chat_composer.rs

use crossterm::event::KeyCode;
use crossterm::event::KeyEvent;
use crossterm::event::KeyEventKind;
use crossterm::event::KeyModifiers;
use ratatui::buffer::Buffer;
use ratatui::layout::Constraint;
use ratatui::layout::Layout;
use ratatui::layout::Margin;
use ratatui::layout::Rect;
use ratatui::style::Style;
use ratatui::style::Stylize;
use ratatui::text::Line;
use ratatui::text::Span;
use ratatui::widgets::Block;
use ratatui::widgets::StatefulWidgetRef;
use ratatui::widgets::WidgetRef;

use super::chat_composer_history::ChatComposerHistory;
use super::command_popup::CommandItem;
use super::command_popup::CommandPopup;
use super::file_search_popup::FileSearchPopup;
use super::footer::FooterMode;
use super::footer::FooterProps;
use super::footer::esc_hint_mode;
use super::footer::footer_height;
use super::footer::render_footer;
use super::footer::reset_mode_after_activity;
use super::footer::toggle_shortcut_mode;
use super::paste_burst::CharDecision;
use super::paste_burst::PasteBurst;
use crate::bottom_pane::paste_burst::FlushResult;
use crate::bottom_pane::prompt_args::expand_custom_prompt;
use crate::bottom_pane::prompt_args::expand_if_numeric_with_positional_args;
use crate::bottom_pane::prompt_args::parse_slash_name;
use crate::bottom_pane::prompt_args::prompt_argument_names;
use crate::bottom_pane::prompt_args::prompt_command_with_arg_placeholders;
use crate::bottom_pane::prompt_args::prompt_has_numeric_placeholders;
use crate::slash_command::SlashCommand;
use crate::slash_command::built_in_slash_commands;
use crate::style::user_message_style;
use codex_protocol::custom_prompts::CustomPrompt;
use codex_protocol::custom_prompts::PROMPTS_CMD_PREFIX;

use crate::app_event::AppEvent;
use crate::app_event_sender::AppEventSender;
use crate::bottom_pane::textarea::TextArea;
use crate::bottom_pane::textarea::TextAreaState;
use crate::clipboard_paste::normalize_pasted_path;
use crate::clipboard_paste::pasted_image_format;
use crate::history_cell;
use crate::ui_consts::LIVE_PREFIX_COLS;
use codex_file_search::FileMatch;
use std::cell::RefCell;
use std::collections::HashMap;
use std::path::Path;
use std::path::PathBuf;
use std::time::Duration;
use std::time::Instant;

/// If the pasted content exceeds this number of characters, replace it with a
/// placeholder in the UI.
const LARGE_PASTE_CHAR_THRESHOLD: usize = 1000;

/// Result returned when the user interacts with the text area.
#[derive(Debug, PartialEq)]
pub enum InputResult {
    Submitted(String),
    Command(SlashCommand),
    None,
}

#[derive(Clone, Debug, PartialEq)]
struct AttachedImage {
    placeholder: String,
    path: PathBuf,
}

enum PromptSelectionMode {
    Completion,
    Submit,
}

enum PromptSelectionAction {
    Insert { text: String, cursor: Option<usize> },
    Submit { text: String },
}

pub(crate) struct ChatComposer {
    textarea: TextArea,
    textarea_state: RefCell<TextAreaState>,
    active_popup: ActivePopup,
    app_event_tx: AppEventSender,
    history: ChatComposerHistory,
    ctrl_c_quit_hint: bool,
    esc_backtrack_hint: bool,
    use_shift_enter_hint: bool,
    dismissed_file_popup_token: Option<String>,
    current_file_query: Option<String>,
    pending_pastes: Vec<(String, String)>,
    has_focus: bool,
    attached_images: Vec<AttachedImage>,
    placeholder_text: String,
    is_task_running: bool,
    // Non-bracketed paste burst tracker.
    paste_burst: PasteBurst,
    // When true, disables paste-burst logic and inserts characters immediately.
    disable_paste_burst: bool,
    custom_prompts: Vec<CustomPrompt>,
    footer_mode: FooterMode,
    footer_hint_override: Option<Vec<(String, String)>>,
    context_window_percent: Option<i64>,
}

/// Popup state – at most one can be visible at any time.
enum ActivePopup {
    None,
    Command(CommandPopup),
    File(FileSearchPopup),
}

const FOOTER_SPACING_HEIGHT: u16 = 0;

impl ChatComposer {
    pub fn new(
        has_input_focus: bool,
        app_event_tx: AppEventSender,
        enhanced_keys_supported: bool,
        placeholder_text: String,
        disable_paste_burst: bool,
    ) -> Self {
        let use_shift_enter_hint = enhanced_keys_supported;

        let mut this = Self {
            textarea: TextArea::new(),
            textarea_state: RefCell::new(TextAreaState::default()),
            active_popup: ActivePopup::None,
            app_event_tx,
            history: ChatComposerHistory::new(),
            ctrl_c_quit_hint: false,
            esc_backtrack_hint: false,
            use_shift_enter_hint,
            dismissed_file_popup_token: None,
            current_file_query: None,
            pending_pastes: Vec::new(),
            has_focus: has_input_focus,
            attached_images: Vec::new(),
            placeholder_text,
            is_task_running: false,
            paste_burst: PasteBurst::default(),
            disable_paste_burst: false,
            custom_prompts: Vec::new(),
            footer_mode: FooterMode::ShortcutSummary,
            footer_hint_override: None,
            context_window_percent: None,
        };
        // Apply configuration via the setter to keep side-effects centralized.
        this.set_disable_paste_burst(disable_paste_burst);
        this
    }

    pub fn desired_height(&self, width: u16) -> u16 {
        let footer_props = self.footer_props();
        let footer_hint_height = self
            .custom_footer_height()
            .unwrap_or_else(|| footer_height(footer_props));
        let footer_spacing = Self::footer_spacing(footer_hint_height);
        let footer_total_height = footer_hint_height + footer_spacing;
        const COLS_WITH_MARGIN: u16 = LIVE_PREFIX_COLS + 1;
        self.textarea
            .desired_height(width.saturating_sub(COLS_WITH_MARGIN))
            + 2
            + match &self.active_popup {
                ActivePopup::None => footer_total_height,
                ActivePopup::Command(c) => c.calculate_required_height(width),
                ActivePopup::File(c) => c.calculate_required_height(),
            }
    }

    fn layout_areas(&self, area: Rect) -> [Rect; 3] {
        let footer_props = self.footer_props();
        let footer_hint_height = self
            .custom_footer_height()
            .unwrap_or_else(|| footer_height(footer_props));
        let footer_spacing = Self::footer_spacing(footer_hint_height);
        let footer_total_height = footer_hint_height + footer_spacing;
        let popup_constraint = match &self.active_popup {
            ActivePopup::Command(popup) => {
                Constraint::Max(popup.calculate_required_height(area.width))
            }
            ActivePopup::File(popup) => Constraint::Max(popup.calculate_required_height()),
            ActivePopup::None => Constraint::Max(footer_total_height),
        };
        let mut area = area;
        if area.height > 1 {
            area.height -= 1;
            area.y += 1;
        }
        let [composer_rect, popup_rect] =
            Layout::vertical([Constraint::Min(1), popup_constraint]).areas(area);
        let mut textarea_rect = composer_rect;
        textarea_rect.width = textarea_rect.width.saturating_sub(
            LIVE_PREFIX_COLS + 1, /* keep a one-column right margin for wrapping */
        );
        textarea_rect.x = textarea_rect.x.saturating_add(LIVE_PREFIX_COLS);
        [composer_rect, textarea_rect, popup_rect]
    }

    fn footer_spacing(footer_hint_height: u16) -> u16 {
        if footer_hint_height == 0 {
            0
        } else {
            FOOTER_SPACING_HEIGHT
        }
    }

    pub fn cursor_pos(&self, area: Rect) -> Option<(u16, u16)> {
        let [_, textarea_rect, _] = self.layout_areas(area);
        let state = *self.textarea_state.borrow();
        self.textarea.cursor_pos_with_state(textarea_rect, state)
    }

    /// Returns true if the composer currently contains no user input.
    pub(crate) fn is_empty(&self) -> bool {
        self.textarea.is_empty()
    }

    /// Record the history metadata advertised by `SessionConfiguredEvent` so
    /// that the composer can navigate cross-session history.
    pub(crate) fn set_history_metadata(&mut self, log_id: u64, entry_count: usize) {
        self.history.set_metadata(log_id, entry_count);
    }

    /// Integrate an asynchronous response to an on-demand history lookup. If
    /// the entry is present and the offset matches the current cursor we
    /// immediately populate the textarea.
    pub(crate) fn on_history_entry_response(
        &mut self,
        log_id: u64,
        offset: usize,
        entry: Option<String>,
    ) -> bool {
        let Some(text) = self.history.on_entry_response(log_id, offset, entry) else {
            return false;
        };
        self.set_text_content(text);
        true
    }

    pub fn handle_paste(&mut self, pasted: String) -> bool {
        let char_count = pasted.chars().count();
        if char_count > LARGE_PASTE_CHAR_THRESHOLD {
            let placeholder = format!("[Pasted Content {char_count} chars]");
            self.textarea.insert_element(&placeholder);
            self.pending_pastes.push((placeholder, pasted));
        } else if char_count > 1 && self.handle_paste_image_path(pasted.clone()) {
            self.textarea.insert_str(" ");
        } else {
            self.textarea.insert_str(&pasted);
        }
        // Explicit paste events should not trigger Enter suppression.
        self.paste_burst.clear_after_explicit_paste();
        // Keep popup sync consistent with key handling: prefer slash popup; only
        // sync file popup when slash popup is NOT active.
        self.sync_command_popup();
        if matches!(self.active_popup, ActivePopup::Command(_)) {
            self.dismissed_file_popup_token = None;
        } else {
            self.sync_file_search_popup();
        }
        true
    }

    pub fn handle_paste_image_path(&mut self, pasted: String) -> bool {
        let Some(path_buf) = normalize_pasted_path(&pasted) else {
            return false;
        };

        match image::image_dimensions(&path_buf) {
            Ok((w, h)) => {
                tracing::info!("OK: {pasted}");
                let format_label = pasted_image_format(&path_buf).label();
                self.attach_image(path_buf, w, h, format_label);
                true
            }
            Err(err) => {
                tracing::info!("ERR: {err}");
                false
            }
        }
    }

    pub(crate) fn set_disable_paste_burst(&mut self, disabled: bool) {
        let was_disabled = self.disable_paste_burst;
        self.disable_paste_burst = disabled;
        if disabled && !was_disabled {
            self.paste_burst.clear_window_after_non_char();
        }
    }

    /// Override the footer hint items displayed beneath the composer. Passing
    /// `None` restores the default shortcut footer.
    pub(crate) fn set_footer_hint_override(&mut self, items: Option<Vec<(String, String)>>) {
        self.footer_hint_override = items;
    }

    /// Replace the entire composer content with `text` and reset cursor.
    pub(crate) fn set_text_content(&mut self, text: String) {
        // Clear any existing content, placeholders, and attachments first.
        self.textarea.set_text("");
        self.pending_pastes.clear();
        self.attached_images.clear();
        self.textarea.set_text(&text);
        self.textarea.set_cursor(0);
        self.sync_command_popup();
        self.sync_file_search_popup();
    }

    pub(crate) fn clear_for_ctrl_c(&mut self) -> Option<String> {
        if self.is_empty() {
            return None;
        }
        let previous = self.current_text();
        self.set_text_content(String::new());
        self.history.reset_navigation();
        self.history.record_local_submission(&previous);
        Some(previous)
    }

    /// Get the current composer text.
    pub(crate) fn current_text(&self) -> String {
        self.textarea.text().to_string()
    }

