feat: Agent Orchestrator — multi-project agent dashboard

Tauri + Svelte 5 + Rust application for orchestrating multiple AI coding agents.
Includes Claude, Aider, Codex, and Ollama provider support, multi-agent
communication (btmsg/bttask), session anchors, plugin sandbox, FTS5 search,
Landlock sandboxing, and 507 vitest + 110 cargo tests.

src-tauri/src/session/layout.rs

@@ -0,0 +1,90 @@
+// Layout state persistence (layout_state table)
+
+use rusqlite::params;
+use serde::{Deserialize, Serialize};
+use super::SessionDb;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct LayoutState {
+    pub preset: String,
+    pub pane_ids: Vec<String>,
+}
+
+impl SessionDb {
+    pub fn save_layout(&self, layout: &LayoutState) -> Result<(), String> {
+        let conn = self.conn.lock().unwrap();
+        let pane_ids_json = serde_json::to_string(&layout.pane_ids)
+            .map_err(|e| format!("Serialize pane_ids failed: {e}"))?;
+        conn.execute(
+            "UPDATE layout_state SET preset = ?1, pane_ids = ?2 WHERE id = 1",
+            params![layout.preset, pane_ids_json],
+        ).map_err(|e| format!("Layout save failed: {e}"))?;
+        Ok(())
+    }
+
+    pub fn load_layout(&self) -> Result<LayoutState, String> {
+        let conn = self.conn.lock().unwrap();
+        let mut stmt = conn
+            .prepare("SELECT preset, pane_ids FROM layout_state WHERE id = 1")
+            .map_err(|e| format!("Layout query failed: {e}"))?;
+
+        stmt.query_row([], |row| {
+            let preset: String = row.get(0)?;
+            let pane_ids_json: String = row.get(1)?;
+            let pane_ids: Vec<String> = serde_json::from_str(&pane_ids_json).unwrap_or_default();
+            Ok(LayoutState { preset, pane_ids })
+        }).map_err(|e| format!("Layout read failed: {e}"))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn make_db() -> SessionDb {
+        let dir = tempfile::tempdir().unwrap();
+        SessionDb::open(&dir.path().to_path_buf()).unwrap()
+    }
+
+    #[test]
+    fn test_load_default_layout() {
+        let db = make_db();
+        let layout = db.load_layout().unwrap();
+        assert_eq!(layout.preset, "1-col");
+        assert!(layout.pane_ids.is_empty());
+    }
+
+    #[test]
+    fn test_save_and_load_layout() {
+        let db = make_db();
+        let layout = LayoutState {
+            preset: "2-col".to_string(),
+            pane_ids: vec!["p1".to_string(), "p2".to_string()],
+        };
+        db.save_layout(&layout).unwrap();
+
+        let loaded = db.load_layout().unwrap();
+        assert_eq!(loaded.preset, "2-col");
+        assert_eq!(loaded.pane_ids, vec!["p1", "p2"]);
+    }
+
+    #[test]
+    fn test_save_layout_overwrites() {
+        let db = make_db();
+        let layout1 = LayoutState {
+            preset: "2-col".to_string(),
+            pane_ids: vec!["p1".to_string()],
+        };
+        db.save_layout(&layout1).unwrap();
+
+        let layout2 = LayoutState {
+            preset: "3-col".to_string(),
+            pane_ids: vec!["a".to_string(), "b".to_string(), "c".to_string()],
+        };
+        db.save_layout(&layout2).unwrap();
+
+        let loaded = db.load_layout().unwrap();
+        assert_eq!(loaded.preset, "3-col");
+        assert_eq!(loaded.pane_ids.len(), 3);
+    }
+}