories → Page, with the cell's value as the page selection
        for cat_name in ctx.model.category_names() {
            let cat = cat_name.to_string();
            if none_cats.contains(&cat) {
                continue;
            }
            effects.push(Box::new(effect::SetAxis {
                category: cat.clone(),
                axis: crate::view::Axis::Page,
            }));
            // If this category was in the drilled cell's key, fix its page
            // selection to the cell's value
            if fixed_cats.contains(&cat) {
                if let Some((_, item)) = self.key.0.iter().find(|(c, _)| c == &cat) {
                    effects.push(Box::new(effect::SetPageSelection {
                        category: cat,
                        item: item.clone(),
                    }));
                }
            }
        }

        effects.push(effect::set_status("Drilled into cell"));
        effects
    }
}

/// Enter tile select mode.
#[derive(Debug)]
pub struct EnterTileSelect;
impl Cmd for EnterTileSelect {
    fn name(&self) -> &'static str {
        "enter-tile-select"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let count = ctx.model.category_names().len();
        if count > 0 {
            vec![
                Box::new(effect::SetTileCatIdx(0)),
                effect::change_mode(AppMode::TileSelect),
            ]
        } else {
            vec![]
        }
    }
}

// ── Panel cursor commands ────────────────────────────────────────────────────

/// Move a panel cursor by delta, clamping to bounds.
#[derive(Debug)]
pub struct MovePanelCursor {
    pub panel: Panel,
    pub delta: i32,
    pub current: usize,
    pub max: usize,
}
impl Cmd for MovePanelCursor {
    fn name(&self) -> &'static str {
        "move-panel-cursor"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let cursor = self.current;
        let max = self.max;
        if max == 0 {
            return vec![];
        }
        let clamped_cursor = cursor.min(max - 1);
        let new = (clamped_cursor as i32 + self.delta).clamp(0, (max - 1) as i32) as usize;
        if new != cursor {
            vec![Box::new(effect::SetPanelCursor {
                panel: self.panel,
                cursor: new,
            })]
        } else {
            vec![]
        }
    }
}

// ── Formula panel commands ──────────────────────────────────────────────────

/// Enter formula edit mode with an empty buffer.
#[derive(Debug)]
pub struct EnterFormulaEdit;
impl Cmd for EnterFormulaEdit {
    fn name(&self) -> &'static str {
        "enter-formula-edit"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![effect::change_mode(AppMode::FormulaEdit {
            buffer: String::new(),
        })]
    }
}

/// Delete the formula at the current cursor position.
#[derive(Debug)]
pub struct DeleteFormulaAtCursor;
impl Cmd for DeleteFormulaAtCursor {
    fn name(&self) -> &'static str {
        "delete-formula-at-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let formulas = ctx.model.formulas();
        let cursor = ctx.formula_cursor.min(formulas.len().saturating_sub(1));
        if cursor < formulas.len() {
            let f = &formulas[cursor];
            let mut effects: Vec<Box<dyn Effect>> = vec![
                Box::new(effect::RemoveFormula {
                    target: f.target.clone(),
                    target_category: f.target_category.clone(),
                }),
                effect::mark_dirty(),
            ];
            if cursor > 0 {
                effects.push(Box::new(effect::SetPanelCursor {
                    panel: Panel::Formula,
                    cursor: cursor - 1,
                }));
            }
            effects
        } else {
            vec![]
        }
    }
}

// ── Category panel commands ─────────────────────────────────────────────────

/// Cycle the axis assignment of the category at the cursor.
#[derive(Debug)]
pub struct CycleAxisAtCursor;
impl Cmd for CycleAxisAtCursor {
    fn name(&self) -> &'static str {
        "cycle-axis-at-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let cat_names = ctx.model.category_names();
        if let Some(cat_name) = cat_names.get(ctx.cat_panel_cursor) {
            vec![Box::new(effect::CycleAxis(cat_name.to_string()))]
        } else {
            vec![]
        }
    }
}

/// Enter ItemAdd mode for the category at the panel cursor.
#[derive(Debug)]
pub struct OpenItemAddAtCursor;
impl Cmd for OpenItemAddAtCursor {
    fn name(&self) -> &'static str {
        "open-item-add-at-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let cat_names = ctx.model.category_names();
        if let Some(cat_name) = cat_names.get(ctx.cat_panel_cursor) {
            vec![effect::change_mode(AppMode::ItemAdd {
                category: cat_name.to_string(),
                buffer: String::new(),
            })]
        } else {
            vec![effect::set_status(
                "No category selected. Press n to add a category first.",
            )]
        }
    }
}

// ── View panel commands ─────────────────────────────────────────────────────

/// Switch to the view at the panel cursor and return to Normal mode.
#[derive(Debug)]
pub struct SwitchViewAtCursor;
impl Cmd for SwitchViewAtCursor {
    fn name(&self) -> &'static str {
        "switch-view-at-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let view_names: Vec<String> = ctx.model.views.keys().cloned().collect();
        if let Some(name) = view_names.get(ctx.view_panel_cursor) {
            vec![
                Box::new(effect::SwitchView(name.clone())),
                effect::change_mode(AppMode::Normal),
            ]
        } else {
            vec![]
        }
    }
}

/// Create a new view, switch to it, and return to Normal mode.
#[derive(Debug)]
pub struct CreateAndSwitchView;
impl Cmd for CreateAndSwitchView {
    fn name(&self) -> &'static str {
        "create-and-switch-view"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let name = format!("View {}", ctx.model.views.len() + 1);
        vec![
            Box::new(effect::CreateView(name.clone())),
            Box::new(effect::SwitchView(name)),
            effect::mark_dirty(),
            effect::change_mode(AppMode::Normal),
        ]
    }
}

/// Delete the view at the panel cursor.
#[derive(Debug)]
pub struct DeleteViewAtCursor;
impl Cmd for DeleteViewAtCursor {
    fn name(&self) -> &'static str {
        "delete-view-at-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let view_names: Vec<String> = ctx.model.views.keys().cloned().collect();
        if let Some(name) = view_names.get(ctx.view_panel_cursor) {
            let mut effects: Vec<Box<dyn Effect>> = vec![
                Box::new(effect::DeleteView(name.clone())),
                effect::mark_dirty(),
            ];
            if ctx.view_panel_cursor > 0 {
                effects.push(Box::new(effect::SetPanelCursor {
                    panel: Panel::View,
                    cursor: ctx.view_panel_cursor - 1,
                }));
            }
            effects
        } else {
            vec![]
        }
    }
}