    /// Attempt to start a burst by retro-capturing recent chars before the cursor.
    pub fn attach_image(&mut self, path: PathBuf, width: u32, height: u32, _format_label: &str) {
        let file_label = path
            .file_name()
            .map(|name| name.to_string_lossy().into_owned())
            .unwrap_or_else(|| "image".to_string());
        let placeholder = format!("[{file_label} {width}x{height}]");
        // Insert as an element to match large paste placeholder behavior:
        // styled distinctly and treated atomically for cursor/mutations.
        self.textarea.insert_element(&placeholder);
        self.attached_images
            .push(AttachedImage { placeholder, path });
    }

    pub fn take_recent_submission_images(&mut self) -> Vec<PathBuf> {
        let images = std::mem::take(&mut self.attached_images);
        images.into_iter().map(|img| img.path).collect()
    }

    pub(crate) fn flush_paste_burst_if_due(&mut self) -> bool {
        self.handle_paste_burst_flush(Instant::now())
    }

    pub(crate) fn is_in_paste_burst(&self) -> bool {
        self.paste_burst.is_active()
    }

    pub(crate) fn recommended_paste_flush_delay() -> Duration {
        PasteBurst::recommended_flush_delay()
    }

    /// Integrate results from an asynchronous file search.
    pub(crate) fn on_file_search_result(&mut self, query: String, matches: Vec<FileMatch>) {
        // Only apply if user is still editing a token starting with `query`.
        let current_opt = Self::current_at_token(&self.textarea);
        let Some(current_token) = current_opt else {
            return;
        };

        if !current_token.starts_with(&query) {
            return;
        }

        if let ActivePopup::File(popup) = &mut self.active_popup {
            popup.set_matches(&query, matches);
        }
    }

    pub fn set_ctrl_c_quit_hint(&mut self, show: bool, has_focus: bool) {
        self.ctrl_c_quit_hint = show;
        if show {
            self.footer_mode = FooterMode::CtrlCReminder;
        } else {
            self.footer_mode = reset_mode_after_activity(self.footer_mode);
        }
        self.set_has_focus(has_focus);
    }

    pub(crate) fn insert_str(&mut self, text: &str) {
        self.textarea.insert_str(text);
        self.sync_command_popup();
        self.sync_file_search_popup();
    }

    /// Handle a key event coming from the main UI.
    pub fn handle_key_event(&mut self, key_event: KeyEvent) -> (InputResult, bool) {
        let result = match &mut self.active_popup {
            ActivePopup::Command(_) => self.handle_key_event_with_slash_popup(key_event),
            ActivePopup::File(_) => self.handle_key_event_with_file_popup(key_event),
            ActivePopup::None => self.handle_key_event_without_popup(key_event),
        };

        // Update (or hide/show) popup after processing the key.
        self.sync_command_popup();
        if matches!(self.active_popup, ActivePopup::Command(_)) {
            self.dismissed_file_popup_token = None;
        } else {
            self.sync_file_search_popup();
        }

        result
    }

    /// Return true if either the slash-command popup or the file-search popup is active.
    pub(crate) fn popup_active(&self) -> bool {
        !matches!(self.active_popup, ActivePopup::None)
    }

    /// Handle key event when the slash-command popup is visible.
    fn handle_key_event_with_slash_popup(&mut self, key_event: KeyEvent) -> (InputResult, bool) {
        if self.handle_shortcut_overlay_key(&key_event) {
            return (InputResult::None, true);
        }
        if key_event.code == KeyCode::Esc {
            let next_mode = esc_hint_mode(self.footer_mode, self.is_task_running);
            if next_mode != self.footer_mode {
                self.footer_mode = next_mode;
                return (InputResult::None, true);
            }
        } else {
            self.footer_mode = reset_mode_after_activity(self.footer_mode);
        }
        let ActivePopup::Command(popup) = &mut self.active_popup else {
            unreachable!();
        };

        match key_event {
            KeyEvent {
                code: KeyCode::Up, ..
            } => {
                popup.move_up();
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Down,
                ..
            } => {
                popup.move_down();
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Esc, ..
            } => {
                // Dismiss the slash popup; keep the current input untouched.
                self.active_popup = ActivePopup::None;
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Tab, ..
            } => {
                // Ensure popup filtering/selection reflects the latest composer text
                // before applying completion.
                let first_line = self.textarea.text().lines().next().unwrap_or("");
                popup.on_composer_text_change(first_line.to_string());
                if let Some(sel) = popup.selected_item() {
                    let mut cursor_target: Option<usize> = None;
                    match sel {
                        CommandItem::Builtin(cmd) => {
                            let starts_with_cmd = first_line
                                .trim_start()
                                .starts_with(&format!("/{}", cmd.command()));
                            if !starts_with_cmd {
                                self.textarea.set_text(&format!("/{} ", cmd.command()));
                            }
                            if !self.textarea.text().is_empty() {
                                cursor_target = Some(self.textarea.text().len());
                            }
                        }
                        CommandItem::UserPrompt(idx) => {
                            if let Some(prompt) = popup.prompt(idx) {
                                match prompt_selection_action(
                                    prompt,
                                    first_line,
                                    PromptSelectionMode::Completion,
                                ) {
                                    PromptSelectionAction::Insert { text, cursor } => {
                                        let target = cursor.unwrap_or(text.len());
                                        self.textarea.set_text(&text);
                                        cursor_target = Some(target);
                                    }
                                    PromptSelectionAction::Submit { .. } => {}
                                }
                            }
                        }
                    }
                    if let Some(pos) = cursor_target {
                        self.textarea.set_cursor(pos);
                    }
                }
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Enter,
                modifiers: KeyModifiers::NONE,
                ..
            } => {
                // If the current line starts with a custom prompt name and includes
                // positional args for a numeric-style template, expand and submit
                // immediately regardless of the popup selection.
                let first_line = self.textarea.text().lines().next().unwrap_or("");
                if let Some((name, _rest)) = parse_slash_name(first_line)
                    && let Some(prompt_name) = name.strip_prefix(&format!("{PROMPTS_CMD_PREFIX}:"))
                    && let Some(prompt) = self.custom_prompts.iter().find(|p| p.name == prompt_name)
                    && let Some(expanded) =
                        expand_if_numeric_with_positional_args(prompt, first_line)
                {
                    self.textarea.set_text("");
                    return (InputResult::Submitted(expanded), true);
                }

                if let Some(sel) = popup.selected_item() {
                    match sel {
                        CommandItem::Builtin(cmd) => {
                            self.textarea.set_text("");
                            return (InputResult::Command(cmd), true);
                        }
                        CommandItem::UserPrompt(idx) => {
                            if let Some(prompt) = popup.prompt(idx) {
                                match prompt_selection_action(
                                    prompt,
                                    first_line,
                                    PromptSelectionMode::Submit,
                                ) {
                                    PromptSelectionAction::Submit { text } => {
                                        self.textarea.set_text("");
                                        return (InputResult::Submitted(text), true);
                                    }
                                    PromptSelectionAction::Insert { text, cursor } => {
                                        let target = cursor.unwrap_or(text.len());
                                        self.textarea.set_text(&text);
                                        self.textarea.set_cursor(target);
                                        return (InputResult::None, true);
                                    }
                                }
                            }
                            return (InputResult::None, true);
                        }
                    }
                }
                // Fallback to default newline handling if no command selected.
                self.handle_key_event_without_popup(key_event)
            }
            input => self.handle_input_basic(input),
        }
    }

    #[inline]
    fn clamp_to_char_boundary(text: &str, pos: usize) -> usize {
        let mut p = pos.min(text.len());
        if p < text.len() && !text.is_char_boundary(p) {
            p = text
                .char_indices()
                .map(|(i, _)| i)
                .take_while(|&i| i <= p)
                .last()
                .unwrap_or(0);
        }
        p
    }

    #[inline]
    fn handle_non_ascii_char(&mut self, input: KeyEvent) -> (InputResult, bool) {
        if let Some(pasted) = self.paste_burst.flush_before_modified_input() {
            self.handle_paste(pasted);
        }
        self.textarea.input(input);
        let text_after = self.textarea.text();
        self.pending_pastes
            .retain(|(placeholder, _)| text_after.contains(placeholder));
        (InputResult::None, true)
    }

    /// Handle key events when file search popup is visible.
    fn handle_key_event_with_file_popup(&mut self, key_event: KeyEvent) -> (InputResult, bool) {
        if self.handle_shortcut_overlay_key(&key_event) {
            return (InputResult::None, true);
        }
        if key_event.code == KeyCode::Esc {
            let next_mode = esc_hint_mode(self.footer_mode, self.is_task_running);
            if next_mode != self.footer_mode {
                self.footer_mode = next_mode;
                return (InputResult::None, true);
            }
        } else {
            self.footer_mode = reset_mode_after_activity(self.footer_mode);
        }
        let ActivePopup::File(popup) = &mut self.active_popup else {
            unreachable!();
        };

        match key_event {
            KeyEvent {
                code: KeyCode::Up, ..
            } => {
                popup.move_up();
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Down,
                ..
            } => {
                popup.move_down();
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Esc, ..
            } => {
                // Hide popup without modifying text, remember token to avoid immediate reopen.
                if let Some(tok) = Self::current_at_token(&self.textarea) {
                    self.dismissed_file_popup_token = Some(tok);
                }
                self.active_popup = ActivePopup::None;
                (InputResult::None, true)
            }
            KeyEvent {
                code: KeyCode::Tab, ..
            }
            | KeyEvent {
                code: KeyCode::Enter,
                modifiers: KeyModifiers::NONE,
                ..
            } => {
                let Some(sel) = popup.selected_match() else {
                    self.active_popup = ActivePopup::None;
                    return (InputResult::None, true);
                };

                let sel_path = sel.to_string();
                // If selected path looks like an image (png/jpeg), attach as image instead of inserting text.
                let is_image = Self::is_image_path(&sel_path);
                if is_image {
                    // Determine dimensions; if that fails fall back to normal path insertion.
                    let path_buf = PathBuf::from(&sel_path);
                    if let Ok((w, h)) = image::image_dimensions(&path_buf) {
                        // Remove the current @token (mirror logic from insert_selected_path without inserting text)
                        // using the flat text and byte-offset cursor API.
                        let cursor_offset = self.textarea.cursor();
                        let text = self.textarea.text();
                        // Clamp to a valid char boundary to avoid panics when slicing.
                        let safe_cursor = Self::clamp_to_char_boundary(text, cursor_offset);
                        let before_cursor = &text[..safe_cursor];
                        let after_cursor = &text[safe_cursor..];

                        // Determine token boundaries in the full text.
                        let start_idx = before_cursor
                            .char_indices()
                            .rfind(|(_, c)| c.is_whitespace())
                            .map(|(idx, c)| idx + c.len_utf8())
                            .unwrap_or(0);
                        let end_rel_idx = after_cursor
                            .char_indices()
                            .find(|(_, c)| c.is_whitespace())
                            .map(|(idx, _)| idx)
                            .unwrap_or(after_cursor.len());
                        let end_idx = safe_cursor + end_rel_idx;

                        self.textarea.replace_range(start_idx..end_idx, "");
                        self.textarea.set_cursor(start_idx);

                        let format_label = match Path::new(&sel_path)
                            .extension()
                            .and_then(|e| e.to_str())
                            .map(str::to_ascii_lowercase)
                        {
                            Some(ext) if ext == "png" => "PNG",
                            Some(ext) if ext == "jpg" || ext == "jpeg" => "JPEG",
                            _ => "IMG",
                        };
                        self.attach_image(path_buf, w, h, format_label);
                        // Add a trailing space to keep typing fluid.
                        self.textarea.insert_str(" ");
                    } else {
                        // Fallback to plain path insertion if metadata read fails.
                        self.insert_selected_path(&sel_path);
                    }
                } else {
                    // Non-image: inserting file path.
                    self.insert_selected_path(&sel_path);
                }
                // No selection: treat Enter as closing the popup/session.
                self.active_popup = ActivePopup::None;
                (InputResult::None, true)
            }
            input => self.handle_input_basic(input),
        }
    }

    fn is_image_path(path: &str) -> bool {
        let lower = path.to_ascii_lowercase();
        lower.ends_with(".png") || lower.ends_with(".jpg") || lower.ends_with(".jpeg")
    }

