feat(ecc2): add split-pane dashboard resizing

ecc2/src/config/mod.rs

@@ -2,7 +2,17 @@ use anyhow::Result;
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
 
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneLayout {
+    #[default]
+    Horizontal,
+    Vertical,
+    Grid,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct Config {
     pub db_path: PathBuf,
     pub worktree_root: PathBuf,
@@ -12,6 +22,7 @@ pub struct Config {
     pub heartbeat_interval_secs: u64,
     pub default_agent: String,
     pub theme: Theme,
+    pub pane_layout: PaneLayout,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -32,6 +43,7 @@ impl Default for Config {
             heartbeat_interval_secs: 30,
             default_agent: "claude".to_string(),
             theme: Theme::Dark,
+            pane_layout: PaneLayout::Horizontal,
         }
     }
 }
@@ -52,3 +64,28 @@ impl Config {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{Config, PaneLayout};
+
+    #[test]
+    fn default_config_uses_horizontal_pane_layout() {
+        assert_eq!(Config::default().pane_layout, PaneLayout::Horizontal);
+    }
+
+    #[test]
+    fn missing_pane_layout_deserializes_to_default() {
+        let cfg: Config = toml::from_str(r#"default_agent = "codex""#).unwrap();
+
+        assert_eq!(cfg.pane_layout, PaneLayout::Horizontal);
+        assert_eq!(cfg.default_agent, "codex");
+    }
+
+    #[test]
+    fn pane_layout_deserializes_from_toml() {
+        let cfg: Config = toml::from_str(r#"pane_layout = "grid""#).unwrap();
+
+        assert_eq!(cfg.pane_layout, PaneLayout::Grid);
+    }
+}

ecc2/src/session/store.rs

@@ -3,6 +3,17 @@ use rusqlite::Connection;
 use std::path::Path;
 
 use super::{Session, SessionMetrics, SessionState};
+use crate::observability::ToolCallEvent;
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct ToolLogEntry {
+    pub tool_name: String,
+    pub input_summary: String,
+    pub output_summary: String,
+    pub duration_ms: u64,
+    pub risk_score: f64,
+    pub timestamp: String,
+}
 
 pub struct StateStore {
     conn: Connection,
@@ -170,16 +181,21 @@ impl StateStore {
 
     pub fn get_session(&self, id: &str) -> Result<Option<Session>> {
         let sessions = self.list_sessions()?;
-        Ok(sessions.into_iter().find(|s| s.id == id || s.id.starts_with(id)))
+        Ok(sessions
+            .into_iter()
+            .find(|s| s.id == id || s.id.starts_with(id)))
     }
 
