feat(orchestration): add bttask CLI + GroupAgentsPanel + btmsg Tauri bridge

Phase 2: bttask CLI (Python, SQLite) — task management with role-based
visibility. Kanban board view. Manager/Architect can create tasks,
Tier 2 agents receive tasks via btmsg only.

Phase 3: GroupAgentConfig in groups.json + Rust backend. GroupAgentsPanel
Svelte component above ProjectGrid with status dots, role icons,
unread badges, start/stop buttons.

Phase 4: btmsg Rust bridge (btmsg.rs) — read/write access to btmsg.db.
6 Tauri commands for agent status, messages, and history.
GroupAgentsPanel polls btmsg.db every 5s for live status updates.

v2/src-tauri/src/btmsg.rs

@@ -0,0 +1,173 @@
+// btmsg — Read-only access to btmsg SQLite database
+// Database at ~/.local/share/bterminal/btmsg.db (created by btmsg CLI)
+
+use rusqlite::{params, Connection, OpenFlags};
+use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
+
+fn db_path() -> PathBuf {
+    dirs::data_dir()
+        .unwrap_or_else(|| PathBuf::from("."))
+        .join("bterminal")
+        .join("btmsg.db")
+}
+
+fn open_db() -> Result<Connection, String> {
+    let path = db_path();
+    if !path.exists() {
+        return Err("btmsg database not found. Run 'btmsg register' first.".into());
+    }
+    Connection::open_with_flags(&path, OpenFlags::SQLITE_OPEN_READ_WRITE)
+        .map_err(|e| format!("Failed to open btmsg.db: {e}"))
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BtmsgAgent {
+    pub id: String,
+    pub name: String,
+    pub role: String,
+    pub group_id: String,
+    pub tier: i32,
+    pub model: Option<String>,
+    pub status: String,
+    pub unread_count: i32,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BtmsgMessage {
+    pub id: String,
+    pub from_agent: String,
+    pub to_agent: String,
+    pub content: String,
+    pub read: bool,
+    pub reply_to: Option<String>,
+    pub created_at: String,
+    pub sender_name: Option<String>,
+    pub sender_role: Option<String>,
+}
+
+pub fn get_agents(group_id: &str) -> Result<Vec<BtmsgAgent>, String> {
+    let db = open_db()?;
+    let mut stmt = db.prepare(
+        "SELECT a.*, (SELECT COUNT(*) FROM messages m WHERE m.to_agent = a.id AND m.read = 0) as unread_count \
+         FROM agents a WHERE a.group_id = ? ORDER BY a.tier, a.role, a.name"
+    ).map_err(|e| format!("Query error: {e}"))?;
+
+    let agents = stmt.query_map(params![group_id], |row| {
+        Ok(BtmsgAgent {
+            id: row.get(0)?,
+            name: row.get(1)?,
+            role: row.get(2)?,
+            group_id: row.get(3)?,
+            tier: row.get(4)?,
+            model: row.get(5)?,
+            status: row.get::<_, Option<String>>(7)?.unwrap_or_else(|| "stopped".into()),
+            unread_count: row.get("unread_count")?,
+        })
+    }).map_err(|e| format!("Query error: {e}"))?;
+
+    agents.collect::<Result<Vec<_>, _>>().map_err(|e| format!("Row error: {e}"))
+}
+
+pub fn unread_count(agent_id: &str) -> Result<i32, String> {
+    let db = open_db()?;
+    db.query_row(
+        "SELECT COUNT(*) FROM messages WHERE to_agent = ? AND read = 0",
+        params![agent_id],
+        |row| row.get(0),
+    ).map_err(|e| format!("Query error: {e}"))
+}
+
+pub fn unread_messages(agent_id: &str) -> Result<Vec<BtmsgMessage>, String> {
+    let db = open_db()?;
+    let mut stmt = db.prepare(
