### 3. The Array Serializer (`runtime.js`)

Finally, update the `saveState()` method in `runtime.js` to serialize arrays
properly so the game persists inventories across reboots.

```javascript
    // In runtime.js -> saveState()
    saveState() {
        const mem = this.vm.memory;
        const newStateVars = Object.keys(mem).map(key => {
            const val = mem[key];
            const type = Array.isArray(val) ? 'ARR' : typeof val === 'number'
? 'NUM' : typeof val === 'boolean' ? 'BOOL' : 'STR';
            
            // Serialize arrays securely using single quotes to bypass the
space-delimiter
            const strVal = type === 'ARR' ? `'${JSON.stringify(val)}'` :
`"${val}"`;
            return `VAR ${key} ${type} ${strVal}`;
        }).join('
');

        const originalFile = fs.readFileSync(this.filePath, 'utf-8');
        const updatedFile = originalFile.replace(
            /```fso-state
[\s\S]*?
```/, 
            `\`\`\`fso-state
${newStateVars}
\`\`\``
        );

        if (this.maxBackups > 0) this.rotateBackups();
        fs.writeFileSync(this.filePath, updatedFile);
    }

```

### The New Capability

With these patches, if Gemma writes:

```fso-code
LBL handle_dig
PULL "RUSTY_KEY"

```

Our engine automatically calculates that the key came from `room_beach` and
went into `INVENTORY`. It dynamically creates the arrays, manipulates the
memory, and saves it to the markdown file cleanly.

Are you ready to test compiling a game that explicitly asks the user to find a
key to open a locked door using the new `PULL` and `HAS` commands?