// ── Tile select commands ────────────────────────────────────────────────────

/// Move the tile select cursor left or right.
#[derive(Debug)]
pub struct MoveTileCursor(pub i32);
impl Cmd for MoveTileCursor {
    fn name(&self) -> &'static str {
        "move-tile-cursor"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let count = ctx.model.category_names().len();
        if count == 0 {
            return vec![];
        }
        let new = (ctx.tile_cat_idx as i32 + self.0).clamp(0, (count - 1) as i32) as usize;
        vec![Box::new(effect::SetTileCatIdx(new))]
    }
}

/// Cycle the axis for the category at the tile cursor, then return to Normal.
#[derive(Debug)]
pub struct CycleAxisForTile;
impl Cmd for CycleAxisForTile {
    fn name(&self) -> &'static str {
        "cycle-axis-for-tile"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let cat_names = ctx.model.category_names();
        if let Some(name) = cat_names.get(ctx.tile_cat_idx) {
            vec![
                Box::new(effect::CycleAxis(name.to_string())),
                effect::mark_dirty(),
                effect::change_mode(AppMode::Normal),
            ]
        } else {
            vec![effect::change_mode(AppMode::Normal)]
        }
    }
}

/// Set a specific axis for the category at the tile cursor, then return to Normal.
#[derive(Debug)]
pub struct SetAxisForTile(pub Axis);
impl Cmd for SetAxisForTile {
    fn name(&self) -> &'static str {
        "set-axis-for-tile"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let cat_names = ctx.model.category_names();
        if let Some(name) = cat_names.get(ctx.tile_cat_idx) {
            vec![
                Box::new(effect::SetAxis {
                    category: name.to_string(),
                    axis: self.0,
                }),
                effect::mark_dirty(),
                effect::change_mode(AppMode::Normal),
            ]
        } else {
            vec![effect::change_mode(AppMode::Normal)]
        }
    }
}

// ── Wizard command ──────────────────────────────────────────────────────────

/// Dispatch the current key to the import wizard effect.
#[derive(Debug)]
pub struct HandleWizardKey;
impl Cmd for HandleWizardKey {
    fn name(&self) -> &'static str {
        "handle-wizard-key"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::WizardKey {
            key_code: ctx.key_code,
        })]
    }
}

// ── Command mode execution ──────────────────────────────────────────────────

/// Execute the command in the "command" buffer (the `:` command line).
#[derive(Debug)]
pub struct ExecuteCommand;
impl Cmd for ExecuteCommand {
    fn name(&self) -> &'static str {
        "execute-command"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let raw = ctx.buffers.get("command").cloned().unwrap_or_default();
        let raw = raw.trim();
        let (cmd_name, rest) = raw
            .split_once(char::is_whitespace)
            .map(|(c, r)| (c, r.trim()))
            .unwrap_or((raw, ""));

        // Default: return to Normal
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();

        match cmd_name {
            "q" | "quit" => {
                if ctx.dirty {
                    effects.push(effect::set_status(
                        "Unsaved changes. Use :q! to force quit or :wq to save+quit.",
                    ));
                } else {
                    effects.push(effect::change_mode(AppMode::Quit));
                }
            }
            "q!" => {
                effects.push(effect::change_mode(AppMode::Quit));
            }
            "w" | "write" => {
                if rest.is_empty() {
                    effects.push(Box::new(effect::Save));
                } else {
                    effects.push(Box::new(effect::SaveAs(std::path::PathBuf::from(rest))));
                }
            }
            "wq" | "x" => {
                effects.push(Box::new(effect::Save));
                effects.push(effect::change_mode(AppMode::Quit));
            }
            "import" => {
                if rest.is_empty() {
                    effects.push(effect::set_status("Usage: :import <path.json>"));
                } else {
                    effects.push(Box::new(effect::StartImportWizard(rest.to_string())));
                }
            }
            "export" => {
                let path = if rest.is_empty() { "export.csv" } else { rest };
                effects.push(Box::new(effect::ExportCsv(std::path::PathBuf::from(path))));
            }
            "add-cat" | "add-category" | "cat" => {
                if rest.is_empty() {
                    effects.push(effect::set_status("Usage: :add-cat <name>"));
                } else {
                    effects.push(Box::new(effect::AddCategory(rest.to_string())));
                    effects.push(effect::mark_dirty());
                }
            }
            "add-item" | "item" => {
                let mut parts = rest.splitn(2, char::is_whitespace);
                let cat = parts.next().unwrap_or("").trim();
                let item = parts.next().unwrap_or("").trim();
                if cat.is_empty() || item.is_empty() {
                    effects.push(effect::set_status("Usage: :add-item <category> <item>"));
                } else {
                    effects.push(Box::new(effect::AddItem {
                        category: cat.to_string(),
                        item: item.to_string(),
                    }));
                    effects.push(effect::mark_dirty());
                    effects.push(effect::set_status("Item added"));
                }
            }
            "add-items" | "items" => {
                let mut parts = rest.splitn(2, char::is_whitespace);
                let cat = parts.next().unwrap_or("").trim().to_string();
                let items_str = parts.next().unwrap_or("").trim().to_string();
                if cat.is_empty() || items_str.is_empty() {
                    effects.push(effect::set_status(
                        "Usage: :add-items <category> item1 item2 ...",
                    ));
                } else {
                    let items: Vec<&str> = items_str.split_whitespace().collect();
                    let count = items.len();
                    for item in &items {
                        effects.push(Box::new(effect::AddItem {
                            category: cat.clone(),
                            item: item.to_string(),
                        }));
                    }
                    effects.push(effect::mark_dirty());
                    effects.push(effect::set_status(format!(
                        "Added {count} items to \"{cat}\".",
                    )));
                }
            }
            "formula" | "add-formula" => {
                if rest.is_empty() {
                    effects.push(Box::new(effect::SetPanelOpen {
                        panel: Panel::Formula,
                        open: true,
                    }));
                    effects.push(effect::change_mode(AppMode::FormulaPanel));
                    return effects; // Don't set mode to Normal
                } else {
                    let mut parts = rest.splitn(2, char::is_whitespace);
                    let cat = parts.next().unwrap_or("").trim();
                    let formula = parts.next().unwrap_or("").trim();
                    if cat.is_empty() || formula.is_empty() {
                        effects.push(effect::set_status(
                            "Usage: :formula <category> <Name = expr>",
                        ));
                    } else {
                        effects.push(Box::new(effect::AddFormula {
                            raw: formula.to_string(),
                            target_category: cat.to_string(),
                        }));
                        effects.push(effect::mark_dirty());
                        effects.push(effect::set_status("Formula added"));
                    }
                }
            }
            "add-view" | "view" => {
                let name = if rest.is_empty() {
                    format!("View {}", ctx.model.views.len() + 1)
                } else {
                    rest.to_string()
                };
                effects.push(Box::new(effect::CreateView(name.clone())));
                effects.push(Box::new(effect::SwitchView(name)));
                effects.push(effect::mark_dirty());
            }
            "set-format" | "fmt" => {
                if rest.is_empty() {
                    effects.push(effect::set_status(
                        "Usage: :set-format <fmt>  e.g. ,.0  ,.2  .4",
                    ));
                } else {
                    effects.push(Box::new(effect::SetNumberFormat(rest.to_string())));
                    effects.push(effect::mark_dirty());
                    effects.push(effect::set_status(format!("Number format set to '{rest}'")));
                }
            }
            "show-item" | "show" => {
                let mut parts = rest.splitn(2, char::is_whitespace);
                let cat = parts.next().unwrap_or("").trim();
                let item = parts.next().unwrap_or("").trim();
                if cat.is_empty() || item.is_empty() {
                    effects.push(effect::set_status("Usage: :show-item <category> <item>"));
                } else {
                    effects.push(Box::new(effect::ShowItem {
                        category: cat.to_string(),
                        item: item.to_string(),
                    }));
                    effects.push(effect::mark_dirty());
                    effects.push(effect::set_status(format!(
                        "Showed \"{item}\" in \"{cat}\""
                    )));
                }
            }
            "help" | "h" => {
                effects.push(effect::change_mode(AppMode::Help));
                return effects; // Don't also set Normal
            }
            "" => {} // just pressed Enter with empty buffer
            other => {
                effects.push(effect::set_status(format!(
                    "Unknown command: :{other}  (try :help)"
                )));
            }
        }