    /// Extract the `@token` that the cursor is currently positioned on, if any.
    ///
    /// The returned string **does not** include the leading `@`.
    ///
    /// Behavior:
    /// - The cursor may be anywhere *inside* the token (including on the
    ///   leading `@`). It does **not** need to be at the end of the line.
    /// - A token is delimited by ASCII whitespace (space, tab, newline).
    /// - If the token under the cursor starts with `@`, that token is
    ///   returned without the leading `@`. This includes the case where the
    ///   token is just "@" (empty query), which is used to trigger a UI hint
    fn current_at_token(textarea: &TextArea) -> Option<String> {
        let cursor_offset = textarea.cursor();
        let text = textarea.text();

        // Adjust the provided byte offset to the nearest valid char boundary at or before it.
        let mut safe_cursor = cursor_offset.min(text.len());
        // If we're not on a char boundary, move back to the start of the current char.
        if safe_cursor < text.len() && !text.is_char_boundary(safe_cursor) {
            // Find the last valid boundary <= cursor_offset.
            safe_cursor = text
                .char_indices()
                .map(|(i, _)| i)
                .take_while(|&i| i <= cursor_offset)
                .last()
                .unwrap_or(0);
        }

        // Split the line around the (now safe) cursor position.
        let before_cursor = &text[..safe_cursor];
        let after_cursor = &text[safe_cursor..];

        // Detect whether we're on whitespace at the cursor boundary.
        let at_whitespace = if safe_cursor < text.len() {
            text[safe_cursor..]
                .chars()
                .next()
                .map(char::is_whitespace)
                .unwrap_or(false)
        } else {
            false
        };

        // Left candidate: token containing the cursor position.
        let start_left = before_cursor
            .char_indices()
            .rfind(|(_, c)| c.is_whitespace())
            .map(|(idx, c)| idx + c.len_utf8())
            .unwrap_or(0);
        let end_left_rel = after_cursor
            .char_indices()
            .find(|(_, c)| c.is_whitespace())
            .map(|(idx, _)| idx)
            .unwrap_or(after_cursor.len());
        let end_left = safe_cursor + end_left_rel;
        let token_left = if start_left < end_left {
            Some(&text[start_left..end_left])
        } else {
            None
        };

        // Right candidate: token immediately after any whitespace from the cursor.
        let ws_len_right: usize = after_cursor
            .chars()
            .take_while(|c| c.is_whitespace())
            .map(char::len_utf8)
            .sum();
        let start_right = safe_cursor + ws_len_right;
        let end_right_rel = text[start_right..]
            .char_indices()
            .find(|(_, c)| c.is_whitespace())
            .map(|(idx, _)| idx)
            .unwrap_or(text.len() - start_right);
        let end_right = start_right + end_right_rel;
        let token_right = if start_right < end_right {
            Some(&text[start_right..end_right])
        } else {
            None
        };

        let left_at = token_left
            .filter(|t| t.starts_with('@'))
            .map(|t| t[1..].to_string());
        let right_at = token_right
            .filter(|t| t.starts_with('@'))
            .map(|t| t[1..].to_string());

        if at_whitespace {
            if right_at.is_some() {
                return right_at;
            }
            if token_left.is_some_and(|t| t == "@") {
                return None;
            }
            return left_at;
        }
        if after_cursor.starts_with('@') {
            return right_at.or(left_at);
        }
        left_at.or(right_at)
    }

    /// Replace the active `@token` (the one under the cursor) with `path`.
    ///
    /// The algorithm mirrors `current_at_token` so replacement works no matter
    /// where the cursor is within the token and regardless of how many
    /// `@tokens` exist in the line.
    fn insert_selected_path(&mut self, path: &str) {
        let cursor_offset = self.textarea.cursor();
        let text = self.textarea.text();
        // Clamp to a valid char boundary to avoid panics when slicing.
        let safe_cursor = Self::clamp_to_char_boundary(text, cursor_offset);

        let before_cursor = &text[..safe_cursor];
        let after_cursor = &text[safe_cursor..];

        // Determine token boundaries.
        let start_idx = before_cursor
            .char_indices()
            .rfind(|(_, c)| c.is_whitespace())
            .map(|(idx, c)| idx + c.len_utf8())
            .unwrap_or(0);

        let end_rel_idx = after_cursor
            .char_indices()
            .find(|(_, c)| c.is_whitespace())
            .map(|(idx, _)| idx)
            .unwrap_or(after_cursor.len());
        let end_idx = safe_cursor + end_rel_idx;

        // If the path contains whitespace, wrap it in double quotes so the
        // local prompt arg parser treats it as a single argument. Avoid adding
        // quotes when the path already contains one to keep behavior simple.
        let needs_quotes = path.chars().any(char::is_whitespace);
        let inserted = if needs_quotes && !path.contains('"') {
            format!("\"{path}\"")
        } else {
            path.to_string()
        };

        // Replace the slice `[start_idx, end_idx)` with the chosen path and a trailing space.
        let mut new_text =
            String::with_capacity(text.len() - (end_idx - start_idx) + inserted.len() + 1);
        new_text.push_str(&text[..start_idx]);
        new_text.push_str(&inserted);
        new_text.push(' ');
        new_text.push_str(&text[end_idx..]);

        self.textarea.set_text(&new_text);
        let new_cursor = start_idx.saturating_add(inserted.len()).saturating_add(1);
        self.textarea.set_cursor(new_cursor);
    }

    /// Handle key event when no popup is visible.
    fn handle_key_event_without_popup(&mut self, key_event: KeyEvent) -> (InputResult, bool) {
        if self.handle_shortcut_overlay_key(&key_event) {
            return (InputResult::None, true);
        }
        if key_event.code == KeyCode::Esc {
            if self.is_empty() {
                let next_mode = esc_hint_mode(self.footer_mode, self.is_task_running);
                if next_mode != self.footer_mode {
                    self.footer_mode = next_mode;
                    return (InputResult::None, true);
                }
            }
        } else {
            self.footer_mode = reset_mode_after_activity(self.footer_mode);
        }
        match key_event {
            KeyEvent {
                code: KeyCode::Char('d'),
                modifiers: crossterm::event::KeyModifiers::CONTROL,
                kind: KeyEventKind::Press,
                ..
            } if self.is_empty() => {
                self.app_event_tx.send(AppEvent::ExitRequest);
                (InputResult::None, true)
            }
            // -------------------------------------------------------------
            // History navigation (Up / Down) – only when the composer is not
            // empty or when the cursor is at the correct position, to avoid
            // interfering with normal cursor movement.
            // -------------------------------------------------------------
            KeyEvent {
                code: KeyCode::Up | KeyCode::Down,
                ..
            } => {
                if self
                    .history
                    .should_handle_navigation(self.textarea.text(), self.textarea.cursor())
                {
                    let replace_text = match key_event.code {
                        KeyCode::Up => self.history.navigate_up(&self.app_event_tx),
                        KeyCode::Down => self.history.navigate_down(&self.app_event_tx),
                        _ => unreachable!(),
                    };
                    if let Some(text) = replace_text {
                        self.set_text_content(text);
                        return (InputResult::None, true);
                    }
                }
                self.handle_input_basic(key_event)
            }
            KeyEvent {
                code: KeyCode::Enter,
                modifiers: KeyModifiers::NONE,
                ..
            } => {
                // If the first line is a bare built-in slash command (no args),
                // dispatch it even when the slash popup isn't visible. This preserves
                // the workflow: type a prefix ("/di"), press Tab to complete to
                // "/diff ", then press Enter to run it. Tab moves the cursor beyond
                // the '/name' token and our caret-based heuristic hides the popup,
                // but Enter should still dispatch the command rather than submit
                // literal text.
                let first_line = self.textarea.text().lines().next().unwrap_or("");
                if let Some((name, rest)) = parse_slash_name(first_line)
                    && rest.is_empty()
                    && let Some((_n, cmd)) = built_in_slash_commands()
                        .into_iter()
                        .find(|(n, _)| *n == name)
                {
                    self.textarea.set_text("");
                    return (InputResult::Command(cmd), true);
                }
                // If we're in a paste-like burst capture, treat Enter as part of the burst
                // and accumulate it rather than submitting or inserting immediately.
                // Do not treat Enter as paste inside a slash-command context.
                let in_slash_context = matches!(self.active_popup, ActivePopup::Command(_))
                    || self
                        .textarea
                        .text()
                        .lines()
                        .next()
                        .unwrap_or("")
                        .starts_with('/');
                if self.paste_burst.is_active() && !in_slash_context {
                    let now = Instant::now();
                    if self.paste_burst.append_newline_if_active(now) {
                        return (InputResult::None, true);
                    }
                }
                // If we have pending placeholder pastes, submit immediately to expand them.
                if !self.pending_pastes.is_empty() {
                    let mut text = self.textarea.text().to_string();
                    self.textarea.set_text("");
                    for (placeholder, actual) in &self.pending_pastes {
                        if text.contains(placeholder) {
                            text = text.replace(placeholder, actual);
                        }
                    }
                    self.pending_pastes.clear();
                    if text.is_empty() {
                        return (InputResult::None, true);
                    }
                    self.history.record_local_submission(&text);
                    return (InputResult::Submitted(text), true);
                }

                // During a paste-like burst, treat Enter as a newline instead of submit.
                let now = Instant::now();
                if self
                    .paste_burst
                    .newline_should_insert_instead_of_submit(now)
                    && !in_slash_context
                {
                    self.textarea.insert_str("\n");
                    self.paste_burst.extend_window(now);
                    return (InputResult::None, true);
                }
                let mut text = self.textarea.text().to_string();
                let original_input = text.clone();
                let input_starts_with_space = original_input.starts_with(' ');
                self.textarea.set_text("");

                // Replace all pending pastes in the text
                for (placeholder, actual) in &self.pending_pastes {
                    if text.contains(placeholder) {
                        text = text.replace(placeholder, actual);
                    }
                }
                self.pending_pastes.clear();

                // If there is neither text nor attachments, suppress submission entirely.
                let has_attachments = !self.attached_images.is_empty();
                text = text.trim().to_string();
                if let Some((name, _rest)) = parse_slash_name(&text) {
                    let treat_as_plain_text = input_starts_with_space || name.contains('/');
                    if !treat_as_plain_text {
                        let is_builtin = built_in_slash_commands()
                            .into_iter()
                            .any(|(command_name, _)| command_name == name);
                        let prompt_prefix = format!("{PROMPTS_CMD_PREFIX}:");
                        let is_known_prompt = name
                            .strip_prefix(&prompt_prefix)
                            .map(|prompt_name| {
                                self.custom_prompts
                                    .iter()
                                    .any(|prompt| prompt.name == prompt_name)
                            })
                            .unwrap_or(false);
                        if !is_builtin && !is_known_prompt {
                            let message = format!(
                                r#"Unrecognized command '/{name}'. Type "/" for a list of supported commands."#
                            );
                            self.app_event_tx.send(AppEvent::InsertHistoryCell(Box::new(
                                history_cell::new_info_event(message, None),
                            )));
                            self.textarea.set_text(&original_input);
                            self.textarea.set_cursor(original_input.len());
                            return (InputResult::None, true);
                        }
                    }
                }

                let expanded_prompt = match expand_custom_prompt(&text, &self.custom_prompts) {
                    Ok(expanded) => expanded,
                    Err(err) => {
                        self.app_event_tx.send(AppEvent::InsertHistoryCell(Box::new(
                            history_cell::new_error_event(err.user_message()),
                        )));
                        self.textarea.set_text(&original_input);
                        self.textarea.set_cursor(original_input.len());
                        return (InputResult::None, true);
                    }
                };
                if let Some(expanded) = expanded_prompt {
                    text = expanded;
                }
                if text.is_empty() && !has_attachments {
                    return (InputResult::None, true);
                }
                if !text.is_empty() {
                    self.history.record_local_submission(&text);
                }
                // Do not clear attached_images here; ChatWidget drains them via take_recent_submission_images().
                (InputResult::Submitted(text), true)
            }
            input => self.handle_input_basic(input),
        }
    }

    fn handle_paste_burst_flush(&mut self, now: Instant) -> bool {
        match self.paste_burst.flush_if_due(now) {
            FlushResult::Paste(pasted) => {
                self.handle_paste(pasted);
                true
            }
            FlushResult::Typed(ch) => {
                // Mirror insert_str() behavior so popups stay in sync when a
                // pending fast char flushes as normal typed input.
                self.textarea.insert_str(ch.to_string().as_str());
                // Keep popup sync consistent with key handling: prefer slash popup; only
                // sync file popup when slash popup is NOT active.
                self.sync_command_popup();
                if matches!(self.active_popup, ActivePopup::Command(_)) {
                    self.dismissed_file_popup_token = None;
                } else {
                    self.sync_file_search_popup();
                }
                true
            }
            FlushResult::None => false,
        }
    }

