taskers_domain/

model.rs

use std::collections::{BTreeMap, BTreeSet};

use indexmap::IndexMap;
use serde::{Deserialize, Deserializer, Serialize};
use thiserror::Error;
use time::OffsetDateTime;

use crate::{
    AttentionState, Direction, LayoutNode, NotificationId, PaneContainerId, PaneId, PaneTabId,
    PaneTabLayoutNode, SessionId, SignalEvent, SignalKind, SignalPaneMetadata, SplitAxis,
    SurfaceId, WindowId, WorkspaceColumnId, WorkspaceId, WorkspaceWindowId, WorkspaceWindowTabId,
};

pub const SESSION_SCHEMA_VERSION: u32 = 7;
pub const DEFAULT_WORKSPACE_WINDOW_WIDTH: i32 = 1280;
pub const DEFAULT_WORKSPACE_WINDOW_HEIGHT: i32 = 860;
pub const DEFAULT_WORKSPACE_WINDOW_GAP: i32 = 10;
pub const MIN_WORKSPACE_WINDOW_WIDTH: i32 = 480;
pub const MIN_WORKSPACE_WINDOW_HEIGHT: i32 = 420;
pub const KEYBOARD_RESIZE_STEP: i32 = 80;
const WORKSPACE_LOG_RETENTION: usize = 200;

fn split_top_level_extent(extent: i32, min_extent: i32) -> (i32, i32) {
    let extent = extent.max(min_extent);
    if extent < min_extent * 2 {
        return (min_extent, min_extent);
    }

    let retained_extent = (extent + 1) / 2;
    let new_extent = extent - retained_extent;
    (retained_extent.max(min_extent), new_extent.max(min_extent))
}

fn insert_window_relative_to_active(
    workspace: &mut Workspace,
    workspace_window_id: WorkspaceWindowId,
    direction: Direction,
) -> Result<(), DomainError> {
    let (source_column_id, source_column_index, source_window_index) = workspace
        .position_for_window(workspace.active_window)
        .ok_or(DomainError::MissingWorkspaceWindow(workspace.active_window))?;

    match direction {
        Direction::Left | Direction::Right => {
            let source_width = workspace
                .columns
                .get(&source_column_id)
                .map(|column| column.width)
                .expect("active column should exist");
            let (retained_width, new_width) =
                split_top_level_extent(source_width, MIN_WORKSPACE_WINDOW_WIDTH);
            let column = workspace
                .columns
                .get_mut(&source_column_id)
                .expect("active column should exist");
            column.width = retained_width;

            let mut new_column = WorkspaceColumnRecord::new(workspace_window_id);
            new_column.width = new_width;
            let insert_index = if matches!(direction, Direction::Left) {
                source_column_index
            } else {
                source_column_index + 1
            };
            workspace.insert_column_at(insert_index, new_column);
        }
        Direction::Up | Direction::Down => {
            let source_window_height = workspace
                .windows
                .get(&workspace.active_window)
                .map(|window| window.height)
                .ok_or(DomainError::MissingWorkspaceWindow(workspace.active_window))?;
            let (retained_height, new_height) =
                split_top_level_extent(source_window_height, MIN_WORKSPACE_WINDOW_HEIGHT);
            let source_window = workspace
                .windows
                .get_mut(&workspace.active_window)
                .ok_or(DomainError::MissingWorkspaceWindow(workspace.active_window))?;
            source_window.height = retained_height;
            let new_window = workspace
                .windows
                .get_mut(&workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
            new_window.height = new_height;

            let column = workspace
                .columns
                .get_mut(&source_column_id)
                .expect("active column should exist");
            let insert_index = if matches!(direction, Direction::Up) {
                source_window_index
            } else {
                source_window_index + 1
            };
            column
                .window_order
                .insert(insert_index, workspace_window_id);
            column.active_window = workspace_window_id;
        }
    }

    Ok(())
}

#[derive(Debug, Error)]
pub enum DomainError {
    #[error("window {0} was not found")]
    MissingWindow(WindowId),
    #[error("workspace {0} was not found")]
    MissingWorkspace(WorkspaceId),
    #[error("workspace column {0} was not found")]
    MissingWorkspaceColumn(WorkspaceColumnId),
    #[error("workspace window {0} was not found")]
    MissingWorkspaceWindow(WorkspaceWindowId),
    #[error("workspace window tab {0} was not found")]
    MissingWorkspaceWindowTab(WorkspaceWindowTabId),
    #[error("pane container {0} was not found")]
    MissingPaneContainer(PaneContainerId),
    #[error("pane {0} was not found")]
    MissingPane(PaneId),
    #[error("surface {0} was not found")]
    MissingSurface(SurfaceId),
    #[error("workspace {workspace_id} does not contain pane {pane_id}")]
    PaneNotInWorkspace {
        workspace_id: WorkspaceId,
        pane_id: PaneId,
    },
    #[error("workspace {workspace_id} pane {pane_id} does not contain surface {surface_id}")]
    SurfaceNotInPane {
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    },
    #[error("{0}")]
    InvalidOperation(&'static str),
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum PaneKind {
    Terminal,
    Browser,
}

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum BrowserProfileMode {
    #[default]
    PersistentDefault,
    Ephemeral,
}

impl BrowserProfileMode {
    pub fn is_ephemeral(self) -> bool {
        matches!(self, Self::Ephemeral)
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct ProgressState {
    /// Progress as permille (0–1000).
    pub value: u16,
    pub label: Option<String>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum PrStatus {
    Open,
    Draft,
    Merged,
    Closed,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PullRequestState {
    pub number: u32,
    pub title: String,
    pub status: PrStatus,
    pub url: String,
}

#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
pub struct PaneMetadata {
    pub title: Option<String>,
    #[serde(default)]
    pub agent_title: Option<String>,
    pub cwd: Option<String>,
    pub url: Option<String>,
    #[serde(default)]
    pub browser_profile_mode: BrowserProfileMode,
    pub repo_name: Option<String>,
    pub git_branch: Option<String>,
    pub ports: Vec<u16>,
    pub agent_kind: Option<String>,
    #[serde(default)]
    pub agent_active: bool,
    #[serde(default)]
    pub agent_command: Option<String>,
    #[serde(default)]
    pub agent_state: Option<WorkspaceAgentState>,
    #[serde(default)]
    pub latest_agent_message: Option<String>,
    pub last_signal_at: Option<OffsetDateTime>,
    #[serde(default)]
    pub progress: Option<ProgressState>,
    #[serde(default)]
    pub pull_requests: Vec<PullRequestState>,
}

#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
pub struct PaneMetadataPatch {
    pub title: Option<String>,
    pub cwd: Option<String>,
    pub url: Option<String>,
    pub browser_profile_mode: Option<BrowserProfileMode>,
    pub repo_name: Option<String>,
    pub git_branch: Option<String>,
    pub ports: Option<Vec<u16>>,
    pub agent_kind: Option<String>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SurfaceAgentSession {
    pub id: SessionId,
    pub kind: String,
    pub title: String,
    pub state: WorkspaceAgentState,
    pub latest_message: Option<String>,
    pub updated_at: OffsetDateTime,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SurfaceAgentProcess {
    pub id: SessionId,
    pub kind: String,
    pub title: String,
    pub started_at: OffsetDateTime,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct InterruptedAgentResume {
    pub kind: String,
    pub title: String,
    pub command: String,
    pub cwd: Option<String>,
    pub captured_at: OffsetDateTime,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SurfaceRecord {
    pub id: SurfaceId,
    pub kind: PaneKind,
    pub metadata: PaneMetadata,
    #[serde(default)]
    pub agent_process: Option<SurfaceAgentProcess>,
    #[serde(default)]
    pub agent_session: Option<SurfaceAgentSession>,
    pub attention: AttentionState,
    pub session_id: SessionId,
    pub command: Option<Vec<String>>,
    #[serde(default)]
    pub interrupted_agent_resume: Option<InterruptedAgentResume>,
}

impl SurfaceRecord {
    pub fn new(kind: PaneKind) -> Self {
        Self {
            id: SurfaceId::new(),
            kind,
            metadata: PaneMetadata::default(),
            agent_process: None,
            agent_session: None,
            attention: AttentionState::Normal,
            session_id: SessionId::new(),
            command: None,
            interrupted_agent_resume: None,
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PaneRecord {
    pub id: PaneId,
    pub surfaces: IndexMap<SurfaceId, SurfaceRecord>,
    pub active_surface: SurfaceId,
}

impl PaneRecord {
    pub fn new(kind: PaneKind) -> Self {
        let surface = SurfaceRecord::new(kind);
        Self::from_surface(surface)
    }

    fn from_surface(surface: SurfaceRecord) -> Self {
        let active_surface = surface.id;
        let mut surfaces = IndexMap::new();
        surfaces.insert(active_surface, surface);
        Self {
            id: PaneId::new(),
            surfaces,
            active_surface,
        }
    }

    pub fn active_surface(&self) -> Option<&SurfaceRecord> {
        self.surfaces.get(&self.active_surface)
    }

    pub fn active_surface_mut(&mut self) -> Option<&mut SurfaceRecord> {
        self.surfaces.get_mut(&self.active_surface)
    }

    pub fn active_metadata(&self) -> Option<&PaneMetadata> {
        self.active_surface().map(|surface| &surface.metadata)
    }

    pub fn active_metadata_mut(&mut self) -> Option<&mut PaneMetadata> {
        self.active_surface_mut()
            .map(|surface| &mut surface.metadata)
    }

    pub fn active_kind(&self) -> Option<PaneKind> {
        self.active_surface().map(|surface| surface.kind.clone())
    }

    pub fn active_attention(&self) -> AttentionState {
        self.active_surface()
            .map(|surface| surface.attention)
            .unwrap_or(AttentionState::Normal)
    }

    pub fn active_session_id(&self) -> Option<SessionId> {
        self.active_surface().map(|surface| surface.session_id)
    }

    pub fn active_command(&self) -> Option<&[String]> {
        self.active_surface()
            .and_then(|surface| surface.command.as_deref())
    }

    pub fn highest_attention(&self) -> AttentionState {
        self.surfaces
            .values()
            .map(|surface| surface.attention)
            .max_by_key(|attention| attention.rank())
            .unwrap_or(AttentionState::Normal)
    }

    pub fn surface_ids(&self) -> impl Iterator<Item = SurfaceId> + '_ {
        self.surfaces.keys().copied()
    }

    fn insert_surface(&mut self, surface: SurfaceRecord) {
        self.active_surface = surface.id;
        self.surfaces.insert(surface.id, surface);
    }

    fn focus_surface(&mut self, surface_id: SurfaceId) -> bool {
        if self.surfaces.contains_key(&surface_id) {
            self.active_surface = surface_id;
            true
        } else {
            false
        }
    }

    fn move_surface(&mut self, surface_id: SurfaceId, to_index: usize) -> bool {
        let Some(from_index) = self.surfaces.get_index_of(&surface_id) else {
            return false;
        };

        let last_index = self.surfaces.len().saturating_sub(1);
        let target_index = to_index.min(last_index);
        if from_index == target_index {
            return true;
        }

        self.surfaces.move_index(from_index, target_index);
        true
    }

    fn normalize_active_surface(&mut self) {
        if !self.surfaces.contains_key(&self.active_surface) {
            self.active_surface = self
                .surfaces
                .first()
                .map(|(surface_id, _)| *surface_id)
                .expect("pane has at least one surface");
        }
    }

    fn normalize(&mut self) {
        if self.surfaces.is_empty() {
            let replacement = SurfaceRecord::new(PaneKind::Terminal);
            self.active_surface = replacement.id;
            self.surfaces.insert(replacement.id, replacement);
            return;
        }

        self.normalize_active_surface();
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PaneTabRecord {
    pub id: PaneTabId,
    pub layout: PaneTabLayoutNode,
    pub active_pane: PaneId,
}

impl PaneTabRecord {
    fn new(pane_id: PaneId) -> Self {
        Self {
            id: PaneTabId::new(),
            layout: PaneTabLayoutNode::leaf(pane_id),
            active_pane: pane_id,
        }
    }

    fn normalize(&mut self, panes: &IndexMap<PaneId, PaneRecord>) -> bool {
        prune_missing_layout_leaves(&mut self.layout, |pane_id| panes.contains_key(&pane_id));
        if self.layout.leaves().is_empty() {
            return false;
        }
        if !self.layout.contains(self.active_pane) {
            self.active_pane = self
                .layout
                .leaves()
                .into_iter()
                .find(|pane_id| panes.contains_key(pane_id))
                .expect("pane tab retains at least one pane");
        }
        true
    }

    fn contains_pane(&self, pane_id: PaneId) -> bool {
        self.layout.contains(pane_id)
    }

    fn focus_pane(&mut self, pane_id: PaneId) -> bool {
        if self.layout.contains(pane_id) {
            self.active_pane = pane_id;
            true
        } else {
            false
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PaneContainerRecord {
    pub id: PaneContainerId,
    pub tabs: IndexMap<PaneTabId, PaneTabRecord>,
    pub active_tab: PaneTabId,
}

impl PaneContainerRecord {
    fn new(pane_id: PaneId) -> Self {
        let first_tab = PaneTabRecord::new(pane_id);
        let active_tab = first_tab.id;
        let mut tabs = IndexMap::new();
        tabs.insert(active_tab, first_tab);
        Self {
            id: PaneContainerId::new(),
            tabs,
            active_tab,
        }
    }

    pub fn active_tab_record(&self) -> Option<&PaneTabRecord> {
        self.tabs.get(&self.active_tab)
    }

    pub fn active_tab_record_mut(&mut self) -> Option<&mut PaneTabRecord> {
        self.tabs.get_mut(&self.active_tab)
    }

    pub fn active_pane(&self) -> Option<PaneId> {
        self.active_tab_record().map(|tab| tab.active_pane)
    }

    pub fn contains_pane(&self, pane_id: PaneId) -> bool {
        self.tabs.values().any(|tab| tab.contains_pane(pane_id))
    }

    pub fn tab_for_pane(&self, pane_id: PaneId) -> Option<PaneTabId> {
        self.tabs
            .values()
            .find_map(|tab| tab.contains_pane(pane_id).then_some(tab.id))
    }

    pub fn focus_tab(&mut self, tab_id: PaneTabId) -> bool {
        if self.tabs.contains_key(&tab_id) {
            self.active_tab = tab_id;
            true
        } else {
            false
        }
    }

    pub fn focus_pane(&mut self, pane_id: PaneId) -> bool {
        let Some(tab_id) = self.tab_for_pane(pane_id) else {
            return false;
        };
        self.active_tab = tab_id;
        self.tabs
            .get_mut(&tab_id)
            .is_some_and(|tab| tab.focus_pane(pane_id))
    }

    fn insert_tab(&mut self, tab: PaneTabRecord, to_index: usize) {
        let tab_id = tab.id;
        self.tabs.insert(tab_id, tab);
        if self.tabs.len() > 1 {
            let last_index = self.tabs.len() - 1;
            let target_index = to_index.min(last_index);
            self.tabs.move_index(last_index, target_index);
        }
        self.active_tab = tab_id;
    }

    fn move_tab(&mut self, tab_id: PaneTabId, to_index: usize) -> bool {
        let Some(from_index) = self.tabs.get_index_of(&tab_id) else {
            return false;
        };
        let last_index = self.tabs.len().saturating_sub(1);
        let target_index = to_index.min(last_index);
        if from_index == target_index {
            return true;
        }
        self.tabs.move_index(from_index, target_index);
        true
    }

    fn remove_tab(&mut self, tab_id: PaneTabId) -> Option<PaneTabRecord> {
        let removed = self.tabs.shift_remove(&tab_id)?;
        if !self.tabs.contains_key(&self.active_tab)
            && let Some((next_tab_id, _)) = self.tabs.first()
        {
            self.active_tab = *next_tab_id;
        }
        Some(removed)
    }

    fn normalize(&mut self, panes: &IndexMap<PaneId, PaneRecord>) -> bool {
        self.tabs.retain(|_, tab| tab.normalize(panes));
        if self.tabs.is_empty() {
            return false;
        }
        if !self.tabs.contains_key(&self.active_tab)
            && let Some((tab_id, _)) = self.tabs.first()
        {
            self.active_tab = *tab_id;
        }
        true
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct NotificationItem {
    pub id: NotificationId,
    pub pane_id: PaneId,
    pub surface_id: SurfaceId,
    #[serde(default = "default_notification_kind")]
    pub kind: SignalKind,
    pub state: AttentionState,
    #[serde(default)]
    pub title: Option<String>,
    #[serde(default)]
    pub subtitle: Option<String>,
    #[serde(default)]
    pub external_id: Option<String>,
    pub message: String,
    pub created_at: OffsetDateTime,
    #[serde(default)]
    pub read_at: Option<OffsetDateTime>,
    pub cleared_at: Option<OffsetDateTime>,
    #[serde(default = "default_notification_delivery_state")]
    pub desktop_delivery: NotificationDeliveryState,
}

impl NotificationItem {
    pub fn unread(&self) -> bool {
        self.cleared_at.is_none() && self.read_at.is_none()
    }

    pub fn active(&self) -> bool {
        self.cleared_at.is_none()
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceLogEntry {
    #[serde(default)]
    pub source: Option<String>,
    pub message: String,
    pub created_at: OffsetDateTime,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct ActivityItem {
    pub notification_id: NotificationId,
    pub workspace_id: WorkspaceId,
    pub workspace_window_id: Option<WorkspaceWindowId>,
    pub pane_id: PaneId,
    pub surface_id: SurfaceId,
    pub kind: SignalKind,
    pub state: AttentionState,
    pub title: Option<String>,
    pub subtitle: Option<String>,
    pub message: String,
    pub read_at: Option<OffsetDateTime>,
    pub created_at: OffsetDateTime,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum NotificationDeliveryState {
    Pending,
    Shown,
    Suppressed,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum WorkspaceAgentState {
    Working,
    Waiting,
    Completed,
    Failed,
}

impl WorkspaceAgentState {
    pub fn label(self) -> &'static str {
        match self {
            Self::Working => "Working",
            Self::Waiting => "Waiting",
            Self::Completed => "Completed",
            Self::Failed => "Failed",
        }
    }

    fn sort_rank(self) -> u8 {
        match self {
            Self::Waiting => 0,
            Self::Working => 1,
            Self::Failed => 2,
            Self::Completed => 3,
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceAgentSummary {
    pub workspace_window_id: WorkspaceWindowId,
    pub pane_id: PaneId,
    pub surface_id: SurfaceId,
    pub agent_kind: String,
    pub title: Option<String>,
    pub state: WorkspaceAgentState,
    pub last_signal_at: Option<OffsetDateTime>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "scope", rename_all = "snake_case")]
pub enum AgentTarget {
    Workspace {
        workspace_id: WorkspaceId,
    },
    Pane {
        workspace_id: WorkspaceId,
        pane_id: PaneId,
    },
    Surface {
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    },
}

fn default_notification_kind() -> SignalKind {
    SignalKind::Notification
}

fn default_notification_delivery_state() -> NotificationDeliveryState {
    NotificationDeliveryState::Shown
}

#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceViewport {
    #[serde(default)]
    pub x: i32,
    #[serde(default)]
    pub y: i32,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum WorkspaceWindowMoveTarget {
    ColumnBefore { column_id: WorkspaceColumnId },
    ColumnAfter { column_id: WorkspaceColumnId },
    StackAbove { window_id: WorkspaceWindowId },
    StackBelow { window_id: WorkspaceWindowId },
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub struct WindowFrame {
    pub x: i32,
    pub y: i32,
    pub width: i32,
    pub height: i32,
}

impl WindowFrame {
    pub fn root() -> Self {
        Self {
            x: 0,
            y: 0,
            width: DEFAULT_WORKSPACE_WINDOW_WIDTH,
            height: DEFAULT_WORKSPACE_WINDOW_HEIGHT,
        }
    }

    pub fn right(self) -> i32 {
        self.x + self.width
    }

    pub fn bottom(self) -> i32 {
        self.y + self.height
    }

    pub fn center_x(self) -> i32 {
        self.x + (self.width / 2)
    }

    pub fn center_y(self) -> i32 {
        self.y + (self.height / 2)
    }

    pub fn shifted(self, direction: Direction) -> Self {
        match direction {
            Direction::Left => Self {
                x: self.x - self.width - DEFAULT_WORKSPACE_WINDOW_GAP,
                ..self
            },
            Direction::Right => Self {
                x: self.x + self.width + DEFAULT_WORKSPACE_WINDOW_GAP,
                ..self
            },
            Direction::Up => Self {
                y: self.y - self.height - DEFAULT_WORKSPACE_WINDOW_GAP,
                ..self
            },
            Direction::Down => Self {
                y: self.y + self.height + DEFAULT_WORKSPACE_WINDOW_GAP,
                ..self
            },
        }
    }

    pub fn resize_by_direction(&mut self, direction: Direction, amount: i32) {
        match direction {
            Direction::Left => {
                self.width = (self.width - amount).max(MIN_WORKSPACE_WINDOW_WIDTH);
            }
            Direction::Right => {
                self.width = (self.width + amount).max(MIN_WORKSPACE_WINDOW_WIDTH);
            }
            Direction::Up => {
                self.height = (self.height - amount).max(MIN_WORKSPACE_WINDOW_HEIGHT);
            }
            Direction::Down => {
                self.height = (self.height + amount).max(MIN_WORKSPACE_WINDOW_HEIGHT);
            }
        }
    }

    pub fn clamp(&mut self) {
        self.width = self.width.max(MIN_WORKSPACE_WINDOW_WIDTH);
        self.height = self.height.max(MIN_WORKSPACE_WINDOW_HEIGHT);
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceWindowTabRecord {
    pub id: WorkspaceWindowTabId,
    pub layout: LayoutNode,
    pub active_container: PaneContainerId,
    pub active_pane: PaneId,
}

impl WorkspaceWindowTabRecord {
    fn new(container_id: PaneContainerId, pane_id: PaneId) -> Self {
        Self {
            id: WorkspaceWindowTabId::new(),
            layout: LayoutNode::leaf(container_id),
            active_container: container_id,
            active_pane: pane_id,
        }
    }

    fn contains_pane(
        &self,
        pane_containers: &IndexMap<PaneContainerId, PaneContainerRecord>,
        pane_id: PaneId,
    ) -> bool {
        self.layout.leaves().into_iter().any(|container_id| {
            pane_containers
                .get(&container_id)
                .is_some_and(|container| container.contains_pane(pane_id))
        })
    }

    fn container_for_pane(
        &self,
        pane_containers: &IndexMap<PaneContainerId, PaneContainerRecord>,
        pane_id: PaneId,
    ) -> Option<PaneContainerId> {
        self.layout.leaves().into_iter().find(|container_id| {
            pane_containers
                .get(container_id)
                .is_some_and(|container| container.contains_pane(pane_id))
        })
    }

    fn focus_pane(
        &mut self,
        pane_containers: &mut IndexMap<PaneContainerId, PaneContainerRecord>,
        pane_id: PaneId,
    ) -> bool {
        let Some(container_id) = self.container_for_pane(pane_containers, pane_id) else {
            return false;
        };
        let Some(container) = pane_containers.get_mut(&container_id) else {
            return false;
        };
        if !container.focus_pane(pane_id) {
            return false;
        }
        self.active_container = container_id;
        self.active_pane = pane_id;
        true
    }

    fn normalize(
        &mut self,
        pane_containers: &IndexMap<PaneContainerId, PaneContainerRecord>,
    ) -> bool {
        prune_missing_layout_leaves(&mut self.layout, |container_id| {
            pane_containers.contains_key(&container_id)
        });
        if self.layout.leaves().is_empty() {
            return false;
        }
        if !self.layout.contains(self.active_container) {
            self.active_container = self
                .layout
                .leaves()
                .into_iter()
                .find(|container_id| pane_containers.contains_key(container_id))
                .expect("window tab retains at least one pane container");
        }
        if !pane_containers
            .get(&self.active_container)
            .is_some_and(|container| container.contains_pane(self.active_pane))
        {
            self.active_pane = pane_containers
                .get(&self.active_container)
                .and_then(PaneContainerRecord::active_pane)
                .expect("active pane container retains an active pane");
        }
        true
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceWindowRecord {
    pub id: WorkspaceWindowId,
    pub height: i32,
    pub tabs: IndexMap<WorkspaceWindowTabId, WorkspaceWindowTabRecord>,
    pub active_tab: WorkspaceWindowTabId,
}

impl WorkspaceWindowRecord {
    fn new(container_id: PaneContainerId, pane_id: PaneId) -> Self {
        let first_tab = WorkspaceWindowTabRecord::new(container_id, pane_id);
        let active_tab = first_tab.id;
        let mut tabs = IndexMap::new();
        tabs.insert(active_tab, first_tab);
        Self {
            id: WorkspaceWindowId::new(),
            height: DEFAULT_WORKSPACE_WINDOW_HEIGHT,
            tabs,
            active_tab,
        }
    }

    pub fn active_tab_record(&self) -> Option<&WorkspaceWindowTabRecord> {
        self.tabs.get(&self.active_tab)
    }

    pub fn active_tab_record_mut(&mut self) -> Option<&mut WorkspaceWindowTabRecord> {
        self.tabs.get_mut(&self.active_tab)
    }

    pub fn active_pane(&self) -> Option<PaneId> {
        self.active_tab_record().map(|tab| tab.active_pane)
    }

    pub fn active_container(&self) -> Option<PaneContainerId> {
        self.active_tab_record().map(|tab| tab.active_container)
    }

    pub fn active_layout(&self) -> Option<&LayoutNode> {
        self.active_tab_record().map(|tab| &tab.layout)
    }

