feat: add boolean shape ops, visual undo tree, and Augmented Canvas branding

- Boolean operations (union, intersection, difference, xor) via i_overlay
  with Path shape rendering using earcutr triangulation
- Visual undo tree with branching history, checkout, and fork (Cmd+H)
  using Arc-based snapshots for structural sharing
- Consistent Augmented Canvas branding across app title, MCP server,
  CLI help text, and error messages
- macOS .app bundle script and Info.plist for Finder integration
- New MCP tool: boolean_op for agent-driven shape composition
- 26 tests passing (5 boolean, 6 history, 15 existing)

crates/agcanvas-mcp/src/tools.rs

@@ -169,6 +169,24 @@ pub struct DeleteDrawingElementParam {
     pub id: String,
 }
 
+#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
+pub struct BooleanOpParam {
+    #[schemars(description = "Session ID to target. If omitted, uses the active session.")]
+    pub session_id: Option<String>,
+    #[schemars(description = "Boolean operation: union, intersection, difference, or xor")]
+    pub operation: String,
+    #[schemars(description = "IDs of drawing elements to combine (minimum 2)")]
+    pub element_ids: Vec<String>,
+    #[schemars(description = "If true, delete source elements after combining")]
+    pub consume: Option<bool>,
+    #[schemars(description = "Fill color for result as hex e.g. '#ff0000'")]
+    pub fill: Option<String>,
+    #[schemars(description = "Stroke color for result as hex e.g. '#ffffff'")]
+    pub stroke_color: Option<String>,
+    #[schemars(description = "Stroke width for result in pixels")]
+    pub stroke_width: Option<f32>,
+}
+
 #[derive(Debug, Clone)]
 pub struct AgCanvasServer {
     ws_url: String,
@@ -185,7 +203,7 @@ impl AgCanvasServer {
     }
 
     #[tool(
-        description = "List all open sessions/tabs in agcanvas. Returns session IDs, names, creator info, description, timestamps, and whether they have SVG or drawing content loaded. Supports sorting."
+        description = "List all open sessions/tabs in Augmented Canvas. Returns session IDs, names, creator info, description, timestamps, and whether they have SVG or drawing content loaded. Supports sorting."
     )]
     async fn list_sessions(
         &self,
@@ -203,7 +221,7 @@ impl AgCanvasServer {
     }
 
     #[tool(
-        description = "Create a new session/tab in agcanvas. The session is created by an agent. Returns the created session with its ID and metadata."
+        description = "Create a new session/tab in Augmented Canvas. The session is created by an agent. Returns the created session with its ID and metadata."
     )]
     async fn create_session(
         &self,
@@ -472,6 +490,37 @@ impl AgCanvasServer {
         self.call_agcanvas(&request).await
     }
 
+    #[tool(
+        description = "Perform a boolean operation (union, intersection, difference, xor) on two or more drawing elements. Combines filled shapes into a new path element. Only works on Rectangle and Ellipse shapes."
+    )]
+    async fn boolean_op(
+        &self,
+        Parameters(params): Parameters<BooleanOpParam>,
+    ) -> Result<CallToolResult, McpError> {
+        let mut request = serde_json::json!({
+            "type": "BooleanOp",
+            "operation": params.operation,
+            "element_ids": params.element_ids,
+        });
+        let obj = request.as_object_mut().unwrap();
+        if let Some(v) = params.session_id {
+            obj.insert("session_id".into(), v.into());
+        }
+        if let Some(v) = params.consume {
+            obj.insert("consume".into(), v.into());
+        }
+        if let Some(v) = params.fill {
+            obj.insert("fill".into(), v.into());
+        }
+        if let Some(v) = params.stroke_color {
+            obj.insert("stroke_color".into(), v.into());
+        }
+        if let Some(v) = params.stroke_width {
+            obj.insert("stroke_width".into(), v.into());
+        }
+        self.call_agcanvas(&request).await
+    }
+
     #[tool(description = "Delete a drawing element by its ID.")]
     async fn delete_drawing_element(
         &self,
@@ -517,7 +566,7 @@ impl AgCanvasServer {
                     let msg = parsed
                         .get("message")
                         .and_then(serde_json::Value::as_str)
-                        .unwrap_or("Unknown error from agcanvas");
+                        .unwrap_or("Unknown error from Augmented Canvas");
                     return Ok(CallToolResult::error(vec![Content::text(msg)]));
                 }
 
@@ -526,7 +575,7 @@ impl AgCanvasServer {
                 Ok(CallToolResult::success(vec![Content::text(pretty)]))
             }
             Err(e) => Ok(CallToolResult::error(vec![Content::text(format!(
-                "Failed to communicate with agcanvas: {}. Make sure agcanvas is running.",
+                "Failed to communicate with Augmented Canvas: {}. Make sure Augmented Canvas is running.",
                 e
             ))])),
         }
@@ -538,10 +587,10 @@ impl ServerHandler for AgCanvasServer {
     fn get_info(&self) -> ServerInfo {
         ServerInfo {
             instructions: Some(
-                "agcanvas MCP server — connects to agcanvas desktop app to query SVG designs, \
+                "Augmented Canvas MCP server — connects to the Augmented Canvas desktop app to query SVG designs, \
                  element trees, and user-drawn shapes. Use describe_canvas to understand the \
                  current design, get_element_tree for structured data, and generate_code for \
-                 code stubs. Requires agcanvas to be running."
+                 code stubs. Requires Augmented Canvas to be running."
                     .into(),
             ),
             capabilities: ServerCapabilities::builder().enable_tools().build(),