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/shared/ipc/contracts.ts

@@ -8,6 +8,8 @@ import type {
   Project,
   ProjectId,
   Scene,
+  SceneDarknessEvent,
+  SceneDarknessState,
   SceneId,
   VideoPlaybackEvent,
   VideoPlaybackState,
@@ -27,6 +29,7 @@ export const ipcChannels = {
     list: 'project.list',
     create: 'project.create',
     open: 'project.open',
+    close: 'project.close',
     saveNow: 'project.saveNow',
     get: 'project.get',
     updateScene: 'project.updateScene',
@@ -68,6 +71,11 @@ export const ipcChannels = {
     dispatch: 'effects.dispatch',
     stateChanged: 'effects.stateChanged',
   },
+  sceneDarkness: {
+    getState: 'sceneDarkness.getState',
+    dispatch: 'sceneDarkness.dispatch',
+    stateChanged: 'sceneDarkness.stateChanged',
+  },
   video: {
     getState: 'video.getState',
     dispatch: 'video.dispatch',
@@ -117,6 +125,7 @@ export type UpdaterProgressEvent = {
 export type IpcEventMap = {
   [ipcChannels.session.stateChanged]: { state: SessionState };
   [ipcChannels.effects.stateChanged]: { state: EffectsState };
+  [ipcChannels.sceneDarkness.stateChanged]: { state: SceneDarknessState };
   [ipcChannels.video.stateChanged]: { state: VideoPlaybackState };
   [ipcChannels.license.statusChanged]: { snapshot: LicenseSnapshot };
   [ipcChannels.windows.multiWindowStateChanged]: { open: boolean };
@@ -154,6 +163,10 @@ export type IpcInvokeMap = {
     req: { projectId: ProjectId };
     res: { project: Project };
   };
+  [ipcChannels.project.close]: {
+    req: Record<string, never>;
+    res: { ok: true };
+  };
   [ipcChannels.project.get]: {
     req: Record<string, never>;
     res: { project: Project | null };
@@ -270,6 +283,14 @@ export type IpcInvokeMap = {
     req: { event: EffectsEvent };
     res: { ok: true };
   };
+  [ipcChannels.sceneDarkness.getState]: {
+    req: Record<string, never>;
+    res: { state: SceneDarknessState };
+  };
+  [ipcChannels.sceneDarkness.dispatch]: {
+    req: { event: SceneDarknessEvent };
+    res: { ok: true };
+  };
   [ipcChannels.video.getState]: {
     req: Record<string, never>;
     res: { state: VideoPlaybackState };
@@ -304,6 +325,7 @@ export type SessionState = {
 export type LegacyIpcEventMap = {
   [ipcChannels.session.stateChanged]: { state: SessionState };
   [ipcChannels.effects.stateChanged]: { state: EffectsState };
+  [ipcChannels.sceneDarkness.stateChanged]: { state: SceneDarknessState };
   [ipcChannels.video.stateChanged]: { state: VideoPlaybackState };
   [ipcChannels.license.statusChanged]: Record<string, never>;
 };
@@ -316,6 +338,7 @@ export type ScenePatch = {
   previewThumbAssetId?: AssetId | null;
   previewVideoAutostart?: boolean;
   previewRotationDeg?: 0 | 90 | 180 | 270;
+  darkenScene?: boolean;
   settings?: Partial<Scene['settings']>;
   media?: Partial<Scene['media']>;
   layout?: Partial<Scene['layout']>;