+        "SELECT m.id, m.from_agent, m.to_agent, m.content, m.read, m.reply_to, m.created_at, \
+         a.name, a.role \
+         FROM messages m JOIN agents a ON m.from_agent = a.id \
+         WHERE m.to_agent = ? AND m.read = 0 ORDER BY m.created_at ASC"
+    ).map_err(|e| format!("Query error: {e}"))?;
+
+    let msgs = stmt.query_map(params![agent_id], |row| {
+        Ok(BtmsgMessage {
+            id: row.get(0)?,
+            from_agent: row.get(1)?,
+            to_agent: row.get(2)?,
+            content: row.get(3)?,
+            read: row.get::<_, i32>(4)? != 0,
+            reply_to: row.get(5)?,
+            created_at: row.get(6)?,
+            sender_name: row.get(7)?,
+            sender_role: row.get(8)?,
+        })
+    }).map_err(|e| format!("Query error: {e}"))?;
+
+    msgs.collect::<Result<Vec<_>, _>>().map_err(|e| format!("Row error: {e}"))
+}
+
+pub fn history(agent_id: &str, other_id: &str, limit: i32) -> Result<Vec<BtmsgMessage>, String> {
+    let db = open_db()?;
+    let mut stmt = db.prepare(
+        "SELECT m.id, m.from_agent, m.to_agent, m.content, m.read, m.reply_to, m.created_at, \
+         a.name, a.role \
+         FROM messages m JOIN agents a ON m.from_agent = a.id \
+         WHERE (m.from_agent = ?1 AND m.to_agent = ?2) OR (m.from_agent = ?2 AND m.to_agent = ?1) \
+         ORDER BY m.created_at ASC LIMIT ?3"
+    ).map_err(|e| format!("Query error: {e}"))?;
+
+    let msgs = stmt.query_map(params![agent_id, other_id, limit], |row| {
+        Ok(BtmsgMessage {
+            id: row.get(0)?,
+            from_agent: row.get(1)?,
+            to_agent: row.get(2)?,
+            content: row.get(3)?,
+            read: row.get::<_, i32>(4)? != 0,
+            reply_to: row.get(5)?,
+            created_at: row.get(6)?,
+            sender_name: row.get(7)?,
+            sender_role: row.get(8)?,
+        })
+    }).map_err(|e| format!("Query error: {e}"))?;
+
+    msgs.collect::<Result<Vec<_>, _>>().map_err(|e| format!("Row error: {e}"))
+}
+
+pub fn send_message(from_agent: &str, to_agent: &str, content: &str) -> Result<String, String> {
+    let db = open_db()?;
+
+    // Get sender's group
+    let group_id: String = db.query_row(
+        "SELECT group_id FROM agents WHERE id = ?",
+        params![from_agent],
+        |row| row.get(0),
+    ).map_err(|e| format!("Sender not found: {e}"))?;
+
+    // Check contact permission
+    let allowed: bool = db.query_row(
+        "SELECT COUNT(*) > 0 FROM contacts WHERE agent_id = ? AND contact_id = ?",
+        params![from_agent, to_agent],
+        |row| row.get(0),
+    ).map_err(|e| format!("Contact check error: {e}"))?;
+
+    if !allowed {
+        return Err(format!("Not allowed to message '{to_agent}'"));
+    }
+
+    let msg_id = uuid::Uuid::new_v4().to_string();
+    db.execute(
+        "INSERT INTO messages (id, from_agent, to_agent, content, group_id) VALUES (?1, ?2, ?3, ?4, ?5)",
+        params![msg_id, from_agent, to_agent, content, group_id],
+    ).map_err(|e| format!("Insert error: {e}"))?;
+
+    Ok(msg_id)
+}
+
+pub fn set_status(agent_id: &str, status: &str) -> Result<(), String> {
+    let db = open_db()?;
+    db.execute(
+        "UPDATE agents SET status = ?, last_active_at = datetime('now') WHERE id = ?",
+        params![status, agent_id],
+    ).map_err(|e| format!("Update error: {e}"))?;
+    Ok(())
+}