fix: [Mnemosyne] Memory persistence export — dump spatial state to JSON

Closes #1188

Automated squash merge by mimo swarm.

nexus/components/spatial-memory.js

@@ -652,11 +652,93 @@ const SpatialMemory = (() => {
     return _selectedId;
   }
 
+  // ─── FILE EXPORT ──────────────────────────────────────
+  function exportToFile() {
+    const index = exportIndex();
+    const json = JSON.stringify(index, null, 2);
+    const date = new Date().toISOString().slice(0, 10);
+    const filename = 'mnemosyne-export-' + date + '.json';
+
+    const blob = new Blob([json], { type: 'application/json' });
+    const url = URL.createObjectURL(blob);
+    const a = document.createElement('a');
+    a.href = url;
+    a.download = filename;
+    document.body.appendChild(a);
+    a.click();
+    document.body.removeChild(a);
+    URL.revokeObjectURL(url);
+
+    console.info('[Mnemosyne] Exported', index.memories.length, 'memories to', filename);
+    return { filename, count: index.memories.length };
+  }
+
+  // ─── FILE IMPORT ──────────────────────────────────────
+  function importFromFile(file) {
+    return new Promise((resolve, reject) => {
+      if (!file) {
+        reject(new Error('No file provided'));
+        return;
+      }
+
+      const reader = new FileReader();
+      reader.onload = function(e) {
+        try {
+          const data = JSON.parse(e.target.result);
+
+          // Schema validation
+          if (!data || typeof data !== 'object') {
+            reject(new Error('Invalid JSON: not an object'));
+            return;
+          }
+          if (typeof data.version !== 'number') {
+            reject(new Error('Invalid schema: missing version field'));
+            return;
+          }
+          if (data.version !== STORAGE_VERSION) {
+            reject(new Error('Version mismatch: got ' + data.version + ', expected ' + STORAGE_VERSION));
+            return;
+          }
+          if (!Array.isArray(data.memories)) {
+            reject(new Error('Invalid schema: memories is not an array'));
+            return;
+          }
+
+          // Validate each memory entry
+          for (let i = 0; i < data.memories.length; i++) {
+            const mem = data.memories[i];
+            if (!mem.id || typeof mem.id !== 'string') {
+              reject(new Error('Invalid memory at index ' + i + ': missing or invalid id'));
+              return;
+            }
+            if (!mem.category || typeof mem.category !== 'string') {
+              reject(new Error('Invalid memory "' + mem.id + '": missing category'));
+              return;
+            }
+          }
+
+          const count = importIndex(data);
+          saveToStorage();
+          console.info('[Mnemosyne] Imported', count, 'memories from file');
+          resolve({ count, total: data.memories.length });
+        } catch (parseErr) {
+          reject(new Error('Failed to parse JSON: ' + parseErr.message));
+        }
+      };
+
+      reader.onerror = function() {
+        reject(new Error('Failed to read file'));
+      };
+
+      reader.readAsText(file);
+    });
+  }
+
   return {
     init, placeMemory, removeMemory, update,
     getMemoryAtPosition, getRegionAtPosition, getMemoriesInRegion, getAllMemories,
     getCrystalMeshes, getMemoryFromMesh, highlightMemory, clearHighlight, getSelectedId,
-    exportIndex, importIndex, searchNearby, REGIONS,
+    exportIndex, importIndex, exportToFile, importFromFile, searchNearby, REGIONS,
     saveToStorage, loadFromStorage, clearStorage,
     runGravityLayout
   };