-    pub fn send_message(
-        &self,
-        from: &str,
-        to: &str,
-        content: &str,
-        msg_type: &str,
-    ) -> Result<()> {
+    pub fn list_tool_logs(&self, session_id: &str, limit: usize) -> Result<Vec<ToolLogEntry>> {
+        let table_entries = self.list_tool_logs_from_table(session_id, limit)?;
+        if !table_entries.is_empty() {
+            return Ok(table_entries);
+        }
+
+        self.list_tool_logs_from_messages(session_id, limit)
+    }
+
+    pub fn send_message(&self, from: &str, to: &str, content: &str, msg_type: &str) -> Result<()> {
         self.conn.execute(
             "INSERT INTO messages (from_session, to_session, content, msg_type, timestamp)
              VALUES (?1, ?2, ?3, ?4, ?5)",
@@ -187,4 +203,76 @@ impl StateStore {
         )?;
         Ok(())
     }
+
+    fn list_tool_logs_from_table(
+        &self,
+        session_id: &str,
+        limit: usize,
+    ) -> Result<Vec<ToolLogEntry>> {
+        let mut stmt = self.conn.prepare(
+            "SELECT tool_name,
+                    COALESCE(input_summary, ''),
+                    COALESCE(output_summary, ''),
+                    COALESCE(duration_ms, 0),
+                    risk_score,
+                    timestamp
+             FROM tool_log
+             WHERE session_id = ?1
+             ORDER BY timestamp DESC
+             LIMIT ?2",
+        )?;
+
+        let entries = stmt
+            .query_map(rusqlite::params![session_id, limit as i64], |row| {
+                Ok(ToolLogEntry {
+                    tool_name: row.get(0)?,
+                    input_summary: row.get(1)?,
+                    output_summary: row.get(2)?,
+                    duration_ms: row.get(3)?,
+                    risk_score: row.get(4)?,
+                    timestamp: row.get(5)?,
+                })
+            })?
+            .collect::<Result<Vec<_>, _>>()?;
+
+        Ok(entries)
+    }
+
+    fn list_tool_logs_from_messages(
+        &self,
+        session_id: &str,
+        limit: usize,
+    ) -> Result<Vec<ToolLogEntry>> {
+        let mut stmt = self.conn.prepare(
+            "SELECT content, timestamp
+             FROM messages
+             WHERE from_session = ?1 AND msg_type = 'tool_call'
+             ORDER BY timestamp DESC
+             LIMIT ?2",
+        )?;
+
+        let rows = stmt
+            .query_map(rusqlite::params![session_id, limit as i64], |row| {
+                Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?))
+            })?
+            .collect::<Result<Vec<_>, _>>()?;
+
+        let entries = rows
+            .into_iter()
+            .filter_map(|(content, timestamp)| {
+                serde_json::from_str::<ToolCallEvent>(&content)
+                    .ok()
+                    .map(|event| ToolLogEntry {
+                        tool_name: event.tool_name,
+                        input_summary: event.input_summary,
+                        output_summary: event.output_summary,
+                        duration_ms: event.duration_ms,
+                        risk_score: event.risk_score,
+                        timestamp,
+                    })
+            })
+            .collect();
+
+        Ok(entries)
+    }
 }

ecc2/src/tui/app.rs

@@ -32,6 +32,10 @@ pub async fn run(db: StateStore, cfg: Config) -> Result<()> {
                     (_, KeyCode::Char('q')) => break,
                     (_, KeyCode::Tab) => dashboard.next_pane(),
                     (KeyModifiers::SHIFT, KeyCode::BackTab) => dashboard.prev_pane(),
+                    (_, KeyCode::Char('+')) | (_, KeyCode::Char('=')) => {
+                        dashboard.increase_pane_size()
+                    }
+                    (_, KeyCode::Char('-')) => dashboard.decrease_pane_size(),
                     (_, KeyCode::Char('j')) | (_, KeyCode::Down) => dashboard.scroll_down(),
                     (_, KeyCode::Char('k')) | (_, KeyCode::Up) => dashboard.scroll_up(),
                     (_, KeyCode::Char('n')) => dashboard.new_session(),

ecc2/src/tui/dashboard.rs

@@ -1,50 +1,78 @@
 use ratatui::{
     prelude::*,
-    widgets::{Block, Borders, List, ListItem, Paragraph, Tabs},
+    widgets::{Block, Borders, List, ListItem, Paragraph, Tabs, Wrap},
 };
 
-use crate::config::Config;
+use crate::config::{Config, PaneLayout};
+use crate::session::store::{StateStore, ToolLogEntry};
 use crate::session::{Session, SessionState};
-use crate::session::store::StateStore;
+
+const DEFAULT_PANE_SIZE_PERCENT: u16 = 35;
+const DEFAULT_GRID_SIZE_PERCENT: u16 = 50;
+const OUTPUT_PANE_PERCENT: u16 = 70;
+const MIN_PANE_SIZE_PERCENT: u16 = 20;
+const MAX_PANE_SIZE_PERCENT: u16 = 80;
+const PANE_RESIZE_STEP_PERCENT: u16 = 5;
+const MAX_LOG_ENTRIES: usize = 12;
 
