feat: support Agent Window sizing (session start --width/--height, window resize) (#52)

- `bsk session start --width <px> --height <px>` opens the Agent Window
  with the given outer size (chrome.windows.create)
- new `bsk window resize --session <id> --width <px> --height <px>`
  resizes the Agent Window at runtime (chrome.windows.update)
- both validated on CLI, daemon and extension sides (100..=7680 CSS px)
- protocol: new tool.window_resize method (BrowserMutation) and
  optional width/height on tool.session_start params; schemas regenerated

crates/bsk-protocol/src/bin/dump-schema.rs

@@ -45,6 +45,9 @@ fn main() {
     dump!(SessionStopParams, "tool_session_stop_params");
     dump!(SessionStopResult, "tool_session_stop_result");
 
+    dump!(WindowResizeParams, "tool_window_resize_params");
+    dump!(WindowResizeResult, "tool_window_resize_result");
+
     dump!(TabListParams, "tool_tab_list_params");
     dump!(TabListResult, "tool_tab_list_result");
     dump!(TabCreateParams, "tool_tab_create_params");

crates/bsk-protocol/src/method.rs

@@ -44,6 +44,8 @@ pub enum Method {
     ToolSessionStart,
     #[serde(rename = "tool.session_stop")]
     ToolSessionStop,
+    #[serde(rename = "tool.window_resize")]
+    ToolWindowResize,
     #[serde(rename = "tool.tab_list")]
     ToolTabList,
     #[serde(rename = "tool.tab_create")]
@@ -140,6 +142,7 @@ impl Method {
             | Method::ToolTabBorrow
             | Method::ToolTabReturn
             | Method::ToolTabSelect
+            | Method::ToolWindowResize
             | Method::ToolNavigate
             | Method::ToolNavigateBack
             | Method::ToolNavigateForward
@@ -272,6 +275,7 @@ mod tests {
         assert!(Method::ToolSelect.is_mutating());
         assert!(Method::ToolEvaluate.is_mutating());
         assert!(Method::ToolRecordStart.is_mutating());
+        assert!(Method::ToolWindowResize.is_mutating());
     }
 
     #[test]

crates/bsk-protocol/src/tools/mod.rs

@@ -12,6 +12,7 @@ pub mod script;
 pub mod session;
 pub mod tabs;
 pub mod waits;
+pub mod window;
 
 pub use console::*;
 pub use dialog::*;
@@ -25,3 +26,4 @@ pub use script::*;
 pub use session::*;
 pub use tabs::*;
 pub use waits::*;
+pub use window::*;

crates/bsk-protocol/src/tools/session.rs

@@ -10,6 +10,12 @@ pub struct SessionStartParams {
     pub session_id: String,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub browser_instance_id: Option<String>,
+    /// Optional Agent Window outer width in CSS pixels (100..=7680).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub width: Option<u32>,
+    /// Optional Agent Window outer height in CSS pixels (100..=7680).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub height: Option<u32>,
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, JsonSchema)]

crates/bsk-protocol/src/tools/window.rs

@@ -0,0 +1,62 @@
+//! Agent Window management tools (`tool.window_*`).
+
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+// ----- window_resize -----
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, JsonSchema)]
+pub struct WindowResizeParams {
+    pub session_id: String,
+    /// New Agent Window outer width in CSS pixels (100..=7680).
+    pub width: u32,
+    /// New Agent Window outer height in CSS pixels (100..=7680).
+    pub height: u32,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, JsonSchema)]
+pub struct WindowResizeResult {
+    pub window_id: i64,
+    pub width: u32,
+    pub height: u32,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    #[test]
+    fn window_resize_params_round_trip() {
+        let params: WindowResizeParams = serde_json::from_value(json!({
+            "session_id": "ab12",
+            "width": 1280,
+            "height": 800,
+        }))
+        .unwrap();
+        assert_eq!(params.session_id, "ab12");
+        assert_eq!(params.width, 1280);
+        assert_eq!(params.height, 800);
+        let encoded = serde_json::to_value(params).unwrap();
+        assert_eq!(
+            encoded,
+            json!({ "session_id": "ab12", "width": 1280, "height": 800 })
+        );
+    }
+
+    #[test]
+    fn window_resize_result_round_trip() {
+        let result: WindowResizeResult = serde_json::from_value(json!({
+            "window_id": 42,
+            "width": 1280,
+            "height": 800,
+        }))
+        .unwrap();
+        assert_eq!(result.window_id, 42);
+        let encoded = serde_json::to_value(result).unwrap();
+        assert_eq!(
+            encoded,
+            json!({ "window_id": 42, "width": 1280, "height": 800 })
+        );
+    }
+}