feat(session): support unfocused agent windows (--no-focus) (#87)

`bsk session start --no-focus` opens the Agent Window in the background
without stealing focus. The flag threads focused=false through
CLI -> daemon IPC -> tool.session_start -> chrome.windows.create; an
omitted `focused` keeps the extension default (true) so older clients
are unaffected.

Reworked onto current main so it composes with #52 window sizing:
AgentWindowApi.create / SessionManager.start (extension), start_session
(CLI) and the daemon's session start now take options objects/structs
({ size, focused }) instead of colliding positional params.

Co-authored-by: alectimison-maker <alec.timison@gmail.com>

crates/bsk-cli/src/daemon/ipc.rs

@@ -42,8 +42,8 @@ use tracing::{debug, warn};
 use super::abort::AbortRegistry;
 use super::queue::{DEFAULT_TOOL_TIMEOUT, DispatchError};
 use super::sessions::{
-    SessionId, StartSessionError, StopSessionError, snapshot_status_entries, start_session,
-    stop_session,
+    AgentWindowOptions, SessionId, StartSessionError, StopSessionError, snapshot_status_entries,
+    start_session, stop_session,
 };
 use super::state::{DAEMON_VERSION, DaemonState, PROTOCOL_VERSION};
 
@@ -545,6 +545,8 @@ struct CliSessionStartParams {
     pub width: Option<u32>,
     #[serde(default)]
     pub height: Option<u32>,
+    #[serde(default)]
+    pub focused: Option<bool>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -638,6 +640,7 @@ async fn handle_session_start(state: &Arc<DaemonState>, params: Value) -> Result
             browser_instance_id: None,
             width: None,
             height: None,
+            focused: None,
         }
     } else {
         serde_json::from_value(params).map_err(|err| RpcError {
@@ -664,7 +667,10 @@ async fn handle_session_start(state: &Arc<DaemonState>, params: Value) -> Result
         &state.sessions,
         &state.tool_queues,
         params.browser_instance_id.as_deref(),
-        window_size,
+        AgentWindowOptions {
+            size: window_size,
+            focused: params.focused,
+        },
         state.config.extension_connect_wait,
         DEFAULT_RPC_TIMEOUT,
     )

crates/bsk-cli/src/daemon/sessions.rs

@@ -390,6 +390,17 @@ pub enum StopSessionError {
 /// of live sessions.
 const SESSION_ID_MAX_RESERVE_ATTEMPTS: u32 = 64;
 
+/// Agent Window creation hints forwarded to the extension on
+/// `tool.session_start`. `None` fields keep the extension-side defaults
+/// (focused window, browser-chosen size).
+#[derive(Debug, Default, Clone, Copy)]
+pub struct AgentWindowOptions {
+    /// Optional outer size as `(width, height)` CSS pixels.
+    pub size: Option<(u32, u32)>,
+    /// Optional focus hint (`None` = extension default: focused).
+    pub focused: Option<bool>,
+}
+
 /// Ask the chosen browser to create a fresh Agent Window for a brand-new
 /// session id, registering the result on success.
 ///
@@ -401,8 +412,7 @@ pub async fn start_session(
     sessions: &Arc<SessionRegistry>,
     queues: &Arc<ToolQueueRegistry>,
     requested: Option<&str>,
-    // Optional Agent Window outer size as `(width, height)` CSS pixels.
-    window_size: Option<(u32, u32)>,
+    window: AgentWindowOptions,
     connect_wait: Duration,
     timeout_dur: Duration,
 ) -> Result<Session, StartSessionError> {
@@ -429,8 +439,9 @@ pub async fn start_session(
     let params = SessionStartParams {
         session_id: session_id.0.clone(),
         browser_instance_id: Some(client.id.0.clone()),
-        width: window_size.map(|(width, _)| width),
-        height: window_size.map(|(_, height)| height),
+        width: window.size.map(|(width, _)| width),
+        height: window.size.map(|(_, height)| height),
+        focused: window.focused,
     };
     let rpc_id = next_rpc_id("sess-start");
     let request = RequestFrame {