 pub struct Dashboard {
     db: StateStore,
     cfg: Config,
     sessions: Vec<Session>,
+    logs: Vec<ToolLogEntry>,
     selected_pane: Pane,
     selected_session: usize,
     show_help: bool,
     scroll_offset: usize,
+    pane_size_percent: u16,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Pane {
     Sessions,
     Output,
     Metrics,
+    Log,
+}
+
+#[derive(Debug, Clone, Copy)]
+struct PaneAreas {
+    sessions: Rect,
+    output: Rect,
+    metrics: Rect,
+    log: Option<Rect>,
 }
 
 impl Dashboard {
     pub fn new(db: StateStore, cfg: Config) -> Self {
+        let pane_size_percent = match cfg.pane_layout {
+            PaneLayout::Grid => DEFAULT_GRID_SIZE_PERCENT,
+            PaneLayout::Horizontal | PaneLayout::Vertical => DEFAULT_PANE_SIZE_PERCENT,
+        };
+
         let sessions = db.list_sessions().unwrap_or_default();
-        Self {
+        let mut dashboard = Self {
             db,
             cfg,
             sessions,
+            logs: Vec::new(),
             selected_pane: Pane::Sessions,
             selected_session: 0,
             show_help: false,
             scroll_offset: 0,
-        }
+            pane_size_percent,
+        };
+        dashboard.refresh_logs();
+        dashboard
     }
 
     pub fn render(&self, frame: &mut Frame) {
         let chunks = Layout::default()
             .direction(Direction::Vertical)
             .constraints([
-                Constraint::Length(3),  // Header
-                Constraint::Min(10),   // Main content
-                Constraint::Length(3), // Status bar
+                Constraint::Length(3),
+                Constraint::Min(10),
+                Constraint::Length(3),
             ])
             .split(frame.area());
 
@@ -53,137 +81,204 @@ impl Dashboard {
         if self.show_help {
             self.render_help(frame, chunks[1]);
         } else {
-            let main_chunks = Layout::default()
-                .direction(Direction::Horizontal)
-                .constraints([
-                    Constraint::Percentage(35), // Session list
-                    Constraint::Percentage(65), // Output/details
-                ])
-                .split(chunks[1]);
+            let pane_areas = self.pane_areas(chunks[1]);
+            self.render_sessions(frame, pane_areas.sessions);
+            self.render_output(frame, pane_areas.output);
+            self.render_metrics(frame, pane_areas.metrics);
 
-            self.render_sessions(frame, main_chunks[0]);
-
-            let right_chunks = Layout::default()
-                .direction(Direction::Vertical)
-                .constraints([
-                    Constraint::Percentage(70), // Output
-                    Constraint::Percentage(30), // Metrics
-                ])
-                .split(main_chunks[1]);
-
-            self.render_output(frame, right_chunks[0]);
-            self.render_metrics(frame, right_chunks[1]);
+            if let Some(log_area) = pane_areas.log {
+                self.render_log(frame, log_area);
+            }
         }
 
         self.render_status_bar(frame, chunks[2]);
     }
 
     fn render_header(&self, frame: &mut Frame, area: Rect) {
-        let running = self.sessions.iter().filter(|s| s.state == SessionState::Running).count();
+        let running = self
+            .sessions
+            .iter()
+            .filter(|session| session.state == SessionState::Running)
+            .count();
         let total = self.sessions.len();
+        let title = format!(
+            " ECC 2.0 | {running} running / {total} total | {} {}% ",
+            self.layout_label(),
+            self.pane_size_percent
+        );
 
-        let title = format!(" ECC 2.0 | {running} running / {total} total ");
-        let tabs = Tabs::new(vec!["Sessions", "Output", "Metrics"])
-            .block(Block::default().borders(Borders::ALL).title(title))
-            .select(match self.selected_pane {
-                Pane::Sessions => 0,
-                Pane::Output => 1,
-                Pane::Metrics => 2,
-            })
-            .highlight_style(Style::default().fg(Color::Cyan).add_modifier(Modifier::BOLD));
+        let tabs = Tabs::new(
+            self.visible_panes()
+                .iter()
+                .map(|pane| pane.title())
+                .collect::<Vec<_>>(),
+        )
+        .block(Block::default().borders(Borders::ALL).title(title))
+        .select(self.selected_pane_index())
+        .highlight_style(
+            Style::default()
+                .fg(Color::Cyan)
+                .add_modifier(Modifier::BOLD),
+        );
 
