Initial TTRPG character meta-builder with visual sheet editor.

Offline Electron app seeds 10 system presets, supports create-from-scratch designer with palette/drag/resize/bricks, and exports .ttrpg-system.json for the player.

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

app/shared/snapshot.ts

@@ -0,0 +1,34 @@
+import { createHash } from 'node:crypto';
+
+import type { SystemDefinition } from './types.ts';
+
+/** Canonical JSON for stable hashing (sorted keys). */
+export function canonicalJson(value: unknown): string {
+  return JSON.stringify(sortKeys(value));
+}
+
+function sortKeys(value: unknown): unknown {
+  if (Array.isArray(value)) return value.map(sortKeys);
+  if (value && typeof value === 'object') {
+    const obj = value as Record<string, unknown>;
+    const out: Record<string, unknown> = {};
+    for (const key of Object.keys(obj).sort()) {
+      out[key] = sortKeys(obj[key]);
+    }
+    return out;
+  }
+  return value;
+}
+
+export function snapshotHash(system: SystemDefinition): string {
+  const payload = {
+    id: system.id,
+    schemaVersion: system.schemaVersion,
+    revision: system.revision,
+    bricks: system.bricks,
+    creationRules: system.creationRules,
+    sheetLayout: system.sheetLayout,
+    compendium: system.compendium,
+  };
+  return createHash('sha256').update(canonicalJson(payload)).digest('hex');
+}