Phytophagous worm identification
I think you have an Indian Lily Moth (of the genus Polytela). It is considered a minor pest. Their habitat seems to only be around India and its surrounding area.

Their worm matches yours ... smooth, dark, but red patches and white spots:

If you dig in your garden, you may encounter these pupae:

And they eventually grow into these beautifully-multicoloured moths:

Here is a video showing their movements and their life cycle:
https://www.youtube.com/watch?v=2l0oxZM_6XY