         frame.render_widget(tabs, area);
     }
 
     fn render_sessions(&self, frame: &mut Frame, area: Rect) {
-        let items: Vec<ListItem> = self
-            .sessions
-            .iter()
-            .enumerate()
-            .map(|(i, s)| {
-                let state_icon = match s.state {
-                    SessionState::Running => "●",
-                    SessionState::Idle => "○",
-                    SessionState::Completed => "✓",
-                    SessionState::Failed => "✗",
-                    SessionState::Stopped => "■",
-                    SessionState::Pending => "◌",
-                };
-                let style = if i == self.selected_session {
-                    Style::default().fg(Color::Cyan).add_modifier(Modifier::BOLD)
-                } else {
-                    Style::default()
-                };
-                let text = format!("{state_icon} {} [{}] {}", &s.id[..8.min(s.id.len())], s.agent_type, s.task);
-                ListItem::new(text).style(style)
-            })
-            .collect();
-
-        let border_style = if self.selected_pane == Pane::Sessions {
-            Style::default().fg(Color::Cyan)
+        let items: Vec<ListItem> = if self.sessions.is_empty() {
+            vec![ListItem::new("No sessions. Press 'n' to start one.")]
         } else {
-            Style::default()
+            self.sessions
+                .iter()
+                .enumerate()
+                .map(|(index, session)| {
+                    let state_icon = match session.state {
+                        SessionState::Running => "●",
+                        SessionState::Idle => "○",
+                        SessionState::Completed => "✓",
+                        SessionState::Failed => "✗",
+                        SessionState::Stopped => "■",
+                        SessionState::Pending => "◌",
+                    };
+
+                    let style = if index == self.selected_session {
+                        Style::default()
+                            .fg(Color::Cyan)
+                            .add_modifier(Modifier::BOLD)
+                    } else {
+                        Style::default()
+                    };
+
+                    let text = format!(
+                        "{state_icon} {} [{}] {}",
+                        &session.id[..8.min(session.id.len())],
+                        session.agent_type,
+                        session.task
+                    );
+
+                    ListItem::new(text).style(style)
+                })
+                .collect()
         };
 
         let list = List::new(items).block(
             Block::default()
                 .borders(Borders::ALL)
                 .title(" Sessions ")
-                .border_style(border_style),
+                .border_style(self.pane_border_style(Pane::Sessions)),
         );
         frame.render_widget(list, area);
     }
 
     fn render_output(&self, frame: &mut Frame, area: Rect) {
-        let content = if let Some(session) = self.sessions.get(self.selected_session) {
-            format!("Agent output for session {}...\n\n(Live streaming coming soon)", session.id)
+        let content = if let Some(session) = self.current_session() {
+            let worktree = session
+                .worktree
+                .as_ref()
+                .map(|worktree| {
+                    format!(
+                        "Worktree: {}\nBranch: {}\n",
+                        worktree.path.display(),
+                        worktree.branch
+                    )
+                })
+                .unwrap_or_default();
+
+            format!(
+                "Session: {}\nAgent: {}\nState: {}\nTask: {}\nUpdated: {}\n{}\
+                 \nLive streaming output is not wired yet. Session context is shown here until the stream viewer lands.",
+                session.id,
+                session.agent_type,
+                session.state,
+                session.task,
+                session.updated_at.format("%Y-%m-%d %H:%M:%S UTC"),
+                worktree
+            )
         } else {
             "No sessions. Press 'n' to start one.".to_string()
         };
 
