feat(scenes): add scene darkness reveal and fix project reopen crash

Add darkenScene with Opening brush in presentation, persist reveal strokes per scene during a session, and close projects properly on return to home. Harden dnd asset streaming to avoid Windows main-process crashes when reopening projects.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/renderer/control/ControlApp.tsx

@@ -7,7 +7,9 @@ import type { GraphNodeId, Scene, SceneId } from '../../shared/types';
 import { useEditorI18n } from '../editor/i18n/EditorI18nContext';
 import { getDndApi } from '../shared/dndApi';
 import { PixiEffectsOverlay } from '../shared/effects/PxiEffectsOverlay';
+import { SceneDarknessOverlay } from '../shared/effects/SceneDarknessOverlay';
 import { useEffectsState } from '../shared/effects/useEffectsState';
+import { useSceneDarknessState } from '../shared/effects/useSceneDarknessState';
 import { Button } from '../shared/ui/controls';
 import { Surface } from '../shared/ui/Surface';
 
@@ -49,6 +51,7 @@ export function ControlApp() {
   const tRef = useRef(t);
   tRef.current = t;
   const [fxState, fx] = useEffectsState();
+  const [sdState, sd] = useSceneDarknessState();
   const [session, setSession] = useState<SessionState | null>(null);
   const historyRef = useRef<GraphNodeId[]>([]);
   const [history, setHistory] = useState<GraphNodeId[]>([]);
@@ -69,7 +72,18 @@ export function ControlApp() {
   const previewHostRef = useRef<HTMLDivElement | null>(null);
   const previewVideoRef = useRef<HTMLVideoElement | null>(null);
   const brushRef = useRef<{
-    tool: 'fog' | 'fire' | 'rain' | 'water' | 'darkness' | 'lightning' | 'sunbeam' | 'poisonCloud' | 'freeze' | 'eraser';
+    tool:
+      | 'fog'
+      | 'fire'
+      | 'rain'
+      | 'water'
+      | 'darkness'
+      | 'lightning'
+      | 'sunbeam'
+      | 'poisonCloud'
+      | 'freeze'
+      | 'exploreBrush'
+      | 'eraser';
     startN?: { x: number; y: number };
     points?: { x: number; y: number; tMs: number }[];
   } | null>(null);
@@ -145,6 +159,7 @@ export function ControlApp() {
   const currentScene =
     project && session?.currentSceneId ? project.scenes[session.currentSceneId] : undefined;
   const isVideoPreviewScene = currentScene?.previewAssetType === 'video';
+  const isDarkenScene = Boolean(currentScene?.darkenScene) && !isVideoPreviewScene;
   const sceneAudioRefs = useMemo(() => currentScene?.media.audios ?? [], [currentScene]);
   // Keep this memo as narrow as possible: project changes on scene switch,
   // but campaign audio list/config often does not.
@@ -609,6 +624,13 @@ export function ControlApp() {
     draftPaintRafRef.current = requestAnimationFrame(() => {
       draftPaintRafRef.current = 0;
       setDraftFxTick((x) => x + 1);
+      const b = brushRef.current;
+      if (b?.tool === 'exploreBrush' && b.points) {
+        void sd.dispatch({
+          kind: 'draft.set',
+          draft: { points: b.points, radiusN: toolRef.current.radiusN },
+        });
+      }
     });
   }
 
@@ -711,6 +733,18 @@ export function ControlApp() {
         },
       });
     }
+    if (b.tool === 'exploreBrush' && b.points && b.points.length > 0) {
+      await sd.dispatch({
+        kind: 'stroke.add',
+        stroke: {
+          id: `sd_${String(createdAtMs)}_${String(seed)}`,
+          seed,
+          createdAtMs,
+          points: b.points,
+          radiusN: tool.radiusN,
+        },
+      });
+    }
     if (b.tool === 'darkness' && b.points && b.points.length > 0) {
       const last = b.points[b.points.length - 1];
       if (last === undefined) return;
@@ -1137,6 +1171,24 @@ export function ControlApp() {
                   </Button>
                 </div>
               </div>
+              {isDarkenScene ? (
+                <div className={styles.effectsGroup}>
+                  <div className={styles.subsectionLabel}>{t('control.darknessControl')}</div>
+                  <div className={styles.iconRow}>
+                    <Button
+                      variant={tool.tool === 'exploreBrush' ? 'primary' : 'ghost'}
+                      iconOnly
+                      title={t('control.explorerBrush')}
+                      ariaLabel={t('control.explorerBrush')}
+                      onClick={() =>
+                        void fx.dispatch({ kind: 'tool.set', tool: { ...tool, tool: 'exploreBrush' } })
+                      }
+                    >
+                      <span className={styles.iconGlyph}>🔦</span>
+                    </Button>
+                  </div>
+                </div>
+              ) : null}
               <div className={styles.radiusRow}>
                 <div className={styles.radiusLabel}>{t('control.brushRadius')}</div>
                 <input
@@ -1235,6 +1287,13 @@ export function ControlApp() {
                       : undefined
                   }
                 />
+                {previewContentRect ? (
+                  <SceneDarknessOverlay
+                    state={sdState}
+                    overlayAlpha={0.5}
+                    viewport={previewContentRect}
+                  />
+                ) : null}
                 <div
                   ref={brushCursorElRef}
                   className={styles.brushCursor}
@@ -1269,6 +1328,15 @@ export function ControlApp() {
                       startN: p,
                       points: [{ x: p.x, y: p.y, tMs: Date.now() }],
                     };
+                    if (tool.tool === 'exploreBrush') {
+                      void sd.dispatch({
+                        kind: 'draft.set',
+                        draft: {
+                          points: [{ x: p.x, y: p.y, tMs: Date.now() }],
+                          radiusN: tool.radiusN,
+                        },
+                      });
+                    }
                     setDraftFxTick((x) => x + 1);
                   }}
                   onPointerMove={(e) => {
@@ -1296,6 +1364,9 @@ export function ControlApp() {
                     void commitStroke();
                   }}
                   onPointerCancel={() => {
+                    if (brushRef.current?.tool === 'exploreBrush') {
+                      void sd.dispatch({ kind: 'draft.set', draft: null });
+                    }
                     brushRef.current = null;
                     setDraftFxTick((x) => x + 1);
                   }}