    /// Handle generic Input events that modify the textarea content.
    fn handle_input_basic(&mut self, input: KeyEvent) -> (InputResult, bool) {
        // If we have a buffered non-bracketed paste burst and enough time has
        // elapsed since the last char, flush it before handling a new input.
        let now = Instant::now();
        self.handle_paste_burst_flush(now);

        if !matches!(input.code, KeyCode::Esc) {
            self.footer_mode = reset_mode_after_activity(self.footer_mode);
        }

        // If we're capturing a burst and receive Enter, accumulate it instead of inserting.
        if matches!(input.code, KeyCode::Enter)
            && self.paste_burst.is_active()
            && self.paste_burst.append_newline_if_active(now)
        {
            return (InputResult::None, true);
        }

        // Intercept plain Char inputs to optionally accumulate into a burst buffer.
        if let KeyEvent {
            code: KeyCode::Char(ch),
            modifiers,
            ..
        } = input
        {
            let has_ctrl_or_alt =
                modifiers.contains(KeyModifiers::CONTROL) || modifiers.contains(KeyModifiers::ALT);
            if !has_ctrl_or_alt {
                // Non-ASCII characters (e.g., from IMEs) can arrive in quick bursts and be
                // misclassified by paste heuristics. Flush any active burst buffer and insert
                // non-ASCII characters directly.
                if !ch.is_ascii() {
                    return self.handle_non_ascii_char(input);
                }

                match self.paste_burst.on_plain_char(ch, now) {
                    CharDecision::BufferAppend => {
                        self.paste_burst.append_char_to_buffer(ch, now);
                        return (InputResult::None, true);
                    }
                    CharDecision::BeginBuffer { retro_chars } => {
                        let cur = self.textarea.cursor();
                        let txt = self.textarea.text();
                        let safe_cur = Self::clamp_to_char_boundary(txt, cur);
                        let before = &txt[..safe_cur];
                        if let Some(grab) =
                            self.paste_burst
                                .decide_begin_buffer(now, before, retro_chars as usize)
                        {
                            if !grab.grabbed.is_empty() {
                                self.textarea.replace_range(grab.start_byte..safe_cur, "");
                            }
                            self.paste_burst.begin_with_retro_grabbed(grab.grabbed, now);
                            self.paste_burst.append_char_to_buffer(ch, now);
                            return (InputResult::None, true);
                        }
                        // If decide_begin_buffer opted not to start buffering,
                        // fall through to normal insertion below.
                    }
                    CharDecision::BeginBufferFromPending => {
                        // First char was held; now append the current one.
                        self.paste_burst.append_char_to_buffer(ch, now);
                        return (InputResult::None, true);
                    }
                    CharDecision::RetainFirstChar => {
                        // Keep the first fast char pending momentarily.
                        return (InputResult::None, true);
                    }
                }
            }
            if let Some(pasted) = self.paste_burst.flush_before_modified_input() {
                self.handle_paste(pasted);
            }
        }

        // For non-char inputs (or after flushing), handle normally.
        // Special handling for backspace on placeholders
        if let KeyEvent {
            code: KeyCode::Backspace,
            ..
        } = input
            && self.try_remove_any_placeholder_at_cursor()
        {
            return (InputResult::None, true);
        }

        // Normal input handling
        self.textarea.input(input);
        let text_after = self.textarea.text();

        // Update paste-burst heuristic for plain Char (no Ctrl/Alt) events.
        let crossterm::event::KeyEvent {
            code, modifiers, ..
        } = input;
        match code {
            KeyCode::Char(_) => {
                let has_ctrl_or_alt = modifiers.contains(KeyModifiers::CONTROL)
                    || modifiers.contains(KeyModifiers::ALT);
                if has_ctrl_or_alt {
                    self.paste_burst.clear_window_after_non_char();
                }
            }
            KeyCode::Enter => {
                // Keep burst window alive (supports blank lines in paste).
            }
            _ => {
                // Other keys: clear burst window (buffer should have been flushed above if needed).
                self.paste_burst.clear_window_after_non_char();
            }
        }

        // Check if any placeholders were removed and remove their corresponding pending pastes
        self.pending_pastes
            .retain(|(placeholder, _)| text_after.contains(placeholder));

        // Keep attached images in proportion to how many matching placeholders exist in the text.
        // This handles duplicate placeholders that share the same visible label.
        if !self.attached_images.is_empty() {
            let mut needed: HashMap<String, usize> = HashMap::new();
            for img in &self.attached_images {
                needed
                    .entry(img.placeholder.clone())
                    .or_insert_with(|| text_after.matches(&img.placeholder).count());
            }

            let mut used: HashMap<String, usize> = HashMap::new();
            let mut kept: Vec<AttachedImage> = Vec::with_capacity(self.attached_images.len());
            for img in self.attached_images.drain(..) {
                let total_needed = *needed.get(&img.placeholder).unwrap_or(&0);
                let used_count = used.entry(img.placeholder.clone()).or_insert(0);
                if *used_count < total_needed {
                    kept.push(img);
                    *used_count += 1;
                }
            }
            self.attached_images = kept;
        }

        (InputResult::None, true)
    }

    /// Attempts to remove an image or paste placeholder if the cursor is at the end of one.
    /// Returns true if a placeholder was removed.
    fn try_remove_any_placeholder_at_cursor(&mut self) -> bool {
        // Clamp the cursor to a valid char boundary to avoid panics when slicing.
        let text = self.textarea.text();
        let p = Self::clamp_to_char_boundary(text, self.textarea.cursor());

        // Try image placeholders first
        let mut out: Option<(usize, String)> = None;
        // Detect if the cursor is at the end of any image placeholder.
        // If duplicates exist, remove the specific occurrence's mapping.
        for (i, img) in self.attached_images.iter().enumerate() {
            let ph = &img.placeholder;
            if p < ph.len() {
                continue;
            }
            let start = p - ph.len();
            if text.get(start..p) != Some(ph.as_str()) {
                continue;
            }

            // Count the number of occurrences of `ph` before `start`.
            let mut occ_before = 0usize;
            let mut search_pos = 0usize;
            while search_pos < start {
                let segment = match text.get(search_pos..start) {
                    Some(s) => s,
                    None => break,
                };
                if let Some(found) = segment.find(ph) {
                    occ_before += 1;
                    search_pos += found + ph.len();
                } else {
                    break;
                }
            }

            // Remove the occ_before-th attached image that shares this placeholder label.
            out = if let Some((remove_idx, _)) = self
                .attached_images
                .iter()
                .enumerate()
                .filter(|(_, img2)| img2.placeholder == *ph)
                .nth(occ_before)
            {
                Some((remove_idx, ph.clone()))
            } else {
                Some((i, ph.clone()))
            };
            break;
        }
        if let Some((idx, placeholder)) = out {
            self.textarea.replace_range(p - placeholder.len()..p, "");
            self.attached_images.remove(idx);
            return true;
        }

        // Also handle when the cursor is at the START of an image placeholder.
        // let result = 'out: {
        let out: Option<(usize, String)> = 'out: {
            for (i, img) in self.attached_images.iter().enumerate() {
                let ph = &img.placeholder;
                if p + ph.len() > text.len() {
                    continue;
                }
                if text.get(p..p + ph.len()) != Some(ph.as_str()) {
                    continue;
                }

                // Count occurrences of `ph` before `p`.
                let mut occ_before = 0usize;
                let mut search_pos = 0usize;
                while search_pos < p {
                    let segment = match text.get(search_pos..p) {
                        Some(s) => s,
                        None => break 'out None,
                    };
                    if let Some(found) = segment.find(ph) {
                        occ_before += 1;
                        search_pos += found + ph.len();
                    } else {
                        break 'out None;
                    }
                }

                if let Some((remove_idx, _)) = self
                    .attached_images
                    .iter()
                    .enumerate()
                    .filter(|(_, img2)| img2.placeholder == *ph)
                    .nth(occ_before)
                {
                    break 'out Some((remove_idx, ph.clone()));
                } else {
                    break 'out Some((i, ph.clone()));
                }
            }
            None
        };

        if let Some((idx, placeholder)) = out {
            self.textarea.replace_range(p..p + placeholder.len(), "");
            self.attached_images.remove(idx);
            return true;
        }

        // Then try pasted-content placeholders
        if let Some(placeholder) = self.pending_pastes.iter().find_map(|(ph, _)| {
            if p < ph.len() {
                return None;
            }
            let start = p - ph.len();
            if text.get(start..p) == Some(ph.as_str()) {
                Some(ph.clone())
            } else {
                None
            }
        }) {
            self.textarea.replace_range(p - placeholder.len()..p, "");
            self.pending_pastes.retain(|(ph, _)| ph != &placeholder);
            return true;
        }

        // Also handle when the cursor is at the START of a pasted-content placeholder.
        if let Some(placeholder) = self.pending_pastes.iter().find_map(|(ph, _)| {
            if p + ph.len() > text.len() {
                return None;
            }
            if text.get(p..p + ph.len()) == Some(ph.as_str()) {
                Some(ph.clone())
            } else {
                None
            }
        }) {
            self.textarea.replace_range(p..p + placeholder.len(), "");
            self.pending_pastes.retain(|(ph, _)| ph != &placeholder);
            return true;
        }

        false
    }

    fn handle_shortcut_overlay_key(&mut self, key_event: &KeyEvent) -> bool {
        if key_event.kind != KeyEventKind::Press {
            return false;
        }

        let toggles = matches!(
            key_event,
            KeyEvent {
                code: KeyCode::Char('?'),
                modifiers: KeyModifiers::NONE,
                ..
            } if self.is_empty()
        );

        if !toggles {
            return false;
        }

        let next = toggle_shortcut_mode(self.footer_mode, self.ctrl_c_quit_hint);
        let changed = next != self.footer_mode;
        self.footer_mode = next;
        changed
    }

    fn footer_props(&self) -> FooterProps {
        FooterProps {
            mode: self.footer_mode(),
            esc_backtrack_hint: self.esc_backtrack_hint,
            use_shift_enter_hint: self.use_shift_enter_hint,
            is_task_running: self.is_task_running,
            context_window_percent: self.context_window_percent,
        }
    }

    fn footer_mode(&self) -> FooterMode {
        match self.footer_mode {
            FooterMode::EscHint => FooterMode::EscHint,
            FooterMode::ShortcutOverlay => FooterMode::ShortcutOverlay,
            FooterMode::CtrlCReminder => FooterMode::CtrlCReminder,
            FooterMode::ShortcutSummary if self.ctrl_c_quit_hint => FooterMode::CtrlCReminder,
            FooterMode::ShortcutSummary if !self.is_empty() => FooterMode::ContextOnly,
            other => other,
        }
    }

    fn custom_footer_height(&self) -> Option<u16> {
        self.footer_hint_override
            .as_ref()
            .map(|items| if items.is_empty() { 0 } else { 1 })
    }