        // Default: return to Normal (unless a command already set a different mode)
        if !effects
            .iter()
            .any(|e| format!("{e:?}").contains("ChangeMode"))
        {
            effects.push(effect::change_mode(AppMode::Normal));
        }

        effects
    }
}

// ── Text buffer commands ─────────────────────────────────────────────────────

/// Read the current value of a named buffer from context.
fn read_buffer(ctx: &CmdContext, name: &str) -> String {
    if name == "search" {
        ctx.search_query.to_string()
    } else {
        ctx.buffers.get(name).cloned().unwrap_or_default()
    }
}

/// Append the pressed character to a named buffer.
#[derive(Debug)]
pub struct AppendChar {
    pub buffer: String,
}
impl Cmd for AppendChar {
    fn name(&self) -> &'static str {
        "append-char"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if let KeyCode::Char(c) = ctx.key_code {
            let mut val = read_buffer(ctx, &self.buffer);
            val.push(c);
            vec![Box::new(effect::SetBuffer {
                name: self.buffer.clone(),
                value: val,
            })]
        } else {
            vec![]
        }
    }
}

/// Pop the last character from a named buffer.
#[derive(Debug)]
pub struct PopChar {
    pub buffer: String,
}
impl Cmd for PopChar {
    fn name(&self) -> &'static str {
        "pop-char"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let mut val = read_buffer(ctx, &self.buffer);
        val.pop();
        vec![Box::new(effect::SetBuffer {
            name: self.buffer.clone(),
            value: val,
        })]
    }
}

// ── Commit commands (mode-specific buffer consumers) ────────────────────────

/// Commit a cell edit: set cell value, advance cursor, return to Normal.
#[derive(Debug)]
pub struct CommitCellEdit {
    pub key: crate::model::cell::CellKey,
    pub value: String,
}
impl Cmd for CommitCellEdit {
    fn name(&self) -> &'static str {
        "commit-cell-edit"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();

        if self.value.is_empty() {
            effects.push(Box::new(effect::ClearCell(self.key.clone())));
        } else if let Ok(n) = self.value.parse::<f64>() {
            effects.push(Box::new(effect::SetCell(
                self.key.clone(),
                CellValue::Number(n),
            )));
        } else {
            effects.push(Box::new(effect::SetCell(
                self.key.clone(),
                CellValue::Text(self.value.clone()),
            )));
        }
        effects.push(effect::mark_dirty());
        effects.push(effect::change_mode(AppMode::Normal));
        // Advance cursor down (typewriter-style)
        let adv = EnterAdvance {
            cursor: CursorState::from_ctx(ctx),
        };
        effects.extend(adv.execute(ctx));
        effects
    }
}

/// Commit a formula from the formula edit buffer.
#[derive(Debug)]
pub struct CommitFormula;
impl Cmd for CommitFormula {
    fn name(&self) -> &'static str {
        "commit-formula"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let buf = ctx.buffers.get("formula").cloned().unwrap_or_default();
        let first_cat = ctx
            .model
            .category_names()
            .into_iter()
            .next()
            .map(String::from);
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();
        if let Some(cat) = first_cat {
            effects.push(Box::new(effect::AddFormula {
                raw: buf,
                target_category: cat,
            }));
            effects.push(effect::mark_dirty());
            effects.push(effect::set_status("Formula added"));
        } else {
            effects.push(effect::set_status("Add at least one category first."));
        }
        effects.push(effect::change_mode(AppMode::FormulaPanel));
        effects
    }
}

/// Commit adding a category, staying in CategoryAdd mode for the next entry.
#[derive(Debug)]
pub struct CommitCategoryAdd;
impl Cmd for CommitCategoryAdd {
    fn name(&self) -> &'static str {
        "commit-category-add"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let buf = ctx.buffers.get("category").cloned().unwrap_or_default();
        let trimmed = buf.trim().to_string();
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();
        if !trimmed.is_empty() {
            effects.push(Box::new(effect::AddCategory(trimmed.clone())));
            effects.push(effect::mark_dirty());
            effects.push(effect::set_status(format!("Added category \"{trimmed}\"")));
        }
        // Clear buffer for next entry
        effects.push(Box::new(effect::SetBuffer {
            name: "category".to_string(),
            value: String::new(),
        }));
        effects
    }
}

/// Commit adding an item, staying in ItemAdd mode for the next entry.
#[derive(Debug)]
pub struct CommitItemAdd;
impl Cmd for CommitItemAdd {
    fn name(&self) -> &'static str {
        "commit-item-add"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let buf = ctx.buffers.get("item").cloned().unwrap_or_default();
        let trimmed = buf.trim().to_string();
        // Get the category from the mode
        let category = if let AppMode::ItemAdd { category, .. } = ctx.mode {
            category.clone()
        } else {
            return vec![];
        };
        let mut effects: Vec<Box<dyn Effect>> = Vec::new();
        if !trimmed.is_empty() {
            effects.push(Box::new(effect::AddItem {
                category,
                item: trimmed.clone(),
            }));
            effects.push(effect::mark_dirty());
            effects.push(effect::set_status(format!("Added \"{trimmed}\"")));
        }
        // Clear buffer for next entry
        effects.push(Box::new(effect::SetBuffer {
            name: "item".to_string(),
            value: String::new(),
        }));
        effects
    }
}

