Gemini TTS API → save WAV and play it in Tasker

[Le- Ze]

Hi, I'm trying to use Google Gemini TTS API in Tasker. The HTTP Request works fine and I get a JSON response back. The response contains base64 encoded PCM audio data. I need to:

1. Extract the base64 from candidates[0].content.parts[0].inlineData.data
2. Convert PCM to WAV (add header)
3. Save as WAV file
4. Play it

I'm using JavaScriptlet with writeFile() to save the file but it's not being created. Has anyone done this successfully? Is writeFile() the right function or is there a better way to save binary files in Tasker?
https://pastebin.com/hau0QrVE