    /// Synchronize `self.command_popup` with the current text in the
    /// textarea. This must be called after every modification that can change
    /// the text so the popup is shown/updated/hidden as appropriate.
    fn sync_command_popup(&mut self) {
        // Determine whether the caret is inside the initial '/name' token on the first line.
        let text = self.textarea.text();
        let first_line_end = text.find('\n').unwrap_or(text.len());
        let first_line = &text[..first_line_end];
        let cursor = self.textarea.cursor();
        let caret_on_first_line = cursor <= first_line_end;

        let is_editing_slash_command_name = if first_line.starts_with('/') && caret_on_first_line {
            // Compute the end of the initial '/name' token (name may be empty yet).
            let token_end = first_line
                .char_indices()
                .find(|(_, c)| c.is_whitespace())
                .map(|(i, _)| i)
                .unwrap_or(first_line.len());
            cursor <= token_end
        } else {
            false
        };
        // If the cursor is currently positioned within an `@token`, prefer the
        // file-search popup over the slash popup so users can insert a file path
        // as an argument to the command (e.g., "/review @docs/...").
        if Self::current_at_token(&self.textarea).is_some() {
            if matches!(self.active_popup, ActivePopup::Command(_)) {
                self.active_popup = ActivePopup::None;
            }
            return;
        }
        match &mut self.active_popup {
            ActivePopup::Command(popup) => {
                if is_editing_slash_command_name {
                    popup.on_composer_text_change(first_line.to_string());
                } else {
                    self.active_popup = ActivePopup::None;
                }
            }
            _ => {
                if is_editing_slash_command_name {
                    let mut command_popup = CommandPopup::new(self.custom_prompts.clone());
                    command_popup.on_composer_text_change(first_line.to_string());
                    self.active_popup = ActivePopup::Command(command_popup);
                }
            }
        }
    }

    pub(crate) fn set_custom_prompts(&mut self, prompts: Vec<CustomPrompt>) {
        self.custom_prompts = prompts.clone();
        if let ActivePopup::Command(popup) = &mut self.active_popup {
            popup.set_prompts(prompts);
        }
    }

    /// Synchronize `self.file_search_popup` with the current text in the textarea.
    /// Note this is only called when self.active_popup is NOT Command.
    fn sync_file_search_popup(&mut self) {
        // Determine if there is an @token underneath the cursor.
        let query = match Self::current_at_token(&self.textarea) {
            Some(token) => token,
            None => {
                self.active_popup = ActivePopup::None;
                self.dismissed_file_popup_token = None;
                return;
            }
        };

        // If user dismissed popup for this exact query, don't reopen until text changes.
        if self.dismissed_file_popup_token.as_ref() == Some(&query) {
            return;
        }

        if !query.is_empty() {
            self.app_event_tx
                .send(AppEvent::StartFileSearch(query.clone()));
        }

        match &mut self.active_popup {
            ActivePopup::File(popup) => {
                if query.is_empty() {
                    popup.set_empty_prompt();
                } else {
                    popup.set_query(&query);
                }
            }
            _ => {
                let mut popup = FileSearchPopup::new();
                if query.is_empty() {
                    popup.set_empty_prompt();
                } else {
                    popup.set_query(&query);
                }
                self.active_popup = ActivePopup::File(popup);
            }
        }

        self.current_file_query = Some(query);
        self.dismissed_file_popup_token = None;
    }

    fn set_has_focus(&mut self, has_focus: bool) {
        self.has_focus = has_focus;
    }

    pub fn set_task_running(&mut self, running: bool) {
        self.is_task_running = running;
    }

    pub(crate) fn set_context_window_percent(&mut self, percent: Option<i64>) {
        if self.context_window_percent != percent {
            self.context_window_percent = percent;
        }
    }

    pub(crate) fn set_esc_backtrack_hint(&mut self, show: bool) {
        self.esc_backtrack_hint = show;
        if show {
            self.footer_mode = esc_hint_mode(self.footer_mode, self.is_task_running);
        } else {
            self.footer_mode = reset_mode_after_activity(self.footer_mode);
        }
    }
}

impl WidgetRef for ChatComposer {
    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
        let [composer_rect, textarea_rect, popup_rect] = self.layout_areas(area);
        match &self.active_popup {
            ActivePopup::Command(popup) => {
                popup.render_ref(popup_rect, buf);
            }
            ActivePopup::File(popup) => {
                popup.render_ref(popup_rect, buf);
            }
            ActivePopup::None => {
                let footer_props = self.footer_props();
                let custom_height = self.custom_footer_height();
                let footer_hint_height =
                    custom_height.unwrap_or_else(|| footer_height(footer_props));
                let footer_spacing = Self::footer_spacing(footer_hint_height);
                let hint_rect = if footer_spacing > 0 && footer_hint_height > 0 {
                    let [_, hint_rect] = Layout::vertical([
                        Constraint::Length(footer_spacing),
                        Constraint::Length(footer_hint_height),
                    ])
                    .areas(popup_rect);
                    hint_rect
                } else {
                    popup_rect
                };
                if let Some(items) = self.footer_hint_override.as_ref() {
                    if !items.is_empty() {
                        let mut spans = Vec::with_capacity(items.len() * 4);
                        for (idx, (key, label)) in items.iter().enumerate() {
                            spans.push(" ".into());
                            spans.push(Span::styled(key.clone(), Style::default().bold()));
                            spans.push(format!(" {label}").into());
                            if idx + 1 != items.len() {
                                spans.push("   ".into());
                            }
                        }
                        let mut custom_rect = hint_rect;
                        if custom_rect.width > 2 {
                            custom_rect.x += 2;
                            custom_rect.width = custom_rect.width.saturating_sub(2);
                        }
                        Line::from(spans).render_ref(custom_rect, buf);
                    }
                } else {
                    render_footer(hint_rect, buf, footer_props);
                }
            }
        }
        let style = user_message_style();
        let mut block_rect = composer_rect;
        block_rect.y = composer_rect.y.saturating_sub(1);
        block_rect.height = composer_rect.height.saturating_add(1);
        Block::default().style(style).render_ref(block_rect, buf);
        buf.set_span(
            composer_rect.x,
            composer_rect.y,
            &"›".bold(),
            composer_rect.width,
        );

        let mut state = self.textarea_state.borrow_mut();
        StatefulWidgetRef::render_ref(&(&self.textarea), textarea_rect, buf, &mut state);
        if self.textarea.text().is_empty() {
            let placeholder = Span::from(self.placeholder_text.as_str()).dim();
            Line::from(vec![placeholder]).render_ref(textarea_rect.inner(Margin::new(0, 0)), buf);
        }
    }
}

fn prompt_selection_action(
    prompt: &CustomPrompt,
    first_line: &str,
    mode: PromptSelectionMode,
) -> PromptSelectionAction {
    let named_args = prompt_argument_names(&prompt.content);
    let has_numeric = prompt_has_numeric_placeholders(&prompt.content);

    match mode {
        PromptSelectionMode::Completion => {
            if !named_args.is_empty() {
                let (text, cursor) =
                    prompt_command_with_arg_placeholders(&prompt.name, &named_args);
                return PromptSelectionAction::Insert {
                    text,
                    cursor: Some(cursor),
                };
            }
            if has_numeric {
                let text = format!("/{PROMPTS_CMD_PREFIX}:{} ", prompt.name);
                return PromptSelectionAction::Insert { text, cursor: None };
            }
            let text = format!("/{PROMPTS_CMD_PREFIX}:{}", prompt.name);
            PromptSelectionAction::Insert { text, cursor: None }
        }
        PromptSelectionMode::Submit => {
            if !named_args.is_empty() {
                let (text, cursor) =
                    prompt_command_with_arg_placeholders(&prompt.name, &named_args);
                return PromptSelectionAction::Insert {
                    text,
                    cursor: Some(cursor),
                };
            }
            if has_numeric {
                if let Some(expanded) = expand_if_numeric_with_positional_args(prompt, first_line) {
                    return PromptSelectionAction::Submit { text: expanded };
                }
                let text = format!("/{PROMPTS_CMD_PREFIX}:{} ", prompt.name);
                return PromptSelectionAction::Insert { text, cursor: None };
            }
            PromptSelectionAction::Submit {
                text: prompt.content.clone(),
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use image::ImageBuffer;
    use image::Rgba;
    use pretty_assertions::assert_eq;
    use std::path::PathBuf;
    use tempfile::tempdir;

    use crate::app_event::AppEvent;
    use crate::bottom_pane::AppEventSender;
    use crate::bottom_pane::ChatComposer;
    use crate::bottom_pane::InputResult;
    use crate::bottom_pane::chat_composer::AttachedImage;
    use crate::bottom_pane::chat_composer::LARGE_PASTE_CHAR_THRESHOLD;
    use crate::bottom_pane::prompt_args::extract_positional_args_for_prompt_line;
    use crate::bottom_pane::textarea::TextArea;
    use tokio::sync::mpsc::unbounded_channel;

    #[test]
    fn footer_hint_row_is_separated_from_composer() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let area = Rect::new(0, 0, 40, 6);
        let mut buf = Buffer::empty(area);
        composer.render_ref(area, &mut buf);

        let row_to_string = |y: u16| {
            let mut row = String::new();
            for x in 0..area.width {
                row.push(buf[(x, y)].symbol().chars().next().unwrap_or(' '));
            }
            row
        };

        let mut hint_row: Option<(u16, String)> = None;
        for y in 0..area.height {
            let row = row_to_string(y);
            if row.contains("? for shortcuts") {
                hint_row = Some((y, row));
                break;
            }
        }

        let (hint_row_idx, hint_row_contents) =
            hint_row.expect("expected footer hint row to be rendered");
        assert_eq!(
            hint_row_idx,
            area.height - 1,
            "hint row should occupy the bottom line: {hint_row_contents:?}",
        );

        assert!(
            hint_row_idx > 0,
            "expected a spacing row above the footer hints",
        );

        let spacing_row = row_to_string(hint_row_idx - 1);
        assert_eq!(
            spacing_row.trim(),
            "",
            "expected blank spacing row above hints but saw: {spacing_row:?}",
        );
    }

    fn snapshot_composer_state<F>(name: &str, enhanced_keys_supported: bool, setup: F)
    where
        F: FnOnce(&mut ChatComposer),
    {
        use ratatui::Terminal;
        use ratatui::backend::TestBackend;

        let width = 100;
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            enhanced_keys_supported,
            "Ask Codex to do anything".to_string(),
            false,
        );
        setup(&mut composer);
        let footer_props = composer.footer_props();
        let footer_lines = footer_height(footer_props);
        let footer_spacing = ChatComposer::footer_spacing(footer_lines);
        let height = footer_lines + footer_spacing + 8;
        let mut terminal = Terminal::new(TestBackend::new(width, height)).unwrap();
        terminal
            .draw(|f| f.render_widget_ref(composer, f.area()))
            .unwrap();
        insta::assert_snapshot!(name, terminal.backend());
    }

    #[test]
    fn footer_mode_snapshots() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        snapshot_composer_state("footer_mode_shortcut_overlay", true, |composer| {
            composer.set_esc_backtrack_hint(true);
            let _ =
                composer.handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
        });

        snapshot_composer_state("footer_mode_ctrl_c_quit", true, |composer| {
            composer.set_ctrl_c_quit_hint(true, true);
        });

        snapshot_composer_state("footer_mode_ctrl_c_interrupt", true, |composer| {
            composer.set_task_running(true);
            composer.set_ctrl_c_quit_hint(true, true);
        });

        snapshot_composer_state("footer_mode_ctrl_c_then_esc_hint", true, |composer| {
            composer.set_ctrl_c_quit_hint(true, true);
            let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE));
        });

        snapshot_composer_state("footer_mode_esc_hint_from_overlay", true, |composer| {
            let _ =
                composer.handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
            let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE));
        });

        snapshot_composer_state("footer_mode_esc_hint_backtrack", true, |composer| {
            composer.set_esc_backtrack_hint(true);
            let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE));
        });

        snapshot_composer_state(
            "footer_mode_overlay_then_external_esc_hint",
            true,
            |composer| {
                let _ = composer
                    .handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
                composer.set_esc_backtrack_hint(true);
            },
        );

        snapshot_composer_state("footer_mode_hidden_while_typing", true, |composer| {
            type_chars_humanlike(composer, &['h']);
        });
    }

    #[test]
    fn esc_hint_stays_hidden_with_draft_content() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            true,
            "Ask Codex to do anything".to_string(),
            false,
        );

        type_chars_humanlike(&mut composer, &['d']);

        assert!(!composer.is_empty());
        assert_eq!(composer.current_text(), "d");
        assert_eq!(composer.footer_mode, FooterMode::ShortcutSummary);
        assert!(matches!(composer.active_popup, ActivePopup::None));

        let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE));

        assert_eq!(composer.footer_mode, FooterMode::ShortcutSummary);
        assert!(!composer.esc_backtrack_hint);
    }