    pub fn active_layout_mut(&mut self) -> Option<&mut LayoutNode> {
        self.active_tab_record_mut().map(|tab| &mut tab.layout)
    }

    pub fn contains_pane(
        &self,
        pane_containers: &IndexMap<PaneContainerId, PaneContainerRecord>,
        pane_id: PaneId,
    ) -> bool {
        self.tabs
            .values()
            .any(|tab| tab.contains_pane(pane_containers, pane_id))
    }

    pub fn tab_for_pane(
        &self,
        pane_containers: &IndexMap<PaneContainerId, PaneContainerRecord>,
        pane_id: PaneId,
    ) -> Option<WorkspaceWindowTabId> {
        self.tabs.values().find_map(|tab| {
            tab.contains_pane(pane_containers, pane_id)
                .then_some(tab.id)
        })
    }

    pub fn focus_tab(&mut self, tab_id: WorkspaceWindowTabId) -> bool {
        if self.tabs.contains_key(&tab_id) {
            self.active_tab = tab_id;
            true
        } else {
            false
        }
    }

    pub fn focus_pane(
        &mut self,
        pane_containers: &mut IndexMap<PaneContainerId, PaneContainerRecord>,
        pane_id: PaneId,
    ) -> bool {
        let Some(tab_id) = self.tab_for_pane(pane_containers, pane_id) else {
            return false;
        };
        self.active_tab = tab_id;
        self.tabs
            .get_mut(&tab_id)
            .is_some_and(|tab| tab.focus_pane(pane_containers, pane_id))
    }

    fn insert_tab(&mut self, tab: WorkspaceWindowTabRecord, to_index: usize) {
        let tab_id = tab.id;
        self.tabs.insert(tab_id, tab);
        if self.tabs.len() > 1 {
            let last_index = self.tabs.len() - 1;
            let target_index = to_index.min(last_index);
            self.tabs.move_index(last_index, target_index);
        }
        self.active_tab = tab_id;
    }

    fn move_tab(&mut self, tab_id: WorkspaceWindowTabId, to_index: usize) -> bool {
        let Some(from_index) = self.tabs.get_index_of(&tab_id) else {
            return false;
        };
        let last_index = self.tabs.len().saturating_sub(1);
        let target_index = to_index.min(last_index);
        if from_index == target_index {
            return true;
        }
        self.tabs.move_index(from_index, target_index);
        true
    }

    fn remove_tab(&mut self, tab_id: WorkspaceWindowTabId) -> Option<WorkspaceWindowTabRecord> {
        let removed = self.tabs.shift_remove(&tab_id)?;
        if !self.tabs.contains_key(&self.active_tab)
            && let Some((next_tab_id, _)) = self.tabs.first()
        {
            self.active_tab = *next_tab_id;
        }
        Some(removed)
    }

    fn normalize(
        &mut self,
        pane_containers: &IndexMap<PaneContainerId, PaneContainerRecord>,
    ) -> bool {
        self.tabs.retain(|_, tab| tab.normalize(pane_containers));
        if self.tabs.is_empty() {
            return false;
        }
        if !self.tabs.contains_key(&self.active_tab)
            && let Some((tab_id, _)) = self.tabs.first()
        {
            self.active_tab = *tab_id;
        }
        true
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceColumnRecord {
    pub id: WorkspaceColumnId,
    pub width: i32,
    pub window_order: Vec<WorkspaceWindowId>,
    pub active_window: WorkspaceWindowId,
}

impl WorkspaceColumnRecord {
    fn new(window_id: WorkspaceWindowId) -> Self {
        Self {
            id: WorkspaceColumnId::new(),
            width: DEFAULT_WORKSPACE_WINDOW_WIDTH,
            window_order: vec![window_id],
            active_window: window_id,
        }
    }

    fn normalize(&mut self, windows: &IndexMap<WorkspaceWindowId, WorkspaceWindowRecord>) {
        self.width = self.width.max(MIN_WORKSPACE_WINDOW_WIDTH);
        self.window_order
            .retain(|window_id| windows.contains_key(window_id));
        if !self.window_order.contains(&self.active_window)
            && let Some(window_id) = self.window_order.first()
        {
            self.active_window = *window_id;
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
pub struct Workspace {
    pub id: WorkspaceId,
    pub label: String,
    pub columns: IndexMap<WorkspaceColumnId, WorkspaceColumnRecord>,
    pub windows: IndexMap<WorkspaceWindowId, WorkspaceWindowRecord>,
    pub active_window: WorkspaceWindowId,
    pub pane_containers: IndexMap<PaneContainerId, PaneContainerRecord>,
    pub panes: IndexMap<PaneId, PaneRecord>,
    pub active_pane: PaneId,
    #[serde(default)]
    pub viewport: WorkspaceViewport,
    pub notifications: Vec<NotificationItem>,
    #[serde(default)]
    pub status_text: Option<String>,
    #[serde(default)]
    pub progress: Option<ProgressState>,
    #[serde(default)]
    pub log_entries: Vec<WorkspaceLogEntry>,
    #[serde(default)]
    pub surface_flash_tokens: BTreeMap<SurfaceId, u64>,
    #[serde(default)]
    pub next_flash_token: u64,
    #[serde(default)]
    pub custom_color: Option<String>,
}

impl<'de> Deserialize<'de> for Workspace {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        Ok(CurrentWorkspaceSerde::deserialize(deserializer)?.into_workspace())
    }
}

impl Workspace {
    pub fn bootstrap(label: impl Into<String>) -> Self {
        let first_pane = PaneRecord::new(PaneKind::Terminal);
        let active_pane = first_pane.id;
        let mut panes = IndexMap::new();
        panes.insert(active_pane, first_pane);
        let first_container = PaneContainerRecord::new(active_pane);
        let first_container_id = first_container.id;
        let mut pane_containers = IndexMap::new();
        pane_containers.insert(first_container_id, first_container);
        let first_window = WorkspaceWindowRecord::new(first_container_id, active_pane);
        let active_window = first_window.id;
        let mut windows = IndexMap::new();
        windows.insert(active_window, first_window);
        let first_column = WorkspaceColumnRecord::new(active_window);
        let mut columns = IndexMap::new();
        columns.insert(first_column.id, first_column);

        Self {
            id: WorkspaceId::new(),
            label: label.into(),
            columns,
            windows,
            active_window,
            pane_containers,
            panes,
            active_pane,
            viewport: WorkspaceViewport::default(),
            notifications: Vec::new(),
            status_text: None,
            progress: None,
            log_entries: Vec::new(),
            surface_flash_tokens: BTreeMap::new(),
            next_flash_token: 0,
            custom_color: None,
        }
    }

    pub fn active_window_record(&self) -> Option<&WorkspaceWindowRecord> {
        self.windows.get(&self.active_window)
    }

    pub fn active_window_record_mut(&mut self) -> Option<&mut WorkspaceWindowRecord> {
        self.windows.get_mut(&self.active_window)
    }

    pub fn column_for_window(&self, window_id: WorkspaceWindowId) -> Option<WorkspaceColumnId> {
        self.columns.iter().find_map(|(column_id, column)| {
            column
                .window_order
                .contains(&window_id)
                .then_some(*column_id)
        })
    }

    pub fn active_column_id(&self) -> Option<WorkspaceColumnId> {
        self.column_for_window(self.active_window)
    }

    fn position_for_window(
        &self,
        window_id: WorkspaceWindowId,
    ) -> Option<(WorkspaceColumnId, usize, usize)> {
        self.columns
            .iter()
            .enumerate()
            .find_map(|(column_index, (column_id, column))| {
                column
                    .window_order
                    .iter()
                    .position(|candidate| *candidate == window_id)
                    .map(|window_index| (*column_id, column_index, window_index))
            })
    }

    pub fn window_for_pane(&self, pane_id: PaneId) -> Option<WorkspaceWindowId> {
        self.windows.iter().find_map(|(window_id, window)| {
            window
                .contains_pane(&self.pane_containers, pane_id)
                .then_some(*window_id)
        })
    }

    fn pane_location(
        &self,
        pane_id: PaneId,
    ) -> Option<(
        WorkspaceWindowId,
        WorkspaceWindowTabId,
        PaneContainerId,
        PaneTabId,
    )> {
        for (window_id, window) in &self.windows {
            for (window_tab_id, window_tab) in &window.tabs {
                let Some(container_id) =
                    window_tab.container_for_pane(&self.pane_containers, pane_id)
                else {
                    continue;
                };
                let Some(container) = self.pane_containers.get(&container_id) else {
                    continue;
                };
                let Some(pane_tab_id) = container.tab_for_pane(pane_id) else {
                    continue;
                };
                return Some((*window_id, *window_tab_id, container_id, pane_tab_id));
            }
        }
        None
    }

    fn container_location(
        &self,
        container_id: PaneContainerId,
    ) -> Option<(WorkspaceWindowId, WorkspaceWindowTabId)> {
        for (window_id, window) in &self.windows {
            for (window_tab_id, window_tab) in &window.tabs {
                if window_tab.layout.contains(container_id) {
                    return Some((*window_id, *window_tab_id));
                }
            }
        }
        None
    }

    fn sync_active_from_window(&mut self, window_id: WorkspaceWindowId) {
        if let Some(window) = self.windows.get(&window_id) {
            self.active_window = window_id;
            self.active_pane = window.active_pane().unwrap_or(self.active_pane);
            if let Some(column_id) = self.column_for_window(window_id)
                && let Some(column) = self.columns.get_mut(&column_id)
            {
                column.active_window = window_id;
            }
        }
    }

    fn focus_window(&mut self, window_id: WorkspaceWindowId) {
        self.sync_active_from_window(window_id);
    }

    fn focus_pane(&mut self, pane_id: PaneId) -> bool {
        let Some(window_id) = self.window_for_pane(pane_id) else {
            return false;
        };
        if let Some(window) = self.windows.get_mut(&window_id) {
            let _ = window.focus_pane(&mut self.pane_containers, pane_id);
        }
        self.sync_active_from_window(window_id);
        true
    }

    fn focus_surface(&mut self, pane_id: PaneId, surface_id: SurfaceId) -> bool {
        let Some(pane) = self.panes.get_mut(&pane_id) else {
            return false;
        };
        if !pane.focus_surface(surface_id) {
            return false;
        }
        self.focus_pane(pane_id)
    }

    fn acknowledge_pane_notifications(&mut self, pane_id: PaneId) {
        let now = OffsetDateTime::now_utc();
        for notification in &mut self.notifications {
            if notification.pane_id == pane_id
                && notification.active()
                && notification.read_at.is_none()
            {
                notification.read_at = Some(now);
            }
        }
    }

    fn acknowledge_surface_notifications(&mut self, pane_id: PaneId, surface_id: SurfaceId) {
        let now = OffsetDateTime::now_utc();
        for notification in &mut self.notifications {
            if notification.pane_id == pane_id
                && notification.surface_id == surface_id
                && notification.active()
                && notification.read_at.is_none()
            {
                notification.read_at = Some(now);
            }
        }
    }

    fn complete_surface_notifications(&mut self, pane_id: PaneId, surface_id: SurfaceId) {
        let now = OffsetDateTime::now_utc();
        for notification in &mut self.notifications {
            if notification.pane_id == pane_id
                && notification.surface_id == surface_id
                && notification.cleared_at.is_none()
            {
                if notification.read_at.is_none() {
                    notification.read_at = Some(now);
                }
                notification.cleared_at = Some(now);
            }
        }
    }

    fn upsert_notification(&mut self, notification: NotificationItem) {
        if let Some(external_id) = notification.external_id.as_deref()
            && let Some(existing) = self.notifications.iter_mut().rev().find(|existing| {
                existing.external_id.as_deref() == Some(external_id)
                    && existing.surface_id == notification.surface_id
            })
        {
            existing.pane_id = notification.pane_id;
            existing.kind = notification.kind;
            existing.state = notification.state;
            existing.title = notification.title;
            existing.subtitle = notification.subtitle;
            existing.message = notification.message;
            existing.created_at = notification.created_at;
            existing.read_at = None;
            existing.cleared_at = None;
            existing.desktop_delivery = NotificationDeliveryState::Pending;
            return;
        }

        self.notifications.push(notification);
    }

    fn active_surface_for_pane(&self, pane_id: PaneId) -> Option<SurfaceId> {
        self.panes.get(&pane_id).map(|pane| pane.active_surface)
    }

    fn notification_target_ids(
        &self,
        target: &AgentTarget,
    ) -> Result<(WorkspaceId, PaneId, SurfaceId), DomainError> {
        match *target {
            AgentTarget::Workspace { workspace_id } => {
                if workspace_id != self.id {
                    return Err(DomainError::MissingWorkspace(workspace_id));
                }
                let pane_id = self.active_pane;
                let surface_id = self.active_surface_for_pane(pane_id).ok_or(
                    DomainError::PaneNotInWorkspace {
                        workspace_id,
                        pane_id,
                    },
                )?;
                Ok((workspace_id, pane_id, surface_id))
            }
            AgentTarget::Pane {
                workspace_id,
                pane_id,
            } => {
                if workspace_id != self.id {
                    return Err(DomainError::MissingWorkspace(workspace_id));
                }
                let surface_id = self.active_surface_for_pane(pane_id).ok_or(
                    DomainError::PaneNotInWorkspace {
                        workspace_id,
                        pane_id,
                    },
                )?;
                Ok((workspace_id, pane_id, surface_id))
            }
            AgentTarget::Surface {
                workspace_id,
                pane_id,
                surface_id,
            } => {
                if workspace_id != self.id {
                    return Err(DomainError::MissingWorkspace(workspace_id));
                }
                if !self
                    .panes
                    .get(&pane_id)
                    .is_some_and(|pane| pane.surfaces.contains_key(&surface_id))
                {
                    return Err(DomainError::SurfaceNotInPane {
                        workspace_id,
                        pane_id,
                        surface_id,
                    });
                }
                Ok((workspace_id, pane_id, surface_id))
            }
        }
    }

    fn clear_notifications_matching(&mut self, target: &AgentTarget) -> Result<(), DomainError> {
        let now = OffsetDateTime::now_utc();
        let mut cleared_surfaces = Vec::new();
        match *target {
            AgentTarget::Workspace { workspace_id } => {
                if workspace_id != self.id {
                    return Err(DomainError::MissingWorkspace(workspace_id));
                }
                for notification in &mut self.notifications {
                    if notification.cleared_at.is_none() {
                        let target = (notification.pane_id, notification.surface_id);
                        if !cleared_surfaces.contains(&target) {
                            cleared_surfaces.push(target);
                        }
                        if notification.read_at.is_none() {
                            notification.read_at = Some(now);
                        }
                        notification.cleared_at = Some(now);
                    }
                }
            }
            AgentTarget::Pane {
                workspace_id,
                pane_id,
            } => {
                if workspace_id != self.id {
                    return Err(DomainError::MissingWorkspace(workspace_id));
                }
                if !self.panes.contains_key(&pane_id) {
                    return Err(DomainError::PaneNotInWorkspace {
                        workspace_id,
                        pane_id,
                    });
                }
                for notification in &mut self.notifications {
                    if notification.pane_id == pane_id && notification.cleared_at.is_none() {
                        let target = (notification.pane_id, notification.surface_id);
                        if !cleared_surfaces.contains(&target) {
                            cleared_surfaces.push(target);
                        }
                        if notification.read_at.is_none() {
                            notification.read_at = Some(now);
                        }
                        notification.cleared_at = Some(now);
                    }
                }
            }
            AgentTarget::Surface {
                workspace_id,
                pane_id,
                surface_id,
            } => {
                if workspace_id != self.id {
                    return Err(DomainError::MissingWorkspace(workspace_id));
                }
                if !self
                    .panes
                    .get(&pane_id)
                    .is_some_and(|pane| pane.surfaces.contains_key(&surface_id))
                {
                    return Err(DomainError::SurfaceNotInPane {
                        workspace_id,
                        pane_id,
                        surface_id,
                    });
                }
                for notification in &mut self.notifications {
                    if notification.pane_id == pane_id
                        && notification.surface_id == surface_id
                        && notification.cleared_at.is_none()
                    {
                        let target = (notification.pane_id, notification.surface_id);
                        if !cleared_surfaces.contains(&target) {
                            cleared_surfaces.push(target);
                        }
                        if notification.read_at.is_none() {
                            notification.read_at = Some(now);
                        }
                        notification.cleared_at = Some(now);
                    }
                }
            }
        }
        for (pane_id, surface_id) in cleared_surfaces {
            self.sync_surface_attention_with_active_notifications(pane_id, surface_id);
        }
        Ok(())
    }

    fn clear_notification(&mut self, notification_id: NotificationId) -> bool {
        let now = OffsetDateTime::now_utc();
        if let Some(notification) = self.notifications.iter_mut().find(|notification| {
            notification.id == notification_id && notification.cleared_at.is_none()
        }) {
            let pane_id = notification.pane_id;
            let surface_id = notification.surface_id;
            if notification.read_at.is_none() {
                notification.read_at = Some(now);
            }
            notification.cleared_at = Some(now);
            self.sync_surface_attention_with_active_notifications(pane_id, surface_id);
            return true;
        }
        false
    }

    fn sync_surface_attention_with_active_notifications(
        &mut self,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) {
        let next_attention = self
            .notifications
            .iter()
            .filter(|notification| {
                notification.pane_id == pane_id
                    && notification.surface_id == surface_id
                    && notification.active()
            })
            .map(|notification| notification.state)
            .max_by_key(|state| state.rank());

        let Some(surface) = self
            .panes
            .get_mut(&pane_id)
            .and_then(|pane| pane.surfaces.get_mut(&surface_id))
        else {
            return;
        };

        if let Some(attention) = next_attention {
            surface.attention = attention;
            return;
        }

        if matches!(
            surface.attention,
            AttentionState::Completed | AttentionState::WaitingInput | AttentionState::Error
        ) {
            surface.attention = AttentionState::Normal;
        }
    }

    fn notification_target(&self, notification_id: NotificationId) -> Option<(PaneId, SurfaceId)> {
        self.notifications
            .iter()
            .find(|notification| notification.id == notification_id)
            .map(|notification| (notification.pane_id, notification.surface_id))
    }

    fn mark_notification_read(&mut self, notification_id: NotificationId) -> bool {
        let now = OffsetDateTime::now_utc();
        if let Some(notification) = self.notifications.iter_mut().find(|notification| {
            notification.id == notification_id && notification.cleared_at.is_none()
        }) {
            if notification.read_at.is_none() {
                notification.read_at = Some(now);
            }
            return true;
        }
        false
    }

    fn set_notification_delivery(
        &mut self,
        notification_id: NotificationId,
        delivery: NotificationDeliveryState,
    ) -> bool {
        if let Some(notification) = self
            .notifications
            .iter_mut()
            .find(|notification| notification.id == notification_id)
        {
            notification.desktop_delivery = delivery;
            return true;
        }
        false
    }

    fn append_log_entry(&mut self, entry: WorkspaceLogEntry) {
        self.log_entries.push(entry);
        let overflow = self
            .log_entries
            .len()
            .saturating_sub(WORKSPACE_LOG_RETENTION);
        if overflow > 0 {
            self.log_entries.drain(0..overflow);
        }
    }

    fn trigger_surface_flash(&mut self, surface_id: SurfaceId) {
        self.next_flash_token = self.next_flash_token.saturating_add(1);
        self.surface_flash_tokens
            .insert(surface_id, self.next_flash_token);
    }

    fn top_level_neighbor(
        &self,
        source_window_id: WorkspaceWindowId,
        direction: Direction,
    ) -> Option<WorkspaceWindowId> {
        let (_, column_index, window_index) = self.position_for_window(source_window_id)?;
        match direction {
            Direction::Left => column_index
                .checked_sub(1)
                .and_then(|index| self.columns.get_index(index))
                .map(|(_, column)| column.active_window),
            Direction::Right => self
                .columns
                .get_index(column_index + 1)
                .map(|(_, column)| column.active_window),
            Direction::Up => self
                .columns
                .get_index(column_index)
                .and_then(|(_, column)| {
                    window_index
                        .checked_sub(1)
                        .and_then(|index| column.window_order.get(index))
                })
                .copied(),
            Direction::Down => self
                .columns
                .get_index(column_index)
                .and_then(|(_, column)| column.window_order.get(window_index + 1))
                .copied(),
        }
    }

    fn fallback_window_after_close(
        &self,
        source_column_index: usize,
        source_window_index: usize,
        same_column_survived: bool,
    ) -> Option<WorkspaceWindowId> {
        if same_column_survived
            && let Some((_, column)) = self.columns.get_index(source_column_index)
        {
            if let Some(window_id) = column.window_order.get(source_window_index) {
                return Some(*window_id);
            }
            if let Some(window_id) = source_window_index
                .checked_sub(1)
                .and_then(|index| column.window_order.get(index))
            {
                return Some(*window_id);
            }
        }

        let right_column_index = if same_column_survived {
            source_column_index + 1
        } else {
            source_column_index
        };
        if let Some((_, column)) = self.columns.get_index(right_column_index)
            && let Some(window_id) = column.window_order.first()
        {
            return Some(*window_id);
        }

        source_column_index
            .checked_sub(1)
            .and_then(|index| self.columns.get_index(index))
            .and_then(|(_, column)| column.window_order.first())
            .copied()
    }

    fn insert_column_at(&mut self, index: usize, column: WorkspaceColumnRecord) {
        let insert_index = index.min(self.columns.len());
        let mut next = IndexMap::with_capacity(self.columns.len() + 1);
        let mut pending = Some(column);
        for (current_index, (column_id, current_column)) in
            std::mem::take(&mut self.columns).into_iter().enumerate()
        {
            if current_index == insert_index
                && let Some(column) = pending.take()
            {
                next.insert(column.id, column);
            }
            next.insert(column_id, current_column);
        }
        if let Some(column) = pending.take() {
            next.insert(column.id, column);
        }
        self.columns = next;
    }

    fn append_missing_windows_to_columns(&mut self) {
        let assigned = self
            .columns
            .values()
            .flat_map(|column| column.window_order.iter().copied())
            .collect::<BTreeSet<_>>();
        for window_id in self.windows.keys().copied().collect::<Vec<_>>() {
            if assigned.contains(&window_id) {
                continue;
            }
            let column = WorkspaceColumnRecord::new(window_id);
            self.columns.insert(column.id, column);
        }
    }

    fn normalize(&mut self) {
        if self.panes.is_empty() || self.pane_containers.is_empty() {
            let id = self.id;
            let label = self.label.clone();
            *self = Self::bootstrap(label);
            self.id = id;
            return;
        }

        for pane in self.panes.values_mut() {
            pane.normalize();
        }

        self.pane_containers
            .retain(|_, pane_container| pane_container.normalize(&self.panes));

        if self.pane_containers.is_empty() {
            let id = self.id;
            let label = self.label.clone();
            *self = Self::bootstrap(label);
            self.id = id;
            return;
        }

        if self.windows.is_empty() {
            let (fallback_container, fallback_pane) = self
                .pane_containers
                .first()
                .and_then(|(pane_container_id, pane_container)| {
                    pane_container
                        .active_pane()
                        .map(|pane_id| (*pane_container_id, pane_id))
                })
                .expect("workspace has at least one pane container");
            let fallback_window = WorkspaceWindowRecord::new(fallback_container, fallback_pane);
            self.active_window = fallback_window.id;
            self.active_pane = fallback_pane;
            self.windows.insert(fallback_window.id, fallback_window);
        }

        self.windows
            .retain(|_, window| window.normalize(&self.pane_containers));

        for window in self.windows.values_mut() {
            window.height = window.height.max(MIN_WORKSPACE_WINDOW_HEIGHT);
        }

        if self.windows.is_empty() {
            let (fallback_container, fallback_pane) = self
                .pane_containers
                .first()
                .and_then(|(pane_container_id, pane_container)| {
                    pane_container
                        .active_pane()
                        .map(|pane_id| (*pane_container_id, pane_id))
                })
                .expect("workspace has at least one pane container");
            let fallback_window = WorkspaceWindowRecord::new(fallback_container, fallback_pane);
            self.active_window = fallback_window.id;
            self.active_pane = fallback_pane;
            self.windows.insert(fallback_window.id, fallback_window);
        }

        for column in self.columns.values_mut() {
            column.normalize(&self.windows);
        }

        let mut assigned = BTreeSet::new();
        for column in self.columns.values_mut() {
            column
                .window_order
                .retain(|window_id| assigned.insert(*window_id));
            if !column.window_order.contains(&column.active_window)
                && let Some(window_id) = column.window_order.first()
            {
                column.active_window = *window_id;
            }
        }
        self.columns
            .retain(|_, column| !column.window_order.is_empty());
        self.append_missing_windows_to_columns();

        if self.columns.is_empty() {
            let fallback_window_id = self
                .windows
                .first()
                .map(|(window_id, _)| *window_id)
                .expect("workspace has at least one window");
            let column = WorkspaceColumnRecord::new(fallback_window_id);
            self.columns.insert(column.id, column);
        }

        if !self.windows.contains_key(&self.active_window) {
            self.active_window = self
                .columns
                .first()
                .map(|(_, column)| column.active_window)
                .expect("workspace has at least one column");
        }
        if !self
            .windows
            .get(&self.active_window)
            .is_some_and(|window| window.contains_pane(&self.pane_containers, self.active_pane))
        {
            self.active_pane = self
                .windows
                .get(&self.active_window)
                .and_then(WorkspaceWindowRecord::active_pane)
                .expect("active window exists");
        }
        self.sync_active_from_window(self.active_window);
    }

    pub fn repo_hint(&self) -> Option<&str> {
        self.panes.values().find_map(|pane| {
            pane.active_metadata()
                .and_then(|metadata| metadata.repo_name.as_deref())
        })
    }

    pub fn attention_counts(&self) -> BTreeMap<AttentionState, usize> {
        let mut counts = BTreeMap::new();
        for pane in self.panes.values() {
            for surface in pane.surfaces.values() {
                *counts.entry(surface.attention).or_insert(0) += 1;
            }
        }
        counts
    }

    pub fn active_surface_id(&self) -> Option<SurfaceId> {
        self.panes
            .get(&self.active_pane)
            .map(|pane| pane.active_surface)
    }

    pub fn agent_summaries(&self, _now: OffsetDateTime) -> Vec<WorkspaceAgentSummary> {
        let mut summaries = self
            .panes
            .iter()
            .flat_map(|(pane_id, pane)| {
                let workspace_window_id = self.window_for_pane(*pane_id);
                pane.surfaces.values().filter_map(move |surface| {
                    let workspace_window_id = workspace_window_id?;
                    let session = surface.agent_session.as_ref()?;
                    Some(WorkspaceAgentSummary {
                        workspace_window_id,
                        pane_id: *pane_id,
                        surface_id: surface.id,
                        agent_kind: session.kind.clone(),
                        title: Some(session.title.clone()),
                        state: session.state,
                        last_signal_at: Some(session.updated_at),
                    })
                })
            })
            .collect::<Vec<_>>();

        summaries.sort_by(|left, right| {
            left.state
                .sort_rank()
                .cmp(&right.state.sort_rank())
                .then_with(|| right.last_signal_at.cmp(&left.last_signal_at))
                .then_with(|| left.agent_kind.cmp(&right.agent_kind))
                .then_with(|| left.pane_id.cmp(&right.pane_id))
                .then_with(|| left.surface_id.cmp(&right.surface_id))
        });

        summaries
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WorkspaceSummary {
    pub workspace_id: WorkspaceId,
    pub label: String,
    pub active_pane: PaneId,
    pub repo_hint: Option<String>,
    pub agent_summaries: Vec<WorkspaceAgentSummary>,
    pub counts_by_attention: BTreeMap<AttentionState, usize>,
    pub highest_attention: AttentionState,
    pub display_attention: AttentionState,
    pub unread_count: usize,
    pub latest_notification: Option<String>,
    pub status_text: Option<String>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct WindowRecord {
    pub id: WindowId,
    pub workspace_order: Vec<WorkspaceId>,
    pub active_workspace: WorkspaceId,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct AppModel {
    pub active_window: WindowId,
    pub windows: IndexMap<WindowId, WindowRecord>,
    pub workspaces: IndexMap<WorkspaceId, Workspace>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PersistedSession {
    pub schema_version: u32,
    pub captured_at: OffsetDateTime,
    pub model: AppModel,
}

impl AppModel {
    pub fn new(label: impl Into<String>) -> Self {
        let window_id = WindowId::new();
        let workspace = Workspace::bootstrap(label);
        let workspace_id = workspace.id;

        let mut windows = IndexMap::new();
        windows.insert(
            window_id,
            WindowRecord {
                id: window_id,
                workspace_order: vec![workspace_id],
                active_workspace: workspace_id,
            },
        );

        let mut workspaces = IndexMap::new();
        workspaces.insert(workspace_id, workspace);

