feat: Add desktop screenshot export with Ctrl/Cmd+P shortcut

Cargo.toml

@@ -15,6 +15,9 @@ bevy-inspector-egui = "0.29.0"
 bevy_picking = { version = "0.15", features = ["bevy_mesh_picking_backend"] }
 bevy_prototype_lyon = "0.13.0"
 console_error_panic_hook = "0.1.7"
+
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+chrono = "0.4"
 enum-iterator = "2.1.0"
 gloo-file = "0.3"
 js-sys = "0.3"

src/bevy_app/mod.rs

@@ -193,6 +193,13 @@ pub fn init_bevy_app(
             .in_set(AllSet),
     );
 
+    // Screenshot system - Ctrl/Cmd+P (desktop only, doesn't conflict with existing shortcuts)
+    #[cfg(not(target_arch = "wasm32"))]
+    app.add_systems(
+        Update,
+        take_screenshot.run_if(input_pressed(MODIFIER).and(input_just_pressed(KeyCode::KeyP))),
+    );
+
     app.add_systems(
         Update,
         (

src/bevy_app/systems/mod.rs

@@ -111,6 +111,8 @@
 
 mod camera;
 mod removal;
+#[cfg(not(target_arch = "wasm32"))]
+mod screenshot;
 mod setup;
 mod spatial_sync;
 mod subsystem;
@@ -120,6 +122,8 @@ mod ui;
 use bevy::ecs::system::{RunSystemOnce, SystemState};
 pub use camera::*;
 pub use removal::*;
+#[cfg(not(target_arch = "wasm32"))]
+pub use screenshot::*;
 pub use setup::*;
 pub use spatial_sync::*;
 pub use subsystem::*;

src/bevy_app/systems/screenshot.rs

@@ -0,0 +1,99 @@
+//! Screenshot capture and export functionality for BERT diagrams.
+//!
+//! This module provides systems for capturing screenshots of the BERT canvas
+//! and saving them to disk with timestamped filenames. Screenshots are only
+//! available on desktop builds (non-wasm).
+//!
+//! ## Key Features
+//!
+//! - **Desktop Only**: Gated behind `#[cfg(not(target_arch = "wasm32"))]`
+//! - **Timestamped Files**: Automatic filename generation with date/time
+//! - **Observer Pattern**: Uses Bevy 0.15's observer-based screenshot API
+//! - **Event Integration**: Uses `SaveSuccessEvent` for user feedback
+//!
+//! ## Architecture
+//!
+//! The screenshot process uses Bevy 0.15's observer pattern:
+//!
+//! 1. **Request Phase**: User triggers screenshot via keyboard shortcut
+//! 2. **Capture Phase**: Bevy captures screenshot and triggers observer
+//! 3. **Save Phase**: Observer saves image to disk with timestamp
+//!
+//! This ensures the frame is fully rendered before capture, avoiding the
+//! blank screenshot issue from previous implementations.
+
+#[cfg(not(target_arch = "wasm32"))]
+use bevy::{
+    prelude::*,
+    render::view::screenshot::{save_to_disk, Screenshot, ScreenshotCaptured},
+};
+
+#[cfg(not(target_arch = "wasm32"))]
+use crate::events::SaveSuccessEvent;
+
+/// Component to track the screenshot filename on the screenshot entity
+#[cfg(not(target_arch = "wasm32"))]
+#[derive(Component)]
+struct ScreenshotPath(String);
+
+/// System that initiates screenshot capture when triggered.
+///
+/// This system spawns a Screenshot component targeting the primary window
+/// with an observer that saves the screenshot to disk when ready.
+///
+/// # Process
+///
+/// 1. Generate timestamped filename
+/// 2. Spawn Screenshot entity with observer and path component
+/// 3. Observer saves screenshot when capture completes
+/// 4. Send success event for toast notification
+///
+/// # Note
+///
+/// This system uses Bevy 0.15's observer pattern which automatically handles
+/// the screenshot lifecycle, including entity cleanup after capture.
+#[cfg(not(target_arch = "wasm32"))]
+pub fn take_screenshot(mut commands: Commands) {
+    let timestamp = chrono::Local::now().format("%Y-%m-%d_%H-%M-%S");
+    let path = format!("bert_screenshot_{}.png", timestamp);
+
+    info!("Initiating screenshot capture: {}", path);
+
+    // Spawn screenshot entity with save observer and path component
+    commands
+        .spawn((Screenshot::primary_window(), ScreenshotPath(path.clone())))
+        .observe(save_to_disk(path.clone()))
+        .observe(screenshot_saved_handler);
+
+    info!("Screenshot scheduled for: {}", path);
+}
+
+/// Observer function that handles screenshot completion and sends success events.
+///
+/// This observer is triggered after the screenshot is captured and saved to disk.
+/// It sends a `SaveSuccessEvent` to notify the user via toast notification.
+///
+/// # Parameters
+///
+/// - `trigger`: Contains the captured screenshot event with image data
+/// - `path_query`: Query to get the screenshot path from the entity
+/// - `save_events`: Event writer for sending success notifications
+#[cfg(not(target_arch = "wasm32"))]
+fn screenshot_saved_handler(
+    trigger: Trigger<ScreenshotCaptured>,
+    path_query: Query<&ScreenshotPath>,
+    mut save_events: EventWriter<SaveSuccessEvent>,
+) {
+    let entity = trigger.entity();
+    if let Ok(screenshot_path) = path_query.get(entity) {
+        let path = &screenshot_path.0;
+        info!("Screenshot saved successfully: {}", path);
+
+        save_events.send(SaveSuccessEvent {
+            file_path: Some(path.clone()),
+            message: format!("Screenshot saved: {}", path),
+        });
+    }
+}
+
+