    #[test]
    fn clear_for_ctrl_c_records_cleared_draft() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_text_content("draft text".to_string());
        assert_eq!(composer.clear_for_ctrl_c(), Some("draft text".to_string()));
        assert!(composer.is_empty());

        assert_eq!(
            composer.history.navigate_up(&composer.app_event_tx),
            Some("draft text".to_string())
        );
    }

    #[test]
    fn question_mark_only_toggles_on_first_char() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let (result, needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
        assert_eq!(result, InputResult::None);
        assert!(needs_redraw, "toggling overlay should request redraw");
        assert_eq!(composer.footer_mode, FooterMode::ShortcutOverlay);

        // Toggle back to prompt mode so subsequent typing captures characters.
        let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
        assert_eq!(composer.footer_mode, FooterMode::ShortcutSummary);

        type_chars_humanlike(&mut composer, &['h']);
        assert_eq!(composer.textarea.text(), "h");
        assert_eq!(composer.footer_mode(), FooterMode::ContextOnly);

        let (result, needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
        assert_eq!(result, InputResult::None);
        assert!(needs_redraw, "typing should still mark the view dirty");
        std::thread::sleep(ChatComposer::recommended_paste_flush_delay());
        let _ = composer.flush_paste_burst_if_due();
        assert_eq!(composer.textarea.text(), "h?");
        assert_eq!(composer.footer_mode, FooterMode::ShortcutSummary);
        assert_eq!(composer.footer_mode(), FooterMode::ContextOnly);
    }

    #[test]
    fn shortcut_overlay_persists_while_task_running() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE));
        assert_eq!(composer.footer_mode, FooterMode::ShortcutOverlay);

        composer.set_task_running(true);

        assert_eq!(composer.footer_mode, FooterMode::ShortcutOverlay);
        assert_eq!(composer.footer_mode(), FooterMode::ShortcutOverlay);
    }

    #[test]
    fn test_current_at_token_basic_cases() {
        let test_cases = vec![
            // Valid @ tokens
            ("@hello", 3, Some("hello".to_string()), "Basic ASCII token"),
            (
                "@file.txt",
                4,
                Some("file.txt".to_string()),
                "ASCII with extension",
            ),
            (
                "hello @world test",
                8,
                Some("world".to_string()),
                "ASCII token in middle",
            ),
            (
                "@test123",
                5,
                Some("test123".to_string()),
                "ASCII with numbers",
            ),
            // Unicode examples
            ("@İstanbul", 3, Some("İstanbul".to_string()), "Turkish text"),
            (
                "@testЙЦУ.rs",
                8,
                Some("testЙЦУ.rs".to_string()),
                "Mixed ASCII and Cyrillic",
            ),
            ("@诶", 2, Some("诶".to_string()), "Chinese character"),
            ("@👍", 2, Some("👍".to_string()), "Emoji token"),
            // Invalid cases (should return None)
            ("hello", 2, None, "No @ symbol"),
            (
                "@",
                1,
                Some("".to_string()),
                "Only @ symbol triggers empty query",
            ),
            ("@ hello", 2, None, "@ followed by space"),
            ("test @ world", 6, None, "@ with spaces around"),
        ];

        for (input, cursor_pos, expected, description) in test_cases {
            let mut textarea = TextArea::new();
            textarea.insert_str(input);
            textarea.set_cursor(cursor_pos);

            let result = ChatComposer::current_at_token(&textarea);
            assert_eq!(
                result, expected,
                "Failed for case: {description} - input: '{input}', cursor: {cursor_pos}"
            );
        }
    }

    #[test]
    fn test_current_at_token_cursor_positions() {
        let test_cases = vec![
            // Different cursor positions within a token
            ("@test", 0, Some("test".to_string()), "Cursor at @"),
            ("@test", 1, Some("test".to_string()), "Cursor after @"),
            ("@test", 5, Some("test".to_string()), "Cursor at end"),
            // Multiple tokens - cursor determines which token
            ("@file1 @file2", 0, Some("file1".to_string()), "First token"),
            (
                "@file1 @file2",
                8,
                Some("file2".to_string()),
                "Second token",
            ),
            // Edge cases
            ("@", 0, Some("".to_string()), "Only @ symbol"),
            ("@a", 2, Some("a".to_string()), "Single character after @"),
            ("", 0, None, "Empty input"),
        ];

        for (input, cursor_pos, expected, description) in test_cases {
            let mut textarea = TextArea::new();
            textarea.insert_str(input);
            textarea.set_cursor(cursor_pos);

            let result = ChatComposer::current_at_token(&textarea);
            assert_eq!(
                result, expected,
                "Failed for cursor position case: {description} - input: '{input}', cursor: {cursor_pos}",
            );
        }
    }

    #[test]
    fn test_current_at_token_whitespace_boundaries() {
        let test_cases = vec![
            // Space boundaries
            (
                "aaa@aaa",
                4,
                None,
                "Connected @ token - no completion by design",
            ),
            (
                "aaa @aaa",
                5,
                Some("aaa".to_string()),
                "@ token after space",
            ),
            (
                "test @file.txt",
                7,
                Some("file.txt".to_string()),
                "@ token after space",
            ),
            // Full-width space boundaries
            (
                "test　@İstanbul",
                8,
                Some("İstanbul".to_string()),
                "@ token after full-width space",
            ),
            (
                "@ЙЦУ　@诶",
                10,
                Some("诶".to_string()),
                "Full-width space between Unicode tokens",
            ),
            // Tab and newline boundaries
            (
                "test\t@file",
                6,
                Some("file".to_string()),
                "@ token after tab",
            ),
        ];

        for (input, cursor_pos, expected, description) in test_cases {
            let mut textarea = TextArea::new();
            textarea.insert_str(input);
            textarea.set_cursor(cursor_pos);

            let result = ChatComposer::current_at_token(&textarea);
            assert_eq!(
                result, expected,
                "Failed for whitespace boundary case: {description} - input: '{input}', cursor: {cursor_pos}",
            );
        }
    }

    #[test]
    fn ascii_prefix_survives_non_ascii_followup() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Char('1'), KeyModifiers::NONE));
        assert!(composer.is_in_paste_burst());

        let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Char('あ'), KeyModifiers::NONE));

        let (result, _) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        match result {
            InputResult::Submitted(text) => assert_eq!(text, "1あ"),
            _ => panic!("expected Submitted"),
        }
    }

    #[test]
    fn handle_paste_small_inserts_text() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let needs_redraw = composer.handle_paste("hello".to_string());
        assert!(needs_redraw);
        assert_eq!(composer.textarea.text(), "hello");
        assert!(composer.pending_pastes.is_empty());

        let (result, _) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        match result {
            InputResult::Submitted(text) => assert_eq!(text, "hello"),
            _ => panic!("expected Submitted"),
        }
    }

    #[test]
    fn empty_enter_returns_none() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Ensure composer is empty and press Enter.
        assert!(composer.textarea.text().is_empty());
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        match result {
            InputResult::None => {}
            other => panic!("expected None for empty enter, got: {other:?}"),
        }
    }

    #[test]
    fn handle_paste_large_uses_placeholder_and_replaces_on_submit() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let large = "x".repeat(LARGE_PASTE_CHAR_THRESHOLD + 10);
        let needs_redraw = composer.handle_paste(large.clone());
        assert!(needs_redraw);
        let placeholder = format!("[Pasted Content {} chars]", large.chars().count());
        assert_eq!(composer.textarea.text(), placeholder);
        assert_eq!(composer.pending_pastes.len(), 1);
        assert_eq!(composer.pending_pastes[0].0, placeholder);
        assert_eq!(composer.pending_pastes[0].1, large);

        let (result, _) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        match result {
            InputResult::Submitted(text) => assert_eq!(text, large),
            _ => panic!("expected Submitted"),
        }
        assert!(composer.pending_pastes.is_empty());
    }

    #[test]
    fn edit_clears_pending_paste() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let large = "y".repeat(LARGE_PASTE_CHAR_THRESHOLD + 1);
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.handle_paste(large);
        assert_eq!(composer.pending_pastes.len(), 1);

        // Any edit that removes the placeholder should clear pending_paste
        composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
        assert!(composer.pending_pastes.is_empty());
    }

    #[test]
    fn ui_snapshots() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;
        use ratatui::Terminal;
        use ratatui::backend::TestBackend;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut terminal = match Terminal::new(TestBackend::new(100, 10)) {
            Ok(t) => t,
            Err(e) => panic!("Failed to create terminal: {e}"),
        };

        let test_cases = vec![
            ("empty", None),
            ("small", Some("short".to_string())),
            ("large", Some("z".repeat(LARGE_PASTE_CHAR_THRESHOLD + 5))),
            ("multiple_pastes", None),
            ("backspace_after_pastes", None),
        ];

        for (name, input) in test_cases {
            // Create a fresh composer for each test case
            let mut composer = ChatComposer::new(
                true,
                sender.clone(),
                false,
                "Ask Codex to do anything".to_string(),
                false,
            );

            if let Some(text) = input {
                composer.handle_paste(text);
            } else if name == "multiple_pastes" {
                // First large paste
                composer.handle_paste("x".repeat(LARGE_PASTE_CHAR_THRESHOLD + 3));
                // Second large paste
                composer.handle_paste("y".repeat(LARGE_PASTE_CHAR_THRESHOLD + 7));
                // Small paste
                composer.handle_paste(" another short paste".to_string());
            } else if name == "backspace_after_pastes" {
                // Three large pastes
                composer.handle_paste("a".repeat(LARGE_PASTE_CHAR_THRESHOLD + 2));
                composer.handle_paste("b".repeat(LARGE_PASTE_CHAR_THRESHOLD + 4));
                composer.handle_paste("c".repeat(LARGE_PASTE_CHAR_THRESHOLD + 6));
                // Move cursor to end and press backspace
                composer.textarea.set_cursor(composer.textarea.text().len());
                composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
            }

            terminal
                .draw(|f| f.render_widget_ref(composer, f.area()))
                .unwrap_or_else(|e| panic!("Failed to draw {name} composer: {e}"));

            insta::assert_snapshot!(name, terminal.backend());
        }
    }

    #[test]
    fn slash_popup_model_first_for_mo_ui() {
        use ratatui::Terminal;
        use ratatui::backend::TestBackend;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);

        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Type "/mo" humanlike so paste-burst doesn’t interfere.
        type_chars_humanlike(&mut composer, &['/', 'm', 'o']);

        let mut terminal = match Terminal::new(TestBackend::new(60, 4)) {
            Ok(t) => t,
            Err(e) => panic!("Failed to create terminal: {e}"),
        };
        terminal
            .draw(|f| f.render_widget_ref(composer, f.area()))
            .unwrap_or_else(|e| panic!("Failed to draw composer: {e}"));

        // Visual snapshot should show the slash popup with /model as the first entry.
        insta::assert_snapshot!("slash_popup_mo", terminal.backend());
    }

    #[test]
    fn slash_popup_model_first_for_mo_logic() {
        use super::super::command_popup::CommandItem;
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );
        type_chars_humanlike(&mut composer, &['/', 'm', 'o']);

        match &composer.active_popup {
            ActivePopup::Command(popup) => match popup.selected_item() {
                Some(CommandItem::Builtin(cmd)) => {
                    assert_eq!(cmd.command(), "model")
                }
                Some(CommandItem::UserPrompt(_)) => {
                    panic!("unexpected prompt selected for '/mo'")
                }
                None => panic!("no selected command for '/mo'"),
            },
            _ => panic!("slash popup not active after typing '/mo'"),
        }
    }

    // Test helper: simulate human typing with a brief delay and flush the paste-burst buffer
    fn type_chars_humanlike(composer: &mut ChatComposer, chars: &[char]) {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;
        for &ch in chars {
            let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Char(ch), KeyModifiers::NONE));
            std::thread::sleep(ChatComposer::recommended_paste_flush_delay());
            let _ = composer.flush_paste_burst_if_due();
        }
    }