        Self {
            active_window: window_id,
            windows,
            workspaces,
        }
    }

    pub fn demo() -> Self {
        let mut model = Self::new("Repo A");
        let primary_workspace = model.active_workspace_id().unwrap_or_else(WorkspaceId::new);
        let first_pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .unwrap_or_else(PaneId::new);

        let _ = model.update_pane_metadata(
            first_pane,
            PaneMetadataPatch {
                title: Some("Codex".into()),
                cwd: Some("/home/notes/Projects/taskers".into()),
                url: None,
                browser_profile_mode: None,
                repo_name: Some("taskers".into()),
                git_branch: Some("main".into()),
                ports: Some(vec![3000]),
                agent_kind: Some("codex".into()),
            },
        );
        let _ = model.apply_signal(
            primary_workspace,
            first_pane,
            SignalEvent::new(
                "demo",
                SignalKind::WaitingInput,
                Some("Waiting for review on workspace bootstrap".into()),
            ),
        );

        let second_window_pane = model
            .create_workspace_window(primary_workspace, Direction::Right)
            .unwrap_or(first_pane);
        let _ = model.update_pane_metadata(
            second_window_pane,
            PaneMetadataPatch {
                title: Some("Claude".into()),
                cwd: Some("/home/notes/Projects/taskers".into()),
                url: None,
                browser_profile_mode: None,
                repo_name: Some("taskers".into()),
                git_branch: Some("feature/bootstrap".into()),
                ports: Some(vec![]),
                agent_kind: Some("claude".into()),
            },
        );
        let split_pane = model
            .split_pane(
                primary_workspace,
                Some(second_window_pane),
                SplitAxis::Vertical,
            )
            .unwrap_or(second_window_pane);
        let _ = model.apply_signal(
            primary_workspace,
            split_pane,
            SignalEvent::new(
                "demo",
                SignalKind::Progress,
                Some("Running long task".into()),
            ),
        );

        let second_workspace = model.create_workspace("Docs");
        let second_pane = model
            .workspaces
            .get(&second_workspace)
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .unwrap_or_else(PaneId::new);
        let _ = model.update_pane_metadata(
            second_pane,
            PaneMetadataPatch {
                title: Some("OpenCode".into()),
                cwd: Some("/home/notes/Documents".into()),
                url: None,
                browser_profile_mode: None,
                repo_name: Some("notes".into()),
                git_branch: Some("docs".into()),
                ports: Some(vec![8080, 8081]),
                agent_kind: Some("opencode".into()),
            },
        );
        let _ = model.apply_signal(
            second_workspace,
            second_pane,
            SignalEvent::new(
                "demo",
                SignalKind::Completed,
                Some("Draft completed, ready for merge".into()),
            ),
        );
        let _ = model.switch_workspace(model.active_window, second_workspace);

        model
    }

    pub fn active_window(&self) -> Option<&WindowRecord> {
        self.windows.get(&self.active_window)
    }

    pub fn active_workspace_id(&self) -> Option<WorkspaceId> {
        self.active_window().map(|window| window.active_workspace)
    }

    pub fn active_workspace(&self) -> Option<&Workspace> {
        self.active_workspace_id()
            .and_then(|workspace_id| self.workspaces.get(&workspace_id))
    }

    pub fn create_workspace(&mut self, label: impl Into<String>) -> WorkspaceId {
        let workspace = Workspace::bootstrap(label);
        let workspace_id = workspace.id;
        self.workspaces.insert(workspace_id, workspace);
        if let Some(window) = self.windows.get_mut(&self.active_window) {
            window.workspace_order.push(workspace_id);
            window.active_workspace = workspace_id;
        }
        workspace_id
    }

    pub fn rename_workspace(
        &mut self,
        workspace_id: WorkspaceId,
        label: impl Into<String>,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.label = label.into();
        Ok(())
    }

    pub fn reorder_workspaces(
        &mut self,
        window_id: WindowId,
        new_order: Vec<WorkspaceId>,
    ) -> Result<(), DomainError> {
        let window = self
            .windows
            .get_mut(&window_id)
            .ok_or(DomainError::MissingWindow(window_id))?;
        let existing: std::collections::HashSet<_> =
            window.workspace_order.iter().copied().collect();
        let proposed: std::collections::HashSet<_> = new_order.iter().copied().collect();
        if existing != proposed {
            return Ok(());
        }
        window.workspace_order = new_order;
        Ok(())
    }

    pub fn switch_workspace(
        &mut self,
        window_id: WindowId,
        workspace_id: WorkspaceId,
    ) -> Result<(), DomainError> {
        let window = self
            .windows
            .get_mut(&window_id)
            .ok_or(DomainError::MissingWindow(window_id))?;
        if !window.workspace_order.contains(&workspace_id) {
            return Err(DomainError::MissingWorkspace(workspace_id));
        }
        window.active_workspace = workspace_id;
        Ok(())
    }

    pub fn create_workspace_window(
        &mut self,
        workspace_id: WorkspaceId,
        direction: Direction,
    ) -> Result<PaneId, DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let (new_pane, new_container, new_pane_id, new_container_id) =
            create_pane_container_bundle(PaneKind::Terminal);
        workspace.panes.insert(new_pane_id, new_pane);
        workspace
            .pane_containers
            .insert(new_container_id, new_container);

        let new_window = WorkspaceWindowRecord::new(new_container_id, new_pane_id);
        let new_window_id = new_window.id;
        workspace.windows.insert(new_window_id, new_window);
        insert_window_relative_to_active(workspace, new_window_id, direction)?;

        workspace.sync_active_from_window(new_window_id);

        Ok(new_pane_id)
    }

    pub fn create_workspace_window_tab(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
    ) -> Result<(WorkspaceWindowTabId, PaneId), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        if !workspace.windows.contains_key(&workspace_window_id) {
            return Err(DomainError::MissingWorkspaceWindow(workspace_window_id));
        }

        let (new_pane, new_container, new_pane_id, new_container_id) =
            create_pane_container_bundle(PaneKind::Terminal);
        workspace.panes.insert(new_pane_id, new_pane);
        workspace
            .pane_containers
            .insert(new_container_id, new_container);

        let window = workspace
            .windows
            .get_mut(&workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        let insert_index = window
            .tabs
            .get_index_of(&window.active_tab)
            .map(|index| index + 1)
            .unwrap_or(window.tabs.len());
        let new_tab = WorkspaceWindowTabRecord::new(new_container_id, new_pane_id);
        let new_tab_id = new_tab.id;
        window.insert_tab(new_tab, insert_index);
        workspace.sync_active_from_window(workspace_window_id);

        Ok((new_tab_id, new_pane_id))
    }

    pub fn create_pane_tab(
        &mut self,
        workspace_id: WorkspaceId,
        pane_container_id: PaneContainerId,
        kind: PaneKind,
    ) -> Result<(PaneTabId, PaneId), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let (window_id, window_tab_id) = workspace
            .container_location(pane_container_id)
            .ok_or(DomainError::MissingPane(workspace.active_pane))?;
        let (new_pane, new_pane_tab, new_pane_id, new_pane_tab_id) = create_pane_tab_bundle(kind);
        workspace.panes.insert(new_pane_id, new_pane);

        let container = workspace
            .pane_containers
            .get_mut(&pane_container_id)
            .ok_or(DomainError::MissingPane(workspace.active_pane))?;
        let insert_index = container
            .tabs
            .get_index_of(&container.active_tab)
            .map(|index| index + 1)
            .unwrap_or(container.tabs.len());
        container.insert_tab(new_pane_tab, insert_index);

        if let Some(window) = workspace.windows.get_mut(&window_id)
            && let Some(window_tab) = window.tabs.get_mut(&window_tab_id)
        {
            window_tab.active_container = pane_container_id;
            window_tab.active_pane = new_pane_id;
        }
        workspace.sync_active_from_window(window_id);
        Ok((new_pane_tab_id, new_pane_id))
    }

    pub fn focus_pane_tab(
        &mut self,
        workspace_id: WorkspaceId,
        pane_container_id: PaneContainerId,
        pane_tab_id: PaneTabId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let (window_id, window_tab_id) = workspace
            .container_location(pane_container_id)
            .ok_or(DomainError::MissingPane(workspace.active_pane))?;
        let container = workspace
            .pane_containers
            .get_mut(&pane_container_id)
            .ok_or(DomainError::MissingPane(workspace.active_pane))?;
        let pane_id = container
            .tabs
            .get(&pane_tab_id)
            .map(|pane_tab| pane_tab.active_pane)
            .ok_or(DomainError::MissingPane(workspace.active_pane))?;
        let _ = container.focus_tab(pane_tab_id);
        if let Some(window) = workspace.windows.get_mut(&window_id)
            && let Some(window_tab) = window.tabs.get_mut(&window_tab_id)
        {
            window_tab.active_container = pane_container_id;
            window_tab.active_pane = pane_id;
        }
        workspace.sync_active_from_window(window_id);
        Ok(())
    }

    pub fn move_pane_tab(
        &mut self,
        workspace_id: WorkspaceId,
        pane_container_id: PaneContainerId,
        pane_tab_id: PaneTabId,
        to_index: usize,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let container = workspace
            .pane_containers
            .get_mut(&pane_container_id)
            .ok_or(DomainError::MissingPane(workspace.active_pane))?;
        if !container.move_tab(pane_tab_id, to_index) {
            return Err(DomainError::MissingPane(workspace.active_pane));
        }
        Ok(())
    }

    pub fn transfer_pane_tab(
        &mut self,
        workspace_id: WorkspaceId,
        source_pane_container_id: PaneContainerId,
        pane_tab_id: PaneTabId,
        target_pane_container_id: PaneContainerId,
        to_index: usize,
    ) -> Result<(), DomainError> {
        if source_pane_container_id == target_pane_container_id {
            return self.move_pane_tab(
                workspace_id,
                source_pane_container_id,
                pane_tab_id,
                to_index,
            );
        }

        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let (source_window_id, source_window_tab_id) = workspace
            .container_location(source_pane_container_id)
            .ok_or(DomainError::MissingPaneContainer(source_pane_container_id))?;
        workspace
            .container_location(target_pane_container_id)
            .ok_or(DomainError::MissingPaneContainer(target_pane_container_id))?;

        let moved_tab = {
            let source_container = workspace
                .pane_containers
                .get_mut(&source_pane_container_id)
                .ok_or(DomainError::MissingPaneContainer(source_pane_container_id))?;
            source_container
                .remove_tab(pane_tab_id)
                .ok_or(DomainError::MissingPane(workspace.active_pane))?
        };
        let target_active_pane = moved_tab.active_pane;

        {
            let target_container = workspace
                .pane_containers
                .get_mut(&target_pane_container_id)
                .ok_or(DomainError::MissingPaneContainer(target_pane_container_id))?;
            target_container.insert_tab(moved_tab, to_index);
        }

        if workspace
            .pane_containers
            .get(&source_pane_container_id)
            .is_some_and(|container| container.tabs.is_empty())
        {
            let remove_source_window_tab = workspace
                .windows
                .get(&source_window_id)
                .and_then(|window| window.tabs.get(&source_window_tab_id))
                .is_some_and(|window_tab| window_tab.layout.leaves().len() <= 1);
            if remove_source_window_tab {
                if let Some(source_window) = workspace.windows.get_mut(&source_window_id) {
                    let _ = source_window.remove_tab(source_window_tab_id);
                }
            } else if let Some(source_window) = workspace.windows.get_mut(&source_window_id)
                && let Some(source_window_tab) = source_window.tabs.get_mut(&source_window_tab_id)
            {
                let _ = close_window_tab_container(source_window_tab, source_pane_container_id);
            }
            remove_pane_containers_from_workspace(workspace, &[source_pane_container_id]);
            if workspace
                .windows
                .get(&source_window_id)
                .is_some_and(|window| window.tabs.is_empty())
            {
                let (source_column_id, _source_column_index, source_window_index) = workspace
                    .position_for_window(source_window_id)
                    .ok_or(DomainError::MissingWorkspaceWindow(source_window_id))?;
                let same_column_survived = {
                    let column = workspace
                        .columns
                        .get_mut(&source_column_id)
                        .ok_or(DomainError::MissingWorkspaceColumn(source_column_id))?;
                    column.window_order.remove(source_window_index);
                    if column.window_order.is_empty() {
                        false
                    } else {
                        if !column.window_order.contains(&column.active_window) {
                            let replacement_index =
                                source_window_index.min(column.window_order.len() - 1);
                            column.active_window = column.window_order[replacement_index];
                        }
                        true
                    }
                };
                if !same_column_survived {
                    workspace.columns.shift_remove(&source_column_id);
                }
                workspace.windows.shift_remove(&source_window_id);
            }
        }

        workspace.normalize();
        let _ = workspace.focus_pane(target_active_pane);
        Ok(())
    }

    pub fn close_pane_tab(
        &mut self,
        workspace_id: WorkspaceId,
        pane_container_id: PaneContainerId,
        pane_tab_id: PaneTabId,
    ) -> Result<(), DomainError> {
        let pane_ids = self
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.pane_containers.get(&pane_container_id))
            .and_then(|container| container.tabs.get(&pane_tab_id))
            .map(|pane_tab| pane_tab.layout.leaves())
            .ok_or(DomainError::MissingPane(
                self.workspaces
                    .get(&workspace_id)
                    .map(|workspace| workspace.active_pane)
                    .unwrap_or_default(),
            ))?;

        for pane_id in pane_ids {
            if self
                .workspaces
                .get(&workspace_id)
                .is_some_and(|workspace| workspace.panes.contains_key(&pane_id))
            {
                self.close_pane(workspace_id, pane_id)?;
            }
        }
        Ok(())
    }

    pub fn focus_workspace_window_tab(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
        workspace_window_tab_id: WorkspaceWindowTabId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let window = workspace
            .windows
            .get_mut(&workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        if !window.focus_tab(workspace_window_tab_id) {
            return Err(DomainError::MissingWorkspaceWindowTab(
                workspace_window_tab_id,
            ));
        }
        workspace.sync_active_from_window(workspace_window_id);
        Ok(())
    }

    pub fn move_workspace_window_tab(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
        workspace_window_tab_id: WorkspaceWindowTabId,
        to_index: usize,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let window = workspace
            .windows
            .get_mut(&workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        if !window.move_tab(workspace_window_tab_id, to_index) {
            return Err(DomainError::MissingWorkspaceWindowTab(
                workspace_window_tab_id,
            ));
        }
        workspace.sync_active_from_window(workspace_window_id);
        Ok(())
    }

    pub fn transfer_workspace_window_tab(
        &mut self,
        workspace_id: WorkspaceId,
        source_workspace_window_id: WorkspaceWindowId,
        workspace_window_tab_id: WorkspaceWindowTabId,
        target_workspace_window_id: WorkspaceWindowId,
        to_index: usize,
    ) -> Result<(), DomainError> {
        if source_workspace_window_id == target_workspace_window_id {
            return self.move_workspace_window_tab(
                workspace_id,
                source_workspace_window_id,
                workspace_window_tab_id,
                to_index,
            );
        }

        let (source_column_id, _source_column_index, source_window_index, remove_source_window) = {
            let workspace = self
                .workspaces
                .get(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let source_window = workspace.windows.get(&source_workspace_window_id).ok_or(
                DomainError::MissingWorkspaceWindow(source_workspace_window_id),
            )?;
            if !workspace.windows.contains_key(&target_workspace_window_id) {
                return Err(DomainError::MissingWorkspaceWindow(
                    target_workspace_window_id,
                ));
            }
            if !source_window.tabs.contains_key(&workspace_window_tab_id) {
                return Err(DomainError::MissingWorkspaceWindowTab(
                    workspace_window_tab_id,
                ));
            }
            let (source_column_id, source_column_index, source_window_index) = workspace
                .position_for_window(source_workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(
                    source_workspace_window_id,
                ))?;
            (
                source_column_id,
                source_column_index,
                source_window_index,
                source_window.tabs.len() == 1,
            )
        };

        let moved_tab = {
            let workspace = self
                .workspaces
                .get_mut(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let source_window = workspace
                .windows
                .get_mut(&source_workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(
                    source_workspace_window_id,
                ))?;
            source_window.remove_tab(workspace_window_tab_id).ok_or(
                DomainError::MissingWorkspaceWindowTab(workspace_window_tab_id),
            )?
        };

        if remove_source_window {
            let workspace = self
                .workspaces
                .get_mut(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let same_column_survived = {
                let column = workspace
                    .columns
                    .get_mut(&source_column_id)
                    .ok_or(DomainError::MissingWorkspaceColumn(source_column_id))?;
                column.window_order.remove(source_window_index);
                if column.window_order.is_empty() {
                    false
                } else {
                    if !column.window_order.contains(&column.active_window) {
                        let replacement_index =
                            source_window_index.min(column.window_order.len() - 1);
                        column.active_window = column.window_order[replacement_index];
                    }
                    true
                }
            };
            if !same_column_survived {
                workspace.columns.shift_remove(&source_column_id);
            }
            workspace.windows.shift_remove(&source_workspace_window_id);
        }

        {
            let workspace = self
                .workspaces
                .get_mut(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let target_window = workspace
                .windows
                .get_mut(&target_workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(
                    target_workspace_window_id,
                ))?;
            target_window.insert_tab(moved_tab, to_index);
            workspace.sync_active_from_window(target_workspace_window_id);
        }

        Ok(())
    }

    pub fn extract_workspace_window_tab(
        &mut self,
        workspace_id: WorkspaceId,
        source_workspace_window_id: WorkspaceWindowId,
        workspace_window_tab_id: WorkspaceWindowTabId,
        target: WorkspaceWindowMoveTarget,
    ) -> Result<WorkspaceWindowId, DomainError> {
        let source_tab_count = self
            .workspaces
            .get(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?
            .windows
            .get(&source_workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(
                source_workspace_window_id,
            ))?
            .tabs
            .len();

        if source_tab_count <= 1 {
            self.move_workspace_window(workspace_id, source_workspace_window_id, target)?;
            return Ok(source_workspace_window_id);
        }

        let moved_tab = {
            let workspace = self
                .workspaces
                .get_mut(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let source_window = workspace
                .windows
                .get_mut(&source_workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(
                    source_workspace_window_id,
                ))?;
            source_window.remove_tab(workspace_window_tab_id).ok_or(
                DomainError::MissingWorkspaceWindowTab(workspace_window_tab_id),
            )?
        };

        let new_window_id = {
            let workspace = self
                .workspaces
                .get_mut(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let mut new_window =
                WorkspaceWindowRecord::new(moved_tab.active_container, moved_tab.active_pane);
            new_window.tabs.clear();
            new_window.active_tab = moved_tab.id;
            new_window.tabs.insert(moved_tab.id, moved_tab);
            let new_window_id = new_window.id;
            workspace.windows.insert(new_window_id, new_window);
            insert_window_relative_to_active(workspace, new_window_id, Direction::Right)?;
            workspace.sync_active_from_window(new_window_id);
            new_window_id
        };

        self.move_workspace_window(workspace_id, new_window_id, target)?;
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.sync_active_from_window(new_window_id);
        Ok(new_window_id)
    }

    pub fn close_workspace_window_tab(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
        workspace_window_tab_id: WorkspaceWindowTabId,
    ) -> Result<(), DomainError> {
        let (tab_containers, close_entire_window) = {
            let workspace = self
                .workspaces
                .get(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let window = workspace
                .windows
                .get(&workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
            let tab = window.tabs.get(&workspace_window_tab_id).ok_or(
                DomainError::MissingWorkspaceWindowTab(workspace_window_tab_id),
            )?;
            (tab.layout.leaves(), window.tabs.len() == 1)
        };

        if close_entire_window {
            if self
                .workspaces
                .get(&workspace_id)
                .is_some_and(|workspace| workspace.windows.len() <= 1)
            {
                return self.close_workspace(workspace_id);
            }

            let workspace = self
                .workspaces
                .get_mut(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;
            let (column_id, column_index, window_index) = workspace
                .position_for_window(workspace_window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
            let column = workspace
                .columns
                .get_mut(&column_id)
                .expect("window column should exist");
            column.window_order.remove(window_index);
            let same_column_survived = !column.window_order.is_empty();
            if same_column_survived {
                if !column.window_order.contains(&column.active_window) {
                    let replacement_index = window_index.min(column.window_order.len() - 1);
                    column.active_window = column.window_order[replacement_index];
                }
            } else {
                workspace.columns.shift_remove(&column_id);
            }
            workspace.windows.shift_remove(&workspace_window_id);
            remove_pane_containers_from_workspace(workspace, &tab_containers);
            if let Some(next_window_id) = workspace.fallback_window_after_close(
                column_index,
                window_index,
                same_column_survived,
            ) {
                workspace.sync_active_from_window(next_window_id);
            }
            return Ok(());
        }

        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let active_pane_was_removed = tab_containers.iter().any(|pane_container_id| {
            workspace
                .pane_containers
                .get(pane_container_id)
                .is_some_and(|pane_container| pane_container.contains_pane(workspace.active_pane))
        });
        let window = workspace
            .windows
            .get_mut(&workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        let _ = window.remove_tab(workspace_window_tab_id).ok_or(
            DomainError::MissingWorkspaceWindowTab(workspace_window_tab_id),
        )?;
        remove_pane_containers_from_workspace(workspace, &tab_containers);
        if workspace.active_window == workspace_window_id {
            workspace.sync_active_from_window(workspace_window_id);
        } else if active_pane_was_removed {
            workspace.sync_active_from_window(workspace.active_window);
        }
        Ok(())
    }

    pub fn split_pane(
        &mut self,
        workspace_id: WorkspaceId,
        target_pane: Option<PaneId>,
        axis: SplitAxis,
    ) -> Result<PaneId, DomainError> {
        let direction = match axis {
            SplitAxis::Horizontal => Direction::Right,
            SplitAxis::Vertical => Direction::Down,
        };
        self.split_pane_direction(workspace_id, target_pane, direction)
    }

    pub fn split_pane_direction(
        &mut self,
        workspace_id: WorkspaceId,
        target_pane: Option<PaneId>,
        direction: Direction,
    ) -> Result<PaneId, DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;

        let target = target_pane.unwrap_or(workspace.active_pane);
        if !workspace.panes.contains_key(&target) {
            return Err(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id: target,
            });
        }

        let (window_id, window_tab_id, container_id, pane_tab_id) = workspace
            .pane_location(target)
            .ok_or(DomainError::MissingPane(target))?;
        let new_pane = PaneRecord::new(PaneKind::Terminal);
        let new_pane_id = new_pane.id;
        workspace.panes.insert(new_pane_id, new_pane);

        if let Some(window) = workspace.windows.get_mut(&window_id) {
            let tab = window
                .tabs
                .get_mut(&window_tab_id)
                .ok_or(DomainError::MissingWorkspaceWindowTab(window_tab_id))?;
            let container = workspace
                .pane_containers
                .get_mut(&container_id)
                .ok_or(DomainError::MissingPane(target))?;
            let pane_tab = container
                .tabs
                .get_mut(&pane_tab_id)
                .ok_or(DomainError::MissingPane(target))?;
            let layout = &mut pane_tab.layout;
            layout.split_leaf_with_direction(target, direction, new_pane_id, 500);
            pane_tab.active_pane = new_pane_id;
            container.active_tab = pane_tab_id;
            tab.active_container = container_id;
            tab.active_pane = new_pane_id;
            let _ = window.focus_tab(window_tab_id);
        }
        workspace.sync_active_from_window(window_id);