-        let border_style = if self.selected_pane == Pane::Output {
-            Style::default().fg(Color::Cyan)
-        } else {
-            Style::default()
-        };
-
-        let paragraph = Paragraph::new(content).block(
-            Block::default()
-                .borders(Borders::ALL)
-                .title(" Output ")
-                .border_style(border_style),
-        );
+        let paragraph = Paragraph::new(content)
+            .block(
+                Block::default()
+                    .borders(Borders::ALL)
+                    .title(" Output ")
+                    .border_style(self.pane_border_style(Pane::Output)),
+            )
+            .scroll((self.scroll_offset_u16(), 0))
+            .wrap(Wrap { trim: false });
         frame.render_widget(paragraph, area);
     }
 
     fn render_metrics(&self, frame: &mut Frame, area: Rect) {
-        let content = if let Some(session) = self.sessions.get(self.selected_session) {
-            let m = &session.metrics;
+        let content = if let Some(session) = self.current_session() {
+            let metrics = &session.metrics;
             format!(
-                "Tokens: {} | Tools: {} | Files: {} | Cost: ${:.4} | Duration: {}s",
-                m.tokens_used, m.tool_calls, m.files_changed, m.cost_usd, m.duration_secs
+                "Tokens: {}\nTools: {}\nFiles: {}\nCost: ${:.4}\nDuration: {}s",
+                metrics.tokens_used,
+                metrics.tool_calls,
+                metrics.files_changed,
+                metrics.cost_usd,
+                metrics.duration_secs
             )
         } else {
             "No metrics available".to_string()
         };
 
-        let border_style = if self.selected_pane == Pane::Metrics {
-            Style::default().fg(Color::Cyan)
+        let paragraph = Paragraph::new(content)
+            .block(
+                Block::default()
+                    .borders(Borders::ALL)
+                    .title(" Metrics ")
+                    .border_style(self.pane_border_style(Pane::Metrics)),
+            )
+            .scroll((self.scroll_offset_u16(), 0))
+            .wrap(Wrap { trim: false });
+        frame.render_widget(paragraph, area);
+    }
+
+    fn render_log(&self, frame: &mut Frame, area: Rect) {
+        let content = if self.current_session().is_none() {
+            "No session selected".to_string()
+        } else if self.logs.is_empty() {
+            "No tool logs available for this session.\n\nTool call observability events will appear here when they are recorded."
+                .to_string()
         } else {
-            Style::default()
+            self.logs
+                .iter()
+                .map(|entry| {
+                    format!(
+                        "[{}] {} | {}ms | risk {:.0}%\ninput: {}\noutput: {}",
+                        self.short_timestamp(&entry.timestamp),
+                        entry.tool_name,
+                        entry.duration_ms,
+                        entry.risk_score * 100.0,
+                        self.log_field(&entry.input_summary),
+                        self.log_field(&entry.output_summary)
+                    )
+                })
+                .collect::<Vec<_>>()
+                .join("\n\n")
         };
 
-        let paragraph = Paragraph::new(content).block(
-            Block::default()
-                .borders(Borders::ALL)
-                .title(" Metrics ")
-                .border_style(border_style),
-        );
+        let paragraph = Paragraph::new(content)
+            .block(
+                Block::default()
+                    .borders(Borders::ALL)
+                    .title(" Log ")
+                    .border_style(self.pane_border_style(Pane::Log)),
+            )
+            .scroll((self.scroll_offset_u16(), 0))
+            .wrap(Wrap { trim: false });
         frame.render_widget(paragraph, area);
     }
 
     fn render_status_bar(&self, frame: &mut Frame, area: Rect) {
-        let text = " [n]ew session  [s]top  [Tab] switch pane  [j/k] scroll  [?] help  [q]uit ";
+        let text = format!(
+            " [n]ew session  [s]top  [Tab] switch pane  [j/k] scroll  [+/-] resize  [{}] layout  [?] help  [q]uit ",
+            self.layout_label()
+        );
+
         let paragraph = Paragraph::new(text)
             .style(Style::default().fg(Color::DarkGray))
             .block(Block::default().borders(Borders::ALL));
@@ -200,6 +295,8 @@ impl Dashboard {
             "  S-Tab   Previous pane",
             "  j/↓     Scroll down",
             "  k/↑     Scroll up",
+            "  +/=     Increase pane size",
+            "  -       Decrease pane size",
             "  r       Refresh",
             "  ?       Toggle help",
             "  q/C-c   Quit",
@@ -215,24 +312,46 @@ impl Dashboard {
     }
 
