fix: installer copies default framework files (AGENTS.md) to mosaicHome (#363)

packages/mosaic/src/config/file-adapter.ts

@@ -1,4 +1,4 @@
-import { readFileSync, existsSync } from 'node:fs';
+import { readFileSync, existsSync, readdirSync, statSync, copyFileSync } from 'node:fs';
 import { join } from 'node:path';
 import type { ConfigService } from './config-service.js';
 import type { SoulConfig, UserConfig, ToolsConfig, InstallAction } from '../types.js';
@@ -140,6 +140,23 @@ export class FileConfigAdapter implements ConfigService {
       preserve: preservePaths,
       excludeGit: true,
     });
+
+    // Copy default root-level .md files (AGENTS.md, STANDARDS.md, etc.)
+    // from framework/defaults/ into mosaicHome root if they don't exist yet.
+    // These are framework contracts — only written on first install, never
+    // overwritten (user may have customized them).
+    const defaultsDir = join(this.sourceDir, 'defaults');
+    if (existsSync(defaultsDir)) {
+      for (const entry of readdirSync(defaultsDir)) {
+        const dest = join(this.mosaicHome, entry);
+        if (!existsSync(dest)) {
+          const src = join(defaultsDir, entry);
+          if (statSync(src).isFile()) {
+            copyFileSync(src, dest);
+          }
+        }
+      }
+    }
   }
 
   /**