        Ok(new_pane_id)
    }

    pub fn focus_workspace_window(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        if !workspace.windows.contains_key(&workspace_window_id) {
            return Err(DomainError::MissingWorkspaceWindow(workspace_window_id));
        }
        workspace.focus_window(workspace_window_id);
        Ok(())
    }

    pub fn focus_pane(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;

        if !workspace.panes.contains_key(&pane_id) {
            return Err(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            });
        }

        workspace.focus_pane(pane_id);
        workspace.acknowledge_pane_notifications(pane_id);
        Ok(())
    }

    pub fn acknowledge_pane_notifications(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        if !workspace.panes.contains_key(&pane_id) {
            return Err(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            });
        }
        workspace.acknowledge_pane_notifications(pane_id);
        Ok(())
    }

    pub fn mark_surface_completed(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        let surface = pane
            .surfaces
            .get_mut(&surface_id)
            .ok_or(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            })?;

        surface.agent_process = None;
        surface.agent_session = None;
        surface.attention = AttentionState::Normal;
        surface.metadata.agent_active = false;
        surface.metadata.agent_state = None;
        surface.metadata.last_signal_at = None;
        surface.metadata.agent_title = None;
        surface.metadata.agent_kind = None;
        surface.metadata.latest_agent_message = None;
        workspace.complete_surface_notifications(pane_id, surface_id);
        Ok(())
    }

    pub fn focus_pane_direction(
        &mut self,
        workspace_id: WorkspaceId,
        direction: Direction,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let active_window_id = workspace.active_window;
        let next_pane = workspace.pane_location(workspace.active_pane).and_then(
            |(_, _window_tab_id, container_id, pane_tab_id)| {
                let container = workspace.pane_containers.get(&container_id)?;
                let pane_tab = container.tabs.get(&pane_tab_id)?;
                pane_tab
                    .layout
                    .focus_neighbor(workspace.active_pane, direction)
            },
        );
        if let Some(next_pane) = next_pane {
            workspace.focus_pane(next_pane);
            return Ok(());
        }

        let next_container = workspace.windows.get(&active_window_id).and_then(|window| {
            let active_container = window.active_container()?;
            let tab = window.active_tab_record()?;
            tab.layout.focus_neighbor(active_container, direction)
        });
        if let Some(next_container) = next_container {
            let next_pane = workspace
                .pane_containers
                .get(&next_container)
                .and_then(PaneContainerRecord::active_pane);
            if let Some(next_pane) = next_pane {
                workspace.focus_pane(next_pane);
                return Ok(());
            }
        }

        if let Some(next_window_id) = workspace.top_level_neighbor(active_window_id, direction) {
            workspace.focus_window(next_window_id);
        }

        Ok(())
    }

    pub fn move_workspace_window(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
        target: WorkspaceWindowMoveTarget,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        if !workspace.windows.contains_key(&workspace_window_id) {
            return Err(DomainError::MissingWorkspaceWindow(workspace_window_id));
        }

        let (source_column_id, _source_column_index, source_window_index) = workspace
            .position_for_window(workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        let source_window_count = workspace
            .columns
            .get(&source_column_id)
            .map(|column| column.window_order.len())
            .unwrap_or_default();

        match target {
            WorkspaceWindowMoveTarget::ColumnBefore { column_id }
            | WorkspaceWindowMoveTarget::ColumnAfter { column_id } => {
                let place_after = matches!(target, WorkspaceWindowMoveTarget::ColumnAfter { .. });
                if !workspace.columns.contains_key(&column_id) {
                    return Err(DomainError::MissingWorkspaceColumn(column_id));
                }
                if source_window_count <= 1 {
                    if source_column_id == column_id {
                        workspace.sync_active_from_window(workspace_window_id);
                        return Ok(());
                    }
                    let source_column = workspace
                        .columns
                        .shift_remove(&source_column_id)
                        .ok_or(DomainError::MissingWorkspaceColumn(source_column_id))?;
                    let mut insert_index = workspace
                        .columns
                        .get_index_of(&column_id)
                        .ok_or(DomainError::MissingWorkspaceColumn(column_id))?;
                    if place_after {
                        insert_index += 1;
                    }
                    workspace.insert_column_at(insert_index, source_column);
                } else {
                    remove_window_from_column(workspace, source_column_id, source_window_index)?;
                    let target_width = workspace
                        .columns
                        .get(&column_id)
                        .map(|column| column.width)
                        .ok_or(DomainError::MissingWorkspaceColumn(column_id))?;
                    let (retained_width, new_width) =
                        split_top_level_extent(target_width, MIN_WORKSPACE_WINDOW_WIDTH);
                    let target_column = workspace
                        .columns
                        .get_mut(&column_id)
                        .ok_or(DomainError::MissingWorkspaceColumn(column_id))?;
                    target_column.width = retained_width;

                    let mut new_column = WorkspaceColumnRecord::new(workspace_window_id);
                    new_column.width = new_width;
                    let insert_index = workspace
                        .columns
                        .get_index_of(&column_id)
                        .ok_or(DomainError::MissingWorkspaceColumn(column_id))?;
                    workspace.insert_column_at(
                        if place_after {
                            insert_index + 1
                        } else {
                            insert_index
                        },
                        new_column,
                    );
                }
            }
            WorkspaceWindowMoveTarget::StackAbove { window_id }
            | WorkspaceWindowMoveTarget::StackBelow { window_id } => {
                let place_below = matches!(target, WorkspaceWindowMoveTarget::StackBelow { .. });
                if workspace_window_id == window_id {
                    workspace.sync_active_from_window(workspace_window_id);
                    return Ok(());
                }
                let (target_column_id, _, _) = workspace
                    .position_for_window(window_id)
                    .ok_or(DomainError::MissingWorkspaceWindow(window_id))?;

                remove_window_from_column(workspace, source_column_id, source_window_index)?;
                let (_, _, target_window_index) = workspace
                    .position_for_window(window_id)
                    .ok_or(DomainError::MissingWorkspaceWindow(window_id))?;
                let insert_index = if place_below {
                    target_window_index + 1
                } else {
                    target_window_index
                };
                let target_column = workspace
                    .columns
                    .get_mut(&target_column_id)
                    .ok_or(DomainError::MissingWorkspaceColumn(target_column_id))?;
                target_column
                    .window_order
                    .insert(insert_index, workspace_window_id);
                target_column.active_window = workspace_window_id;
            }
        }

        workspace.normalize();
        workspace.sync_active_from_window(workspace_window_id);
        Ok(())
    }

    pub fn resize_active_window(
        &mut self,
        workspace_id: WorkspaceId,
        direction: Direction,
        amount: i32,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let active_window = workspace.active_window;
        let (column_id, _, _) = workspace
            .position_for_window(active_window)
            .ok_or(DomainError::MissingWorkspaceWindow(active_window))?;
        match direction {
            Direction::Left => {
                let column = workspace
                    .columns
                    .get_mut(&column_id)
                    .ok_or(DomainError::MissingWorkspaceWindow(active_window))?;
                column.width = (column.width - amount).max(MIN_WORKSPACE_WINDOW_WIDTH);
            }
            Direction::Right => {
                let column = workspace
                    .columns
                    .get_mut(&column_id)
                    .ok_or(DomainError::MissingWorkspaceWindow(active_window))?;
                column.width = (column.width + amount).max(MIN_WORKSPACE_WINDOW_WIDTH);
            }
            Direction::Up => {
                let window = workspace
                    .active_window_record_mut()
                    .ok_or(DomainError::MissingWorkspaceWindow(active_window))?;
                window.height = (window.height - amount).max(MIN_WORKSPACE_WINDOW_HEIGHT);
            }
            Direction::Down => {
                let window = workspace
                    .active_window_record_mut()
                    .ok_or(DomainError::MissingWorkspaceWindow(active_window))?;
                window.height = (window.height + amount).max(MIN_WORKSPACE_WINDOW_HEIGHT);
            }
        }
        Ok(())
    }

    pub fn resize_active_pane_split(
        &mut self,
        workspace_id: WorkspaceId,
        direction: Direction,
        amount: i32,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let active_pane = workspace.active_pane;
        let (_, _, container_id, pane_tab_id) = workspace
            .pane_location(active_pane)
            .ok_or(DomainError::MissingPane(active_pane))?;
        let layout = workspace
            .pane_containers
            .get_mut(&container_id)
            .and_then(|container| container.tabs.get_mut(&pane_tab_id))
            .map(|pane_tab| &mut pane_tab.layout)
            .ok_or(DomainError::MissingPane(active_pane))?;
        layout.resize_leaf(active_pane, direction, amount);
        Ok(())
    }

    pub fn set_workspace_column_width(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_column_id: WorkspaceColumnId,
        width: i32,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let column = workspace
            .columns
            .get_mut(&workspace_column_id)
            .ok_or(DomainError::MissingWorkspaceColumn(workspace_column_id))?;
        column.width = width.max(MIN_WORKSPACE_WINDOW_WIDTH);
        Ok(())
    }

    pub fn set_workspace_window_height(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
        height: i32,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let window = workspace
            .windows
            .get_mut(&workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        window.height = height.max(MIN_WORKSPACE_WINDOW_HEIGHT);
        Ok(())
    }

    pub fn set_window_split_ratio(
        &mut self,
        workspace_id: WorkspaceId,
        workspace_window_id: WorkspaceWindowId,
        path: &[bool],
        ratio: u16,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let window = workspace
            .windows
            .get_mut(&workspace_window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        let layout = window
            .active_layout_mut()
            .ok_or(DomainError::MissingWorkspaceWindow(workspace_window_id))?;
        layout.set_ratio_at_path(path, ratio);
        Ok(())
    }

    pub fn set_pane_tab_split_ratio(
        &mut self,
        workspace_id: WorkspaceId,
        pane_container_id: PaneContainerId,
        pane_tab_id: PaneTabId,
        path: &[bool],
        ratio: u16,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane_tab = workspace
            .pane_containers
            .get_mut(&pane_container_id)
            .and_then(|pane_container| pane_container.tabs.get_mut(&pane_tab_id))
            .ok_or(DomainError::MissingPaneContainer(pane_container_id))?;
        pane_tab.layout.set_ratio_at_path(path, ratio);
        Ok(())
    }

    pub fn set_workspace_viewport(
        &mut self,
        workspace_id: WorkspaceId,
        viewport: WorkspaceViewport,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.viewport = viewport;
        Ok(())
    }

    pub fn update_pane_metadata(
        &mut self,
        pane_id: PaneId,
        patch: PaneMetadataPatch,
    ) -> Result<(), DomainError> {
        let surface_id = self
            .workspaces
            .values()
            .find_map(|workspace| {
                workspace
                    .panes
                    .get(&pane_id)
                    .map(|pane| pane.active_surface)
            })
            .ok_or(DomainError::MissingPane(pane_id))?;
        self.update_surface_metadata(surface_id, patch)
    }

    pub fn update_surface_metadata(
        &mut self,
        surface_id: SurfaceId,
        patch: PaneMetadataPatch,
    ) -> Result<(), DomainError> {
        let pane = self
            .workspaces
            .values_mut()
            .find_map(|workspace| {
                workspace
                    .panes
                    .values_mut()
                    .find(|pane| pane.surfaces.contains_key(&surface_id))
            })
            .ok_or(DomainError::MissingSurface(surface_id))?;
        let surface = pane
            .surfaces
            .get_mut(&surface_id)
            .ok_or(DomainError::MissingSurface(surface_id))?;

        if patch.title.is_some() {
            surface.metadata.title = patch.title;
        }
        if patch.cwd.is_some() {
            surface.metadata.cwd = patch.cwd;
        }
        if patch.url.is_some() {
            surface.metadata.url = patch.url;
        }
        if let Some(browser_profile_mode) = patch.browser_profile_mode {
            surface.metadata.browser_profile_mode = browser_profile_mode;
        }
        if patch.repo_name.is_some() {
            surface.metadata.repo_name = patch.repo_name;
        }
        if patch.git_branch.is_some() {
            surface.metadata.git_branch = patch.git_branch;
        }
        if let Some(ports) = patch.ports {
            surface.metadata.ports = ports;
        }
        if patch.agent_kind.is_some() {
            surface.metadata.agent_kind = patch.agent_kind;
        }

        Ok(())
    }

    pub fn apply_signal(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        event: SignalEvent,
    ) -> Result<(), DomainError> {
        let surface_id = self
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        self.apply_surface_signal(workspace_id, pane_id, surface_id, event)
    }

    pub fn apply_surface_signal(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
        event: SignalEvent,
    ) -> Result<(), DomainError> {
        let SignalEvent {
            source,
            kind,
            message,
            metadata,
            timestamp,
        } = event;
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        let surface = pane
            .surfaces
            .get_mut(&surface_id)
            .ok_or(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            })?;

        let agent_signal = is_agent_signal(surface, &source, metadata.as_ref());
        let normalized_message = normalized_signal_message(message.as_deref());
        let metadata_reported_inactive = metadata
            .as_ref()
            .and_then(|metadata| metadata.agent_active)
            .is_some_and(|active| !active);
        let metadata_clears_agent_identity =
            matches!(kind, SignalKind::Metadata) && metadata_reported_inactive;
        let (surface_attention, should_acknowledge_surface_notifications) = {
            let mut acknowledged_inactive_resolution = false;
            if agent_signal && matches!(kind, SignalKind::Started) {
                surface.metadata.latest_agent_message = None;
            }
            if let Some(metadata) = metadata.as_ref() {
                surface.metadata.title = metadata.title.clone();
                surface.metadata.agent_title = metadata.agent_title.clone();
                surface.metadata.cwd = metadata.cwd.clone();
                surface.metadata.repo_name = metadata.repo_name.clone();
                surface.metadata.git_branch = metadata.git_branch.clone();
                surface.metadata.ports = metadata.ports.clone();
                surface.metadata.agent_kind = normalized_agent_kind(metadata.agent_kind.as_deref());
                surface.metadata.agent_command =
                    normalized_agent_command(metadata.agent_command.as_deref());
                if let Some(agent_active) = metadata.agent_active {
                    surface.metadata.agent_active = agent_active;
                }
                if metadata_clears_agent_identity {
                    surface.agent_process = None;
                    surface.agent_session = None;
                    surface.metadata.agent_state = None;
                    surface.metadata.agent_command = None;
                    surface.metadata.latest_agent_message = None;
                    surface.metadata.last_signal_at = None;
                    surface.attention = AttentionState::Normal;
                    acknowledged_inactive_resolution = true;
                }
            }
            if agent_signal {
                let agent_identity = agent_identity_for_surface(surface, metadata.as_ref());
                if let Some(agent_state) = signal_agent_state(&kind) {
                    surface.metadata.agent_state = Some(agent_state);
                    match kind {
                        SignalKind::Started | SignalKind::Progress => {
                            if let Some((agent_kind, title)) = agent_identity.clone() {
                                set_agent_turn(
                                    surface,
                                    agent_kind,
                                    title,
                                    WorkspaceAgentState::Working,
                                    normalized_message.clone(),
                                    timestamp,
                                );
                            }
                        }
                        SignalKind::WaitingInput | SignalKind::Notification => {
                            if (surface.agent_process.is_some() || surface.agent_session.is_some())
                                && let Some((agent_kind, title)) = agent_identity.clone()
                            {
                                set_agent_turn(
                                    surface,
                                    agent_kind,
                                    title,
                                    WorkspaceAgentState::Waiting,
                                    normalized_message.clone(),
                                    timestamp,
                                );
                            }
                        }
                        SignalKind::Completed | SignalKind::Error => {
                            let session_state = match kind {
                                SignalKind::Completed => WorkspaceAgentState::Completed,
                                SignalKind::Error => WorkspaceAgentState::Failed,
                                _ => unreachable!("only completed/error reach this branch"),
                            };
                            let session_message = normalized_message
                                .clone()
                                .or_else(|| surface.metadata.latest_agent_message.clone());
                            if let Some((agent_kind, title)) = agent_identity.clone() {
                                set_agent_turn(
                                    surface,
                                    agent_kind,
                                    title,
                                    session_state,
                                    session_message,
                                    timestamp,
                                );
                            }
                        }
                        SignalKind::Metadata => {}
                    }
                }
                if let Some(message) = normalized_message.as_ref() {
                    surface.metadata.latest_agent_message = Some(message.clone());
                }
            }
            if !matches!(kind, SignalKind::Metadata) {
                surface.metadata.last_signal_at = Some(timestamp);
                surface.attention = map_signal_to_attention(&kind);
                if let Some(agent_active) = signal_agent_active(&kind) {
                    surface.metadata.agent_active = agent_active;
                }
            } else if metadata_reported_inactive
                && (surface.agent_process.is_some() || surface.agent_session.is_some())
            {
                surface.agent_process = None;
                surface.agent_session = None;
                surface.attention = AttentionState::Normal;
                surface.metadata.agent_command = None;
                surface.metadata.agent_state = None;
                surface.metadata.latest_agent_message = None;
                surface.metadata.last_signal_at = None;
                acknowledged_inactive_resolution = true;
            }

            (surface.attention, acknowledged_inactive_resolution)
        };
        let notification_title = surface_notification_title(surface);
        let notification_message = if signal_creates_notification(&source, &kind) {
            notification_message_for_signal(&kind, normalized_message, &notification_title, surface)
        } else {
            None
        };

        if should_acknowledge_surface_notifications {
            workspace.complete_surface_notifications(pane_id, surface_id);
        }

        if let Some(message) = notification_message {
            workspace.upsert_notification(NotificationItem {
                id: NotificationId::new(),
                pane_id,
                surface_id,
                kind,
                state: surface_attention,
                title: notification_title,
                subtitle: None,
                external_id: None,
                message,
                created_at: timestamp,
                read_at: None,
                cleared_at: None,
                desktop_delivery: NotificationDeliveryState::Pending,
            });
        }

        Ok(())
    }

    pub fn create_surface(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        kind: PaneKind,
    ) -> Result<SurfaceId, DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        let surface = SurfaceRecord::new(kind);
        let surface_id = surface.id;
        pane.insert_surface(surface);
        workspace.focus_pane(pane_id);
        Ok(surface_id)
    }

    pub fn focus_surface(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        if !workspace.focus_surface(pane_id, surface_id) {
            return Err(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            });
        }
        workspace.acknowledge_surface_notifications(pane_id, surface_id);
        Ok(())
    }

    pub fn set_workspace_status(
        &mut self,
        workspace_id: WorkspaceId,
        text: String,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let normalized = text.trim();
        workspace.status_text = (!normalized.is_empty()).then(|| normalized.to_owned());
        Ok(())
    }

    pub fn clear_workspace_status(&mut self, workspace_id: WorkspaceId) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.status_text = None;
        Ok(())
    }

    pub fn set_workspace_progress(
        &mut self,
        workspace_id: WorkspaceId,
        progress: ProgressState,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.progress = Some(ProgressState {
            value: progress.value.min(1000),
            label: progress.label,
        });
        Ok(())
    }

    pub fn clear_workspace_progress(
        &mut self,
        workspace_id: WorkspaceId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.progress = None;
        Ok(())
    }

    pub fn append_workspace_log(
        &mut self,
        workspace_id: WorkspaceId,
        entry: WorkspaceLogEntry,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.append_log_entry(entry);
        Ok(())
    }

    pub fn clear_workspace_log(&mut self, workspace_id: WorkspaceId) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.log_entries.clear();
        Ok(())
    }

    pub fn create_agent_notification(
        &mut self,
        target: AgentTarget,
        kind: SignalKind,
        title: Option<String>,
        subtitle: Option<String>,
        external_id: Option<String>,
        message: String,
        state: AttentionState,
    ) -> Result<(), DomainError> {
        let workspace_id = match target {
            AgentTarget::Workspace { workspace_id }
            | AgentTarget::Pane { workspace_id, .. }
            | AgentTarget::Surface { workspace_id, .. } => workspace_id,
        };
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let (_, pane_id, surface_id) = workspace.notification_target_ids(&target)?;
        let now = OffsetDateTime::now_utc();
        let normalized_title = title
            .map(|value| value.trim().to_owned())
            .filter(|value| !value.is_empty());
        let normalized_subtitle = subtitle
            .map(|value| value.trim().to_owned())
            .filter(|value| !value.is_empty());
        let normalized_external_id = external_id
            .map(|value| value.trim().to_owned())
            .filter(|value| !value.is_empty());

        if let Some(pane) = workspace.panes.get_mut(&pane_id)
            && let Some(surface) = pane.surfaces.get_mut(&surface_id)
        {
            let normalized_kind = normalized_title
                .as_deref()
                .and_then(|title| normalized_agent_kind(Some(title)));
            match state {
                AttentionState::Busy | AttentionState::WaitingInput => {
                    surface.attention = state;
                }
                AttentionState::Normal | AttentionState::Completed | AttentionState::Error => {
                    surface.attention = state;
                }
            }
            surface.metadata.last_signal_at = Some(now);
            surface.metadata.agent_state =
                surface.agent_session.as_ref().map(|session| session.state);
            surface.metadata.agent_active = surface.agent_process.is_some();
            surface.metadata.latest_agent_message = Some(message.clone());
            if let Some(agent_title) = normalized_title.clone() {
                surface.metadata.agent_title = Some(agent_title.clone());
                if let Some(agent_kind) = normalized_kind {
                    surface.metadata.agent_kind = Some(agent_kind);
                }
            }
        }

        workspace.upsert_notification(NotificationItem {
            id: NotificationId::new(),
            pane_id,
            surface_id,
            kind,
            state,
            title: normalized_title,
            subtitle: normalized_subtitle,
            external_id: normalized_external_id,
            message,
            created_at: now,
            read_at: None,
            cleared_at: None,
            desktop_delivery: NotificationDeliveryState::Pending,
        });
        Ok(())
    }

    pub fn clear_agent_notifications(&mut self, target: AgentTarget) -> Result<(), DomainError> {
        let workspace_id = match target {
            AgentTarget::Workspace { workspace_id }
            | AgentTarget::Pane { workspace_id, .. }
            | AgentTarget::Surface { workspace_id, .. } => workspace_id,
        };
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.clear_notifications_matching(&target)
    }

    pub fn start_surface_agent_session(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
        agent_kind: String,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let surface = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?
            .surfaces
            .get_mut(&surface_id)
            .ok_or(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            })?;

        let normalized_kind = normalized_agent_kind(Some(agent_kind.as_str()))
            .ok_or(DomainError::InvalidOperation("invalid agent kind"))?;
        let now = OffsetDateTime::now_utc();
        surface.agent_process = Some(SurfaceAgentProcess {
            id: SessionId::new(),
            kind: normalized_kind.clone(),
            title: agent_display_title(&normalized_kind),
            started_at: now,
        });
        surface.agent_session = None;
        surface.attention = AttentionState::Normal;
        surface.metadata.agent_kind = Some(normalized_kind);
        surface.metadata.agent_title = surface
            .agent_process
            .as_ref()
            .map(|process| process.title.clone());
        surface.metadata.agent_active = true;
        surface.metadata.agent_state = None;
        surface.metadata.latest_agent_message = None;
        surface.metadata.last_signal_at = None;

        Ok(())
    }

    pub fn stop_surface_agent_session(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
        exit_status: i32,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let title = {
            let surface = workspace
                .panes
                .get_mut(&pane_id)
                .ok_or(DomainError::PaneNotInWorkspace {
                    workspace_id,
                    pane_id,
                })?
                .surfaces
                .get_mut(&surface_id)
                .ok_or(DomainError::SurfaceNotInPane {
                    workspace_id,
                    pane_id,
                    surface_id,
                })?;

            let title = surface
                .agent_process
                .as_ref()
                .map(|process| process.title.clone())
                .or_else(|| {
                    surface
                        .agent_session
                        .as_ref()
                        .map(|session| session.title.clone())
                });
            surface.agent_process = None;
            surface.agent_session = None;
            surface.attention = AttentionState::Normal;
            surface.metadata.agent_active = false;
            surface.metadata.agent_command = None;
            surface.metadata.agent_state = None;
            surface.metadata.agent_title = None;
            surface.metadata.agent_kind = None;
            surface.metadata.latest_agent_message = None;
            surface.metadata.last_signal_at = None;
            title
        };

        if exit_status != 0 && exit_status != 130 {
            workspace.upsert_notification(NotificationItem {
                id: NotificationId::new(),
                pane_id,
                surface_id,
                kind: SignalKind::Error,
                state: AttentionState::Error,
                title,
                subtitle: None,
                external_id: None,
                message: format!("Exited with status {exit_status}"),
                created_at: OffsetDateTime::now_utc(),
                read_at: None,
                cleared_at: None,
                desktop_delivery: NotificationDeliveryState::Pending,
            });
            if let Some(surface) = workspace
                .panes
                .get_mut(&pane_id)
                .and_then(|pane| pane.surfaces.get_mut(&surface_id))
            {
                surface.attention = AttentionState::Error;
            }
        }