     pub fn next_pane(&mut self) {
-        self.selected_pane = match self.selected_pane {
-            Pane::Sessions => Pane::Output,
-            Pane::Output => Pane::Metrics,
-            Pane::Metrics => Pane::Sessions,
-        };
+        let visible_panes = self.visible_panes();
+        let next_index = self
+            .selected_pane_index()
+            .checked_add(1)
+            .map(|index| index % visible_panes.len())
+            .unwrap_or(0);
+
+        self.selected_pane = visible_panes[next_index];
+        self.scroll_offset = 0;
     }
 
     pub fn prev_pane(&mut self) {
-        self.selected_pane = match self.selected_pane {
-            Pane::Sessions => Pane::Metrics,
-            Pane::Output => Pane::Sessions,
-            Pane::Metrics => Pane::Output,
+        let visible_panes = self.visible_panes();
+        let previous_index = if self.selected_pane_index() == 0 {
+            visible_panes.len() - 1
+        } else {
+            self.selected_pane_index() - 1
         };
+
+        self.selected_pane = visible_panes[previous_index];
+        self.scroll_offset = 0;
+    }
+
+    pub fn increase_pane_size(&mut self) {
+        self.pane_size_percent =
+            (self.pane_size_percent + PANE_RESIZE_STEP_PERCENT).min(MAX_PANE_SIZE_PERCENT);
+    }
+
+    pub fn decrease_pane_size(&mut self) {
+        self.pane_size_percent = self
+            .pane_size_percent
+            .saturating_sub(PANE_RESIZE_STEP_PERCENT)
+            .max(MIN_PANE_SIZE_PERCENT);
     }
 
     pub fn scroll_down(&mut self) {
         if self.selected_pane == Pane::Sessions && !self.sessions.is_empty() {
             self.selected_session = (self.selected_session + 1).min(self.sessions.len() - 1);
+            self.scroll_offset = 0;
+            self.refresh_logs();
         } else {
             self.scroll_offset = self.scroll_offset.saturating_add(1);
         }
@@ -240,14 +359,19 @@ impl Dashboard {
 
     pub fn scroll_up(&mut self) {
         if self.selected_pane == Pane::Sessions {
+            let previous_index = self.selected_session;
             self.selected_session = self.selected_session.saturating_sub(1);
+
+            if self.selected_session != previous_index {
+                self.scroll_offset = 0;
+                self.refresh_logs();
+            }
         } else {
             self.scroll_offset = self.scroll_offset.saturating_sub(1);
         }
     }
 
     pub fn new_session(&mut self) {
-        // TODO: Open a dialog to create a new session
         tracing::info!("New session dialog requested");
     }
 
@@ -259,7 +383,7 @@ impl Dashboard {
     }
 
     pub fn refresh(&mut self) {
-        self.sessions = self.db.list_sessions().unwrap_or_default();
+        self.sync_from_store();
     }
 