/// Commit an export from the export buffer.
#[derive(Debug)]
pub struct CommitExport;
impl Cmd for CommitExport {
    fn name(&self) -> &'static str {
        "commit-export"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let buf = ctx.buffers.get("export").cloned().unwrap_or_default();
        vec![
            Box::new(effect::ExportCsv(std::path::PathBuf::from(buf))),
            effect::change_mode(AppMode::Normal),
        ]
    }
}

/// Exit search mode (clears search_mode flag).
#[derive(Debug)]
pub struct ExitSearchMode;
impl Cmd for ExitSearchMode {
    fn name(&self) -> &'static str {
        "exit-search-mode"
    }
    fn execute(&self, _ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::SetSearchMode(false))]
    }
}

/// Append a character to the search query.
#[derive(Debug)]
pub struct SearchAppendChar;
impl Cmd for SearchAppendChar {
    fn name(&self) -> &'static str {
        "search-append-char"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        if let KeyCode::Char(c) = ctx.key_code {
            let mut q = ctx.search_query.to_string();
            q.push(c);
            vec![Box::new(effect::SetSearchQuery(q))]
        } else {
            vec![]
        }
    }
}

/// Pop the last character from the search query.
#[derive(Debug)]
pub struct SearchPopChar;
impl Cmd for SearchPopChar {
    fn name(&self) -> &'static str {
        "search-pop-char"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let mut q = ctx.search_query.to_string();
        q.pop();
        vec![Box::new(effect::SetSearchQuery(q))]
    }
}

/// Handle backspace in command mode — pop char or return to Normal if empty.
#[derive(Debug)]
pub struct CommandModeBackspace;
impl Cmd for CommandModeBackspace {
    fn name(&self) -> &'static str {
        "command-mode-backspace"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        let val = ctx.buffers.get("command").cloned().unwrap_or_default();
        if val.is_empty() {
            vec![effect::change_mode(AppMode::Normal)]
        } else {
            let mut val = val;
            val.pop();
            vec![Box::new(effect::SetBuffer {
                name: "command".to_string(),
                value: val,
            })]
        }
    }
}

// ── Parseable model-mutation commands ────────────────────────────────────────
// These are thin Cmd wrappers around effects, constructible from string args.
// They share the same execution path as keymap-dispatched commands.

macro_rules! effect_cmd {
    ($name:ident, $cmd_name:expr, $parse:expr, $exec:expr) => {
        #[derive(Debug)]
        pub struct $name(pub Vec<String>);
        impl Cmd for $name {
            fn name(&self) -> &'static str {
                $cmd_name
            }
            fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
                let args = &self.0;
                #[allow(clippy::redundant_closure_call)]
                ($exec)(args, ctx)
            }
        }
        impl $name {
            pub fn parse(args: &[String]) -> Result<Box<dyn Cmd>, String> {
                #[allow(clippy::redundant_closure_call)]
                ($parse)(args)?;
                Ok(Box::new($name(args.to_vec())))
            }
        }
    };
}

effect_cmd!(
    AddCategoryCmd,
    "add-category",
    |args: &[String]| require_args("add-category", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::AddCategory(args[0].clone()))]
    }
);

effect_cmd!(
    AddItemCmd,
    "add-item",
    |args: &[String]| require_args("add-item", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::AddItem {
            category: args[0].clone(),
            item: args[1].clone(),
        })]
    }
);

effect_cmd!(
    AddItemInGroupCmd,
    "add-item-in-group",
    |args: &[String]| require_args("add-item-in-group", args, 3),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::AddItemInGroup {
            category: args[0].clone(),
            item: args[1].clone(),
            group: args[2].clone(),
        })]
    }
);

effect_cmd!(
    SetCellCmd,
    "set-cell",
    |args: &[String]| {
        if args.len() < 2 {
            Err("set-cell requires a value and at least one Cat/Item coordinate".to_string())
        } else {
            Ok(())
        }
    },
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        let value = if let Ok(n) = args[0].parse::<f64>() {
            CellValue::Number(n)
        } else {
            CellValue::Text(args[0].clone())
        };
        let coords: Vec<(String, String)> = args[1..]
            .iter()
            .filter_map(|s| {
                let (cat, item) = s.split_once('/')?;
                Some((cat.to_string(), item.to_string()))
            })
            .collect();
        let key = crate::model::cell::CellKey::new(coords);
        vec![Box::new(effect::SetCell(key, value))]
    }
);

effect_cmd!(
    AddFormulaCmd,
    "add-formula",
    |args: &[String]| require_args("add-formula", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::AddFormula {
            target_category: args[0].clone(),
            raw: args[1].clone(),
        })]
    }
);

effect_cmd!(
    RemoveFormulaCmd,
    "remove-formula",
    |args: &[String]| require_args("remove-formula", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::RemoveFormula {
            target_category: args[0].clone(),
            target: args[1].clone(),
        })]
    }
);

effect_cmd!(
    CreateViewCmd,
    "create-view",
    |args: &[String]| require_args("create-view", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::CreateView(args[0].clone()))]
    }
);

effect_cmd!(
    DeleteViewCmd,
    "delete-view",
    |args: &[String]| require_args("delete-view", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::DeleteView(args[0].clone()))]
    }
);

effect_cmd!(
    SwitchViewCmd,
    "switch-view",
    |args: &[String]| require_args("switch-view", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::SwitchView(args[0].clone()))]
    }
);

effect_cmd!(
    SetAxisCmd,
    "set-axis",
    |args: &[String]| require_args("set-axis", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        let axis = match args[1].to_lowercase().as_str() {
            "row" => Axis::Row,
            "column" | "col" => Axis::Column,
            "page" => Axis::Page,
            "none" => Axis::None,
            _ => return vec![], // parse step already validated
        };
        vec![Box::new(effect::SetAxis {
            category: args[0].clone(),
            axis,
        })]
    }
);

effect_cmd!(
    SetPageCmd,
    "set-page",
    |args: &[String]| require_args("set-page", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::SetPageSelection {
            category: args[0].clone(),
            item: args[1].clone(),
        })]
    }
);

effect_cmd!(
    ToggleGroupCmd,
    "toggle-group",
    |args: &[String]| require_args("toggle-group", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::ToggleGroup {
            category: args[0].clone(),
            group: args[1].clone(),
        })]
    }
);

effect_cmd!(
    HideItemCmd,
    "hide-item",
    |args: &[String]| require_args("hide-item", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::HideItem {
            category: args[0].clone(),
            item: args[1].clone(),
        })]
    }
);

effect_cmd!(
    ShowItemCmd,
    "show-item",
    |args: &[String]| require_args("show-item", args, 2),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::ShowItem {
            category: args[0].clone(),
            item: args[1].clone(),
        })]
    }
);