        Ok(())
    }

    pub fn dismiss_surface_alert(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        workspace.clear_notifications_matching(&AgentTarget::Surface {
            workspace_id,
            pane_id,
            surface_id,
        })?;

        let surface = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?
            .surfaces
            .get_mut(&surface_id)
            .ok_or(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            })?;

        surface.agent_session = None;
        surface.attention = AttentionState::Normal;
        surface.metadata.agent_active = surface.agent_process.is_some();
        surface.metadata.agent_command = None;
        surface.metadata.agent_state = None;
        if surface.agent_process.is_none() {
            surface.metadata.agent_title = None;
            surface.metadata.agent_kind = None;
        }
        surface.metadata.latest_agent_message = None;
        surface.metadata.last_signal_at = None;

        Ok(())
    }

    pub fn recover_interrupted_agent_resumes(&mut self) -> usize {
        self.recover_interrupted_agent_resumes_for_missing_sessions(|_| false)
    }

    pub fn recover_interrupted_agent_resumes_for_missing_sessions<F>(
        &mut self,
        session_exists: F,
    ) -> usize
    where
        F: Fn(SessionId) -> bool,
    {
        let mut recovered = 0;

        for workspace in self.workspaces.values_mut() {
            let mut pending_notifications = Vec::new();
            for pane in workspace.panes.values_mut() {
                for surface in pane.surfaces.values_mut() {
                    if surface.kind != PaneKind::Terminal {
                        continue;
                    }
                    if surface.interrupted_agent_resume.is_some() {
                        continue;
                    }
                    if session_exists(surface.session_id) {
                        continue;
                    }

                    let process = surface.agent_process.as_ref().cloned();
                    let session = surface.agent_session.as_ref().cloned();
                    if process.is_none() && session.is_none() {
                        continue;
                    }

                    let agent_kind = process
                        .as_ref()
                        .map(|value| value.kind.clone())
                        .or_else(|| session.as_ref().map(|value| value.kind.clone()));
                    let agent_title = process
                        .as_ref()
                        .map(|value| value.title.clone())
                        .or_else(|| session.as_ref().map(|value| value.title.clone()))
                        .or_else(|| surface.metadata.agent_title.clone());
                    let captured_at = process
                        .as_ref()
                        .map(|value| value.started_at)
                        .or_else(|| session.as_ref().map(|value| value.updated_at))
                        .unwrap_or_else(OffsetDateTime::now_utc);
                    let command =
                        normalized_agent_command(surface.metadata.agent_command.as_deref());

                    surface.agent_process = None;
                    surface.agent_session = None;
                    surface.metadata.agent_active = false;
                    surface.metadata.agent_state = None;
                    surface.metadata.latest_agent_message = None;
                    surface.metadata.last_signal_at = None;
                    surface.attention = AttentionState::Normal;

                    let Some(command) = command else {
                        surface.metadata.agent_command = None;
                        surface.metadata.agent_title = None;
                        surface.metadata.agent_kind = None;
                        continue;
                    };
                    let Some(kind) = agent_kind else {
                        surface.metadata.agent_command = None;
                        surface.metadata.agent_title = None;
                        surface.metadata.agent_kind = None;
                        continue;
                    };

                    let title = agent_title.unwrap_or_else(|| agent_display_title(&kind));
                    surface.metadata.agent_kind = Some(kind.clone());
                    surface.metadata.agent_title = Some(title.clone());
                    surface.metadata.agent_command = Some(command.clone());
                    surface.attention = AttentionState::WaitingInput;
                    surface.interrupted_agent_resume = Some(InterruptedAgentResume {
                        kind: kind.clone(),
                        title: title.clone(),
                        command,
                        cwd: surface.metadata.cwd.clone(),
                        captured_at,
                    });
                    pending_notifications.push(NotificationItem {
                        id: NotificationId::new(),
                        pane_id: pane.id,
                        surface_id: surface.id,
                        kind: SignalKind::WaitingInput,
                        state: AttentionState::WaitingInput,
                        title: Some(title),
                        subtitle: Some("Interrupted agent".into()),
                        external_id: Some(interrupted_agent_resume_external_id(surface.id)),
                        message:
                            "Taskers closed while this agent was still running. Open the pane to run it again."
                                .into(),
                        created_at: OffsetDateTime::now_utc(),
                        read_at: None,
                        cleared_at: None,
                        desktop_delivery: NotificationDeliveryState::Pending,
                    });
                    recovered += 1;
                }
            }
            for notification in pending_notifications {
                workspace.upsert_notification(notification);
            }
        }

        recovered
    }

    pub fn dismiss_interrupted_agent_resume(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        let surface = pane
            .surfaces
            .get_mut(&surface_id)
            .ok_or(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            })?;

        surface.interrupted_agent_resume = None;
        surface.metadata.agent_command = None;
        surface.metadata.agent_title = None;
        surface.metadata.agent_kind = None;
        surface.attention = AttentionState::Normal;
        workspace.notifications.retain(|item| {
            item.external_id.as_deref()
                != Some(interrupted_agent_resume_external_id(surface_id).as_str())
        });
        Ok(())
    }

    pub fn clear_notification(
        &mut self,
        notification_id: NotificationId,
    ) -> Result<(), DomainError> {
        for workspace in self.workspaces.values_mut() {
            if workspace.clear_notification(notification_id) {
                return Ok(());
            }
        }
        Err(DomainError::InvalidOperation("notification not found"))
    }

    pub fn mark_notification_delivery(
        &mut self,
        notification_id: NotificationId,
        delivery: NotificationDeliveryState,
    ) -> Result<(), DomainError> {
        for workspace in self.workspaces.values_mut() {
            if workspace.set_notification_delivery(notification_id, delivery) {
                return Ok(());
            }
        }
        Err(DomainError::InvalidOperation("notification not found"))
    }

    pub fn trigger_surface_flash(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        if !workspace
            .panes
            .get(&pane_id)
            .is_some_and(|pane| pane.surfaces.contains_key(&surface_id))
        {
            return Err(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            });
        }
        workspace.trigger_surface_flash(surface_id);
        Ok(())
    }

    pub fn focus_latest_unread(&mut self, window_id: WindowId) -> Result<bool, DomainError> {
        let window = self
            .windows
            .get(&window_id)
            .ok_or(DomainError::MissingWindow(window_id))?;
        let target = window
            .workspace_order
            .iter()
            .filter_map(|workspace_id| self.workspaces.get(workspace_id))
            .flat_map(|workspace| {
                workspace
                    .notifications
                    .iter()
                    .filter(|notification| notification.unread())
                    .map(move |notification| (workspace.id, notification))
            })
            .max_by_key(|(_, notification)| notification.created_at)
            .map(|(_, notification)| notification.id);

        let Some(notification_id) = target else {
            return Ok(false);
        };

        self.open_notification(window_id, notification_id)?;
        Ok(true)
    }

    pub fn open_notification(
        &mut self,
        window_id: WindowId,
        notification_id: NotificationId,
    ) -> Result<(), DomainError> {
        let mut target = None;
        for workspace in self.workspaces.values() {
            if let Some((pane_id, surface_id)) = workspace.notification_target(notification_id) {
                target = Some((workspace.id, pane_id, surface_id));
                break;
            }
        }

        let (workspace_id, pane_id, surface_id) =
            target.ok_or(DomainError::InvalidOperation("notification not found"))?;
        self.switch_workspace(window_id, workspace_id)?;
        self.focus_surface(workspace_id, pane_id, surface_id)?;

        for workspace in self.workspaces.values_mut() {
            if workspace.mark_notification_read(notification_id) {
                return Ok(());
            }
        }

        Err(DomainError::InvalidOperation("notification not found"))
    }

    pub fn close_surface(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<(), DomainError> {
        let close_entire_pane = self
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?
            .surfaces
            .len()
            <= 1;

        if close_entire_pane {
            return self.close_pane(workspace_id, pane_id);
        }

        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        if pane.surfaces.shift_remove(&surface_id).is_none() {
            return Err(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            });
        }
        pane.normalize();
        workspace
            .notifications
            .retain(|item| item.surface_id != surface_id);
        if workspace.active_pane == pane_id {
            workspace.acknowledge_pane_notifications(pane_id);
        }
        Ok(())
    }

    pub fn move_surface(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
        to_index: usize,
    ) -> Result<(), DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let pane = workspace
            .panes
            .get_mut(&pane_id)
            .ok_or(DomainError::PaneNotInWorkspace {
                workspace_id,
                pane_id,
            })?;
        if !pane.move_surface(surface_id, to_index) {
            return Err(DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            });
        }
        Ok(())
    }

    fn take_surface_from_pane(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
        surface_id: SurfaceId,
    ) -> Result<SurfaceRecord, DomainError> {
        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let source_pane =
            workspace
                .panes
                .get_mut(&pane_id)
                .ok_or(DomainError::PaneNotInWorkspace {
                    workspace_id,
                    pane_id,
                })?;
        let moved_surface = source_pane.surfaces.shift_remove(&surface_id).ok_or(
            DomainError::SurfaceNotInPane {
                workspace_id,
                pane_id,
                surface_id,
            },
        )?;
        if !source_pane.surfaces.is_empty() {
            source_pane.normalize_active_surface();
        }
        Ok(moved_surface)
    }

    fn should_close_source_pane(&self, workspace_id: WorkspaceId, pane_id: PaneId) -> bool {
        self.workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .is_some_and(|pane| pane.surfaces.is_empty())
    }

    fn retarget_surface_state(
        &mut self,
        source_workspace_id: WorkspaceId,
        target_workspace_id: WorkspaceId,
        surface_id: SurfaceId,
        target_pane_id: PaneId,
    ) -> Result<(), DomainError> {
        if source_workspace_id == target_workspace_id {
            let workspace = self
                .workspaces
                .get_mut(&source_workspace_id)
                .ok_or(DomainError::MissingWorkspace(source_workspace_id))?;
            for notification in &mut workspace.notifications {
                if notification.surface_id == surface_id {
                    notification.pane_id = target_pane_id;
                }
            }
            return Ok(());
        }

        let (mut moved_notifications, moved_flash_token) = {
            let source_workspace = self
                .workspaces
                .get_mut(&source_workspace_id)
                .ok_or(DomainError::MissingWorkspace(source_workspace_id))?;
            let moved_flash_token = source_workspace.surface_flash_tokens.remove(&surface_id);
            let mut moved_notifications = Vec::new();
            source_workspace.notifications.retain(|notification| {
                if notification.surface_id == surface_id {
                    moved_notifications.push(notification.clone());
                    false
                } else {
                    true
                }
            });
            (moved_notifications, moved_flash_token)
        };

        let target_workspace = self
            .workspaces
            .get_mut(&target_workspace_id)
            .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
        for notification in &mut moved_notifications {
            notification.pane_id = target_pane_id;
        }
        target_workspace.notifications.extend(moved_notifications);
        if let Some(token) = moved_flash_token {
            target_workspace
                .surface_flash_tokens
                .insert(surface_id, token);
        }
        Ok(())
    }

    pub fn transfer_surface(
        &mut self,
        source_workspace_id: WorkspaceId,
        source_pane_id: PaneId,
        surface_id: SurfaceId,
        target_workspace_id: WorkspaceId,
        target_pane_id: PaneId,
        to_index: usize,
    ) -> Result<(), DomainError> {
        if source_workspace_id == target_workspace_id && source_pane_id == target_pane_id {
            return self.move_surface(source_workspace_id, source_pane_id, surface_id, to_index);
        }

        {
            let source_workspace = self
                .workspaces
                .get(&source_workspace_id)
                .ok_or(DomainError::MissingWorkspace(source_workspace_id))?;
            let target_workspace = self
                .workspaces
                .get(&target_workspace_id)
                .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
            if !source_workspace.panes.contains_key(&source_pane_id) {
                return Err(DomainError::PaneNotInWorkspace {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                });
            }
            if !target_workspace.panes.contains_key(&target_pane_id) {
                return Err(DomainError::PaneNotInWorkspace {
                    workspace_id: target_workspace_id,
                    pane_id: target_pane_id,
                });
            }
            if !source_workspace
                .panes
                .get(&source_pane_id)
                .is_some_and(|pane| pane.surfaces.contains_key(&surface_id))
            {
                return Err(DomainError::SurfaceNotInPane {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                    surface_id,
                });
            }
        }

        let moved_surface =
            self.take_surface_from_pane(source_workspace_id, source_pane_id, surface_id)?;
        let should_close_source_pane =
            self.should_close_source_pane(source_workspace_id, source_pane_id);

        {
            let workspace = self
                .workspaces
                .get_mut(&target_workspace_id)
                .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
            let target_pane = workspace.panes.get_mut(&target_pane_id).ok_or(
                DomainError::PaneNotInWorkspace {
                    workspace_id: target_workspace_id,
                    pane_id: target_pane_id,
                },
            )?;
            target_pane.insert_surface(moved_surface);
            if target_pane.surfaces.len() > 1 {
                let last_index = target_pane.surfaces.len() - 1;
                let target_index = to_index.min(last_index);
                let _ = target_pane.move_surface(surface_id, target_index);
            }
            target_pane.active_surface = surface_id;
            let _ = workspace.focus_surface(target_pane_id, surface_id);
        }
        self.retarget_surface_state(
            source_workspace_id,
            target_workspace_id,
            surface_id,
            target_pane_id,
        )?;

        if should_close_source_pane {
            self.close_pane(source_workspace_id, source_pane_id)?;
        }

        if source_workspace_id != target_workspace_id {
            self.switch_workspace(self.active_window, target_workspace_id)?;
        }

        let workspace = self
            .workspaces
            .get_mut(&target_workspace_id)
            .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
        let _ = workspace.focus_surface(target_pane_id, surface_id);

        Ok(())
    }

    pub fn move_surface_to_split(
        &mut self,
        source_workspace_id: WorkspaceId,
        source_pane_id: PaneId,
        surface_id: SurfaceId,
        target_workspace_id: WorkspaceId,
        target_pane_id: PaneId,
        direction: Direction,
    ) -> Result<PaneId, DomainError> {
        {
            let source_workspace = self
                .workspaces
                .get(&source_workspace_id)
                .ok_or(DomainError::MissingWorkspace(source_workspace_id))?;
            let source_pane = source_workspace.panes.get(&source_pane_id).ok_or(
                DomainError::PaneNotInWorkspace {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                },
            )?;
            let target_workspace = self
                .workspaces
                .get(&target_workspace_id)
                .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
            if !target_workspace.panes.contains_key(&target_pane_id) {
                return Err(DomainError::PaneNotInWorkspace {
                    workspace_id: target_workspace_id,
                    pane_id: target_pane_id,
                });
            }
            if !source_pane.surfaces.contains_key(&surface_id) {
                return Err(DomainError::SurfaceNotInPane {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                    surface_id,
                });
            }
            if source_workspace_id == target_workspace_id
                && source_pane_id == target_pane_id
                && source_pane.surfaces.len() <= 1
            {
                return Err(DomainError::InvalidOperation(
                    "cannot split a pane from its only surface",
                ));
            }
        }

        let target_location = self
            .workspaces
            .get(&target_workspace_id)
            .and_then(|workspace| workspace.pane_location(target_pane_id))
            .ok_or(DomainError::MissingPane(target_pane_id))?;
        let (target_window_id, target_window_tab_id, target_container_id, target_pane_tab_id) =
            target_location;

        let moved_surface =
            self.take_surface_from_pane(source_workspace_id, source_pane_id, surface_id)?;
        let new_pane = PaneRecord::from_surface(moved_surface);
        let new_pane_id = new_pane.id;

        let should_close_source_pane =
            self.should_close_source_pane(source_workspace_id, source_pane_id);

        {
            let workspace = self
                .workspaces
                .get_mut(&target_workspace_id)
                .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
            workspace.panes.insert(new_pane_id, new_pane);

            let target_window = workspace
                .windows
                .get_mut(&target_window_id)
                .ok_or(DomainError::MissingPane(target_pane_id))?;
            let _ = target_window.focus_tab(target_window_tab_id);
            let target_container = workspace
                .pane_containers
                .get_mut(&target_container_id)
                .ok_or(DomainError::MissingPane(target_pane_id))?;
            let target_pane_tab = target_container
                .tabs
                .get_mut(&target_pane_tab_id)
                .ok_or(DomainError::MissingPane(target_pane_id))?;
            let layout = &mut target_pane_tab.layout;
            layout.split_leaf_with_direction(target_pane_id, direction, new_pane_id, 500);
            target_pane_tab.active_pane = new_pane_id;
            target_container.active_tab = target_pane_tab_id;
            if let Some(target_tab) = target_window.tabs.get_mut(&target_window_tab_id) {
                target_tab.active_container = target_container_id;
                target_tab.active_pane = new_pane_id;
            }
            workspace.sync_active_from_window(target_window_id);
            let _ = workspace.focus_surface(new_pane_id, surface_id);
        }
        self.retarget_surface_state(
            source_workspace_id,
            target_workspace_id,
            surface_id,
            new_pane_id,
        )?;

        if should_close_source_pane {
            self.close_pane(source_workspace_id, source_pane_id)?;
        }

        if source_workspace_id != target_workspace_id {
            self.switch_workspace(self.active_window, target_workspace_id)?;
        }

        let workspace = self
            .workspaces
            .get_mut(&target_workspace_id)
            .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
        let _ = workspace.focus_surface(new_pane_id, surface_id);

        Ok(new_pane_id)
    }

    pub fn move_surface_to_workspace(
        &mut self,
        source_workspace_id: WorkspaceId,
        source_pane_id: PaneId,
        surface_id: SurfaceId,
        target_workspace_id: WorkspaceId,
    ) -> Result<PaneId, DomainError> {
        if source_workspace_id == target_workspace_id {
            return Err(DomainError::InvalidOperation(
                "surface is already in the target workspace",
            ));
        }

        {
            let source_workspace = self
                .workspaces
                .get(&source_workspace_id)
                .ok_or(DomainError::MissingWorkspace(source_workspace_id))?;
            if !self.workspaces.contains_key(&target_workspace_id) {
                return Err(DomainError::MissingWorkspace(target_workspace_id));
            }
            let source_pane = source_workspace.panes.get(&source_pane_id).ok_or(
                DomainError::PaneNotInWorkspace {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                },
            )?;
            if !source_pane.surfaces.contains_key(&surface_id) {
                return Err(DomainError::SurfaceNotInPane {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                    surface_id,
                });
            }
        }

        let moved_surface =
            self.take_surface_from_pane(source_workspace_id, source_pane_id, surface_id)?;

        let should_close_source_pane =
            self.should_close_source_pane(source_workspace_id, source_pane_id);

        let new_pane = PaneRecord::from_surface(moved_surface);
        let new_pane_id = new_pane.id;
        let new_container = PaneContainerRecord::new(new_pane_id);
        let new_container_id = new_container.id;
        let new_window = WorkspaceWindowRecord::new(new_container_id, new_pane_id);
        let new_window_id = new_window.id;

        {
            let target_workspace = self
                .workspaces
                .get_mut(&target_workspace_id)
                .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
            target_workspace.panes.insert(new_pane_id, new_pane);
            target_workspace
                .pane_containers
                .insert(new_container_id, new_container);
            target_workspace.windows.insert(new_window_id, new_window);
            insert_window_relative_to_active(target_workspace, new_window_id, Direction::Right)?;
            target_workspace.sync_active_from_window(new_window_id);
            let _ = target_workspace.focus_surface(new_pane_id, surface_id);
        }
        self.retarget_surface_state(
            source_workspace_id,
            target_workspace_id,
            surface_id,
            new_pane_id,
        )?;

        if should_close_source_pane {
            self.close_pane(source_workspace_id, source_pane_id)?;
        }

        self.switch_workspace(self.active_window, target_workspace_id)?;
        let target_workspace = self
            .workspaces
            .get_mut(&target_workspace_id)
            .ok_or(DomainError::MissingWorkspace(target_workspace_id))?;
        let _ = target_workspace.focus_surface(new_pane_id, surface_id);

        Ok(new_pane_id)
    }

    pub fn close_pane(
        &mut self,
        workspace_id: WorkspaceId,
        pane_id: PaneId,
    ) -> Result<(), DomainError> {
        {
            let workspace = self
                .workspaces
                .get(&workspace_id)
                .ok_or(DomainError::MissingWorkspace(workspace_id))?;

            if !workspace.panes.contains_key(&pane_id) {
                return Err(DomainError::PaneNotInWorkspace {
                    workspace_id,
                    pane_id,
                });
            }

            if workspace.panes.len() <= 1 {
                return self.close_workspace(workspace_id);
            }
        }

        let workspace = self
            .workspaces
            .get_mut(&workspace_id)
            .ok_or(DomainError::MissingWorkspace(workspace_id))?;
        let (window_id, window_tab_id, container_id, pane_tab_id) = workspace
            .pane_location(pane_id)
            .ok_or(DomainError::MissingPane(pane_id))?;
        let (column_id, column_index, window_index) = workspace
            .position_for_window(window_id)
            .ok_or(DomainError::MissingWorkspaceWindow(window_id))?;

        let (pane_tab_leaf_count, container_tab_count, window_container_count, window_tab_count) = {
            let container = workspace
                .pane_containers
                .get(&container_id)
                .ok_or(DomainError::MissingPane(pane_id))?;
            let pane_tab = container
                .tabs
                .get(&pane_tab_id)
                .ok_or(DomainError::MissingPane(pane_id))?;
            let window = workspace
                .windows
                .get(&window_id)
                .ok_or(DomainError::MissingWorkspaceWindow(window_id))?;
            let window_tab = window
                .tabs
                .get(&window_tab_id)
                .ok_or(DomainError::MissingWorkspaceWindowTab(window_tab_id))?;
            (
                pane_tab.layout.leaves().len(),
                container.tabs.len(),
                window_tab.layout.leaves().len(),
                window.tabs.len(),
            )
        };

        if pane_tab_leaf_count <= 1 {
            if container_tab_count > 1 {
                let active_pane_was_removed = workspace.active_pane == pane_id;
                let active_window_was_removed = workspace.active_window == window_id;

                let container = workspace
                    .pane_containers
                    .get_mut(&container_id)
                    .ok_or(DomainError::MissingPane(pane_id))?;
                let _ = container
                    .remove_tab(pane_tab_id)
                    .ok_or(DomainError::MissingPane(pane_id))?;
                remove_panes_from_workspace(workspace, &[pane_id]);

                if let Some(window) = workspace.windows.get_mut(&window_id)
                    && let Some(window_tab) = window.tabs.get_mut(&window_tab_id)
                {
                    window_tab.active_container = container_id;
                    window_tab.active_pane = workspace
                        .pane_containers
                        .get(&container_id)
                        .and_then(PaneContainerRecord::active_pane)
                        .expect("pane container retains an active pane");
                }

                if active_window_was_removed {
                    workspace.sync_active_from_window(window_id);
                } else if active_pane_was_removed {
                    workspace.sync_active_from_window(workspace.active_window);
                }
                return Ok(());
            }

            if window_container_count > 1 {
                let active_pane_was_removed = workspace.active_pane == pane_id;
                if let Some(window) = workspace.windows.get_mut(&window_id) {
                    let window_tab = window
                        .tabs
                        .get_mut(&window_tab_id)
                        .ok_or(DomainError::MissingWorkspaceWindowTab(window_tab_id))?;
                    let fallback_container = close_window_tab_container(window_tab, container_id)
                        .or_else(|| window_tab.layout.leaves().into_iter().next())
                        .expect("window tab should retain at least one pane container");
                    window_tab.active_container = fallback_container;
                    window_tab.active_pane = workspace
                        .pane_containers
                        .get(&fallback_container)
                        .and_then(PaneContainerRecord::active_pane)
                        .expect("window tab should retain an active pane");
                    let _ = window.focus_tab(window_tab_id);
                }
                remove_pane_containers_from_workspace(workspace, &[container_id]);
                if workspace.active_window == window_id {
                    workspace.sync_active_from_window(window_id);
                } else if active_pane_was_removed {
                    workspace.sync_active_from_window(workspace.active_window);
                }
                return Ok(());
            }

            if window_tab_count > 1 {
                return self.close_workspace_window_tab(workspace_id, window_id, window_tab_id);
            }
            if workspace.windows.len() > 1 {
                let tab_containers = workspace
                    .windows
                    .get(&window_id)
                    .and_then(|window| window.tabs.get(&window_tab_id))
                    .map(|tab| tab.layout.leaves())
                    .unwrap_or_else(|| vec![container_id]);
                let column = workspace
                    .columns
                    .get_mut(&column_id)
                    .expect("window column should exist");
                column.window_order.remove(window_index);
                let same_column_survived = !column.window_order.is_empty();
                if same_column_survived {
                    if !column.window_order.contains(&column.active_window) {
                        let replacement_index = window_index.min(column.window_order.len() - 1);
                        column.active_window = column.window_order[replacement_index];
                    }
                } else {
                    workspace.columns.shift_remove(&column_id);
                }

                workspace.windows.shift_remove(&window_id);
                remove_pane_containers_from_workspace(workspace, &tab_containers);
                if let Some(next_window_id) = workspace.fallback_window_after_close(
                    column_index,
                    window_index,
                    same_column_survived,
                ) {
                    workspace.sync_active_from_window(next_window_id);
                }
                return Ok(());
            }
        }

        if let Some(window) = workspace.windows.get_mut(&window_id) {
            let container = workspace
                .pane_containers
                .get_mut(&container_id)
                .ok_or(DomainError::MissingPane(pane_id))?;
            let pane_tab = container
                .tabs
                .get_mut(&pane_tab_id)
                .ok_or(DomainError::MissingPane(pane_id))?;
            let fallback_focus = close_pane_tab_layout_pane(pane_tab, pane_id)
                .or_else(|| pane_tab.layout.leaves().into_iter().next())
                .expect("pane tab should retain at least one pane");
            pane_tab.active_pane = fallback_focus;
            container.active_tab = pane_tab_id;
            let window_tab = window
                .tabs
                .get_mut(&window_tab_id)
                .ok_or(DomainError::MissingWorkspaceWindowTab(window_tab_id))?;
            window_tab.active_container = container_id;
            window_tab.active_pane = fallback_focus;
            let _ = window.focus_tab(window_tab_id);
        }
        remove_panes_from_workspace(workspace, &[pane_id]);

        if workspace.active_window == window_id {
            workspace.sync_active_from_window(window_id);
        } else if workspace.active_pane == pane_id {
            workspace.sync_active_from_window(workspace.active_window);
        }