    #[test]
    fn slash_init_dispatches_command_and_does_not_submit_literal_text() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Type the slash command.
        type_chars_humanlike(&mut composer, &['/', 'i', 'n', 'i', 't']);

        // Press Enter to dispatch the selected command.
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        // When a slash command is dispatched, the composer should return a
        // Command result (not submit literal text) and clear its textarea.
        match result {
            InputResult::Command(cmd) => {
                assert_eq!(cmd.command(), "init");
            }
            InputResult::Submitted(text) => {
                panic!("expected command dispatch, but composer submitted literal text: {text}")
            }
            InputResult::None => panic!("expected Command result for '/init'"),
        }
        assert!(composer.textarea.is_empty(), "composer should be cleared");
    }

    #[test]
    fn extract_args_supports_quoted_paths_single_arg() {
        let args = extract_positional_args_for_prompt_line(
            "/prompts:review \"docs/My File.md\"",
            "review",
        );
        assert_eq!(args, vec!["docs/My File.md".to_string()]);
    }

    #[test]
    fn extract_args_supports_mixed_quoted_and_unquoted() {
        let args =
            extract_positional_args_for_prompt_line("/prompts:cmd \"with spaces\" simple", "cmd");
        assert_eq!(args, vec!["with spaces".to_string(), "simple".to_string()]);
    }

    #[test]
    fn slash_tab_completion_moves_cursor_to_end() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        type_chars_humanlike(&mut composer, &['/', 'c']);

        let (_result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Tab, KeyModifiers::NONE));

        assert_eq!(composer.textarea.text(), "/compact ");
        assert_eq!(composer.textarea.cursor(), composer.textarea.text().len());
    }

    #[test]
    fn slash_tab_then_enter_dispatches_builtin_command() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Type a prefix and complete with Tab, which inserts a trailing space
        // and moves the cursor beyond the '/name' token (hides the popup).
        type_chars_humanlike(&mut composer, &['/', 'd', 'i']);
        let (_res, _redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Tab, KeyModifiers::NONE));
        assert_eq!(composer.textarea.text(), "/diff ");

        // Press Enter: should dispatch the command, not submit literal text.
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        match result {
            InputResult::Command(cmd) => assert_eq!(cmd.command(), "diff"),
            InputResult::Submitted(text) => {
                panic!("expected command dispatch after Tab completion, got literal submit: {text}")
            }
            InputResult::None => panic!("expected Command result for '/diff'"),
        }
        assert!(composer.textarea.is_empty());
    }

    #[test]
    fn slash_mention_dispatches_command_and_inserts_at() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        type_chars_humanlike(&mut composer, &['/', 'm', 'e', 'n', 't', 'i', 'o', 'n']);

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        match result {
            InputResult::Command(cmd) => {
                assert_eq!(cmd.command(), "mention");
            }
            InputResult::Submitted(text) => {
                panic!("expected command dispatch, but composer submitted literal text: {text}")
            }
            InputResult::None => panic!("expected Command result for '/mention'"),
        }
        assert!(composer.textarea.is_empty(), "composer should be cleared");
        composer.insert_str("@");
        assert_eq!(composer.textarea.text(), "@");
    }

    #[test]
    fn test_multiple_pastes_submission() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Define test cases: (paste content, is_large)
        let test_cases = [
            ("x".repeat(LARGE_PASTE_CHAR_THRESHOLD + 3), true),
            (" and ".to_string(), false),
            ("y".repeat(LARGE_PASTE_CHAR_THRESHOLD + 7), true),
        ];

        // Expected states after each paste
        let mut expected_text = String::new();
        let mut expected_pending_count = 0;

        // Apply all pastes and build expected state
        let states: Vec<_> = test_cases
            .iter()
            .map(|(content, is_large)| {
                composer.handle_paste(content.clone());
                if *is_large {
                    let placeholder = format!("[Pasted Content {} chars]", content.chars().count());
                    expected_text.push_str(&placeholder);
                    expected_pending_count += 1;
                } else {
                    expected_text.push_str(content);
                }
                (expected_text.clone(), expected_pending_count)
            })
            .collect();

        // Verify all intermediate states were correct
        assert_eq!(
            states,
            vec![
                (
                    format!("[Pasted Content {} chars]", test_cases[0].0.chars().count()),
                    1
                ),
                (
                    format!(
                        "[Pasted Content {} chars] and ",
                        test_cases[0].0.chars().count()
                    ),
                    1
                ),
                (
                    format!(
                        "[Pasted Content {} chars] and [Pasted Content {} chars]",
                        test_cases[0].0.chars().count(),
                        test_cases[2].0.chars().count()
                    ),
                    2
                ),
            ]
        );

        // Submit and verify final expansion
        let (result, _) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        if let InputResult::Submitted(text) = result {
            assert_eq!(text, format!("{} and {}", test_cases[0].0, test_cases[2].0));
        } else {
            panic!("expected Submitted");
        }
    }

    #[test]
    fn test_placeholder_deletion() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Define test cases: (content, is_large)
        let test_cases = [
            ("a".repeat(LARGE_PASTE_CHAR_THRESHOLD + 5), true),
            (" and ".to_string(), false),
            ("b".repeat(LARGE_PASTE_CHAR_THRESHOLD + 6), true),
        ];

        // Apply all pastes
        let mut current_pos = 0;
        let states: Vec<_> = test_cases
            .iter()
            .map(|(content, is_large)| {
                composer.handle_paste(content.clone());
                if *is_large {
                    let placeholder = format!("[Pasted Content {} chars]", content.chars().count());
                    current_pos += placeholder.len();
                } else {
                    current_pos += content.len();
                }
                (
                    composer.textarea.text().to_string(),
                    composer.pending_pastes.len(),
                    current_pos,
                )
            })
            .collect();

        // Delete placeholders one by one and collect states
        let mut deletion_states = vec![];

        // First deletion
        composer.textarea.set_cursor(states[0].2);
        composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
        deletion_states.push((
            composer.textarea.text().to_string(),
            composer.pending_pastes.len(),
        ));

        // Second deletion
        composer.textarea.set_cursor(composer.textarea.text().len());
        composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
        deletion_states.push((
            composer.textarea.text().to_string(),
            composer.pending_pastes.len(),
        ));

        // Verify all states
        assert_eq!(
            deletion_states,
            vec![
                (" and [Pasted Content 1006 chars]".to_string(), 1),
                (" and ".to_string(), 0),
            ]
        );
    }

    #[test]
    fn test_partial_placeholder_deletion() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Define test cases: (cursor_position_from_end, expected_pending_count)
        let test_cases = [
            5, // Delete from middle - should clear tracking
            0, // Delete from end - should clear tracking
        ];

        let paste = "x".repeat(LARGE_PASTE_CHAR_THRESHOLD + 4);
        let placeholder = format!("[Pasted Content {} chars]", paste.chars().count());

        let states: Vec<_> = test_cases
            .into_iter()
            .map(|pos_from_end| {
                composer.handle_paste(paste.clone());
                composer
                    .textarea
                    .set_cursor(placeholder.len() - pos_from_end);
                composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
                let result = (
                    composer.textarea.text().contains(&placeholder),
                    composer.pending_pastes.len(),
                );
                composer.textarea.set_text("");
                result
            })
            .collect();

        assert_eq!(
            states,
            vec![
                (false, 0), // After deleting from middle
                (false, 0), // After deleting from end
            ]
        );
    }

    // --- Image attachment tests ---
    #[test]
    fn attach_image_and_submit_includes_image_paths() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );
        let path = PathBuf::from("/tmp/image1.png");
        composer.attach_image(path.clone(), 32, 16, "PNG");
        composer.handle_paste(" hi".into());
        let (result, _) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        match result {
            InputResult::Submitted(text) => assert_eq!(text, "[image1.png 32x16] hi"),
            _ => panic!("expected Submitted"),
        }
        let imgs = composer.take_recent_submission_images();
        assert_eq!(vec![path], imgs);
    }

    #[test]
    fn attach_image_without_text_submits_empty_text_and_images() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );
        let path = PathBuf::from("/tmp/image2.png");
        composer.attach_image(path.clone(), 10, 5, "PNG");
        let (result, _) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
        match result {
            InputResult::Submitted(text) => assert_eq!(text, "[image2.png 10x5]"),
            _ => panic!("expected Submitted"),
        }
        let imgs = composer.take_recent_submission_images();
        assert_eq!(imgs.len(), 1);
        assert_eq!(imgs[0], path);
        assert!(composer.attached_images.is_empty());
    }

    #[test]
    fn image_placeholder_backspace_behaves_like_text_placeholder() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );
        let path = PathBuf::from("/tmp/image3.png");
        composer.attach_image(path.clone(), 20, 10, "PNG");
        let placeholder = composer.attached_images[0].placeholder.clone();

        // Case 1: backspace at end
        composer.textarea.move_cursor_to_end_of_line(false);
        composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
        assert!(!composer.textarea.text().contains(&placeholder));
        assert!(composer.attached_images.is_empty());

        // Re-add and test backspace in middle: should break the placeholder string
        // and drop the image mapping (same as text placeholder behavior).
        composer.attach_image(path, 20, 10, "PNG");
        let placeholder2 = composer.attached_images[0].placeholder.clone();
        // Move cursor to roughly middle of placeholder
        if let Some(start_pos) = composer.textarea.text().find(&placeholder2) {
            let mid_pos = start_pos + (placeholder2.len() / 2);
            composer.textarea.set_cursor(mid_pos);
            composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
            assert!(!composer.textarea.text().contains(&placeholder2));
            assert!(composer.attached_images.is_empty());
        } else {
            panic!("Placeholder not found in textarea");
        }
    }

    #[test]
    fn backspace_with_multibyte_text_before_placeholder_does_not_panic() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Insert an image placeholder at the start
        let path = PathBuf::from("/tmp/image_multibyte.png");
        composer.attach_image(path, 10, 5, "PNG");
        // Add multibyte text after the placeholder
        composer.textarea.insert_str("日本語");

        // Cursor is at end; pressing backspace should delete the last character
        // without panicking and leave the placeholder intact.
        composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));

        assert_eq!(composer.attached_images.len(), 1);
        assert!(
            composer
                .textarea
                .text()
                .starts_with("[image_multibyte.png 10x5]")
        );
    }

    #[test]
    fn deleting_one_of_duplicate_image_placeholders_removes_matching_entry() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let path1 = PathBuf::from("/tmp/image_dup1.png");
        let path2 = PathBuf::from("/tmp/image_dup2.png");

        composer.attach_image(path1, 10, 5, "PNG");
        // separate placeholders with a space for clarity
        composer.handle_paste(" ".into());
        composer.attach_image(path2.clone(), 10, 5, "PNG");

        let placeholder1 = composer.attached_images[0].placeholder.clone();
        let placeholder2 = composer.attached_images[1].placeholder.clone();
        let text = composer.textarea.text().to_string();
        let start1 = text.find(&placeholder1).expect("first placeholder present");
        let end1 = start1 + placeholder1.len();
        composer.textarea.set_cursor(end1);

        // Backspace should delete the first placeholder and its mapping.
        composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));

        let new_text = composer.textarea.text().to_string();
        assert_eq!(
            0,
            new_text.matches(&placeholder1).count(),
            "first placeholder removed"
        );
        assert_eq!(
            1,
            new_text.matches(&placeholder2).count(),
            "second placeholder remains"
        );
        assert_eq!(
            vec![AttachedImage {
                path: path2,
                placeholder: "[image_dup2.png 10x5]".to_string()
            }],
            composer.attached_images,
            "one image mapping remains"
        );
    }

    #[test]
    fn pasting_filepath_attaches_image() {
        let tmp = tempdir().expect("create TempDir");
        let tmp_path: PathBuf = tmp.path().join("codex_tui_test_paste_image.png");
        let img: ImageBuffer<Rgba<u8>, Vec<u8>> =
            ImageBuffer::from_fn(3, 2, |_x, _y| Rgba([1, 2, 3, 255]));
        img.save(&tmp_path).expect("failed to write temp png");