effect_cmd!(
    SaveAsCmd,
    "save-as",
    |args: &[String]| require_args("save-as", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::SaveAs(std::path::PathBuf::from(&args[0])))]
    }
);

effect_cmd!(
    LoadModelCmd,
    "load",
    |args: &[String]| require_args("load", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::LoadModel(std::path::PathBuf::from(
            &args[0],
        )))]
    }
);

effect_cmd!(
    ExportCsvCmd,
    "export-csv",
    |args: &[String]| require_args("export-csv", args, 1),
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::ExportCsv(std::path::PathBuf::from(
            &args[0],
        )))]
    }
);

effect_cmd!(
    ImportJsonCmd,
    "import-json",
    |args: &[String]| {
        if args.is_empty() {
            Err("import-json requires a path".to_string())
        } else {
            Ok(())
        }
    },
    |args: &Vec<String>, _ctx: &CmdContext| -> Vec<Box<dyn Effect>> {
        vec![Box::new(effect::ImportJsonHeadless {
            path: std::path::PathBuf::from(&args[0]),
            model_name: args.get(1).cloned(),
            array_path: args.get(2).cloned(),
        })]
    }
);

/// Build the default command registry with all commands.
/// Registry names MUST match the `Cmd::name()` return value.
pub fn default_registry() -> CmdRegistry {
    let mut r = CmdRegistry::new();

    // ── Model mutations (effect_cmd! wrappers) ───────────────────────────
    r.register_pure(&AddCategoryCmd(vec![]), AddCategoryCmd::parse);
    r.register_pure(&AddItemCmd(vec![]), AddItemCmd::parse);
    r.register_pure(&AddItemInGroupCmd(vec![]), AddItemInGroupCmd::parse);
    r.register_pure(&SetCellCmd(vec![]), SetCellCmd::parse);
    r.register(
        &ClearCellCommand { key: CellKey::new(vec![]) },
        |args| {
            if args.is_empty() {
                return Err("clear-cell requires at least one Cat/Item coordinate".into());
            }
            Ok(Box::new(ClearCellCommand {
                key: parse_cell_key_from_args(args),
            }))
        },
        |_args, ctx| {
            let key = ctx.cell_key.clone().ok_or("no cell at cursor")?;
            Ok(Box::new(ClearCellCommand { key }))
        },
    );
    r.register_pure(&AddFormulaCmd(vec![]), AddFormulaCmd::parse);
    r.register_pure(&RemoveFormulaCmd(vec![]), RemoveFormulaCmd::parse);
    r.register_pure(&CreateViewCmd(vec![]), CreateViewCmd::parse);
    r.register_pure(&DeleteViewCmd(vec![]), DeleteViewCmd::parse);
    r.register_pure(&SwitchViewCmd(vec![]), SwitchViewCmd::parse);
    r.register_pure(&SetAxisCmd(vec![]), SetAxisCmd::parse);
    r.register_pure(&SetPageCmd(vec![]), SetPageCmd::parse);
    r.register_pure(&ToggleGroupCmd(vec![]), ToggleGroupCmd::parse);
    r.register_pure(&HideItemCmd(vec![]), HideItemCmd::parse);
    r.register_pure(&ShowItemCmd(vec![]), ShowItemCmd::parse);
    r.register_pure(&SaveAsCmd(vec![]), SaveAsCmd::parse);
    r.register_pure(&LoadModelCmd(vec![]), LoadModelCmd::parse);
    r.register_pure(&ExportCsvCmd(vec![]), ExportCsvCmd::parse);
    r.register_pure(&ImportJsonCmd(vec![]), ImportJsonCmd::parse);

    // ── Navigation ───────────────────────────────────────────────────────
    r.register(
        &MoveSelection { dr: 0, dc: 0, cursor: CursorState::default() },
        |args| {
            require_args("move-selection", args, 2)?;
            let dr = args[0].parse::<i32>().map_err(|e| e.to_string())?;
            let dc = args[1].parse::<i32>().map_err(|e| e.to_string())?;
            Ok(Box::new(MoveSelection {
                dr,
                dc,
                cursor: CursorState {
                    row: 0,
                    col: 0,
                    row_count: 0,
                    col_count: 0,
                    row_offset: 0,
                    col_offset: 0,
                },
            }))
        },
        |args, ctx| {
            require_args("move-selection", args, 2)?;
            let dr = args[0].parse::<i32>().map_err(|e| e.to_string())?;
            let dc = args[1].parse::<i32>().map_err(|e| e.to_string())?;
            Ok(Box::new(MoveSelection {
                dr,
                dc,
                cursor: CursorState::from_ctx(ctx),
            }))
        },
    );
    r.register(
        &JumpToFirstRow { col: 0 },
        |_| Ok(Box::new(JumpToFirstRow { col: 0 })),
        |_, ctx| {
            Ok(Box::new(JumpToFirstRow {
                col: ctx.selected.1,
            }))
        },
    );
    r.register(
        &JumpToLastRow { col: 0, row_count: 0, row_offset: 0 },
        |_| {
            Ok(Box::new(JumpToLastRow {
                col: 0,
                row_count: 0,
                row_offset: 0,
            }))
        },
        |_, ctx| {
            Ok(Box::new(JumpToLastRow {
                col: ctx.selected.1,
                row_count: ctx.row_count,
                row_offset: ctx.row_offset,
            }))
        },
    );
    r.register(
        &JumpToFirstCol { row: 0 },
        |_| Ok(Box::new(JumpToFirstCol { row: 0 })),
        |_, ctx| {
            Ok(Box::new(JumpToFirstCol {
                row: ctx.selected.0,
            }))
        },
    );
    r.register(
        &JumpToLastCol { row: 0, col_count: 0, col_offset: 0 },
        |_| {
            Ok(Box::new(JumpToLastCol {
                row: 0,
                col_count: 0,
                col_offset: 0,
            }))
        },
        |_, ctx| {
            Ok(Box::new(JumpToLastCol {
                row: ctx.selected.0,
                col_count: ctx.col_count,
                col_offset: ctx.col_offset,
            }))
        },
    );
    r.register(
        &ScrollRows { delta: 0, cursor: CursorState::default() },
        |args| {
            require_args("scroll-rows", args, 1)?;
            let n = args[0].parse::<i32>().map_err(|e| e.to_string())?;
            Ok(Box::new(ScrollRows {
                delta: n,
                cursor: CursorState {
                    row: 0,
                    col: 0,
                    row_count: 0,
                    col_count: 0,
                    row_offset: 0,
                    col_offset: 0,
                },
            }))
        },
        |args, ctx| {
            require_args("scroll-rows", args, 1)?;
            let n = args[0].parse::<i32>().map_err(|e| e.to_string())?;
            Ok(Box::new(ScrollRows {
                delta: n,
                cursor: CursorState::from_ctx(ctx),
            }))
        },
    );
    r.register(
        &EnterAdvance { cursor: CursorState::default() },
        |_| {
            Ok(Box::new(EnterAdvance {
                cursor: CursorState {
                    row: 0,
                    col: 0,
                    row_count: 0,
                    col_count: 0,
                    row_offset: 0,
                    col_offset: 0,
                },
            }))
        },
        |_, ctx| {
            Ok(Box::new(EnterAdvance {
                cursor: CursorState::from_ctx(ctx),
            }))
        },
    );

