feat: save games and edit scene darkness

Persist show state to local saves; author map darkness in scene editor with bake-to-scene and help updates.

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

app/main/gameSave/gameSavesStore.ts

@@ -0,0 +1,84 @@
+import crypto from 'node:crypto';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+
+import { defaultGameSaveName } from '../../shared/gameSave/buildSnapshot';
+import { GAME_SAVE_SCHEMA_VERSION, type GameSaveBody, type GameSaveFile, type GameSaveListItem } from '../../shared/types/gameSave';
+
+function safeSegment(raw: string): string {
+  const cleaned = raw.replace(/[^a-zA-Z0-9_-]/g, '');
+  if (!cleaned || cleaned === '.' || cleaned === '..') throw new Error('GAME_SAVE_BAD_ID');
+  return cleaned;
+}
+
+export class GameSavesStore {
+  private readonly rootDir: string;
+
+  constructor(userData: string) {
+    this.rootDir = path.join(userData, 'game-saves');
+  }
+
+  async list(projectId: string): Promise<GameSaveListItem[]> {
+    const dir = this.projectDir(projectId);
+    let names: string[] = [];
+    try {
+      names = await fs.readdir(dir);
+    } catch {
+      return [];
+    }
+    const items: GameSaveListItem[] = [];
+    for (const name of names) {
+      if (!name.endsWith('.json')) continue;
+      try {
+        const file = await this.readFile(path.join(dir, name));
+        if (file.projectId !== projectId) continue;
+        items.push({ id: file.id, name: file.name, savedAt: file.savedAt });
+      } catch {
+        continue;
+      }
+    }
+    items.sort((a, b) => (a.savedAt < b.savedAt ? 1 : a.savedAt > b.savedAt ? -1 : 0));
+    return items;
+  }
+
+  async read(projectId: string, id: string): Promise<GameSaveFile> {
+    const filePath = this.filePath(projectId, id);
+    try {
+      const file = await this.readFile(filePath);
+      if (file.projectId !== projectId || file.id !== id) throw new Error('GAME_SAVE_NOT_FOUND');
+      return file;
+    } catch (err) {
+      if (err instanceof Error && err.message.startsWith('GAME_SAVE_')) throw err;
+      throw new Error('GAME_SAVE_NOT_FOUND');
+    }
+  }
+
+  async write(projectId: string, body: GameSaveBody, opts: { id: string | null; name: string }): Promise<GameSaveListItem> {
+    if (body.projectId !== projectId) throw new Error('GAME_SAVE_PROJECT_MISMATCH');
+    const id = opts.id ? safeSegment(opts.id) : `gs_${crypto.randomBytes(8).toString('hex')}`;
+    const name = opts.name.trim() || defaultGameSaveName();
+    const savedAt = new Date().toISOString();
+    const file: GameSaveFile = { ...body, id, name, savedAt, schemaVersion: GAME_SAVE_SCHEMA_VERSION };
+    const filePath = this.filePath(projectId, id);
+    await fs.mkdir(path.dirname(filePath), { recursive: true });
+    await fs.writeFile(filePath, JSON.stringify(file), 'utf8');
+    return { id, name, savedAt };
+  }
+
+  private projectDir(projectId: string): string {
+    return path.join(this.rootDir, safeSegment(projectId));
+  }
+
+  private filePath(projectId: string, id: string): string {
+    return path.join(this.projectDir(projectId), `${safeSegment(id)}.json`);
+  }
+
+  private async readFile(filePath: string): Promise<GameSaveFile> {
+    const raw = await fs.readFile(filePath, 'utf8');
+    const parsed = JSON.parse(raw) as GameSaveFile;
+    if (!parsed || parsed.schemaVersion !== GAME_SAVE_SCHEMA_VERSION || typeof parsed.id !== 'string') {
+      throw new Error('GAME_SAVE_NOT_FOUND');
+    }
+    return parsed;
+  }
+}