        Ok(())
    }

    pub fn close_workspace(&mut self, workspace_id: WorkspaceId) -> Result<(), DomainError> {
        if !self.workspaces.contains_key(&workspace_id) {
            return Err(DomainError::MissingWorkspace(workspace_id));
        }

        if self.workspaces.len() <= 1 {
            self.create_workspace("Workspace 1");
        }

        self.workspaces.shift_remove(&workspace_id);

        for window in self.windows.values_mut() {
            window.workspace_order.retain(|id| *id != workspace_id);
            if window.active_workspace == workspace_id
                && let Some(first) = window.workspace_order.first()
            {
                window.active_workspace = *first;
            }
        }

        Ok(())
    }

    pub fn workspace_summaries(
        &self,
        window_id: WindowId,
    ) -> Result<Vec<WorkspaceSummary>, DomainError> {
        let window = self
            .windows
            .get(&window_id)
            .ok_or(DomainError::MissingWindow(window_id))?;
        let now = OffsetDateTime::now_utc();

        let summaries = window
            .workspace_order
            .iter()
            .filter_map(|workspace_id| self.workspaces.get(workspace_id))
            .map(|workspace| {
                let counts = workspace.attention_counts();
                let agent_summaries = workspace.agent_summaries(now);
                let highest_attention = workspace
                    .panes
                    .values()
                    .map(PaneRecord::highest_attention)
                    .max_by_key(|attention| attention.rank())
                    .unwrap_or(AttentionState::Normal);
                let unread = workspace
                    .notifications
                    .iter()
                    .filter(|notification| notification.unread())
                    .collect::<Vec<_>>();
                let unread_attention = unread
                    .iter()
                    .map(|notification| notification.state)
                    .max_by_key(|attention| attention.rank());
                let latest_notification = unread
                    .iter()
                    .max_by_key(|notification| notification.created_at)
                    .map(|notification| notification.message.clone());

                WorkspaceSummary {
                    workspace_id: workspace.id,
                    label: workspace.label.clone(),
                    active_pane: workspace.active_pane,
                    repo_hint: workspace.repo_hint().map(str::to_owned),
                    agent_summaries,
                    counts_by_attention: counts,
                    highest_attention,
                    display_attention: unread_attention.unwrap_or(highest_attention),
                    unread_count: unread.len(),
                    latest_notification,
                    status_text: workspace.status_text.clone(),
                }
            })
            .collect();

        Ok(summaries)
    }

    pub fn activity_items(&self) -> Vec<ActivityItem> {
        let mut items = self
            .workspaces
            .values()
            .flat_map(|workspace| {
                workspace
                    .notifications
                    .iter()
                    .filter(|notification| notification.active())
                    .map(move |notification| ActivityItem {
                        notification_id: notification.id,
                        workspace_id: workspace.id,
                        workspace_window_id: workspace.window_for_pane(notification.pane_id),
                        pane_id: notification.pane_id,
                        surface_id: notification.surface_id,
                        kind: notification.kind.clone(),
                        state: notification.state,
                        title: notification.title.clone(),
                        subtitle: notification.subtitle.clone(),
                        message: notification.message.clone(),
                        read_at: notification.read_at,
                        created_at: notification.created_at,
                    })
            })
            .collect::<Vec<_>>();

        items.sort_by(|left, right| right.created_at.cmp(&left.created_at));
        items
    }

    pub fn snapshot(&self) -> PersistedSession {
        PersistedSession {
            schema_version: SESSION_SCHEMA_VERSION,
            captured_at: OffsetDateTime::now_utc(),
            model: self.clone(),
        }
    }
}

#[derive(Debug, Deserialize)]
struct CurrentWorkspaceSerde {
    id: WorkspaceId,
    label: String,
    columns: IndexMap<WorkspaceColumnId, WorkspaceColumnRecord>,
    windows: IndexMap<WorkspaceWindowId, WorkspaceWindowRecord>,
    active_window: WorkspaceWindowId,
    pane_containers: IndexMap<PaneContainerId, PaneContainerRecord>,
    panes: IndexMap<PaneId, PaneRecord>,
    active_pane: PaneId,
    #[serde(default)]
    viewport: WorkspaceViewport,
    #[serde(default)]
    notifications: Vec<NotificationItem>,
    #[serde(default)]
    status_text: Option<String>,
    #[serde(default)]
    progress: Option<ProgressState>,
    #[serde(default)]
    log_entries: Vec<WorkspaceLogEntry>,
    #[serde(default)]
    surface_flash_tokens: BTreeMap<SurfaceId, u64>,
    #[serde(default)]
    next_flash_token: u64,
    #[serde(default)]
    custom_color: Option<String>,
}

impl CurrentWorkspaceSerde {
    fn into_workspace(self) -> Workspace {
        let mut workspace = Workspace {
            id: self.id,
            label: self.label,
            columns: self.columns,
            windows: self.windows,
            active_window: self.active_window,
            pane_containers: self.pane_containers,
            panes: self.panes,
            active_pane: self.active_pane,
            viewport: self.viewport,
            notifications: self.notifications,
            status_text: self.status_text,
            progress: self.progress,
            log_entries: self.log_entries,
            surface_flash_tokens: self.surface_flash_tokens,
            next_flash_token: self.next_flash_token,
            custom_color: self.custom_color,
        };
        workspace.normalize();
        workspace
    }
}

fn signal_kind_creates_notification(kind: &SignalKind) -> bool {
    matches!(
        kind,
        SignalKind::Completed | SignalKind::WaitingInput | SignalKind::Error
    )
}

fn is_agent_kind(agent_kind: Option<&str>) -> bool {
    normalized_agent_kind(agent_kind).is_some()
}

fn is_agent_hook_source(source: &str) -> bool {
    source.trim().starts_with("agent-hook:")
}

fn normalized_agent_kind(agent_kind: Option<&str>) -> Option<String> {
    let normalized = agent_kind
        .map(str::trim)
        .filter(|agent| !agent.is_empty())
        .map(|agent| agent.to_ascii_lowercase())?;
    match normalized.as_str() {
        "shell" => None,
        "claude code" | "claude-code" => Some("claude".into()),
        other => Some(other.to_string()),
    }
}

fn normalized_agent_command(command: Option<&str>) -> Option<String> {
    command
        .map(str::trim)
        .filter(|value| !value.is_empty())
        .map(str::to_owned)
}

fn interrupted_agent_resume_external_id(surface_id: SurfaceId) -> String {
    format!("interrupted-agent-resume:{surface_id}")
}

fn agent_display_title(agent_kind: &str) -> String {
    match agent_kind {
        "codex" => "Codex".into(),
        "claude" => "Claude".into(),
        "opencode" => "OpenCode".into(),
        "aider" => "Aider".into(),
        other => other.to_string(),
    }
}

fn agent_identity_for_surface(
    surface: &SurfaceRecord,
    metadata: Option<&SignalPaneMetadata>,
) -> Option<(String, String)> {
    if let Some(process) = surface.agent_process.as_ref() {
        return Some((process.kind.clone(), process.title.clone()));
    }

    let kind = surface.metadata.agent_kind.clone().or_else(|| {
        metadata.and_then(|metadata| normalized_agent_kind(metadata.agent_kind.as_deref()))
    })?;
    let title = surface
        .metadata
        .agent_title
        .clone()
        .or_else(|| metadata.and_then(|metadata| metadata.agent_title.clone()))
        .unwrap_or_else(|| agent_display_title(&kind));
    Some((kind, title))
}

fn set_agent_turn(
    surface: &mut SurfaceRecord,
    kind: String,
    title: String,
    state: WorkspaceAgentState,
    latest_message: Option<String>,
    updated_at: OffsetDateTime,
) {
    match surface.agent_session.as_mut() {
        Some(session) => {
            session.kind = kind;
            session.title = title;
            session.state = state;
            session.latest_message = latest_message;
            session.updated_at = updated_at;
        }
        None => {
            surface.agent_session = Some(SurfaceAgentSession {
                id: SessionId::new(),
                kind,
                title,
                state,
                latest_message,
                updated_at,
            });
        }
    }
}

fn is_agent_signal(
    surface: &SurfaceRecord,
    source: &str,
    metadata: Option<&SignalPaneMetadata>,
) -> bool {
    is_agent_hook_source(source)
        || is_agent_kind(metadata.and_then(|metadata| metadata.agent_kind.as_deref()))
        || surface.agent_process.is_some()
        || surface.agent_session.is_some()
}

fn normalized_signal_message(message: Option<&str>) -> Option<String> {
    message
        .map(str::trim)
        .filter(|message| !message.is_empty())
        .map(str::to_owned)
}

fn surface_notification_title(surface: &SurfaceRecord) -> Option<String> {
    if let Some(session) = surface.agent_session.as_ref() {
        return Some(session.title.clone());
    }

    if let Some(process) = surface.agent_process.as_ref() {
        return Some(process.title.clone());
    }

    surface
        .metadata
        .agent_title
        .as_deref()
        .or(surface.metadata.title.as_deref())
        .map(str::trim)
        .filter(|title| !title.is_empty())
        .map(str::to_owned)
}

fn notification_message_for_signal(
    kind: &SignalKind,
    explicit_message: Option<String>,
    notification_title: &Option<String>,
    surface: &SurfaceRecord,
) -> Option<String> {
    match kind {
        SignalKind::Metadata | SignalKind::Started | SignalKind::Progress => None,
        SignalKind::Notification => explicit_message.or_else(|| notification_title.clone()),
        SignalKind::WaitingInput => explicit_message.or_else(|| notification_title.clone()),
        SignalKind::Completed | SignalKind::Error => explicit_message
            .or_else(|| surface.metadata.latest_agent_message.clone())
            .or_else(|| notification_title.clone()),
    }
}

fn signal_creates_notification(source: &str, kind: &SignalKind) -> bool {
    match kind {
        SignalKind::Notification => !is_agent_hook_source(source),
        _ => signal_kind_creates_notification(kind),
    }
}

fn remove_window_from_column(
    workspace: &mut Workspace,
    column_id: WorkspaceColumnId,
    window_index: usize,
) -> Result<(), DomainError> {
    let remove_column = {
        let column = workspace
            .columns
            .get_mut(&column_id)
            .ok_or(DomainError::MissingWorkspaceColumn(column_id))?;
        if window_index >= column.window_order.len() {
            return Err(DomainError::MissingWorkspaceColumn(column_id));
        }
        column.window_order.remove(window_index);
        if column.window_order.is_empty() {
            true
        } else {
            if !column.window_order.contains(&column.active_window) {
                let replacement_index = window_index.min(column.window_order.len() - 1);
                column.active_window = column.window_order[replacement_index];
            }
            false
        }
    };
    if remove_column {
        workspace.columns.shift_remove(&column_id);
    }
    Ok(())
}

fn create_pane_tab_bundle(kind: PaneKind) -> (PaneRecord, PaneTabRecord, PaneId, PaneTabId) {
    let pane = PaneRecord::new(kind);
    let pane_id = pane.id;
    let pane_tab = PaneTabRecord::new(pane_id);
    let pane_tab_id = pane_tab.id;
    (pane, pane_tab, pane_id, pane_tab_id)
}

fn create_pane_container_bundle(
    kind: PaneKind,
) -> (PaneRecord, PaneContainerRecord, PaneId, PaneContainerId) {
    let pane = PaneRecord::new(kind);
    let pane_id = pane.id;
    let pane_container = PaneContainerRecord::new(pane_id);
    let pane_container_id = pane_container.id;
    (pane, pane_container, pane_id, pane_container_id)
}

fn prune_missing_layout_leaves<LeafId, F>(layout: &mut crate::SplitLayoutNode<LeafId>, mut keep: F)
where
    LeafId: Copy + Eq,
    F: FnMut(LeafId) -> bool,
{
    for leaf_id in layout.leaves() {
        if !keep(leaf_id) {
            let _ = layout.remove_leaf(leaf_id);
        }
    }
}

fn remove_pane_containers_from_workspace(
    workspace: &mut Workspace,
    pane_container_ids: &[PaneContainerId],
) {
    let pane_container_set = pane_container_ids.iter().copied().collect::<BTreeSet<_>>();
    let pane_ids = pane_container_set
        .iter()
        .filter_map(|pane_container_id| workspace.pane_containers.get(pane_container_id))
        .flat_map(|pane_container| pane_container.tabs.values())
        .flat_map(|pane_tab| pane_tab.layout.leaves())
        .collect::<Vec<_>>();
    for pane_container_id in &pane_container_set {
        workspace.pane_containers.shift_remove(pane_container_id);
    }
    remove_panes_from_workspace(workspace, &pane_ids);
}

fn remove_panes_from_workspace(workspace: &mut Workspace, pane_ids: &[PaneId]) {
    let pane_set = pane_ids.iter().copied().collect::<BTreeSet<_>>();
    let surface_set = pane_set
        .iter()
        .filter_map(|pane_id| workspace.panes.get(pane_id))
        .flat_map(|pane| pane.surface_ids())
        .collect::<BTreeSet<_>>();
    for pane_id in &pane_set {
        workspace.panes.shift_remove(pane_id);
    }
    workspace
        .notifications
        .retain(|item| !pane_set.contains(&item.pane_id));
    workspace
        .surface_flash_tokens
        .retain(|surface_id, _| !surface_set.contains(surface_id));
}

fn close_pane_tab_layout_pane(tab: &mut PaneTabRecord, pane_id: PaneId) -> Option<PaneId> {
    let fallback = [
        Direction::Right,
        Direction::Down,
        Direction::Left,
        Direction::Up,
    ]
    .into_iter()
    .find_map(|direction| tab.layout.focus_neighbor(pane_id, direction))
    .or_else(|| {
        tab.layout
            .leaves()
            .into_iter()
            .find(|candidate| *candidate != pane_id)
    });
    let removed = tab.layout.remove_leaf(pane_id);
    removed.then_some(fallback).flatten()
}

fn close_window_tab_container(
    tab: &mut WorkspaceWindowTabRecord,
    pane_container_id: PaneContainerId,
) -> Option<PaneContainerId> {
    let fallback = [
        Direction::Right,
        Direction::Down,
        Direction::Left,
        Direction::Up,
    ]
    .into_iter()
    .find_map(|direction| tab.layout.focus_neighbor(pane_container_id, direction))
    .or_else(|| {
        tab.layout
            .leaves()
            .into_iter()
            .find(|candidate| *candidate != pane_container_id)
    });
    let removed = tab.layout.remove_leaf(pane_container_id);
    removed.then_some(fallback).flatten()
}

fn map_signal_to_attention(kind: &SignalKind) -> AttentionState {
    match kind {
        SignalKind::Metadata => AttentionState::Normal,
        SignalKind::Started | SignalKind::Progress => AttentionState::Busy,
        SignalKind::Completed => AttentionState::Completed,
        SignalKind::WaitingInput => AttentionState::WaitingInput,
        SignalKind::Error => AttentionState::Error,
        SignalKind::Notification => AttentionState::WaitingInput,
    }
}

fn signal_agent_active(kind: &SignalKind) -> Option<bool> {
    match kind {
        SignalKind::Metadata => None,
        SignalKind::Started | SignalKind::Progress | SignalKind::WaitingInput => Some(true),
        SignalKind::Completed | SignalKind::Error => Some(false),
        SignalKind::Notification => None,
    }
}

fn signal_agent_state(kind: &SignalKind) -> Option<WorkspaceAgentState> {
    match kind {
        SignalKind::Metadata => None,
        SignalKind::Started | SignalKind::Progress => Some(WorkspaceAgentState::Working),
        SignalKind::WaitingInput | SignalKind::Notification => Some(WorkspaceAgentState::Waiting),
        SignalKind::Completed => Some(WorkspaceAgentState::Completed),
        SignalKind::Error => Some(WorkspaceAgentState::Failed),
    }
}

#[cfg(test)]
mod tests {
    use serde_json::json;
    use time::Duration;

    use super::*;
    use crate::SignalPaneMetadata;

    #[test]
    fn bootstrap_workspace_uses_default_internal_window_size() {
        let model = AppModel::new("Main");
        let workspace = model.active_workspace().expect("workspace");
        let column = workspace.columns.values().next().expect("column");
        let window = workspace.windows.values().next().expect("window");

        assert_eq!(column.width, DEFAULT_WORKSPACE_WINDOW_WIDTH);
        assert_eq!(window.height, DEFAULT_WORKSPACE_WINDOW_HEIGHT);
        assert_eq!(WindowFrame::root().width, DEFAULT_WORKSPACE_WINDOW_WIDTH);
        assert_eq!(WindowFrame::root().height, DEFAULT_WORKSPACE_WINDOW_HEIGHT);
    }

    #[test]
    fn creating_workspace_windows_creates_columns_and_stacks() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_window_id = model
            .active_workspace()
            .map(|workspace| workspace.active_window)
            .expect("window");

        let right_pane = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window created");
        let stacked_pane = model
            .create_workspace_window(workspace_id, Direction::Down)
            .expect("stacked window created");
        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let right_column = workspace
            .columns
            .values()
            .find(|column| column.window_order.contains(&workspace.active_window))
            .expect("active column");

        assert_eq!(workspace.windows.len(), 3);
        assert_eq!(workspace.columns.len(), 2);
        assert_eq!(workspace.active_pane, stacked_pane);
        assert_eq!(right_column.width, DEFAULT_WORKSPACE_WINDOW_WIDTH / 2);
        assert_eq!(right_column.window_order.len(), 2);
        assert_ne!(workspace.active_window, first_window_id);
        assert!(workspace.columns.values().any(|column| {
            column.window_order == vec![first_window_id]
                && column.width == DEFAULT_WORKSPACE_WINDOW_WIDTH / 2
        }));
        let upper_window_id = right_column.window_order[0];
        assert_eq!(
            workspace
                .windows
                .get(&upper_window_id)
                .expect("window")
                .active_pane()
                .expect("active pane"),
            right_pane
        );
        assert_eq!(
            workspace
                .windows
                .get(&upper_window_id)
                .expect("window")
                .height,
            (DEFAULT_WORKSPACE_WINDOW_HEIGHT + 1) / 2
        );
        assert_eq!(
            workspace
                .windows
                .get(&workspace.active_window)
                .expect("window")
                .height,
            DEFAULT_WORKSPACE_WINDOW_HEIGHT / 2
        );
    }

    #[test]
    fn creating_workspace_window_clamps_split_column_width_to_minimum() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let workspace = model.active_workspace().expect("workspace");
        let column_id = workspace.active_column_id().expect("active column");

        model
            .set_workspace_column_width(workspace_id, column_id, MIN_WORKSPACE_WINDOW_WIDTH + 80)
            .expect("set width");
        model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window created");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let widths = workspace
            .columns
            .values()
            .map(|column| column.width)
            .collect::<Vec<_>>();
        assert_eq!(
            widths,
            vec![MIN_WORKSPACE_WINDOW_WIDTH, MIN_WORKSPACE_WINDOW_WIDTH]
        );
    }

    #[test]
    fn creating_workspace_window_clamps_split_window_height_to_minimum() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let window_id = model
            .active_workspace()
            .map(|workspace| workspace.active_window)
            .expect("active window");

        model
            .set_workspace_window_height(workspace_id, window_id, MIN_WORKSPACE_WINDOW_HEIGHT + 50)
            .expect("set height");
        model
            .create_workspace_window(workspace_id, Direction::Down)
            .expect("window created");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let heights = workspace
            .windows
            .values()
            .map(|window| window.height)
            .collect::<Vec<_>>();
        assert_eq!(
            heights,
            vec![MIN_WORKSPACE_WINDOW_HEIGHT, MIN_WORKSPACE_WINDOW_HEIGHT]
        );
    }

    #[test]
    fn split_pane_updates_inner_layout_and_focus() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .expect("pane");

        let new_pane = model
            .split_pane(workspace_id, Some(first_pane), SplitAxis::Vertical)
            .expect("split works");
        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let active_window = workspace.active_window_record().expect("window");
        let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) =
            workspace.pane_location(new_pane).expect("pane location");

        assert_eq!(workspace.active_pane, new_pane);
        assert_eq!(
            active_window.active_layout().expect("layout").leaves(),
            vec![pane_container_id]
        );
        assert_eq!(
            workspace
                .pane_containers
                .get(&pane_container_id)
                .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
                .expect("pane tab")
                .layout
                .leaves(),
            vec![first_pane, new_pane]
        );
    }

    #[test]
    fn split_pane_direction_places_new_pane_on_requested_side() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .expect("pane");

        let left_pane = model
            .split_pane_direction(workspace_id, Some(first_pane), Direction::Left)
            .expect("split left");
        let upper_pane = model
            .split_pane_direction(workspace_id, Some(first_pane), Direction::Up)
            .expect("split up");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let active_window = workspace.active_window_record().expect("window");
        let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) =
            workspace.pane_location(upper_pane).expect("pane location");

        assert_eq!(workspace.active_pane, upper_pane);
        assert_eq!(
            active_window.active_layout().expect("layout").leaves(),
            vec![pane_container_id]
        );
        assert_eq!(
            workspace
                .pane_containers
                .get(&pane_container_id)
                .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
                .expect("pane tab")
                .layout
                .leaves(),
            vec![left_pane, upper_pane, first_pane]
        );
    }

    #[test]
    fn directional_focus_prefers_inner_split_before_neighboring_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .expect("pane");
        let split_right_pane = model
            .split_pane(workspace_id, Some(first_pane), SplitAxis::Horizontal)
            .expect("split");
        let right_window_pane = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window");
        model
            .focus_pane(workspace_id, first_pane)
            .expect("focus first pane");
        model
            .focus_pane_direction(workspace_id, Direction::Right)
            .expect("move right");

        assert_eq!(
            model
                .workspaces
                .get(&workspace_id)
                .expect("workspace")
                .active_pane,
            split_right_pane
        );

        model
            .focus_pane_direction(workspace_id, Direction::Right)
            .expect("move right again");
        assert_eq!(
            model
                .workspaces
                .get(&workspace_id)
                .expect("workspace")
                .active_pane,
            right_window_pane
        );

        model
            .focus_pane_direction(workspace_id, Direction::Left)
            .expect("move left");

        assert_eq!(
            model
                .workspaces
                .get(&workspace_id)
                .expect("workspace")
                .active_pane,
            split_right_pane
        );
    }

    #[test]
    fn closing_last_pane_in_window_removes_window_and_falls_back() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let right_window_pane = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window");
        let lower_window_pane = model
            .create_workspace_window(workspace_id, Direction::Down)
            .expect("window");

        model
            .close_pane(workspace_id, lower_window_pane)
            .expect("close pane");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        assert_eq!(workspace.windows.len(), 2);
        assert!(!workspace.panes.contains_key(&lower_window_pane));
        assert_eq!(workspace.active_pane, right_window_pane);
        let right_column = workspace
            .columns
            .values()
            .find(|column| column.window_order.contains(&workspace.active_window))
            .expect("right column");
        assert_eq!(right_column.window_order.len(), 1);
    }

    #[test]
    fn moving_single_window_column_reorders_columns_and_preserves_width() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_window_id = model.active_workspace().expect("workspace").active_window;
        let right_window_pane = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window");
        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let right_window_id = workspace
            .window_for_pane(right_window_pane)
            .expect("right window id");
        let left_column_id = workspace
            .column_for_window(first_window_id)
            .expect("left column");
        let right_column_id = workspace
            .column_for_window(right_window_id)
            .expect("right column");
        let _ = workspace;

        model
            .set_workspace_column_width(
                workspace_id,
                right_column_id,
                DEFAULT_WORKSPACE_WINDOW_WIDTH + 240,
            )
            .expect("set width");
        model
            .move_workspace_window(
                workspace_id,
                right_window_id,
                WorkspaceWindowMoveTarget::ColumnBefore {
                    column_id: left_column_id,
                },
            )
            .expect("move window");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let ordered_columns = workspace.columns.values().collect::<Vec<_>>();
        assert_eq!(ordered_columns.len(), 2);
        assert_eq!(ordered_columns[0].window_order, vec![right_window_id]);
        assert_eq!(
            ordered_columns[0].width,
            DEFAULT_WORKSPACE_WINDOW_WIDTH + 240
        );
        assert_eq!(ordered_columns[1].window_order, vec![first_window_id]);
        assert_eq!(workspace.active_window, right_window_id);
    }