    // ── Cell operations ──────────────────────────────────────────────────
    r.register(
        &YankCell { key: CellKey::new(vec![]) },
        |args| {
            if args.is_empty() {
                return Err("yank requires at least one Cat/Item coordinate".into());
            }
            Ok(Box::new(YankCell {
                key: parse_cell_key_from_args(args),
            }))
        },
        |_args, ctx| {
            let key = ctx.cell_key.clone().ok_or("no cell at cursor")?;
            Ok(Box::new(YankCell { key }))
        },
    );
    r.register(
        &PasteCell { key: CellKey::new(vec![]) },
        |args| {
            if args.is_empty() {
                return Err("paste requires at least one Cat/Item coordinate".into());
            }
            Ok(Box::new(PasteCell {
                key: parse_cell_key_from_args(args),
            }))
        },
        |_args, ctx| {
            let key = ctx.cell_key.clone().ok_or("no cell at cursor")?;
            Ok(Box::new(PasteCell { key }))
        },
    );
    // clear-cell is registered above (unified: ctx.cell_key or explicit coords)

    // ── View / page ──────────────────────────────────────────────────────
    r.register_nullary(|| Box::new(TransposeAxes));
    r.register_nullary(|| Box::new(PageNext));
    r.register_nullary(|| Box::new(PagePrev));

    // ── Mode changes ─────────────────────────────────────────────────────
    r.register_nullary(|| Box::new(ForceQuit));
    r.register_nullary(|| Box::new(SaveAndQuit));
    r.register_nullary(|| Box::new(SaveCmd));
    r.register_nullary(|| Box::new(EnterSearchMode));
    r.register(
        &EnterEditMode { initial_value: String::new() },
        |args| {
            let val = args.first().cloned().unwrap_or_default();
            Ok(Box::new(EnterEditMode { initial_value: val }))
        },
        |_args, ctx| {
            let current = ctx
                .cell_key
                .as_ref()
                .and_then(|k| ctx.model.get_cell(k).cloned())
                .map(|v| v.to_string())
                .unwrap_or_default();
            Ok(Box::new(EnterEditMode {
                initial_value: current,
            }))
        },
    );
    r.register_nullary(|| Box::new(EnterExportPrompt));
    r.register_nullary(|| Box::new(EnterFormulaEdit));
    r.register_nullary(|| Box::new(EnterTileSelect));
    r.register(
        &DrillIntoCell {
            key: crate::model::cell::CellKey::new(vec![]),
        },
        |args| {
            if args.is_empty() {
                return Err("drill-into-cell requires Cat/Item coordinates".into());
            }
            Ok(Box::new(DrillIntoCell {
                key: parse_cell_key_from_args(args),
            }))
        },
        |_args, ctx| {
            let key = ctx.cell_key.clone().ok_or("no cell at cursor")?;
            Ok(Box::new(DrillIntoCell { key }))
        },
    );
    r.register_nullary(|| Box::new(ViewBackCmd));
    r.register_nullary(|| Box::new(ViewForwardCmd));
    r.register_pure(&NamedCmd("enter-mode"), |args| {
        require_args("enter-mode", args, 1)?;
        let mode = match args[0].as_str() {
            "normal" => AppMode::Normal,
            "help" => AppMode::Help,
            "formula-panel" => AppMode::FormulaPanel,
            "category-panel" => AppMode::CategoryPanel,
            "view-panel" => AppMode::ViewPanel,
            "tile-select" => AppMode::TileSelect,
            "command" => AppMode::CommandMode {
                buffer: String::new(),
            },
            "category-add" => AppMode::CategoryAdd {
                buffer: String::new(),
            },
            "editing" => AppMode::Editing {
                buffer: String::new(),
            },
            "formula-edit" => AppMode::FormulaEdit {
                buffer: String::new(),
            },
            "export-prompt" => AppMode::ExportPrompt {
                buffer: String::new(),
            },
            other => return Err(format!("Unknown mode: {other}")),
        };
        Ok(Box::new(EnterMode(mode)))
    });

    // ── Search ───────────────────────────────────────────────────────────
    r.register_pure(&NamedCmd("search-navigate"), |args| {
        let forward = args.first().map(|s| s != "backward").unwrap_or(true);
        Ok(Box::new(SearchNavigate(forward)))
    });
    r.register_nullary(|| Box::new(SearchOrCategoryAdd));
    r.register_nullary(|| Box::new(ExitSearchMode));
    r.register_nullary(|| Box::new(SearchAppendChar));
    r.register_nullary(|| Box::new(SearchPopChar));