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let needs_redraw = composer.handle_paste(tmp_path.to_string_lossy().to_string());
        assert!(needs_redraw);
        assert!(
            composer
                .textarea
                .text()
                .starts_with("[codex_tui_test_paste_image.png 3x2] ")
        );

        let imgs = composer.take_recent_submission_images();
        assert_eq!(imgs, vec![tmp_path]);
    }

    #[test]
    fn selecting_custom_prompt_without_args_submits_content() {
        let prompt_text = "Hello from saved prompt";

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        // Inject prompts as if received via event.
        composer.set_custom_prompts(vec![CustomPrompt {
            name: "my-prompt".to_string(),
            path: "/tmp/my-prompt.md".to_string().into(),
            content: prompt_text.to_string(),
            description: None,
            argument_hint: None,
        }]);

        type_chars_humanlike(
            &mut composer,
            &[
                '/', 'p', 'r', 'o', 'm', 'p', 't', 's', ':', 'm', 'y', '-', 'p', 'r', 'o', 'm',
                'p', 't',
            ],
        );

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(InputResult::Submitted(prompt_text.to_string()), result);
        assert!(composer.textarea.is_empty());
    }

    #[test]
    fn custom_prompt_submission_expands_arguments() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "my-prompt".to_string(),
            path: "/tmp/my-prompt.md".to_string().into(),
            content: "Review $USER changes on $BRANCH".to_string(),
            description: None,
            argument_hint: None,
        }]);

        composer
            .textarea
            .set_text("/prompts:my-prompt USER=Alice BRANCH=main");

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(
            InputResult::Submitted("Review Alice changes on main".to_string()),
            result
        );
        assert!(composer.textarea.is_empty());
    }

    #[test]
    fn custom_prompt_submission_accepts_quoted_values() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "my-prompt".to_string(),
            path: "/tmp/my-prompt.md".to_string().into(),
            content: "Pair $USER with $BRANCH".to_string(),
            description: None,
            argument_hint: None,
        }]);

        composer
            .textarea
            .set_text("/prompts:my-prompt USER=\"Alice Smith\" BRANCH=dev-main");

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(
            InputResult::Submitted("Pair Alice Smith with dev-main".to_string()),
            result
        );
        assert!(composer.textarea.is_empty());
    }

    #[test]
    fn slash_path_input_submits_without_command_error() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, mut rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer
            .textarea
            .set_text("/Users/example/project/src/main.rs");

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        if let InputResult::Submitted(text) = result {
            assert_eq!(text, "/Users/example/project/src/main.rs");
        } else {
            panic!("expected Submitted");
        }
        assert!(composer.textarea.is_empty());
        match rx.try_recv() {
            Ok(event) => panic!("unexpected event: {event:?}"),
            Err(tokio::sync::mpsc::error::TryRecvError::Empty) => {}
            Err(err) => panic!("unexpected channel state: {err:?}"),
        }
    }

    #[test]
    fn slash_with_leading_space_submits_as_text() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, mut rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.textarea.set_text(" /this-looks-like-a-command");

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        if let InputResult::Submitted(text) = result {
            assert_eq!(text, "/this-looks-like-a-command");
        } else {
            panic!("expected Submitted");
        }
        assert!(composer.textarea.is_empty());
        match rx.try_recv() {
            Ok(event) => panic!("unexpected event: {event:?}"),
            Err(tokio::sync::mpsc::error::TryRecvError::Empty) => {}
            Err(err) => panic!("unexpected channel state: {err:?}"),
        }
    }

    #[test]
    fn custom_prompt_invalid_args_reports_error() {
        let (tx, mut rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "my-prompt".to_string(),
            path: "/tmp/my-prompt.md".to_string().into(),
            content: "Review $USER changes".to_string(),
            description: None,
            argument_hint: None,
        }]);

        composer
            .textarea
            .set_text("/prompts:my-prompt USER=Alice stray");

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(InputResult::None, result);
        assert_eq!(
            "/prompts:my-prompt USER=Alice stray",
            composer.textarea.text()
        );

        let mut found_error = false;
        while let Ok(event) = rx.try_recv() {
            if let AppEvent::InsertHistoryCell(cell) = event {
                let message = cell
                    .display_lines(80)
                    .into_iter()
                    .map(|line| line.to_string())
                    .collect::<Vec<_>>()
                    .join("\n");
                assert!(message.contains("expected key=value"));
                found_error = true;
                break;
            }
        }
        assert!(found_error, "expected error history cell to be sent");
    }

    #[test]
    fn custom_prompt_missing_required_args_reports_error() {
        let (tx, mut rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "my-prompt".to_string(),
            path: "/tmp/my-prompt.md".to_string().into(),
            content: "Review $USER changes on $BRANCH".to_string(),
            description: None,
            argument_hint: None,
        }]);

        // Provide only one of the required args
        composer.textarea.set_text("/prompts:my-prompt USER=Alice");

        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(InputResult::None, result);
        assert_eq!("/prompts:my-prompt USER=Alice", composer.textarea.text());

        let mut found_error = false;
        while let Ok(event) = rx.try_recv() {
            if let AppEvent::InsertHistoryCell(cell) = event {
                let message = cell
                    .display_lines(80)
                    .into_iter()
                    .map(|line| line.to_string())
                    .collect::<Vec<_>>()
                    .join("\n");
                assert!(message.to_lowercase().contains("missing required args"));
                assert!(message.contains("BRANCH"));
                found_error = true;
                break;
            }
        }
        assert!(
            found_error,
            "expected missing args error history cell to be sent"
        );
    }

    #[test]
    fn selecting_custom_prompt_with_args_expands_placeholders() {
        // Support $1..$9 and $ARGUMENTS in prompt content.
        let prompt_text = "Header: $1\nArgs: $ARGUMENTS\nNinth: $9\n";

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "my-prompt".to_string(),
            path: "/tmp/my-prompt.md".to_string().into(),
            content: prompt_text.to_string(),
            description: None,
            argument_hint: None,
        }]);

        // Type the slash command with two args and hit Enter to submit.
        type_chars_humanlike(
            &mut composer,
            &[
                '/', 'p', 'r', 'o', 'm', 'p', 't', 's', ':', 'm', 'y', '-', 'p', 'r', 'o', 'm',
                'p', 't', ' ', 'f', 'o', 'o', ' ', 'b', 'a', 'r',
            ],
        );
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        let expected = "Header: foo\nArgs: foo bar\nNinth: \n".to_string();
        assert_eq!(InputResult::Submitted(expected), result);
    }

    #[test]
    fn numeric_prompt_positional_args_does_not_error() {
        // Ensure that a prompt with only numeric placeholders does not trigger
        // key=value parsing errors when given positional arguments.
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "elegant".to_string(),
            path: "/tmp/elegant.md".to_string().into(),
            content: "Echo: $ARGUMENTS".to_string(),
            description: None,
            argument_hint: None,
        }]);

        // Type positional args; should submit with numeric expansion, no errors.
        composer.textarea.set_text("/prompts:elegant hi");
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(InputResult::Submitted("Echo: hi".to_string()), result);
        assert!(composer.textarea.is_empty());
    }

    #[test]
    fn selecting_custom_prompt_with_no_args_inserts_template() {
        let prompt_text = "X:$1 Y:$2 All:[$ARGUMENTS]";

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "p".to_string(),
            path: "/tmp/p.md".to_string().into(),
            content: prompt_text.to_string(),
            description: None,
            argument_hint: None,
        }]);

        type_chars_humanlike(
            &mut composer,
            &['/', 'p', 'r', 'o', 'm', 'p', 't', 's', ':', 'p'],
        );
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        // With no args typed, selecting the prompt inserts the command template
        // and does not submit immediately.
        assert_eq!(InputResult::None, result);
        assert_eq!("/prompts:p ", composer.textarea.text());
    }

    #[test]
    fn selecting_custom_prompt_preserves_literal_dollar_dollar() {
        // '$$' should remain untouched.
        let prompt_text = "Cost: $$ and first: $1";

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "price".to_string(),
            path: "/tmp/price.md".to_string().into(),
            content: prompt_text.to_string(),
            description: None,
            argument_hint: None,
        }]);

        type_chars_humanlike(
            &mut composer,
            &[
                '/', 'p', 'r', 'o', 'm', 'p', 't', 's', ':', 'p', 'r', 'i', 'c', 'e', ' ', 'x',
            ],
        );
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        assert_eq!(
            InputResult::Submitted("Cost: $$ and first: x".to_string()),
            result
        );
    }

    #[test]
    fn selecting_custom_prompt_reuses_cached_arguments_join() {
        let prompt_text = "First: $ARGUMENTS\nSecond: $ARGUMENTS";

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        composer.set_custom_prompts(vec![CustomPrompt {
            name: "repeat".to_string(),
            path: "/tmp/repeat.md".to_string().into(),
            content: prompt_text.to_string(),
            description: None,
            argument_hint: None,
        }]);

        type_chars_humanlike(
            &mut composer,
            &[
                '/', 'p', 'r', 'o', 'm', 'p', 't', 's', ':', 'r', 'e', 'p', 'e', 'a', 't', ' ',
                'o', 'n', 'e', ' ', 't', 'w', 'o',
            ],
        );
        let (result, _needs_redraw) =
            composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));

        let expected = "First: one two\nSecond: one two".to_string();
        assert_eq!(InputResult::Submitted(expected), result);
    }

    #[test]
    fn burst_paste_fast_small_buffers_and_flushes_on_stop() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let count = 32;
        for _ in 0..count {
            let _ =
                composer.handle_key_event(KeyEvent::new(KeyCode::Char('a'), KeyModifiers::NONE));
            assert!(
                composer.is_in_paste_burst(),
                "expected active paste burst during fast typing"
            );
            assert!(
                composer.textarea.text().is_empty(),
                "text should not appear during burst"
            );
        }

        assert!(
            composer.textarea.text().is_empty(),
            "text should remain empty until flush"
        );
        std::thread::sleep(ChatComposer::recommended_paste_flush_delay());
        let flushed = composer.flush_paste_burst_if_due();
        assert!(flushed, "expected buffered text to flush after stop");
        assert_eq!(composer.textarea.text(), "a".repeat(count));
        assert!(
            composer.pending_pastes.is_empty(),
            "no placeholder for small burst"
        );
    }

    #[test]
    fn burst_paste_fast_large_inserts_placeholder_on_flush() {
        use crossterm::event::KeyCode;
        use crossterm::event::KeyEvent;
        use crossterm::event::KeyModifiers;

        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let count = LARGE_PASTE_CHAR_THRESHOLD + 1; // > threshold to trigger placeholder
        for _ in 0..count {
            let _ =
                composer.handle_key_event(KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE));
        }

        // Nothing should appear until we stop and flush
        assert!(composer.textarea.text().is_empty());
        std::thread::sleep(ChatComposer::recommended_paste_flush_delay());
        let flushed = composer.flush_paste_burst_if_due();
        assert!(flushed, "expected flush after stopping fast input");

        let expected_placeholder = format!("[Pasted Content {count} chars]");
        assert_eq!(composer.textarea.text(), expected_placeholder);
        assert_eq!(composer.pending_pastes.len(), 1);
        assert_eq!(composer.pending_pastes[0].0, expected_placeholder);
        assert_eq!(composer.pending_pastes[0].1.len(), count);
        assert!(composer.pending_pastes[0].1.chars().all(|c| c == 'x'));
    }

    #[test]
    fn humanlike_typing_1000_chars_appears_live_no_placeholder() {
        let (tx, _rx) = unbounded_channel::<AppEvent>();
        let sender = AppEventSender::new(tx);
        let mut composer = ChatComposer::new(
            true,
            sender,
            false,
            "Ask Codex to do anything".to_string(),
            false,
        );

        let count = LARGE_PASTE_CHAR_THRESHOLD; // 1000 in current config
        let chars: Vec<char> = vec!['z'; count];
        type_chars_humanlike(&mut composer, &chars);

        assert_eq!(composer.textarea.text(), "z".repeat(count));
        assert!(composer.pending_pastes.is_empty());
    }
}