    #[test]
    fn moving_stacked_window_sideways_creates_a_new_column() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_window_id = model.active_workspace().expect("workspace").active_window;
        let lower_window_pane = model
            .create_workspace_window(workspace_id, Direction::Down)
            .expect("window");
        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let lower_window_id = workspace
            .window_for_pane(lower_window_pane)
            .expect("lower window id");
        let source_column_id = workspace
            .column_for_window(first_window_id)
            .expect("source column");
        let _ = workspace;

        model
            .set_workspace_column_width(
                workspace_id,
                source_column_id,
                DEFAULT_WORKSPACE_WINDOW_WIDTH + 400,
            )
            .expect("set width");
        model
            .move_workspace_window(
                workspace_id,
                lower_window_id,
                WorkspaceWindowMoveTarget::ColumnAfter {
                    column_id: source_column_id,
                },
            )
            .expect("move window");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let ordered_columns = workspace.columns.values().collect::<Vec<_>>();
        assert_eq!(ordered_columns.len(), 2);
        let expected_split_width = (DEFAULT_WORKSPACE_WINDOW_WIDTH + 400) / 2;
        assert_eq!(ordered_columns[0].window_order, vec![first_window_id]);
        assert_eq!(ordered_columns[0].width, expected_split_width);
        assert_eq!(ordered_columns[1].window_order, vec![lower_window_id]);
        assert_eq!(ordered_columns[1].width, expected_split_width);
        assert_eq!(workspace.active_window, lower_window_id);
    }

    #[test]
    fn moving_window_into_stack_removes_empty_source_column() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_window_id = model.active_workspace().expect("workspace").active_window;
        let right_window_pane = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window");
        let right_window_id = model
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.window_for_pane(right_window_pane))
            .expect("right window id");

        model
            .move_workspace_window(
                workspace_id,
                right_window_id,
                WorkspaceWindowMoveTarget::StackBelow {
                    window_id: first_window_id,
                },
            )
            .expect("stack window");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let only_column = workspace.columns.values().next().expect("single column");
        assert_eq!(workspace.columns.len(), 1);
        assert_eq!(
            only_column.window_order,
            vec![first_window_id, right_window_id]
        );
        assert_eq!(workspace.active_window, right_window_id);
    }

    #[test]
    fn moving_surface_reorders_pane_without_changing_active_surface() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface id");

        let second_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("second surface");
        let third_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("third surface");

        model
            .focus_surface(workspace_id, pane_id, second_surface_id)
            .expect("focus second surface");
        model
            .move_surface(workspace_id, pane_id, second_surface_id, 0)
            .expect("move second surface to front");

        let pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .expect("pane");
        let order = pane.surface_ids().collect::<Vec<_>>();

        assert_eq!(
            order,
            vec![second_surface_id, first_surface_id, third_surface_id]
        );
        assert_eq!(pane.active_surface, second_surface_id);
    }

    #[test]
    fn moving_surface_clamps_to_end_of_pane() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface id");
        let second_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("second surface");
        let third_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("third surface");

        model
            .move_surface(workspace_id, pane_id, first_surface_id, usize::MAX)
            .expect("move first surface to end");

        let pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .expect("pane");
        let order = pane.surface_ids().collect::<Vec<_>>();

        assert_eq!(
            order,
            vec![second_surface_id, third_surface_id, first_surface_id]
        );
    }

    #[test]
    fn moving_surface_to_current_index_is_a_noop() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface id");
        let second_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("second surface");

        model
            .move_surface(workspace_id, pane_id, second_surface_id, 1)
            .expect("move second surface to current slot");

        let pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .expect("pane");
        let order = pane.surface_ids().collect::<Vec<_>>();

        assert_eq!(order, vec![first_surface_id, second_surface_id]);
        assert_eq!(pane.active_surface, second_surface_id);
    }

    #[test]
    fn transferring_surface_to_another_pane_focuses_target_pane() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let target_pane_id = model
            .split_pane(workspace_id, Some(source_pane_id), SplitAxis::Horizontal)
            .expect("split");
        let target_placeholder_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&target_pane_id))
            .and_then(|pane| pane.surface_ids().next())
            .expect("placeholder");

        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .and_then(|pane| pane.surface_ids().next())
            .expect("first surface");
        let second_surface_id = model
            .create_surface(workspace_id, source_pane_id, PaneKind::Browser)
            .expect("second surface");

        model
            .transfer_surface(
                workspace_id,
                source_pane_id,
                second_surface_id,
                workspace_id,
                target_pane_id,
                0,
            )
            .expect("transfer");

        let workspace = model.active_workspace().expect("workspace");
        let source_order = workspace
            .panes
            .get(&source_pane_id)
            .expect("source pane")
            .surface_ids()
            .collect::<Vec<_>>();
        let target_pane = workspace.panes.get(&target_pane_id).expect("target pane");
        let target_order = target_pane.surface_ids().collect::<Vec<_>>();

        assert_eq!(source_order, vec![first_surface_id]);
        assert_eq!(target_order, vec![second_surface_id, target_placeholder_id]);
        assert_eq!(target_pane.active_surface, second_surface_id);
        assert_eq!(workspace.active_pane, target_pane_id);
    }

    #[test]
    fn moving_surface_to_split_from_same_pane_creates_neighbor_pane() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .map(|pane| pane.active_surface)
            .expect("first surface");
        let moved_surface_id = model
            .create_surface(workspace_id, source_pane_id, PaneKind::Browser)
            .expect("second surface");

        let new_pane_id = model
            .move_surface_to_split(
                workspace_id,
                source_pane_id,
                moved_surface_id,
                workspace_id,
                source_pane_id,
                Direction::Right,
            )
            .expect("move to split");

        let workspace = model.active_workspace().expect("workspace");
        let window = workspace.active_window_record().expect("window");
        let source_pane = workspace.panes.get(&source_pane_id).expect("source pane");
        let target_pane = workspace.panes.get(&new_pane_id).expect("new pane");
        let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) =
            workspace.pane_location(new_pane_id).expect("pane location");

        assert_eq!(
            window.active_layout().expect("layout").leaves(),
            vec![pane_container_id]
        );
        assert_eq!(
            workspace
                .pane_containers
                .get(&pane_container_id)
                .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
                .expect("pane tab")
                .layout
                .leaves(),
            vec![source_pane_id, new_pane_id]
        );
        assert_eq!(
            source_pane.surface_ids().collect::<Vec<_>>(),
            vec![first_surface_id]
        );
        assert_eq!(
            target_pane.surface_ids().collect::<Vec<_>>(),
            vec![moved_surface_id]
        );
        assert_eq!(workspace.active_pane, new_pane_id);
        assert_eq!(target_pane.active_surface, moved_surface_id);
    }

    #[test]
    fn moving_surface_to_split_across_windows_closes_empty_source_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let target_pane_id = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("window");
        let target_window_id = model
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.window_for_pane(target_pane_id))
            .expect("target window");
        let moved_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface");

        let new_pane_id = model
            .move_surface_to_split(
                workspace_id,
                source_pane_id,
                moved_surface_id,
                workspace_id,
                target_pane_id,
                Direction::Left,
            )
            .expect("move to split");

        let workspace = model.active_workspace().expect("workspace");
        let target_window = workspace.windows.get(&target_window_id).expect("window");
        let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) =
            workspace.pane_location(new_pane_id).expect("pane location");

        assert_eq!(workspace.windows.len(), 1);
        assert!(!workspace.panes.contains_key(&source_pane_id));
        assert_eq!(workspace.active_window, target_window_id);
        assert_eq!(workspace.active_pane, new_pane_id);
        assert_eq!(
            target_window.active_layout().expect("layout").leaves(),
            vec![pane_container_id]
        );
        assert_eq!(
            workspace
                .pane_containers
                .get(&pane_container_id)
                .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
                .expect("pane tab")
                .layout
                .leaves(),
            vec![new_pane_id, target_pane_id]
        );
        assert_eq!(
            workspace
                .panes
                .get(&new_pane_id)
                .expect("new pane")
                .surface_ids()
                .collect::<Vec<_>>(),
            vec![moved_surface_id]
        );
    }

    #[test]
    fn moving_only_surface_to_split_from_same_pane_is_rejected() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface");

        let error = model
            .move_surface_to_split(
                workspace_id,
                pane_id,
                surface_id,
                workspace_id,
                pane_id,
                Direction::Right,
            )
            .expect_err("reject self split of only surface");

        assert!(matches!(
            error,
            DomainError::InvalidOperation("cannot split a pane from its only surface")
        ));
    }

    #[test]
    fn moving_surface_to_another_workspace_creates_new_window_and_switches_workspace() {
        let mut model = AppModel::new("Main");
        let source_workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .map(|pane| pane.active_surface)
            .expect("first surface");
        let moved_surface_id = model
            .create_surface(source_workspace_id, source_pane_id, PaneKind::Browser)
            .expect("second surface");
        let target_workspace_id = model.create_workspace("Secondary");

        let new_pane_id = model
            .move_surface_to_workspace(
                source_workspace_id,
                source_pane_id,
                moved_surface_id,
                target_workspace_id,
            )
            .expect("move to workspace");

        let source_workspace = model
            .workspaces
            .get(&source_workspace_id)
            .expect("source workspace");
        let target_workspace = model
            .workspaces
            .get(&target_workspace_id)
            .expect("target workspace");
        let moved_window_id = target_workspace
            .window_for_pane(new_pane_id)
            .expect("moved window");

        assert_eq!(model.active_workspace_id(), Some(target_workspace_id));
        assert_eq!(
            source_workspace
                .panes
                .get(&source_pane_id)
                .expect("source pane")
                .surface_ids()
                .collect::<Vec<_>>(),
            vec![first_surface_id]
        );
        assert_eq!(
            target_workspace
                .panes
                .get(&new_pane_id)
                .expect("new pane")
                .surface_ids()
                .collect::<Vec<_>>(),
            vec![moved_surface_id]
        );
        assert_eq!(target_workspace.active_window, moved_window_id);
        assert_eq!(target_workspace.active_pane, new_pane_id);
    }

    #[test]
    fn transferring_surface_to_existing_pane_in_another_workspace_moves_notifications_and_flash() {
        let mut model = AppModel::new("Main");
        let source_workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let _first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .map(|pane| pane.active_surface)
            .expect("first surface");
        let moved_surface_id = model
            .create_surface(source_workspace_id, source_pane_id, PaneKind::Browser)
            .expect("second surface");
        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id: source_workspace_id,
                    pane_id: source_pane_id,
                    surface_id: moved_surface_id,
                },
                SignalKind::Notification,
                Some("Needs review".into()),
                None,
                Some("review-1".into()),
                "Check this browser tab".into(),
                AttentionState::WaitingInput,
            )
            .expect("notification");
        model
            .trigger_surface_flash(source_workspace_id, source_pane_id, moved_surface_id)
            .expect("flash");

        let target_workspace_id = model.create_workspace("Secondary");
        let target_pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .transfer_surface(
                source_workspace_id,
                source_pane_id,
                moved_surface_id,
                target_workspace_id,
                target_pane_id,
                usize::MAX,
            )
            .expect("transfer");

        let source_workspace = model
            .workspaces
            .get(&source_workspace_id)
            .expect("source workspace");
        let target_workspace = model
            .workspaces
            .get(&target_workspace_id)
            .expect("target workspace");
        let target_pane = target_workspace
            .panes
            .get(&target_pane_id)
            .expect("target pane");

        assert_eq!(model.active_workspace_id(), Some(target_workspace_id));
        assert!(
            !source_workspace
                .notifications
                .iter()
                .any(|notification| notification.surface_id == moved_surface_id)
        );
        assert!(
            source_workspace
                .surface_flash_tokens
                .get(&moved_surface_id)
                .is_none()
        );
        assert!(
            target_pane
                .surface_ids()
                .collect::<Vec<_>>()
                .contains(&moved_surface_id)
        );
        assert_eq!(target_pane.active_surface, moved_surface_id);
        assert!(target_workspace.notifications.iter().any(|notification| {
            notification.surface_id == moved_surface_id && notification.pane_id == target_pane_id
        }));
        assert!(
            target_workspace
                .surface_flash_tokens
                .get(&moved_surface_id)
                .is_some()
        );
    }

    #[test]
    fn transferring_active_surface_normalizes_the_source_pane() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let remaining_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .map(|pane| pane.active_surface)
            .expect("remaining surface");
        let moved_surface_id = model
            .create_surface(workspace_id, source_pane_id, PaneKind::Browser)
            .expect("second surface");
        let target_pane_id = model
            .split_pane(workspace_id, Some(source_pane_id), SplitAxis::Horizontal)
            .expect("split pane");

        model
            .transfer_surface(
                workspace_id,
                source_pane_id,
                moved_surface_id,
                workspace_id,
                target_pane_id,
                usize::MAX,
            )
            .expect("transfer");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let source_pane = workspace.panes.get(&source_pane_id).expect("source pane");

        assert_eq!(source_pane.active_surface, remaining_surface_id);
        assert_eq!(
            source_pane.active_surface().map(|surface| surface.id),
            Some(remaining_surface_id)
        );
        assert_eq!(
            source_pane.surface_ids().collect::<Vec<_>>(),
            vec![remaining_surface_id]
        );
    }

    #[test]
    fn moving_surface_to_split_in_another_workspace_closes_empty_source_pane() {
        let mut model = AppModel::new("Main");
        let source_workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let anchor_pane_id = model
            .split_pane(
                source_workspace_id,
                Some(source_pane_id),
                SplitAxis::Horizontal,
            )
            .expect("split source workspace");
        model
            .focus_pane(source_workspace_id, source_pane_id)
            .expect("focus source pane");
        let moved_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .map(|pane| pane.active_surface)
            .expect("moved surface");

        let target_workspace_id = model.create_workspace("Secondary");
        let target_pane_id = model.active_workspace().expect("workspace").active_pane;

        let new_pane_id = model
            .move_surface_to_split(
                source_workspace_id,
                source_pane_id,
                moved_surface_id,
                target_workspace_id,
                target_pane_id,
                Direction::Left,
            )
            .expect("move to split");

        let source_workspace = model
            .workspaces
            .get(&source_workspace_id)
            .expect("source workspace");
        let target_workspace = model
            .workspaces
            .get(&target_workspace_id)
            .expect("target workspace");
        let target_window_id = target_workspace
            .window_for_pane(target_pane_id)
            .expect("target window");
        let target_window = target_workspace
            .windows
            .get(&target_window_id)
            .expect("target window record");
        let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) = target_workspace
            .pane_location(new_pane_id)
            .expect("pane location");

        assert_eq!(model.active_workspace_id(), Some(target_workspace_id));
        assert!(!source_workspace.panes.contains_key(&source_pane_id));
        assert!(source_workspace.panes.contains_key(&anchor_pane_id));
        assert_eq!(
            target_window.active_layout().expect("layout").leaves(),
            vec![pane_container_id]
        );
        assert_eq!(
            target_workspace
                .pane_containers
                .get(&pane_container_id)
                .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
                .expect("pane tab")
                .layout
                .leaves(),
            vec![new_pane_id, target_pane_id]
        );
        assert_eq!(target_workspace.active_pane, new_pane_id);
        assert_eq!(
            target_workspace
                .panes
                .get(&new_pane_id)
                .expect("new pane")
                .surface_ids()
                .collect::<Vec<_>>(),
            vec![moved_surface_id]
        );
    }

    #[test]
    fn transferring_last_surface_closes_the_source_pane() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let target_pane_id = model
            .split_pane(workspace_id, Some(source_pane_id), SplitAxis::Horizontal)
            .expect("split");
        let moved_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&source_pane_id))
            .and_then(|pane| pane.surface_ids().next())
            .expect("surface");

        model
            .transfer_surface(
                workspace_id,
                source_pane_id,
                moved_surface_id,
                workspace_id,
                target_pane_id,
                usize::MAX,
            )
            .expect("transfer");

        let workspace = model.active_workspace().expect("workspace");
        assert!(!workspace.panes.contains_key(&source_pane_id));
        let target_order = workspace
            .panes
            .get(&target_pane_id)
            .expect("target pane")
            .surface_ids()
            .collect::<Vec<_>>();
        assert!(target_order.contains(&moved_surface_id));
        assert_eq!(workspace.active_pane, target_pane_id);
    }

    #[test]
    fn closing_surface_after_reorder_removes_the_requested_surface() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let first_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface id");
        let second_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("second surface");
        let third_surface_id = model
            .create_surface(workspace_id, pane_id, PaneKind::Terminal)
            .expect("third surface");

        model
            .move_surface(workspace_id, pane_id, first_surface_id, 2)
            .expect("move first surface to end");
        model
            .close_surface(workspace_id, pane_id, second_surface_id)
            .expect("close second surface");

        let pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .expect("pane");
        let order = pane.surface_ids().collect::<Vec<_>>();

        assert_eq!(order, vec![third_surface_id, first_surface_id]);
        assert!(!order.contains(&second_surface_id));
    }

    #[test]
    fn resizing_window_and_split_updates_state() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .expect("pane");
        let second_pane = model
            .split_pane(workspace_id, Some(first_pane), SplitAxis::Horizontal)
            .expect("split");

        model
            .focus_pane(workspace_id, second_pane)
            .expect("focus second pane");
        model
            .resize_active_pane_split(workspace_id, Direction::Right, 60)
            .expect("resize split");
        model
            .resize_active_window(workspace_id, Direction::Right, 120)
            .expect("resize window");
        model
            .resize_active_window(workspace_id, Direction::Down, 90)
            .expect("resize height");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let window = workspace.active_window_record().expect("window");
        let column = workspace
            .active_column_id()
            .and_then(|column_id| workspace.columns.get(&column_id))
            .expect("column");
        let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) =
            workspace.pane_location(second_pane).expect("pane location");
        let pane_tab = workspace
            .pane_containers
            .get(&pane_container_id)
            .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
            .expect("pane tab");
        let PaneTabLayoutNode::Split { ratio, .. } = &pane_tab.layout else {
            panic!("expected split layout");
        };
        assert_eq!(*ratio, 440);
        assert_eq!(column.width, DEFAULT_WORKSPACE_WINDOW_WIDTH + 120);
        assert_eq!(window.height, DEFAULT_WORKSPACE_WINDOW_HEIGHT + 90);
    }

    #[test]
    fn setting_pane_tab_split_ratio_updates_target_split() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .expect("pane");
        let second_pane = model
            .split_pane(workspace_id, Some(first_pane), SplitAxis::Horizontal)
            .expect("split");

        let (pane_container_id, pane_tab_id) = {
            let workspace = model.workspaces.get(&workspace_id).expect("workspace");
            let (_window_id, _window_tab_id, pane_container_id, pane_tab_id) =
                workspace.pane_location(second_pane).expect("pane location");
            (pane_container_id, pane_tab_id)
        };

        model
            .set_pane_tab_split_ratio(workspace_id, pane_container_id, pane_tab_id, &[], 700)
            .expect("set split ratio");

        let workspace = model.workspaces.get(&workspace_id).expect("workspace");
        let pane_tab = workspace
            .pane_containers
            .get(&pane_container_id)
            .and_then(|pane_container| pane_container.tabs.get(&pane_tab_id))
            .expect("pane tab");
        let PaneTabLayoutNode::Split { ratio, .. } = &pane_tab.layout else {
            panic!("expected split layout");
        };
        assert_eq!(*ratio, 700);
    }

    #[test]
    fn clean_break_rejects_legacy_workspace_layouts() {
        let workspace_id = WorkspaceId::new();
        let window_id = WindowId::new();
        let left_pane = PaneRecord::new(PaneKind::Terminal);
        let right_pane = PaneRecord::new(PaneKind::Terminal);

        let encoded = json!({
            "schema_version": 1,
            "captured_at": OffsetDateTime::now_utc(),
            "model": {
                "active_window": window_id,
                "windows": {
                    window_id.to_string(): {
                        "id": window_id,
                        "workspace_order": [workspace_id],
                        "active_workspace": workspace_id
                    }
                },
                "workspaces": {
                    workspace_id.to_string(): {
                        "id": workspace_id,
                        "label": "Main",
                        "layout": {
                            "kind": "scrollable_tiling",
                            "columns": [
                                {"panes": [left_pane.id]},
                                {"panes": [right_pane.id]}
                            ],
                            "viewport": {"x": 64, "y": 24}
                        },
                        "panes": {
                            left_pane.id.to_string(): left_pane,
                            right_pane.id.to_string(): right_pane
                        },
                        "active_pane": right_pane.id,
                        "notifications": []
                    }
                }
            }
        });

        let decoded = serde_json::from_value::<PersistedSession>(encoded);
        assert!(decoded.is_err());
    }

    #[test]
    fn signals_flow_into_activity_and_summary() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.first().map(|(pane_id, _)| *pane_id))
            .expect("pane");

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::new(
                    "test",
                    SignalKind::WaitingInput,
                    Some("Need approval".into()),
                ),
            )
            .expect("signal applied");

        let summaries = model
            .workspace_summaries(model.active_window)
            .expect("summary available");
        let summary = summaries.first().expect("summary");

        assert_eq!(summary.highest_attention, AttentionState::WaitingInput);
        assert_eq!(
            summary
                .counts_by_attention
                .get(&AttentionState::WaitingInput)
                .copied(),
            Some(1)
        );
        assert_eq!(model.activity_items().len(), 1);
    }

    #[test]
    fn persisted_session_roundtrips() {
        let model = AppModel::demo();
        let snapshot = model.snapshot();
        let encoded = serde_json::to_string_pretty(&snapshot).expect("serialize");
        let decoded: PersistedSession = serde_json::from_str(&encoded).expect("deserialize");

        assert_eq!(decoded.schema_version, SESSION_SCHEMA_VERSION);
        assert_eq!(decoded.model.workspaces.len(), model.workspaces.len());
    }

    #[test]
    fn notification_signal_maps_to_waiting_attention() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::new(
                    "notify:Codex",
                    SignalKind::Notification,
                    Some("Turn complete".into()),
                ),
            )
            .expect("signal applied");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(PaneRecord::active_surface)
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::WaitingInput);
    }

    #[test]
    fn agent_hook_notification_updates_context_without_creating_attention_item() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "agent-hook:codex",
                    SignalKind::Notification,
                    Some("Turn complete".into()),
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("notification applied");

        let workspace = model.active_workspace().expect("workspace");
        let surface = workspace
            .panes
            .get(&pane_id)
            .and_then(PaneRecord::active_surface)
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::WaitingInput);
        assert_eq!(
            surface.metadata.latest_agent_message.as_deref(),
            Some("Turn complete")
        );
        assert_eq!(
            surface.metadata.agent_state,
            Some(WorkspaceAgentState::Waiting)
        );
        assert!(workspace.notifications.is_empty());
    }

    #[test]
    fn stop_signal_uses_cached_agent_message_for_final_notification() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "agent-hook:codex",
                    SignalKind::Notification,
                    Some("Turn complete".into()),
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("notification applied");

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "agent-hook:codex",
                    SignalKind::Completed,
                    None,
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(false),
                        agent_command: None,
                    }),
                ),
            )
            .expect("completed applied");

        let workspace = model.active_workspace().expect("workspace");
        let notification = workspace
            .notifications
            .last()
            .expect("completion notification");
        assert_eq!(notification.kind, SignalKind::Completed);
        assert_eq!(notification.state, AttentionState::Completed);
        assert_eq!(notification.message, "Turn complete");
        assert_eq!(notification.title.as_deref(), Some("Codex"));

        let surface = workspace
            .panes
            .get(&pane_id)
            .and_then(PaneRecord::active_surface)
            .expect("surface");
        let session = surface
            .agent_session
            .as_ref()
            .expect("completed signal should preserve recent agent session");
        assert_eq!(
            surface.metadata.agent_state,
            Some(WorkspaceAgentState::Completed)
        );
        assert!(!surface.metadata.agent_active);
        assert_eq!(session.state, WorkspaceAgentState::Completed);
        assert_eq!(session.latest_message.as_deref(), Some("Turn complete"));
    }

    #[test]
    fn progress_signals_update_attention_without_creating_activity_items() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .update_pane_metadata(
                pane_id,
                PaneMetadataPatch {
                    title: Some("Codex".into()),
                    cwd: None,
                    url: None,
                    browser_profile_mode: None,
                    repo_name: None,
                    git_branch: None,
                    ports: None,
                    agent_kind: Some("codex".into()),
                },
            )
            .expect("metadata updated");
        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::new("test", SignalKind::Progress, Some("Still working".into())),
            )
            .expect("signal applied");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(PaneRecord::active_surface)
            .expect("surface");

        assert_eq!(surface.attention, AttentionState::Busy);
        assert!(model.activity_items().is_empty());
    }

    #[test]
    fn started_signals_do_not_create_attention_items() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "agent-hook:codex",
                    SignalKind::Started,
                    None,
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("started applied");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(PaneRecord::active_surface)
            .expect("surface");

        assert_eq!(surface.attention, AttentionState::Busy);
        assert!(model.activity_items().is_empty());
    }

    #[test]
    fn metadata_signals_for_shell_prompt_clear_stale_agent_identity() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let stale_timestamp = OffsetDateTime::now_utc() - Duration::minutes(20);

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent {
                    source: "test".into(),
                    kind: SignalKind::Completed,
                    message: Some("Done".into()),
                    metadata: Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(false),
                        agent_command: None,
                    }),
                    timestamp: stale_timestamp,
                },
            )
            .expect("completed signal applied");

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "test",
                    SignalKind::Metadata,
                    None,
                    Some(SignalPaneMetadata {
                        title: Some("taskers".into()),
                        agent_title: None,
                        cwd: Some("/tmp".into()),
                        repo_name: Some("taskers".into()),
                        git_branch: Some("main".into()),
                        ports: Vec::new(),
                        agent_kind: Some("shell".into()),
                        agent_active: Some(false),
                        agent_command: None,
                    }),
                ),
            )
            .expect("metadata signal applied");

        let summaries = model
            .workspace_summaries(model.active_window)
            .expect("workspace summaries");
        assert!(
            summaries
                .first()
                .expect("summary")
                .agent_summaries
                .is_empty()
        );