    // ── Panel operations ─────────────────────────────────────────────────
    r.register(
        &TogglePanelAndFocus { panel: Panel::Formula, currently_open: false },
        |args| {
            require_args("toggle-panel-and-focus", args, 1)?;
            let panel = parse_panel(&args[0])?;
            Ok(Box::new(TogglePanelAndFocus {
                panel,
                currently_open: false,
            }))
        },
        |args, ctx| {
            require_args("toggle-panel-and-focus", args, 1)?;
            let panel = parse_panel(&args[0])?;
            let currently_open = match panel {
                Panel::Formula => ctx.formula_panel_open,
                Panel::Category => ctx.category_panel_open,
                Panel::View => ctx.view_panel_open,
            };
            Ok(Box::new(TogglePanelAndFocus {
                panel,
                currently_open,
            }))
        },
    );
    r.register(
        &TogglePanelVisibility { panel: Panel::Formula, currently_open: false },
        |args| {
            require_args("toggle-panel-visibility", args, 1)?;
            let panel = parse_panel(&args[0])?;
            Ok(Box::new(TogglePanelVisibility {
                panel,
                currently_open: false,
            }))
        },
        |args, ctx| {
            require_args("toggle-panel-visibility", args, 1)?;
            let panel = parse_panel(&args[0])?;
            let currently_open = match panel {
                Panel::Formula => ctx.formula_panel_open,
                Panel::Category => ctx.category_panel_open,
                Panel::View => ctx.view_panel_open,
            };
            Ok(Box::new(TogglePanelVisibility {
                panel,
                currently_open,
            }))
        },
    );
    r.register(
        &CyclePanelFocus { formula_open: false, category_open: false, view_open: false },
        |_| {
            Ok(Box::new(CyclePanelFocus {
                formula_open: false,
                category_open: false,
                view_open: false,
            }))
        },
        |_, ctx| {
            Ok(Box::new(CyclePanelFocus {
                formula_open: ctx.formula_panel_open,
                category_open: ctx.category_panel_open,
                view_open: ctx.view_panel_open,
            }))
        },
    );
    r.register(
        &MovePanelCursor { panel: Panel::Formula, delta: 0, current: 0, max: 0 },
        |args| {
            require_args("move-panel-cursor", args, 2)?;
            let panel = parse_panel(&args[0])?;
            let delta = args[1].parse::<i32>().map_err(|e| e.to_string())?;
            Ok(Box::new(MovePanelCursor {
                panel,
                delta,
                current: 0,
                max: 0,
            }))
        },
        |args, ctx| {
            require_args("move-panel-cursor", args, 2)?;
            let panel = parse_panel(&args[0])?;
            let delta = args[1].parse::<i32>().map_err(|e| e.to_string())?;
            let (current, max) = match panel {
                Panel::Formula => (ctx.formula_cursor, ctx.model.formulas().len()),
                Panel::Category => (ctx.cat_panel_cursor, ctx.model.category_names().len()),
                Panel::View => (ctx.view_panel_cursor, ctx.model.views.len()),
            };
            Ok(Box::new(MovePanelCursor {
                panel,
                delta,
                current,
                max,
            }))
        },
    );
    r.register_nullary(|| {
        Box::new(DeleteFormulaAtCursor)
    });
    r.register_nullary(|| Box::new(CycleAxisAtCursor));
    r.register_nullary(|| Box::new(OpenItemAddAtCursor));
    r.register_nullary(|| Box::new(SwitchViewAtCursor));
    r.register_nullary(|| Box::new(CreateAndSwitchView));
    r.register_nullary(|| Box::new(DeleteViewAtCursor));

    // ── Tile select ──────────────────────────────────────────────────────
    r.register_pure(&NamedCmd("move-tile-cursor"), |args| {
        require_args("move-tile-cursor", args, 1)?;
        let delta = args[0].parse::<i32>().map_err(|e| e.to_string())?;
        Ok(Box::new(MoveTileCursor(delta)))
    });
    r.register_nullary(|| Box::new(CycleAxisForTile));
    r.register_pure(&NamedCmd("set-axis-for-tile"), |args| {
        require_args("set-axis-for-tile", args, 1)?;
        let axis = parse_axis(&args[0])?;
        Ok(Box::new(SetAxisForTile(axis)))
    });

    // ── Grid operations ──────────────────────────────────────────────────
    r.register_nullary(|| {
        Box::new(ToggleGroupUnderCursor)
    });
    r.register_nullary(|| {
        Box::new(ToggleColGroupUnderCursor)
    });
    r.register_nullary(|| Box::new(HideSelectedRowItem));

    // ── Text buffer ──────────────────────────────────────────────────────
    r.register_pure(&NamedCmd("append-char"), |args| {
        require_args("append-char", args, 1)?;
        Ok(Box::new(AppendChar {
            buffer: args[0].clone(),
        }))
    });
    r.register_pure(&NamedCmd("pop-char"), |args| {
        require_args("pop-char", args, 1)?;
        Ok(Box::new(PopChar {
            buffer: args[0].clone(),
        }))
    });
    r.register_nullary(|| Box::new(CommandModeBackspace));

    // ── Commit ───────────────────────────────────────────────────────────
    r.register(
        &CommitCellEdit { key: CellKey::new(vec![]), value: String::new() },
        |args| {
            // parse: commit-cell-edit <value> <Cat/Item>...
            if args.len() < 2 {
                return Err("commit-cell-edit requires a value and coords".into());
            }
            Ok(Box::new(CommitCellEdit {
                key: parse_cell_key_from_args(&args[1..]),
                value: args[0].clone(),
            }))
        },
        |_args, ctx| {
            let key = ctx.cell_key.clone().ok_or("no cell at cursor")?;
            let value = read_buffer(ctx, "edit");
            Ok(Box::new(CommitCellEdit { key, value }))
        },
    );
    r.register_nullary(|| Box::new(CommitFormula));
    r.register_nullary(|| Box::new(CommitCategoryAdd));
    r.register_nullary(|| Box::new(CommitItemAdd));
    r.register_nullary(|| Box::new(CommitExport));
    r.register_nullary(|| Box::new(ExecuteCommand));

    // ── Wizard ───────────────────────────────────────────────────────────
    r.register_nullary(|| Box::new(HandleWizardKey));

    r
}

fn parse_panel(s: &str) -> Result<Panel, String> {
    match s {
        "formula" => Ok(Panel::Formula),
        "category" => Ok(Panel::Category),
        "view" => Ok(Panel::View),
        other => Err(format!("Unknown panel: {other}")),
    }
}

fn parse_axis(s: &str) -> Result<Axis, String> {
    match s.to_lowercase().as_str() {
        "row" => Ok(Axis::Row),
        "column" | "col" => Ok(Axis::Column),
        "page" => Ok(Axis::Page),
        "none" => Ok(Axis::None),
        other => Err(format!("Unknown axis: {other}")),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::model::cell::{CellKey, CellValue};
    use crate::model::Model;

    static EMPTY_BUFFERS: std::sync::LazyLock<HashMap<String, String>> =
        std::sync::LazyLock::new(HashMap::new);

    fn make_ctx(model: &Model) -> CmdContext<'_> {
        let view = model.active_view();
        let layout = GridLayout::new(model, view);
        let (sr, sc) = view.selected;
        CmdContext {
            model,
            mode: &AppMode::Normal,
            selected: view.selected,
            row_offset: view.row_offset,
            col_offset: view.col_offset,
            search_query: "",
            yanked: &None,
            dirty: false,
            search_mode: false,
            formula_panel_open: false,
            category_panel_open: false,
            view_panel_open: false,
            formula_cursor: 0,
            cat_panel_cursor: 0,
            view_panel_cursor: 0,
            tile_cat_idx: 0,
            buffers: &EMPTY_BUFFERS,
            none_cats: layout.none_cats.clone(),
            view_back_stack: Vec::new(),
            view_forward_stack: Vec::new(),
            cell_key: layout.cell_key(sr, sc),
            row_count: layout.row_count(),
            col_count: layout.col_count(),
            key_code: KeyCode::Null,
        }
    }

    fn two_cat_model() -> Model {
        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("Type").unwrap().add_item("Clothing");
        m.category_mut("Month").unwrap().add_item("Jan");
        m.category_mut("Month").unwrap().add_item("Feb");
        m
    }