     pub fn toggle_help(&mut self) {
@@ -267,7 +391,254 @@ impl Dashboard {
     }
 
     pub async fn tick(&mut self) {
-        // Periodic refresh every few ticks
+        self.sync_from_store();
+    }
+
+    fn sync_from_store(&mut self) {
         self.sessions = self.db.list_sessions().unwrap_or_default();
+        self.clamp_selected_session();
+        self.ensure_selected_pane_visible();
+        self.refresh_logs();
+    }
+
+    fn current_session(&self) -> Option<&Session> {
+        self.sessions.get(self.selected_session)
+    }
+
+    fn refresh_logs(&mut self) {
+        let session_id = self.current_session().map(|session| session.id.clone());
+
+        self.logs = session_id
+            .and_then(|id| self.db.list_tool_logs(&id, MAX_LOG_ENTRIES).ok())
+            .unwrap_or_default();
+    }
+
+    fn clamp_selected_session(&mut self) {
+        if self.sessions.is_empty() {
+            self.selected_session = 0;
+            return;
+        }
+
+        self.selected_session = self.selected_session.min(self.sessions.len() - 1);
+    }
+
+    fn ensure_selected_pane_visible(&mut self) {
+        if !self.visible_panes().contains(&self.selected_pane) {
+            self.selected_pane = Pane::Sessions;
+        }
+    }
+
+    fn pane_areas(&self, area: Rect) -> PaneAreas {
+        match self.cfg.pane_layout {
+            PaneLayout::Horizontal => {
+                let columns = Layout::default()
+                    .direction(Direction::Horizontal)
+                    .constraints(self.primary_constraints())
+                    .split(area);
+                let right_rows = Layout::default()
+                    .direction(Direction::Vertical)
+                    .constraints([
+                        Constraint::Percentage(OUTPUT_PANE_PERCENT),
+                        Constraint::Percentage(100 - OUTPUT_PANE_PERCENT),
+                    ])
+                    .split(columns[1]);
+
+                PaneAreas {
+                    sessions: columns[0],
+                    output: right_rows[0],
+                    metrics: right_rows[1],
+                    log: None,
+                }
+            }
+            PaneLayout::Vertical => {
+                let rows = Layout::default()
+                    .direction(Direction::Vertical)
+                    .constraints(self.primary_constraints())
+                    .split(area);
+                let bottom_columns = Layout::default()
+                    .direction(Direction::Horizontal)
+                    .constraints([
+                        Constraint::Percentage(OUTPUT_PANE_PERCENT),
+                        Constraint::Percentage(100 - OUTPUT_PANE_PERCENT),
+                    ])
+                    .split(rows[1]);
+
+                PaneAreas {
+                    sessions: rows[0],
+                    output: bottom_columns[0],
+                    metrics: bottom_columns[1],
+                    log: None,
+                }
+            }
+            PaneLayout::Grid => {
+                let rows = Layout::default()
+                    .direction(Direction::Vertical)
+                    .constraints(self.primary_constraints())
+                    .split(area);
+                let top_columns = Layout::default()
+                    .direction(Direction::Horizontal)
+                    .constraints(self.primary_constraints())
+                    .split(rows[0]);
+                let bottom_columns = Layout::default()
+                    .direction(Direction::Horizontal)
+                    .constraints(self.primary_constraints())
+                    .split(rows[1]);
+
+                PaneAreas {
+                    sessions: top_columns[0],
+                    output: top_columns[1],
+                    metrics: bottom_columns[0],
+                    log: Some(bottom_columns[1]),
+                }
+            }
+        }
+    }
+
+    fn primary_constraints(&self) -> [Constraint; 2] {
+        [
+            Constraint::Percentage(self.pane_size_percent),
+            Constraint::Percentage(100 - self.pane_size_percent),
+        ]
+    }
+
+    fn visible_panes(&self) -> &'static [Pane] {
+        match self.cfg.pane_layout {
+            PaneLayout::Grid => &[Pane::Sessions, Pane::Output, Pane::Metrics, Pane::Log],