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(PaneRecord::active_surface)
            .expect("surface");
        assert_eq!(surface.metadata.agent_kind, None);
        assert_eq!(surface.metadata.agent_title, None);
        assert_eq!(surface.metadata.agent_state, None);
        assert_eq!(surface.metadata.latest_agent_message, None);
        assert_eq!(surface.attention, AttentionState::Normal);
        assert_eq!(surface.metadata.last_signal_at, None);
    }

    #[test]
    fn marking_surface_completed_clears_activity_and_keeps_recent_completed_status() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface id");

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "test",
                    SignalKind::WaitingInput,
                    Some("Need review".into()),
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("waiting signal applied");

        assert_eq!(model.activity_items().len(), 1);

        model
            .mark_surface_completed(workspace_id, pane_id, surface_id)
            .expect("mark completed");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(PaneRecord::active_surface)
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::Normal);
        assert!(model.activity_items().is_empty());

        let summaries = model
            .workspace_summaries(model.active_window)
            .expect("workspace summaries");
        assert_eq!(
            summaries
                .first()
                .and_then(|summary| summary.agent_summaries.first())
                .map(|summary| summary.state),
            None
        );
    }

    #[test]
    fn metadata_inactive_resolves_waiting_agent_state() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "test",
                    SignalKind::WaitingInput,
                    Some("Need input".into()),
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("waiting signal applied");

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "test",
                    SignalKind::Metadata,
                    None,
                    Some(SignalPaneMetadata {
                        title: Some("codex :: taskers".into()),
                        agent_title: None,
                        cwd: Some("/tmp".into()),
                        repo_name: Some("taskers".into()),
                        git_branch: Some("main".into()),
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(false),
                        agent_command: None,
                    }),
                ),
            )
            .expect("metadata signal applied");

        let workspace = model.active_workspace().expect("workspace");
        let surface = workspace
            .panes
            .get(&pane_id)
            .and_then(PaneRecord::active_surface)
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::Normal);
        assert!(surface.agent_session.is_none());
        assert!(!surface.metadata.agent_active);
        assert_eq!(surface.metadata.agent_state, None);
        assert_eq!(surface.metadata.latest_agent_message, None);
        assert_eq!(surface.metadata.last_signal_at, None);
        assert!(
            workspace
                .notifications
                .iter()
                .all(|item| item.cleared_at.is_some())
        );

        let summaries = model
            .workspace_summaries(model.active_window)
            .expect("workspace summaries");
        assert_eq!(
            summaries
                .first()
                .and_then(|summary| summary.agent_summaries.first())
                .map(|summary| summary.state),
            None
        );
    }

    #[test]
    fn focusing_waiting_agent_does_not_clear_attention_item() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let window_id = model.active_window;
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface id");

        model
            .apply_signal(
                workspace_id,
                pane_id,
                SignalEvent::with_metadata(
                    "test",
                    SignalKind::WaitingInput,
                    Some("Need review".into()),
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("waiting signal applied");

        let other_workspace_id = model.create_workspace("Docs");
        assert_eq!(model.activity_items().len(), 1);

        model
            .switch_workspace(window_id, workspace_id)
            .expect("switch back to waiting workspace");
        model
            .focus_surface(workspace_id, pane_id, surface_id)
            .expect("focus waiting surface");

        let activity_items = model.activity_items();
        assert_eq!(activity_items.len(), 1);
        assert_eq!(activity_items[0].state, AttentionState::WaitingInput);
        assert_eq!(
            model
                .workspaces
                .get(&workspace_id)
                .expect("workspace")
                .notifications
                .iter()
                .filter(|item| item.cleared_at.is_none())
                .count(),
            1
        );
        assert_eq!(model.active_workspace_id(), Some(workspace_id));
        assert_ne!(workspace_id, other_workspace_id);
    }

    #[test]
    fn workspace_agent_state_flows_into_summary_and_logs_are_bounded() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");

        model
            .set_workspace_status(workspace_id, "Running import".into())
            .expect("set status");
        model
            .set_workspace_progress(
                workspace_id,
                ProgressState {
                    value: 420,
                    label: Some("42%".into()),
                },
            )
            .expect("set progress");

        for index in 0..205 {
            model
                .append_workspace_log(
                    workspace_id,
                    WorkspaceLogEntry {
                        source: Some("codex".into()),
                        message: format!("log {index}"),
                        created_at: OffsetDateTime::now_utc(),
                    },
                )
                .expect("append log");
        }

        let summary = model
            .workspace_summaries(model.active_window)
            .expect("workspace summaries")
            .into_iter()
            .find(|summary| summary.workspace_id == workspace_id)
            .expect("workspace summary");
        let workspace = model.workspaces.get(&workspace_id).expect("workspace");

        assert_eq!(summary.status_text.as_deref(), Some("Running import"));
        assert_eq!(
            workspace.progress.as_ref().map(|progress| progress.value),
            Some(420)
        );
        assert_eq!(workspace.log_entries.len(), 200);
        assert_eq!(
            workspace
                .log_entries
                .first()
                .map(|entry| entry.message.as_str()),
            Some("log 5")
        );
        assert_eq!(
            workspace
                .log_entries
                .last()
                .map(|entry| entry.message.as_str()),
            Some("log 204")
        );
    }

    #[test]
    fn focusing_latest_unread_prefers_newest_notification_in_active_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface");
        let second_workspace_id = model.create_workspace("Secondary");

        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Notification,
                Some("Older".into()),
                None,
                None,
                "First".into(),
                AttentionState::WaitingInput,
            )
            .expect("older notification");
        std::thread::sleep(std::time::Duration::from_millis(2));
        model
            .create_agent_notification(
                AgentTarget::Workspace {
                    workspace_id: second_workspace_id,
                },
                SignalKind::Notification,
                Some("Newest".into()),
                None,
                None,
                "Second".into(),
                AttentionState::WaitingInput,
            )
            .expect("newer notification");

        let focused = model
            .focus_latest_unread(model.active_window)
            .expect("focus latest unread");

        assert!(focused);
        assert_eq!(model.active_workspace_id(), Some(second_workspace_id));
    }

    #[test]
    fn opening_notification_marks_it_read_without_clearing() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Notification,
                Some("Heads up".into()),
                None,
                None,
                "Review needed".into(),
                AttentionState::WaitingInput,
            )
            .expect("notification");

        let notification_id = model
            .active_workspace()
            .and_then(|workspace| workspace.notifications.last())
            .map(|notification| notification.id)
            .expect("notification id");

        model
            .open_notification(model.active_window, notification_id)
            .expect("open notification");

        let notification = model
            .active_workspace()
            .and_then(|workspace| {
                workspace
                    .notifications
                    .iter()
                    .find(|notification| notification.id == notification_id)
            })
            .expect("notification");
        assert!(notification.read_at.is_some());
        assert!(notification.cleared_at.is_none());
        assert_eq!(model.activity_items().len(), 1);
        assert!(
            model
                .activity_items()
                .iter()
                .all(|item| item.read_at.is_some())
        );
    }

    #[test]
    fn focusing_hidden_pane_activates_its_container_tab() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane_id = model.active_workspace().expect("workspace").active_pane;
        let (container_id, first_pane_tab_id) = {
            let workspace = model.active_workspace().expect("workspace");
            let (_, _, container_id, pane_tab_id) = workspace
                .pane_location(first_pane_id)
                .expect("pane location");
            (container_id, pane_tab_id)
        };
        let (second_pane_tab_id, second_pane_id) = model
            .create_pane_tab(workspace_id, container_id, PaneKind::Terminal)
            .expect("create pane tab");

        model
            .focus_pane_tab(workspace_id, container_id, first_pane_tab_id)
            .expect("focus original pane tab");
        model
            .focus_pane(workspace_id, second_pane_id)
            .expect("focus hidden pane");

        let workspace = model.active_workspace().expect("workspace");
        let container = workspace
            .pane_containers
            .get(&container_id)
            .expect("pane container");
        assert_eq!(container.active_tab, second_pane_tab_id);
        assert_eq!(workspace.active_pane, second_pane_id);
    }

    #[test]
    fn opening_notification_surfaces_hidden_pane_tab() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_pane_id = model.active_workspace().expect("workspace").active_pane;
        let (container_id, first_pane_tab_id) = {
            let workspace = model.active_workspace().expect("workspace");
            let (_, _, container_id, pane_tab_id) = workspace
                .pane_location(first_pane_id)
                .expect("pane location");
            (container_id, pane_tab_id)
        };
        let (second_pane_tab_id, second_pane_id) = model
            .create_pane_tab(workspace_id, container_id, PaneKind::Terminal)
            .expect("create pane tab");
        let second_surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&second_pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("second surface");

        model
            .focus_pane_tab(workspace_id, container_id, first_pane_tab_id)
            .expect("focus original pane tab");
        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id: second_pane_id,
                    surface_id: second_surface_id,
                },
                SignalKind::Notification,
                Some("Heads up".into()),
                None,
                None,
                "Review hidden pane".into(),
                AttentionState::WaitingInput,
            )
            .expect("notification");
        let notification_id = model
            .active_workspace()
            .and_then(|workspace| workspace.notifications.last())
            .map(|notification| notification.id)
            .expect("notification id");

        model
            .open_notification(model.active_window, notification_id)
            .expect("open notification");

        let workspace = model.active_workspace().expect("workspace");
        let container = workspace
            .pane_containers
            .get(&container_id)
            .expect("pane container");
        assert_eq!(container.active_tab, second_pane_tab_id);
        assert_eq!(workspace.active_pane, second_pane_id);
    }

    #[test]
    fn agent_notifications_do_not_create_live_agent_sessions() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Notification,
                Some("Codex".into()),
                None,
                None,
                "Need input".into(),
                AttentionState::WaitingInput,
            )
            .expect("notification");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface record");
        assert!(surface.agent_session.is_none());
        assert_eq!(surface.metadata.agent_kind.as_deref(), Some("codex"));
        assert_eq!(surface.metadata.agent_title.as_deref(), Some("Codex"));
        assert_eq!(surface.metadata.agent_state, None);
        assert!(!surface.metadata.agent_active);
        assert_eq!(
            surface.metadata.latest_agent_message.as_deref(),
            Some("Need input")
        );
        assert_eq!(surface.attention, AttentionState::WaitingInput);
    }

    #[test]
    fn clearing_notification_moves_it_out_of_active_activity() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Notification,
                Some("Heads up".into()),
                None,
                None,
                "Review needed".into(),
                AttentionState::WaitingInput,
            )
            .expect("notification");

        let notification_id = model
            .active_workspace()
            .and_then(|workspace| workspace.notifications.last())
            .map(|notification| notification.id)
            .expect("notification id");

        model
            .clear_notification(notification_id)
            .expect("clear notification");

        assert!(model.activity_items().is_empty());
        let notification = model
            .active_workspace()
            .and_then(|workspace| {
                workspace
                    .notifications
                    .iter()
                    .find(|notification| notification.id == notification_id)
            })
            .expect("notification");
        assert!(notification.read_at.is_some());
        assert!(notification.cleared_at.is_some());
        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::Normal);
    }

    #[test]
    fn clearing_notification_keeps_surface_attention_when_another_alert_is_still_active() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Notification,
                Some("Heads up".into()),
                None,
                None,
                "Review needed".into(),
                AttentionState::WaitingInput,
            )
            .expect("waiting notification");
        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Error,
                Some("Heads up".into()),
                None,
                None,
                "Build failed".into(),
                AttentionState::Error,
            )
            .expect("error notification");

        let first_notification_id = model
            .active_workspace()
            .and_then(|workspace| workspace.notifications.first())
            .map(|notification| notification.id)
            .expect("notification id");

        model
            .clear_notification(first_notification_id)
            .expect("clear notification");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::Error);
    }

    #[test]
    fn dismiss_surface_alert_clears_completed_agent_presentation() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .create_agent_notification(
                AgentTarget::Surface {
                    workspace_id,
                    pane_id,
                    surface_id,
                },
                SignalKind::Completed,
                Some("Codex".into()),
                None,
                None,
                "Finished".into(),
                AttentionState::Completed,
            )
            .expect("completed notification");

        model
            .dismiss_surface_alert(workspace_id, pane_id, surface_id)
            .expect("dismiss alert");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::Normal);
        assert_eq!(surface.metadata.agent_active, false);
        assert_eq!(surface.metadata.agent_state, None);
        assert_eq!(surface.metadata.agent_title, None);
        assert_eq!(surface.metadata.agent_kind, None);
        assert_eq!(surface.metadata.last_signal_at, None);
        assert_eq!(surface.metadata.latest_agent_message, None);
    }

    #[test]
    fn dismiss_surface_alert_clears_working_agent_presentation() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .start_surface_agent_session(workspace_id, pane_id, surface_id, "codex".into())
            .expect("working session");
        model
            .apply_surface_signal(
                workspace_id,
                pane_id,
                surface_id,
                SignalEvent::with_metadata(
                    "agent-hook:codex",
                    SignalKind::Started,
                    Some("Working".into()),
                    Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                ),
            )
            .expect("started signal applied");

        model
            .dismiss_surface_alert(workspace_id, pane_id, surface_id)
            .expect("dismiss alert");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface");
        assert_eq!(surface.attention, AttentionState::Normal);
        assert!(surface.agent_process.is_some());
        assert!(surface.agent_session.is_none());
        assert_eq!(surface.metadata.agent_active, true);
        assert_eq!(surface.metadata.agent_state, None);
        assert_eq!(surface.metadata.agent_title.as_deref(), Some("Codex"));
        assert_eq!(surface.metadata.agent_kind.as_deref(), Some("codex"));
        assert_eq!(surface.metadata.last_signal_at, None);
        assert_eq!(surface.metadata.latest_agent_message, None);
    }

    #[test]
    fn late_agent_notification_does_not_recreate_live_session_after_stop() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .start_surface_agent_session(workspace_id, pane_id, surface_id, "codex".into())
            .expect("start agent");
        model
            .stop_surface_agent_session(workspace_id, pane_id, surface_id, 0)
            .expect("stop agent");
        model
            .apply_surface_signal(
                workspace_id,
                pane_id,
                surface_id,
                SignalEvent {
                    source: "agent-hook:codex".into(),
                    kind: SignalKind::Notification,
                    message: Some("Turn complete".into()),
                    metadata: Some(SignalPaneMetadata {
                        title: None,
                        agent_title: Some("Codex".into()),
                        cwd: None,
                        repo_name: None,
                        git_branch: None,
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: None,
                    }),
                    timestamp: OffsetDateTime::now_utc(),
                },
            )
            .expect("late notification");

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface record");
        assert!(surface.agent_session.is_none());
        assert_eq!(surface.attention, AttentionState::WaitingInput);
    }

    #[test]
    fn recover_interrupted_agent_resume_converts_live_agent_into_resume_offer() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .start_surface_agent_session(workspace_id, pane_id, surface_id, "codex".into())
            .expect("start agent");
        model
            .apply_surface_signal(
                workspace_id,
                pane_id,
                surface_id,
                SignalEvent::with_metadata(
                    "shell",
                    SignalKind::Metadata,
                    None,
                    Some(SignalPaneMetadata {
                        title: Some("codex :: taskers".into()),
                        agent_title: Some("Codex".into()),
                        cwd: Some("/tmp/taskers".into()),
                        repo_name: Some("taskers".into()),
                        git_branch: Some("main".into()),
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: Some("codex --model gpt-5".into()),
                    }),
                ),
            )
            .expect("metadata signal applied");

        assert_eq!(model.recover_interrupted_agent_resumes(), 1);

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface");
        let resume = surface
            .interrupted_agent_resume
            .as_ref()
            .expect("resume offer");
        assert_eq!(resume.kind, "codex");
        assert_eq!(resume.title, "Codex");
        assert_eq!(resume.command, "codex --model gpt-5");
        assert_eq!(resume.cwd.as_deref(), Some("/tmp/taskers"));
        assert!(surface.agent_process.is_none());
        assert!(surface.agent_session.is_none());
        assert_eq!(surface.attention, AttentionState::WaitingInput);
        assert_eq!(surface.metadata.agent_active, false);
        assert_eq!(
            model
                .activity_items()
                .iter()
                .any(|item| item.surface_id == surface_id),
            true
        );
    }

    #[test]
    fn recover_interrupted_agent_resume_clears_stale_agent_without_command() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .map(|surface| surface.id)
            .expect("surface");

        model
            .start_surface_agent_session(workspace_id, pane_id, surface_id, "codex".into())
            .expect("start agent");

        assert_eq!(model.recover_interrupted_agent_resumes(), 0);

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface_id))
            .expect("surface");
        assert!(surface.interrupted_agent_resume.is_none());
        assert!(surface.agent_process.is_none());
        assert!(surface.agent_session.is_none());
        assert_eq!(surface.metadata.agent_command, None);
        assert_eq!(surface.metadata.agent_kind, None);
        assert_eq!(surface.attention, AttentionState::Normal);
    }

    #[test]
    fn recover_interrupted_agent_resume_skips_surfaces_with_live_terminal_sessions() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.active_surface())
            .cloned()
            .expect("surface");

        model
            .start_surface_agent_session(workspace_id, pane_id, surface.id, "codex".into())
            .expect("start agent");
        model
            .apply_surface_signal(
                workspace_id,
                pane_id,
                surface.id,
                SignalEvent::with_metadata(
                    "shell",
                    SignalKind::Metadata,
                    None,
                    Some(SignalPaneMetadata {
                        title: Some("codex :: taskers".into()),
                        agent_title: Some("Codex".into()),
                        cwd: Some("/tmp/taskers".into()),
                        repo_name: Some("taskers".into()),
                        git_branch: Some("main".into()),
                        ports: Vec::new(),
                        agent_kind: Some("codex".into()),
                        agent_active: Some(true),
                        agent_command: Some("codex --model gpt-5".into()),
                    }),
                ),
            )
            .expect("metadata signal applied");

        assert_eq!(
            model.recover_interrupted_agent_resumes_for_missing_sessions(|session_id| {
                session_id == surface.session_id
            }),
            0
        );

        let surface = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .and_then(|pane| pane.surfaces.get(&surface.id))
            .expect("surface");
        assert!(surface.interrupted_agent_resume.is_none());
        assert!(surface.agent_process.is_some());
        assert_eq!(surface.metadata.agent_active, true);
    }

    #[test]
    fn triggering_surface_flash_advances_workspace_flash_token() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let pane_id = model.active_workspace().expect("workspace").active_pane;
        let surface_id = model
            .active_workspace()
            .and_then(|workspace| workspace.panes.get(&pane_id))
            .map(|pane| pane.active_surface)
            .expect("surface");

        model
            .trigger_surface_flash(workspace_id, pane_id, surface_id)
            .expect("trigger first flash");
        let first_token = model
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.surface_flash_tokens.get(&surface_id))
            .copied()
            .expect("first flash token");
        model
            .trigger_surface_flash(workspace_id, pane_id, surface_id)
            .expect("trigger second flash");
        let second_token = model
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.surface_flash_tokens.get(&surface_id))
            .copied()
            .expect("second flash token");

        assert!(second_token > first_token);
    }

    #[test]
    fn creating_workspace_window_tab_adds_blank_terminal_tab_and_focuses_it() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let window_id = model.active_workspace().expect("workspace").active_window;

        let (tab_id, pane_id) = model
            .create_workspace_window_tab(workspace_id, window_id)
            .expect("create window tab");

        let workspace = model.active_workspace().expect("workspace");
        let window = workspace.windows.get(&window_id).expect("window");
        let pane = workspace.panes.get(&pane_id).expect("new pane");

        assert_eq!(window.tabs.len(), 2);
        assert_eq!(window.active_tab, tab_id);
        assert_eq!(workspace.active_window, window_id);
        assert_eq!(workspace.active_pane, pane_id);
        assert_eq!(pane.surfaces.len(), 1);
        assert_eq!(
            pane.active_surface().map(|surface| surface.kind.clone()),
            Some(PaneKind::Terminal)
        );
    }

    #[test]
    fn closing_last_window_tab_closes_workspace_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let first_window_id = model.active_workspace().expect("workspace").active_window;

        model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("create second window");

        let closing_tab_id = model
            .workspaces
            .get(&workspace_id)
            .and_then(|workspace| workspace.windows.get(&first_window_id))
            .map(|window| window.active_tab)
            .expect("window tab");

        model
            .close_workspace_window_tab(workspace_id, first_window_id, closing_tab_id)
            .expect("close last tab");

        let workspace = model.active_workspace().expect("workspace");
        assert!(!workspace.windows.contains_key(&first_window_id));
        assert_eq!(workspace.windows.len(), 1);
    }

    #[test]
    fn transferring_window_tab_merges_into_target_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_window_id = model.active_workspace().expect("workspace").active_window;
        let (tab_id, _) = model
            .create_workspace_window_tab(workspace_id, source_window_id)
            .expect("create second tab");
        let target_pane_id = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("create second window");
        let target_window_id = model
            .active_workspace()
            .and_then(|workspace| workspace.window_for_pane(target_pane_id))
            .expect("target window");

        model
            .transfer_workspace_window_tab(
                workspace_id,
                source_window_id,
                tab_id,
                target_window_id,
                usize::MAX,
            )
            .expect("transfer window tab");

        let workspace = model.active_workspace().expect("workspace");
        assert_eq!(
            workspace
                .windows
                .get(&source_window_id)
                .map(|window| window.tabs.len()),
            Some(1)
        );
        assert_eq!(
            workspace
                .windows
                .get(&target_window_id)
                .map(|window| window.tabs.len()),
            Some(2)
        );
        assert_eq!(workspace.active_window, target_window_id);
    }

    #[test]
    fn transferring_pane_tab_merges_into_target_container() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let (source_container_id, source_original_tab_id) = {
            let workspace = model.active_workspace().expect("workspace");
            let (_, _, container_id, pane_tab_id) = workspace
                .pane_location(source_pane_id)
                .expect("pane location");
            (container_id, pane_tab_id)
        };
        let (moved_tab_id, moved_pane_id) = model
            .create_pane_tab(workspace_id, source_container_id, PaneKind::Terminal)
            .expect("create pane tab");

        let target_pane_id = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("create second window");
        let (target_window_id, _, target_container_id, target_original_tab_id) = {
            let workspace = model.active_workspace().expect("workspace");
            workspace
                .pane_location(target_pane_id)
                .expect("target pane location")
        };

        model
            .transfer_pane_tab(
                workspace_id,
                source_container_id,
                moved_tab_id,
                target_container_id,
                usize::MAX,
            )
            .expect("transfer pane tab");

        let workspace = model.active_workspace().expect("workspace");
        let source_container = workspace
            .pane_containers
            .get(&source_container_id)
            .expect("source container");
        let target_container = workspace
            .pane_containers
            .get(&target_container_id)
            .expect("target container");

        assert_eq!(
            source_container.tabs.keys().copied().collect::<Vec<_>>(),
            vec![source_original_tab_id]
        );
        assert_eq!(
            target_container.tabs.keys().copied().collect::<Vec<_>>(),
            vec![target_original_tab_id, moved_tab_id]
        );
        assert_eq!(target_container.active_tab, moved_tab_id);
        assert_eq!(workspace.active_window, target_window_id);
        assert_eq!(workspace.active_pane, moved_pane_id);
    }

    #[test]
    fn transferring_last_pane_tab_removes_empty_source_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_window_id = model.active_workspace().expect("workspace").active_window;
        let source_pane_id = model.active_workspace().expect("workspace").active_pane;
        let (source_container_id, moved_tab_id) = {
            let workspace = model.active_workspace().expect("workspace");
            let (_, _, container_id, pane_tab_id) = workspace
                .pane_location(source_pane_id)
                .expect("pane location");
            (container_id, pane_tab_id)
        };

        let target_pane_id = model
            .create_workspace_window(workspace_id, Direction::Right)
            .expect("create second window");
        let (target_window_id, _, target_container_id, _) = {
            let workspace = model.active_workspace().expect("workspace");
            workspace
                .pane_location(target_pane_id)
                .expect("target pane location")
        };

        model
            .transfer_pane_tab(
                workspace_id,
                source_container_id,
                moved_tab_id,
                target_container_id,
                usize::MAX,
            )
            .expect("transfer last pane tab");

        let workspace = model.active_workspace().expect("workspace");
        assert!(!workspace.windows.contains_key(&source_window_id));
        assert_eq!(workspace.active_window, target_window_id);
        assert_eq!(
            workspace
                .pane_containers
                .get(&target_container_id)
                .map(|container| container.tabs.len()),
            Some(2)
        );
    }

    #[test]
    fn extracting_window_tab_creates_new_workspace_window() {
        let mut model = AppModel::new("Main");
        let workspace_id = model.active_workspace_id().expect("workspace");
        let source_window_id = model.active_workspace().expect("workspace").active_window;
        let (tab_id, pane_id) = model
            .create_workspace_window_tab(workspace_id, source_window_id)
            .expect("create second tab");

        let extracted_window_id = model
            .extract_workspace_window_tab(
                workspace_id,
                source_window_id,
                tab_id,
                WorkspaceWindowMoveTarget::StackBelow {
                    window_id: source_window_id,
                },
            )
            .expect("extract tab");

        let workspace = model.active_workspace().expect("workspace");
        assert_eq!(workspace.windows.len(), 2);
        assert_eq!(
            workspace
                .windows
                .get(&source_window_id)
                .map(|window| window.tabs.len()),
            Some(1)
        );
        assert_eq!(
            workspace.window_for_pane(pane_id),
            Some(extracted_window_id)
        );
        assert_eq!(workspace.active_window, extracted_window_id);
    }
}