    #[test]
    fn move_selection_down_produces_set_selected() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = MoveSelection {
            dr: 1,
            dc: 0,
            cursor: CursorState::from_ctx(&ctx),
        };
        let effects = cmd.execute(&ctx);
        // Should produce at least SetSelected
        assert!(!effects.is_empty());
    }

    #[test]
    fn move_selection_clamps_to_bounds() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        // Try to move way past the end
        let cmd = MoveSelection {
            dr: 100,
            dc: 100,
            cursor: CursorState::from_ctx(&ctx),
        };
        let effects = cmd.execute(&ctx);
        assert!(!effects.is_empty());
    }

    #[test]
    fn quit_when_dirty_shows_warning() {
        let m = two_cat_model();
        let mut bufs = HashMap::new();
        bufs.insert("command".to_string(), "q".to_string());
        let mut ctx = make_ctx(&m);
        ctx.dirty = true;
        ctx.buffers = &bufs;
        let cmd = ExecuteCommand;
        let effects = cmd.execute(&ctx);
        let dbg = format!("{:?}", effects);
        assert!(dbg.contains("SetStatus"), "Expected SetStatus, got: {dbg}");
    }

    #[test]
    fn quit_when_clean_produces_quit_mode() {
        let m = two_cat_model();
        let mut bufs = HashMap::new();
        bufs.insert("command".to_string(), "q".to_string());
        let mut ctx = make_ctx(&m);
        ctx.buffers = &bufs;
        let cmd = ExecuteCommand;
        let effects = cmd.execute(&ctx);
        let dbg = format!("{:?}", effects);
        assert!(
            dbg.contains("ChangeMode"),
            "Expected ChangeMode, got: {dbg}"
        );
    }

    #[test]
    fn clear_selected_cell_produces_clear_and_dirty() {
        let mut m = two_cat_model();
        let key = CellKey::new(vec![
            ("Type".to_string(), "Food".to_string()),
            ("Month".to_string(), "Jan".to_string()),
        ]);
        m.set_cell(key, CellValue::Number(42.0));
        let ctx = make_ctx(&m);
        let cmd = ClearCellCommand {
            key: ctx.cell_key.clone().unwrap(),
        };
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 2); // ClearCell + MarkDirty
    }

    #[test]
    fn yank_cell_produces_set_yanked() {
        let mut m = two_cat_model();
        let key = CellKey::new(vec![
            ("Type".to_string(), "Food".to_string()),
            ("Month".to_string(), "Jan".to_string()),
        ]);
        m.set_cell(key, CellValue::Number(99.0));
        let ctx = make_ctx(&m);
        let cmd = YankCell {
            key: ctx.cell_key.clone().unwrap(),
        };
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 2); // SetYanked + SetStatus
    }

    #[test]
    fn toggle_panel_and_focus_opens_and_enters_mode() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = TogglePanelAndFocus {
            panel: effect::Panel::Formula,
            currently_open: false,
        };
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 2); // SetPanelOpen + ChangeMode
        let dbg = format!("{:?}", effects[1]);
        assert!(
            dbg.contains("FormulaPanel"),
            "Expected FormulaPanel mode, got: {dbg}"
        );
    }

    #[test]
    fn toggle_panel_and_focus_closes_when_open() {
        let m = two_cat_model();
        let mut ctx = make_ctx(&m);
        ctx.formula_panel_open = true;
        let cmd = TogglePanelAndFocus {
            panel: effect::Panel::Formula,
            currently_open: true,
        };
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 1); // SetPanelOpen only, no mode change
    }

    #[test]
    fn enter_advance_moves_down() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = EnterAdvance {
            cursor: CursorState::from_ctx(&ctx),
        };
        let effects = cmd.execute(&ctx);
        assert!(!effects.is_empty());
        let dbg = format!("{:?}", effects[0]);
        assert!(
            dbg.contains("SetSelected(1, 0)"),
            "Expected row 1, got: {dbg}"
        );
    }

    #[test]
    fn search_navigate_with_empty_query_returns_nothing() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = SearchNavigate(true);
        let effects = cmd.execute(&ctx);
        assert!(effects.is_empty());
    }

    #[test]
    fn enter_edit_mode_produces_editing_mode() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = EnterEditMode {
            initial_value: String::new(),
        };
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 2); // SetBuffer + ChangeMode
        let dbg = format!("{:?}", effects[1]);
        assert!(dbg.contains("Editing"), "Expected Editing mode, got: {dbg}");
    }

    #[test]
    fn enter_tile_select_with_categories() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = EnterTileSelect;
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 2); // SetTileCatIdx + ChangeMode
        let dbg = format!("{:?}", effects[1]);
        assert!(
            dbg.contains("TileSelect"),
            "Expected TileSelect mode, got: {dbg}"
        );
    }

    #[test]
    fn enter_tile_select_no_categories() {
        let m = Model::new("Empty");
        let ctx = make_ctx(&m);
        let cmd = EnterTileSelect;
        let effects = cmd.execute(&ctx);
        assert!(effects.is_empty());
    }

    #[test]
    fn toggle_group_under_cursor_returns_empty_without_groups() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = ToggleGroupUnderCursor;
        let effects = cmd.execute(&ctx);
        // No groups defined, so nothing to toggle
        assert!(effects.is_empty());
    }

    #[test]
    fn search_or_category_add_without_query_opens_category_add() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = SearchOrCategoryAdd;
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 2); // SetPanelOpen + ChangeMode
        let dbg = format!("{:?}", effects[1]);
        assert!(
            dbg.contains("CategoryAdd"),
            "Expected CategoryAdd, got: {dbg}"
        );
    }

    #[test]
    fn cycle_panel_focus_with_no_panels_open() {
        let m = two_cat_model();
        let ctx = make_ctx(&m);
        let cmd = CyclePanelFocus {
            formula_open: false,
            category_open: false,
            view_open: false,
        };
        let effects = cmd.execute(&ctx);
        assert!(effects.is_empty());
    }

    #[test]
    fn cycle_panel_focus_with_formula_panel_open() {
        let m = two_cat_model();
        let mut ctx = make_ctx(&m);
        ctx.formula_panel_open = true;
        let cmd = CyclePanelFocus {
            formula_open: true,
            category_open: false,
            view_open: false,
        };
        let effects = cmd.execute(&ctx);
        assert_eq!(effects.len(), 1);
        let dbg = format!("{:?}", effects[0]);
        assert!(
            dbg.contains("FormulaPanel"),
            "Expected FormulaPanel, got: {dbg}"
        );
    }
}