+            PaneLayout::Horizontal | PaneLayout::Vertical => {
+                &[Pane::Sessions, Pane::Output, Pane::Metrics]
+            }
+        }
+    }
+
+    fn selected_pane_index(&self) -> usize {
+        self.visible_panes()
+            .iter()
+            .position(|pane| *pane == self.selected_pane)
+            .unwrap_or(0)
+    }
+
+    fn pane_border_style(&self, pane: Pane) -> Style {
+        if self.selected_pane == pane {
+            Style::default().fg(Color::Cyan)
+        } else {
+            Style::default()
+        }
+    }
+
+    fn layout_label(&self) -> &'static str {
+        match self.cfg.pane_layout {
+            PaneLayout::Horizontal => "horizontal",
+            PaneLayout::Vertical => "vertical",
+            PaneLayout::Grid => "grid",
+        }
+    }
+
+    fn scroll_offset_u16(&self) -> u16 {
+        self.scroll_offset.min(u16::MAX as usize) as u16
+    }
+
+    fn log_field<'a>(&self, value: &'a str) -> &'a str {
+        let trimmed = value.trim();
+        if trimmed.is_empty() {
+            "n/a"
+        } else {
+            trimmed
+        }
+    }
+
+    fn short_timestamp(&self, timestamp: &str) -> String {
+        chrono::DateTime::parse_from_rfc3339(timestamp)
+            .map(|value| value.format("%H:%M:%S").to_string())
+            .unwrap_or_else(|_| timestamp.to_string())
+    }
+}
+
+impl Pane {
+    fn title(self) -> &'static str {
+        match self {
+            Pane::Sessions => "Sessions",
+            Pane::Output => "Output",
+            Pane::Metrics => "Metrics",
+            Pane::Log => "Log",
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        Dashboard, Pane, DEFAULT_GRID_SIZE_PERCENT, MAX_PANE_SIZE_PERCENT, MIN_PANE_SIZE_PERCENT,
+    };
+    use crate::config::{Config, PaneLayout};
+    use crate::session::store::StateStore;
+    use ratatui::layout::Rect;
+
+    fn dashboard_for(layout: PaneLayout) -> Dashboard {
+        let mut cfg = Config::default();
+        cfg.pane_layout = layout;
+
+        let db_path =
+            std::env::temp_dir().join(format!("ecc-dashboard-test-{}.db", uuid::Uuid::new_v4()));
+        let db = StateStore::open(&db_path).unwrap();
+
+        Dashboard::new(db, cfg)
+    }
+
+    #[test]
+    fn grid_layout_uses_four_panes_in_two_rows() {
+        let dashboard = dashboard_for(PaneLayout::Grid);
+        let areas = dashboard.pane_areas(Rect::new(0, 0, 100, 40));
+        let log_area = areas.log.expect("grid layout should render a log pane");
+
+        assert_eq!(areas.sessions.y, areas.output.y);
+        assert_eq!(areas.metrics.y, log_area.y);
+        assert!(areas.metrics.y > areas.sessions.y);
+        assert_eq!(areas.sessions.x, 0);
+        assert_eq!(areas.metrics.x, 0);
+        assert!(areas.output.x > areas.sessions.x);
+        assert!(log_area.x > areas.metrics.x);
+    }
+
+    #[test]
+    fn non_grid_layouts_hide_the_log_pane() {
+        let horizontal = dashboard_for(PaneLayout::Horizontal);
+        let vertical = dashboard_for(PaneLayout::Vertical);
+
+        assert!(horizontal
+            .pane_areas(Rect::new(0, 0, 100, 40))
+            .log
+            .is_none());
+        assert!(vertical.pane_areas(Rect::new(0, 0, 100, 40)).log.is_none());
+    }
+
+    #[test]
+    fn pane_navigation_includes_log_only_for_grid_layouts() {
+        let mut horizontal = dashboard_for(PaneLayout::Horizontal);
+        horizontal.next_pane();
+        horizontal.next_pane();
+        horizontal.next_pane();
+        assert_eq!(horizontal.selected_pane, Pane::Sessions);
+
+        let mut grid = dashboard_for(PaneLayout::Grid);
+        grid.next_pane();
+        grid.next_pane();
+        grid.next_pane();
+        assert_eq!(grid.selected_pane, Pane::Log);
+    }
+
+    #[test]
+    fn pane_resize_clamps_to_supported_bounds() {
+        let mut dashboard = dashboard_for(PaneLayout::Grid);
+        assert_eq!(dashboard.pane_size_percent, DEFAULT_GRID_SIZE_PERCENT);
+
+        for _ in 0..20 {
+            dashboard.increase_pane_size();
+        }
+        assert_eq!(dashboard.pane_size_percent, MAX_PANE_SIZE_PERCENT);
+
+        for _ in 0..40 {
+            dashboard.decrease_pane_size();
+        }
+        assert_eq!(dashboard.pane_size_percent, MIN_PANE_SIZE_PERCENT);
     }
 }